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[Articles Home]  [Add Article]  

Time for a New Portable Power Pack?

from Chris J. Smith, K1CJS on June 6, 2007
View comments about this article!

Time for a New Portable Power Pack?

By Chris J. Smith, K1CJS



The summer season is here again, and for those of us who get out of the shack and into the backyard or those wide open spaces, the thought of bringing that rig with you and making a few contacts may be on your mind. On the other hand, hurricane season is also here again on the east coast, and there are some who are thinking of updating those emergency go kits that some of us keep in readiness.

Those were a few of my thoughts when I started going through my equipment from last year, especially when I contemplated having to lug around a car battery so I could power my gear and other 12 volt goodies out where there is no power readily available. I figured on using a car battery because I had a spare, and for the past seven or eight years, I had run off a pair of garden tractor batteries. One of those batteries had gone too far to save and the other was not much better off--they were both old. However, the car battery I thought about using weighed more than those two batteries combined. There was also the fact of the dangers of wet cell batteries, tolerable in smaller, lighter batteries, but increasingly greater in larger, heavier ones. With all those considerations in mind, it was obviously time for a newer, safer power pack.

I had thought about getting one of those car starting power packs, but in my opinion there were too many strikes against them to make that a viable option. Modifying the pack to eliminate the extra connectors on it which were useless to me (my vehicle has an aftermarket dual battery system) and putting Anderson Power Poles on it, the length of time those packs may have been sitting on the shelf waiting to be bought (or in transit in those cargo containers from overseas), getting the right size battery replacement if the battery did go bad, and other considerations led me to believe a better alternative was to plan and build a new portable power pack, even though the initial cost may be more than an off the shelf unit.

I started with the consideration of the gel cells themselves. I figured that replacement batteries, although not an issue now, may be in the future. I chose a commonly found and readily available battery, the 12 volt 7 amp hour size that have been and still are common as replacements in burglar and smaller fire alarm panels. They're readily available at most electrical supply houses and electronics stores and cost $20 to $25 each. For extended operating time, I chose to build the pack with four of them wired in parallel.


The type battery selected for the project, Approximate size is 6 1/2" x 2 ½" x 3 ½". Each battery weighs approximately 8 lbs.

I then measured and figured what would be needed to construct the pack, and came up with a minimum size for the box that would house the unit--but what kind of box should I use? I wanted something that would be easily transportable and durable and would "cushion" the batteries inside. I was about to go shopping for a box when I remembered my habit of saving things I may use again--maybe something in the garage would do? After a little looking I had the perfect box--an old polyethylene tool box that was sturdy enough to do the job and just about the right size. The box itself is water resistant, but that was a moot point because of the construction of the power pole socket.


The old toolbox---with a new purpose.

Then I looked in the ol’ shack junkbox, and came up with a terminal strip, two blade type in-line fuse holders and the 4 needed 30 amp fuses (two spares). Each fuse protects two of the Anderson Power Pole pairs. A couple of years ago I had bought three power pole sockets like the one shown here to use in the shack and had only used two—now, as you see, the third one has found a home.


The Anderson Power Pole socket cut into one end of the toolbox top.

Add to the parts list a few lengths of ten and twelve gauge wire and a couple of pieces of wood to mount the terminal strip and to use as spacers. Total time spent modifying, assembling and wiring the unit came to about four hours. The result of all this, as you can see, is a custom built power pack, probably a little more expensive than an off the shelf unit, but with none of the unneeded bells and whistles. Charging is easily accomplished by connecting a battery charger to the powerpole connector.


The inside wiring. The fuse holders are at the top and bottom of the terminal strip. A later refinement will probably be circuit breakers, set into the lid on either side of the 4 power pole sockets, for easier access.

If everything needed for this mini-project were bought new, the cost would probably be in the $120 to $140 dollar range--my cost for the needed materials for the one I built was about $85—reduced by some junk box contributions and one ‘save it, it may be useful’ old tool box.

Of course, some of you have different requirements for your standby pack, you may need greater capacity or not as much. One nice part of this idea is you can modify it as you need to--make it larger or smaller, or convert/plan for extra space for a place to hold harnesses or other needed accessories. Other plusses are you can build it as you see fit and you don't have to go with something pre-made and possibly not suitable for your uses.

One cautionary note--if you build one of these power packs, make sure the toolbox you use is made of heavy gauge polyethylene—especially if you use a larger box to house more or larger batteries. The cheap $7 to $10 toolboxes readily available at discount stores (Wal-Mart and K-Mart) just will not stand up to the weight of the batteries—my finished pack weighs in at just under 40 lbs. Either the box will crack open spilling the batteries and tearing out the wiring or the handle will pull off the box itself and the whole thing will fall. Believe me, you don’t want your toes under those batteries if they do fall!

Comments and suggestions on improvements and or additions are welcome.

Member Comments:
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Time for a New Portable Power Pack?  
by KC8VWM on June 6, 2007 Mail this to a friend!

I'm sure it would make a nice addition for my FT-817ND.

I see you have added fuses and I really like the organized terminal strips for added safety and ease of later replacement.

I would probobly add a cheap 5 watt solar panel and a built in voltage meter for battery "status" information.

Now all I have to figure out is what I did with that old toolbox on wheels I used to have kicking around the garage exactly?

Great article. Nicely done. When do we start building one? :)

73 de Charles - KC8VWM
 
RE: Time for a New Portable Power Pack?  
by N3JWN on June 6, 2007 Mail this to a friend!
2 Years ago Costco had a portable Battery Pac/w air pump light volt meter/w& std 18" Battery cables with Large battery alligator Clamps 12 cord & 110 volt ac cord for charging. Ive opened it up theres an 80 ampeher /hr Gell Cell inside this unit... I've used it with the Icom 706 and ran the radio for 6 days without charging!! Intermittent operation on H.F and vhf !!!Charged the second one I bought and then switched out and charged the other unit I used off the car's 12 volt system uning the 12 volt cord that was included used it twice ti restart the Jeep in the middle of the winter so its very versital and runs the radio also at not a bad price $50.00 nothing to build Just used some alligator wire jumpers I already had!! try it you'll like it!! be safe have fun take care Dick / n3jwn
 
Time for a New Portable Power Pack?  
by KB9YUR on June 6, 2007 Mail this to a friend!
Nice setup. I've been using a Nomad 300 portable power pack and a 21 watt solar panel from www.solarsense.com for the last 6 years with my Yaesu FT-290RII. It not only provides 12 volts, but also 120v AC up to 300 watts.
 
Time for a New Portable Power Pack?  
by KB1GMX on June 6, 2007 Mail this to a friend!
Over4 years ago for field and home use I built a similar box. Instead of using gell cells I used a lawn tractor battery with spillproof caps. Whats interesting is I also used a similar looking box as its cheap but heavy plastic.

I chose the lawn tractor battery as they are generally available cheap, usually around $18-22 and are around 35AH.

The cover when open also exposes a connector pannel of
Anderson power poles, a voltmeter, charge current meter
for the solar pannel input. I use a 20W pannel to maintain/charge it with a MicroM+ charge controller.

There is enough space under the connector pannel for a small 1A smart charger to maintain the battery if there is no sun.

I use it in the field to run the VHF field day station
using a Tentec 6&2. the rest of the year the solar pannel gets mounted and it runs the QRP VHF station.


Allison
 
RE: Time for a New Portable Power Pack?  
by N8BOA on June 6, 2007 Mail this to a friend!
"One cautionary note" You may want to make sure you have some type of ventilation so you don't have gas build up inside Yes Gel-cels are "sealed". But ????
Thanks
Sean
 
RE: Time for a New Portable Power Pack?  
by W4LGH on June 6, 2007 Mail this to a friend!
I used a Sears Craftsman RED toolbox and built an entire station in/on it. Inside the box, the tool tray is just that, holds screwdrivers/plyers/dykes/cresent wrench/etc...some extra connectors, barrels and stuff. Under the tool tray, I have mounted 2 10amp sealed batteries, it holds a small MFJ tuner and 51' longwire antenna. I built this to use my FT-817 rig, but have since sold that and now use it with a FT-857-D. The box is wired with 2 cigar resepticles as well as anderson powerpoles. Pretty universal, has everything you need.
Photos can be seen on my website.

73 de W4LGH - ALan
http://www.w4lgh.com
 
Time for a New Portable Power Pack?  
by AA3YW on June 6, 2007 Mail this to a friend!
Warning! Emergency power is a good idea, but don't forget about electrical safety in the process! There doesn't appear to be a fuse or blocking diode on each battery in this design and never parallel batteries especially when charging. Batteries or cells should always be connected in series to get the desired voltage. Batteries and cells can short out and cause an over current condition if they're in parallel circuit and possibly cause a fire. To gain battery capacity use larger cells 2V or 6V in series to get the desired 12V. If you have to parallel batteries in an emergency us a blocking diode so batteries don't discharge their current into other batteries and please use fuses between each battery and or cells to prevent a fires.

73's
Dave AA3YW
 
RE: Time for a New Portable Power Pack?  
by KC0SHZ on June 6, 2007 Mail this to a friend!
This may be just a dumb question, but how do you charge these batteries?
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 6, 2007 Mail this to a friend!
AA3YW--

You bring up some points that are applicable to larger more powerful battery banks that supply and are charged at many, many times the amperage this pack is meant to be used at. But even light duty industrial applications utilizing battery banks seldom use either of these precautions. On the other hand, a series-parallel battery pack MUST have the safety measures you have mentioned.

These gel cells are designed to be used in unattended or fully automatic installations without blocking diodes or individual battery fuses. The diodes introduce voltage drop and necessitate rewiring to charge the batteries, something that is impractical in an unattended system.

The individual fuses can cause problems in a simple multiple battery configuration like this one, such as a fuse letting go which would drop one battery out of the pack (electrically) without any indication--putting more drain on the remaining batteries, possibly over the level they are designed to function at. This causes decreased standby time and may also cause heating and the possibility of catastrophic failure of the battery pack.

I applaud your thinking of safety and protection, but it is overkill in this instance. The precautions you outline are meant for another type backup system entirely.
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 6, 2007 Mail this to a friend!
"This may be just a dumb question, but how do you charge these batteries?"

I did mention it in the article, but just briefly. Charging is accomplished by just plugging a charger into the anderson power pole connector on the pack itself.

I use an automatic charger which is marketed for float charging motorcycle/lawn tractor batteries over the off season. It was adapted for use with the old pack (the two garden tractor batteries) and is well suited to this one as well. I use it for a day or so every month to keep the batteries topped off.
 
RE: Time for a New Portable Power Pack?  
by KB8ASO on June 6, 2007 Mail this to a friend!
Doesn't that battery in the article say MADE IN CHINA? ;'>

"(or in transit in those cargo containers from overseas)"
 
RE: Time for a New Portable Power Pack?  
by KX8N on June 6, 2007 Mail this to a friend!
"Doesn't that battery in the article say MADE IN CHINA? ;'> "

Must have been bought at Wal-Mart.
 
RE: Time for a New Portable Power Pack?  
by AD4U on June 6, 2007 Mail this to a friend!
Thanks for a thought provoking article. Another option is buying one of the gel-cell jump start things avaliable at most any auto supply house or even Walmart. I bought one with a 17 AHr gel-cell battery with AC and DC charger for $39.95. They also had one just like it with a 200 watt 120 VAC inverter attached for $59.95. It even has a "real" volt meter. All that is needed is a little "surgery" to remove the battery jump clips and add an Anderson connector (or what ever type of connector you need) to the #2 leads. The one I bought has a cigarette lighter type 12V connector already installed for HT type uses. One caution - the output leads are not fused.
 
RE: Time for a New Portable Power Pack?  
by N0OKS on June 6, 2007 Mail this to a friend!
I am surprised at everyone’s enthusiasm for antiquated technology gel cell batteries. NiMH or Li ion batteries have a higher power density so they weigh less per ampere hour of capacity. The down side is that you need to be careful when you charge NiMH or Li ion batteries. Hooking them up to a convention battery charger is an invitation to disaster.

You would need to put the AA NiMH batteries in holders in the portable power source and then remove them, one at a time, and charge them in a specially designed charger. Tedious to do. But there are other benefits than merely reducing the weight and size of your portable power source.

The first benefit of using NiMH batteries is 11 or 12 of them in series to give 13.2 or 14.4 volts. Gel cells start out a 12.8, or so, volts when freshly charged. The voltage decreases continually until the battery is discharged. It is important to consider the less than optimal voltage that is being supplied to the radio. Radio spec sheets do not list, normally, the radio’s performance at voltages lower than the rated voltage, say 13.8 volts.

12 NiMH batteries will yield 14.4 volts, 1.2 volts per battery, until they are discharged. 14.4 volts is not too high for almost any radio. You will get the rated performance of your radio all the way to discharge.

Another advantage of NiMH batteries is longevity. I have read that 500 charge / discharge cycles is the norm for NiMH batteries. How many years of operating portable at a more appropriate voltage does that amount to? I use a lot of AA NiMH batteries for my wedding photography. Yup, I need to take them out of the battery holders and place them one by one in my charger. Tedious. But I have batteries that are several years old that still hold a full charge.

The portable power supply that K1CJS describes uses four, 7 AH, batteries that cost $20 to $25 each. The total weight is 40 pounds.

AA NiMH batteries weigh about one ounce each. They are currently available with a capacity of 2,500 mAH and cost no more than $1.25 each. Fourteen of them, with battery holders, would weigh about a pound and have about one third the AH capacity of the batteries K1CJS uses. So you need 42, 2,500 mAH, AA NiMH batteries, with holders. The cost would be $52.50, just more than double the cost of the Gel Cell batteries and the weigh would be three pounds. A NiMH power supply comparable to the four battery K1CJS power supply would cost $210 for the batteries but weigh just twelve pounds plus a couple of pounds for the box and all.

NiMH based portable power supplies cost a whole lot more for the batteries; are tedious to recharge; but will result in a package that is about a third as heavy and will be much smaller; will provide a more appropriate voltage for your radios and last many more charge / discharge cycles.

Mark, NØOKS
 
RE: Time for a New Portable Power Pack?  
by KI6EAA on June 6, 2007 Mail this to a friend!
Great article. I built a similar box for qrp and to run my HT for extended periods. It isn't as heavy duty as your settup, but works for my application. If you have access to the ARRL Emergency Power book, there are several articles about safety and voltage over/under protection which are worth reading.

Couple of thoughts..
Box- I only needed two 7ah-12v batteries. So I found a suitable box at the Container Store. It was about $10. Drilling/punching the case was easy.

In/Out- I also used PowerPoles for in and out, in addition to a cigarette lighter socket for light duty work, such as charging a FR handheld and a cellphone.

Charger- I built a couple of different ones, utilizing the TI and the Maxim charger chips, and a circuit from the Radio Handbook (solar charger). Ended up packing a low cost dual stage charger from All Electronics. Much cheaper than all the parts I bought, and it works fine. Another option is a small (350-500) Personal Computer UPS, seeming always on sale at computer stores. I paid $29 with a $15 rebate for mine. For about $15 I got a small 12ah battery, a battery charger, and a 110v inverter. Not a bad deal.

Other- I found a small toolkit (pliers, screwdriver w/bits) of decent quality for $5 and a DVM for $10 at the local hardward store bargain bin. No need to take along your good tools. All Electronics also has in-line fuse assemblies and connectors for their batteries (Molex). I got a small pile of PowerPoles at the local HRO when I bought a cable for HT to external antenna. I tossed in a 2m jpole (made from 450 ohm line) and a simple 20m diople. When northern California shakes again, I will be ready.... at least the radio communications part!

If you are starting to build a portable box from scratch, consider visiting www.allelectronics.com . I found batteries, a $12 wall wart charger, cigarette light socket, solar cell assemblies, and wire for resonable prices. If you need bigger batteries, as the author does, consider visiting a local alarm installation company. They usually have decent used batteries and would love not to have to pay toxic waste fees to get rid of them.
 
Time for a New Portable Power Pack?  
by WA8MEA on June 6, 2007 Mail this to a friend!
Excuse me, but somebody said "lawn mower batteries" in one of the posts, and I flash-backed to this non-ham experiment:

Several Christmas's ago we got three of our sons these electric scooters that were very popular. They had good speed, but only ran for a brief time before a total recharge was needed. (And usually overnight.)

When the gel cell inside finally went to that big recycling center in the sky, I went to price a new one:

$40!!!!

Then it hit me. A little lawn mower battery! I saw I had enough room at the front of the scooter to bungee cord it in place. They were half the price. So I went for it!

I wired it up. Now the kids can ride ALL DAY thanks to this garden tractor battery! And the speed is a little faster because we've gone from 11 to 12 volts to approx. 13 to 14 volts.

73, Bill - WA8MEA
http://HamRadioFun.com
 
Time for a New Portable Power Pack?  
by ALLENCB on June 6, 2007 Mail this to a friend!
Nice project, one that I considered doing until I found one of those battery booster packs at Wal-Mart. I can't recall the exact specs offhand, but it put out a few hundred amps, had two cigarette lighter plugs, a set of jumper cables, and a built in lamp. It can take a day and a half to charge from full discharge, but it has a gauge that tells you how much charge is left and a chart that tells you how long to charge it for a given level of discharge. It has a built-in carrying handle as well. Total weight was about 25lbs.

With two 12v outlets, I could run an inverter on one and use the other for 12dv apps. It lacks the radio specific connections, but it'll get as much use for camping and emergencies, so I can overlook that.

$70.

Chris
KI4POT
 
Time for a New Portable Power Pack?  
by KE5OFO on June 6, 2007 Mail this to a friend!
Thats a pretty nice setup. I have been thinking about building somthing like that to provide 12v for my FT-470. I am going to bulid mine with one 7ah batery running to a cig lighter plug. I will charge it with a bag phone cell phone charger. It will be cased in a nice black vinal hard case from a '70 vintage super 8 movie camera and a nice wide camera strap. My father has a setup like this to power his camcorder for extended periods. I think it cost him around $75.00 back in the '80s. I will be able to put it together for less than $25 as all I will need to get is a new batery.
 
RE: Time for a New Portable Power Pack?  
by WA1RNE on June 6, 2007 Mail this to a friend!

Folks, the Ultratech battery is not a gell cell battery - much better actually.

This is a VRLA or Valve Regulated Lead Acid battery which is AGM based and includes a one way valve to prevent bursting if overcharged.

There are also substitutes available from various sources that offer slight upgrades in performance, such as the Universal Power UB1280, 12 volt 8 Ah capacity.


....WA1RNE
 
RE: Time for a New Portable Power Pack?  
by KD6NEM on June 6, 2007 Mail this to a friend!
Very true that AGM is much better than Gel Cells for most applications. IF you are patient enough to current limit your charging of a true Gel-Cell you can get by with greater depth of discharge than with AGM's. Too fast even for a couple minutes say good bye to your gel cell, though! AGM's are significantly more rugged and can be recharged MUCH faster, leaving them as a better choice for most folks. I sure wish we supposedly tech savvy people would quit using such generic names lumping different battery technologies together. AGM's & Gel Cells might look alike & both are spill proof, but they really are quite different in their manners otherwise.

And by the way, a pair of new matched batteries can be run in parallel without many worries at all, just don't ever mix different sizes, ages, or brands. They MUST be matched.

Stu Bryant KD6NEM
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 6, 2007 Mail this to a friend!
Thanks for the correction--however, if you ask for an AGM battery at some of the electrical supply houses you'll get a strange look and a "What?" from the counterman. Ask for a gel cell, however, and you'll get what you see here. I sometimes wonder if semantics gets in the way--more often than not--even if the terminology used isn't exact!

I did alarm installations for quite a few years (a couple of careers ago!) and I do know that modern batteries are much better, more rugged and less expensive than what they used to be.

I also know that these batteries--whether it be AGM or gel cells come off their peak voltage down to around 12 volts fairly quickly, but they do not have a steady decrease in voltage level. They'll hold around 12 volts for a while depending on the load on them) and then their voltage level drops off more rapidly. If those batteries steadily declined as one poster said, they wouldn't be as useful as backup batteries in fire and burglar alarm systems as they are.

Although AGM batteries are different from what gel cells used to be, they are still batteries that have minimum liquid electrolyte and can be used with the battery mounted in any position--the original definition of a gel cell.
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 6, 2007 Mail this to a friend!
BTW, the battery does say made in China on it. Generally speaking, however, these batteries, by virtue of some of their uses, are somewhat fresher than those batteries in those starter packs.

The path the battery takes on its way to the consumer is somewhat shorter. Consider this--for the batteries I used here, the path was:

Battery manufacturer ----> shipping ----> warehouse ----> distributor ----> end user.

For the starter packs, however the path probably looks something like this depending on how long the packs themselves have been waiting to be sold:

Battery manufacturer ----> shipping ----> warehouse ----> pack manufacturer ----> shipping ----> warehouse ----> distributor ----> retail warehouse ----> retail store ----> end user.

So I will stick by my original statement, that the length of time those batteries in the starter packs have been on the shelf or in transit is greater than what the time the batteries I used were.
 
RE: Time for a New Portable Power Pack?  
by N6AJR on June 6, 2007 Mail this to a friend!
nice idea, I use multiple batteries in parallel , onse set charged by a powergate, and the other charged by some small solar. the ones in the shack are sla, and the ones outside are deep cycle lead acid. I get my sealed batteries from a wheel chair place called spinlife, if the order is over a hundred bucks, free shipping.


spinlife.com

lots of different battery sizes
 
RE: Time for a New Portable Power Pack?  
by WA5ZNU on June 6, 2007 Mail this to a friend!
N0OKS wrote:
>NiMH or Li ion batteries have a higher power density so they weigh less per ampere hour of capacity.

NiMH self-discharge is a killer for any readiness application. A lead battery will holds its charge for at least a year. The Li+ batteries are good in this respect as well, and are also denser, but they still have significant safety issues and a large cost disadvantage. For many uses, AGM batteries are the appropriate choice.

 
Time for a New Portable Power Pack?  
by PE1HZG on June 6, 2007 Mail this to a friend!
Lead cells don't like to be over-discharged, below 2V/cell is not a good idea. (voltage drops under load, this is under unloaded conditions)

So, it makes sense to monitor the voltage. Two ideas:
1. On some packs, I've added a meter, resistor and
*zener*, so the left of the meter is +10V
and we have better accuracy.
2. Or, add a LED w/ resistor and again, zener, so the
LED will switch off if the voltage is too low.
If the LED shuts off, it's time to stop

Hope this helps,

Geert Jan
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 6, 2007 Mail this to a friend!
"I am surprised at everyone’s enthusiasm for antiquated technology gel cell batteries. NiMH or Li ion batteries have a higher power density so they weigh less per ampere hour of capacity........

.......The portable power supply that K1CJS describes uses four, 7 AH, batteries that cost $20 to $25 each. The total weight is 40 pounds. AA NiMH batteries weigh about one ounce each. They are currently available with a capacity of 2,500 mAH and cost no more than $1.25 each."

Mark, if you want to power a handy talkie, the batteries you describe would be fine. However, to power a mobile rig and a receiver--for any length of time, (which was the purpose of the one I made) you would need more than the 42 batteries you specify. Those 2500mah cells you describe are not meant to supply such current for any length of time--unless you series/parallel a lot more of them than you may think. They just don't have the current handling capacity--or the storage capacity, for that matter--the batteries used for this project do.

The cost, therefore would be much, much greater than you believe it to be--possibly as much as five to ten times greater once the costs of the battery holders, connectors and wiring were taken into account.

Antiquated technology? I don't think so. However, what you suggest doing is like running a house during a power outage with a 1000 watt generator. You may light a couple of lights and a small TV, but let the refrigerator start up and you're in a lot of trouble!
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 6, 2007 Mail this to a friend!
"Lead cells don't like to be over-discharged, below 2V/cell is not a good idea. (voltage drops under load, this is under unloaded conditions) So, it makes sense to monitor the voltage."

It certainly does, and the methods suggested are great! This is the sort of thing I meant when I asked for suggestions. This thought didn't occur to me.

If I may, there is a voltage monitor meter available for about $10 that can be wired into the circuit easily that would give a direct readout of battery voltage if you wanted it.

Thanks!
 
Time for a New Portable Power Pack?  
by VE4HQ on June 6, 2007 Mail this to a friend!
I use a marine/RV Power Pack used to power a trolling motor, It is rated 800 cranking amps and has a 33ah deep-cycle (GEL) battery in it.It has red and green lights plus a head light and compas in it.There is also a compressor to blow up you air matress etc.It comes with a AC charger,but can be charged from a vehicle's cigarette light or a solar cell.
This one is a Motomaster NAUTIULUS available in Canada at the Canadian tire stores. Check it out on their web site under powerpacks. Tom VE4HQ.
 
Time for a New Portable Power Pack?  
by KF4ZMT on June 6, 2007 Mail this to a friend!
Great article! I'd like to see more postings like this one.
 
RE: Time for a New Portable Power Pack?  
by WR8Y on June 6, 2007 Mail this to a friend!
AA3YW:

""""There doesn't appear to be a fuse or blocking diode on each battery in this design and never parallel batteries especially when charging. Batteries or cells should always be connected in series to get the desired voltage. Batteries and cells can short out and cause an over current condition if they're in parallel circuit and possibly cause a fire.""""

NEVER? Every ambulance in the USA has two batteries in parallel - with only the battery switch between them. My service van: same thing, two batteries with an "ambulance" switch. What's the big deal?
 
RE: Time for a New Portable Power Pack?  
by N0OKS on June 6, 2007 Mail this to a friend!
Chris

You are right, it would take a lot of batteries to equal what you have, and I pointed that out. Sub C sized NiMH batteries are used in model electric cars for racing and the current draw is significant. Anyhow, I guess I am thinking low power, QRP, not a 100 watt rig from a battery. The 28 AH set up you have would run a K2 for a week of normal operating. Higher cost, yes, but lower weight, smaller package and a more appropriate votage for the radio are the advantages of a NiMH battery based portable power supply.

And you could buy a chip and make a recharger for the batteries alleviating the need to take them all out and put them in a commercial charger.
 
RE: Time for a New Portable Power Pack?  
by WB2WIK on June 6, 2007 Mail this to a friend!
Nice article, but I didn't see where you describe where the fuses are installed in the circuit. They're shown in the photograph and briefly discussed to indicate their existence, but a schematic diagram would be nice to show proper placement, which of course should be closest to the battery terminals both electrically and physically, so that an inadvertent short circuit across screw terminals exposed when you open the box will be guaranteed to blow a fuse before someone accidentally welds his ring finger inside.

Nice work!

WB2WIK/6
 
RE: Time for a New Portable Power Pack?  
by K0BG on June 6, 2007 Mail this to a friend!
Not only every ambulance, but every diesel truck as well. In the latter case, all there is between them is a cable. I've run a second battery in my mobile for years paralleled without any problems what so ever. There are fuses, but these are to protect the wire, not the batteries.

Alan, KØBG
www.k0bg.com
 
Time for a New Portable Power Pack?  
by W8KQE on June 6, 2007 Mail this to a friend!
You can use any portable rechargeable car battery charger as a power supply as well. Many even have a 'cigarette lighter type' jack to power lower amperage rigs, like QRP radios.
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 6, 2007 Mail this to a friend!
The fuses are on the positive lead at the end of the circuit just before the power poles, 2 power poles on each side. The batteries are paralleled between the power pole connections. I thought about a schematic after submitting the story, it was a little late to put it in. I'll gladly e-mail a schematic to anyone who wants it, my e-mail is in my profile.

 
Time for a New Portable Power Pack?  
by KG7RS on June 6, 2007 Mail this to a friend!
Great article. I operate mostly in the field and have used a similar setup for a number of years. Mine uses 2 parallel-connected 18A/hr sealed lead-acid batteries inside a heavy-duty soft-sided camera bag. I use 1" closed-cell foam inner padding to provide protection and give shape to the bag. Recharging is provided by a 1.5A Schumacher automatic charger available at most discounters and auto dealers. There is one significant shortcoming with this setup. Fully charged, the pack outputs 12.6VDC. Many modern HF rigs need 11.8VDC minimum to operate trouble-free. This is certainly the case with my Yaesu FT-857D. When the pack discharges near or below this point, nasty behavior is noted, starting with transmit audio distortion. Output power drops like a rock too. About 3 months ago, I stumbled onto an outstanding solution to this problem. N8XJK has designed a switching-mode battery "booster" that bumps up the battery voltage to 13.8VDC. This little box is very efficient, only adding the voltage difference between input battery voltage and the 13.8VDC output. It's very well RF shielded and emits no discernible hash or noise normally associated with the use of switching power supplies in the HF spectra. It can even be automatically enabled during transmit by RF sensing to improve the efficiency even more. A small company in MI is producing this product and the price is reasonable. For me, it has been exactly what I was looking for and completely solves the battery voltage output problem, greatly increasing my operating time.
73 all, John, KG7RS
 
Time for a New Portable Power Pack?  
by KB5DPE on June 7, 2007 Mail this to a friend!
"...but don't forget about electrical safety in the process! There doesn't appear to be a fuse or blocking diode on each battery in this design and never parallel batteries especially when charging. Batteries or cells should always be connected in series to get the desired voltage."

Apparently this poster hasn't visited any commercial/public safety communications sites lately. Batteries are paralleled usually in groups of four to eight (depending on transmitter size and usage) and diodes and/or fuses are not used at the individual batteries because of issues with voltage drop and reliability. These installations are in strict compliance with the battery manufacturer's specifications and local codes.
My own home standby power system (not for ham radio use) consists of four banks of seven 46ah AGM VRLA batteries in series/parallel for an output of 48 volts at just over 300ah. This feeds a commercially made 5kw inverter/multi-stage charger/automatic switch. The advantages over a generator are many, noise being most important to me (and, no doubt, my neighbors). Disadvantages include battery replacement cost though batteries are spec.'d in this application at 10year nominal life (we'll see!). To say that I've experienced no problems in the several years this system has been in use is meaningless. I've known reckless drivers that drive that way for decades without an accident, which proves nothing. I do, however rely on the battery manufacturer to provide safe and reliable information and I have followed it explicitly. Also, being hard wired to the electrical mains, it had to pass inspection. I'm not an authority on backup power systems, so I try to learn from what the professionals are doing. So far, for the few brief outages we've had, this system has worked well. My next project, hopefully before the batteries start dying, will be to replace the large number of batteries with hydrogen fuel cells and a much smaller number of batteries. I've been reading that their prices are coming down and some are apparently available in the surplus market. Some more food for thought.
Tom
 
RE: Time for a New Portable Power Pack?  
by KB5DPE on June 7, 2007 Mail this to a friend!
By the way, I apologize for going off on an off-topic tangent. I started out trying to make a case for parallel connected batteries and got somewhat distracted. This certainly is not a PORTABLE system. SORRY.
Tom
 
RE: Time for a New Portable Power Pack?  
by AD5X on June 7, 2007 Mail this to a friend!
Regarding multiple AA NiMH batteries: These may be a problem for QRP as well. If you use multiple cells in a battery holder, you may find excessive voltage drop at higher currents. As an example, I built a 10-cell pack for my IC-703. I quickly would drop into the low battery saver mode (less than 11V sensed by the radio) when operating at 10 watts, which requires 2.1 amps on my IC-703. I looked at the pack separately under load and found about a 1.5V drop under this current draw. This was due to the steel spring contact interfaces with the batteries, as well as the small interconnecting steel wires between the batteries. The problem does not occur with welded pack batteries. I documented these measurements in one of the articles on my website.

Phil - AD5X
www.ad5x.com
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 7, 2007 Mail this to a friend!
"......Apparently this poster hasn't visited any commercial/public safety communications sites lately. Batteries are paralleled usually in groups of four to eight (depending on transmitter size and usage) and diodes and/or fuses are not used at the individual batteries......"

One other point about battery isolation--common sense tells you that a diode would not be used at each battery if the battery were of a rechargeable type--the diode would prevent the battery from receiving charging current.
 
Time for a New Portable Power Pack?  
by AA3YW on June 7, 2007 Mail this to a friend!
Gee! That's funny all the commercial systems that I've designed in my 25 + years as an electrical design engineer have used fusible links in there positive leads! All commercial vehicles are required to have a fusible link (FUSE) in their battery system. Just because you don't see them doesn't mean there not there. I just wanted to make sure people are aware of the safety issues around batteries. Check and understand the battery specifications when designing these systems! I don't want to hear of a battery exploding in a Hams face or causing a Ham Shack fire. Be Safe!

73's

Dave AA3YW
 
Time for a New Portable Power Pack?  
by KD7YPD on June 7, 2007 Mail this to a friend!
One hint on parallel battery banks is to keep the wire leads the same length. Although minimal, the difference in voltage drop with mismached leads between banks, can cause mismatched banks and shorten the life. With different lengths each bank is charging at a different voltage.

I like the idea of using NiMH. I raced RC cars for a few years and was always amazed how much current a NiCad pack could take. The problem with batteries is the heavy current draw dropping the voltage. It's not good for the batteries and it's not good for the application it's hooked up to.

I've been following the price on Ultracaps for about ten years now,(and still waiting for the price to drop). Using caps to handle the high current side of things would allow me to design around a fairly constant current on the batteries. I would have a little more room to play around with metering in the system without always worrying about going below critical voltage. I could limit the current charging the caps and use solar more effectivly.

During heavy transmit times it might be like waiting for the flash on a camera to charge. I have a hard time thinking in Farads, like 3000F...

http://www.maxwell.com/ultracapacitors/index.asp

Anyone played around with these?
 
RE: Time for a New Portable Power Pack?  
by K2GW on June 7, 2007 Mail this to a friend!
Very Nice. I'm glad you've created a power pack for portable use! The vast majority of our emergency operations are from locations other than one's own home, so you're going in the right direction.

Also, Gel Cels or AGM's are much better than wetcell lawn mower batteries for this type of operation as they're safer from a spillage/leakage view point and can be safely charged indoors without Hydrogen risks, so that was a good choice. They also handle deep discharge better than a starting type wetcell.

One suggestion for others to avoid the whole parallel/series debate. You indicated that you could get the 7 AH gel cells for $20 apiece. As you used 4 of them to give you 28 AH, folks might want to look at gelcells in the 28-35 AH capacity size to begin with. I picked up one at Dayton for $65. One of these will run a 20 watt FM transmitter for a twelve hour shift of the typical EmComm duty cycle.

This size fits nicely in a softside nine-pack cooler available at your local discount store. Fused leads ending in Anderson PowerPoles are easily snaked out for charging or supply.

BTW, for those debating parrallel versus series, two books I recommend are "Managing 12 Volts" available through Amazon.com and "Emergency Power" available from the ARRL.

73

Gary, K2GW





 
RE: Time for a New Portable Power Pack?  
by WA1RNE on June 7, 2007 Mail this to a friend!

A good quality charger - integrated with the carrying case would add the finishing touch to this project. (but not inside for thermal reasons)


I've had good luck with chargers manufactured by ChargeTek for marine applications, charging very large deep cycle battery banks. This smaller 1.5 ampere model would be great for this application. It's only 6" L x 3.16" W x 2.6" H, weighs 3 lbs and is waterproof:

Dealer:

http://www.batterystuff.com/battery-chargers/12-volt/marine-chargers/CK150.html

The manual:

http://www.chargetek.com/CT-CK150.pdf


....WA1RNE
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 7, 2007 Mail this to a friend!
Dave,
There is a difference between a fusable link and a fuse, although they are included in a circuit for much the same reason. If you would note, I have included two fuses in the circuitry of the pack for short circuit protection.

Fusable links are located in the leads between a battery and its load and/or between a charging source and a battery, but they are not commonly included on one or both leads of individual paralleled batteries. Dual batteries used in the starting circuit of diesel powered vehicles are not individually separated by fuseable links.

Some of the larger, more elaborate commercial diesel tractors may have six 12 volt batteries connected in parallel to supply starting current to turn over its diesel engine. Such vehicles do have fusable links (as you say--they are required) but between the battery bank and the vehicle electrical system--not the individual batteries.

I am all for safety, I don't want an accident to hurt anyone, but there is such a thing as carrying it too far and impairing the usefulness of the battery pack.

As a side note, what happens when you try to feed a rig with wires that are of too small a wire gauge? You get impaired performance of the rig and a safety hazard from possible overheating of the wires. So, as you can see, it's a trade-off between one safety issue and another. I would rather protect from something that there is more of a chance happening.

73, Chris
 
Time for a New Portable Power Pack?  
by N7XB on June 7, 2007 Mail this to a friend!
I commend the author for a nifty looking battery box. However, it appears he has assembled a 40-pound, $85-$120 box that gives him 28 AH of DC power.

I can go into Costco today and buy an 85 AH deep cycle battery that is basically the same size and weight for $20-$40 less.

I use ONE of those 7 AH batteries with my FT-817. If I need more AH, the deep cycle battery offers a far better value - in AH, $$$ saved, and performance - than this project.

Nice job, though.

Bruce N7XB
 
RE: Time for a New Portable Power Pack?  
by W1RKW on June 7, 2007 Mail this to a friend!
A simple blown fuse indicator for the battery pack, a light bulb or LED with dropping resistor wired in parallel with the fuse.
 
RE: Time for a New Portable Power Pack?  
by N1EY on June 7, 2007 Mail this to a friend!
NX7B:

What about transporting this battery in your car and utilizing power or charging it in your car?

I worry about deep cycle AGM batteries for marine or diesel applications being charged in the car while mobile.

Am I wrong to be worried?

thanks
n1ey
 
RE: Time for a New Portable Power Pack?  
by KB5DPE on June 7, 2007 Mail this to a friend!
"Gee! That's funny all the commercial systems that I've designed in my 25 + years as an electrical design engineer have used fusible links in there positive leads!"

YES! That'll teach me to post something just before I'm ready to go to bed. I stand by my comment about the FUSE and diodes, however in my frenzied cut and paste to finish my comment, I left out the part about a circuit breaker (preferably automatic reset). I've never seen a fusible link used but I don't see why not. Only problem, if the problem goes away, you've got to go out to the site to replace it. Hope I didn't lead a newby astray however, there are plenty of people here who jumped on it right away so, hopefully, no harm done. Another example of "be sure brain is engaged before putting fingers in gear" With tail tucked firmly between my legs, I think I'll sit this evening out.
Tom
 
RE: Time for a New Portable Power Pack?  
by KD6NEM on June 7, 2007 Mail this to a friend!
I suspect a heavily discharged AGM just attached in parallel to a vehicle's starting battery might suck so much current from the starting battery that you may have problems like severely heating the connections & cables, never mind the arc flash from connecting it (if near H2 from the starting battery or gasoline vapors) and significantly draining the starting battery. You would be right to be concerned, although if you could isolate the AGM & regulate the current to it it could be done.

Whatever you do, get it charged back up ASAP or else you are throwing your money away in the form of decreased battery life. Waiting "even just a week" to recharge is a slow (or not so slow!) death to even premium batteries. If I cannot get home in a couple hours if I have discharged it very much at all I'll find a place to plug in my charger for my AGM.

Stu KD6NEM
 
RE: Time for a New Portable Power Pack?  
by KA1OS on June 7, 2007 Mail this to a friend!
I like the clean, careful construction. That's excellent practice for building reliable projects. Nice job, Chris!

I suspect I've got an insane paranoia about exposed connections, particularly in mobile applications. I know the toolcase lid should provide the necessary protection but if a stray bit of metal happened to get into the box and bounce around... OK, even then probably nothing would happen. I don't think I've got OCD but I wouldn't feel relaxed putting it into mobile service until I had "Murphy-protected" the terminal strip with some covers.
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 7, 2007 Mail this to a friend!
"What about transporting this battery in your car and utilizing power or charging it in your car? I worry about deep cycle AGM batteries for marine or diesel applications being charged in the car while mobile. Am I wrong to be worried?"

Not at all! This is why I specified charging should be done through the Anderson Power Poles--which have a thirty amp fuse protecting each pair. If a connection were made to charge the pack from a car, an overcurrent condition such as you mention would blow the thirty amp in line fuse.

Of course, the trick would be not to allow the pack to become that discharged in the first place--something that sometimes may happen, no matter how careful we may be.
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 7, 2007 Mail this to a friend!
"YES! That'll teach me to post something just before I'm ready to go to bed.......I think I'll sit this evening out."

Hey, Tom, it happens to us all. I thought about including a schematic after I submitted this article. Sometimes the thought just gets lost or misstated. 73!
 
RE: Time for a New Portable Power Pack?  
by KC8QFP on June 7, 2007 Mail this to a friend!
I once used an old shopping cart for portable battery power that made mobility much easier than toting around forty pounds of Gel Cell's in a plastic case that might fall apart and explode all over the place. You can get plastic battery boxes at many auto parts or mariner suppliers to put the battery inside the cart. Some better shopping carts have four wheels, but even the two wheelers are OK for transporting all yer junk. You can tote your gel-cell (I like those for electric wheelchairs best), charger, rigs, wires, and antenna. I used cardboard for the sides and bottum of my cart, since I did not use it much, but masonite also makes for good sides and bottum.

Another alternative that I thought would be a good porta-power station is a COOLER with wheels. Yah, I know you'd prefer using it to keep the beer cold instead, and that's where the shopping cart is better. But the cooler with wheels will keep things nice a dry too. The main point is WHEELS! Then one deep cycle wheelchair battery should do OK. (Heck, those dudes ride around all day on those buggers)! Another nice thing to have in your porta-power setup is an inverter for your old tube rigs HIHI! Also provide some kind of lighting in the box.

I used the toolbox, and did not like it - plastic is too flimsy, and it is too heavy and clumsy. Wheels are much better.

73! Don
 
Time for a New Portable Power Pack?  
by KG4YUS on June 7, 2007 Mail this to a friend!
$85.00???
Deep Cycle battery works fine for me and is a sight cheaper.
 
RE: Time for a New Portable Power Pack?  
by N7XB on June 7, 2007 Mail this to a friend!
N1EY:

"What about transporting this (deep cycle) battery in your car and utilizing power or charging it in your car?

I worry about deep cycle AGM batteries for marine or diesel applications being charged in the car while mobile.

Am I wrong to be worried?"

I don't know. It never occurred to me to be operating mobile from a recharging deep cycle battery instead of directly from the truck electrical system. Why would anyone do that?

My preference for a deep cycle battery over this project is for stationary portable (non mobile) operating. I liteally run my laptop (via inverter) and FT-817 all weekend from a deep cycle battery that I recharge with a smart charger when I get home.

I would not want to try that with only 28 AH available.

Again, this project got too abitious with four batteries, that resulted in a box comparable in size and weight to a deep cycle battery, with 1/4 the AH at a higher cost.

Put another way: Would anyone buy this setup commercially? $85 - $120 for a 40 lb. 28 AH tool box is not a better mouse trap.

Bruce N7XB
 
RE: Time for a New Portable Power Pack?  
by KC8VWM on June 7, 2007 Mail this to a friend!
Are we still "focusing" on the fuse issue? :)

73 de Charles - KC8VWM
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 8, 2007 Mail this to a friend!
"Again, this project got too abitious with four batteries, that resulted in a box comparable in size and weight to a deep cycle battery, with 1/4 the AH at a higher cost."

I'll stand by what I believe is a suitable setup for my uses--as I said in the article, your uses may vary and the project can be modified to suit those uses. If you can get AGM type deep cycle 100 AH batteries cheaper than $80, by all means, do it. Getting a container to hold the battery, the terminals, connectors and wiring pushes the cost up again.

Sealed cell type batteries are better for this type setup, but if you are referring to a wet cell type deep cycle battery, I considered the danger involved with that type battery in the article. I didn't want the extra hazard involved with wet type batteries, or I would have used the car battery I had.

I'm not trying to reinvent the mousetrap--I went the more costly route and bought the new batteries. As another poster said, used batteries of this type with life left in them are available cheap--sometimes as low as $5.00 each--sometimes for nothing! That would bring the cost of the project down to $20 or $30!

The bottom line is the project is an idea for portable power system--alter it and make it the way you prefer. If you prefer using a wheeled box, do it. Different type batteries or more of this type? Go for it.

Those who don't like the idea or the setup don't have to make it. Simple enough? But, after seeing this project, if you have an idea of your own and gain benefit from seeing this completed project, then my purposes for submitting it is accomplished.
 
Time for a New Portable Power Pack?  
by W2MSK on June 8, 2007 Mail this to a friend!
You cannot charge batteries in parallel correctly. The battery with the highest internal resistance, lowest capacity or fault will be the determining charge factor for the array. They must be charged independently.
 
RE: Time for a New Portable Power Pack?  
by KC8QFP on June 8, 2007 Mail this to a friend!
<<< The bottom line is the project is an idea for portable power system--alter it and make it the way you prefer. If you prefer using a wheeled box, do it. Different type batteries or more of this type? Go for it >>>
===================================================

Well isn't that one reason why people post their opinions and ideas on here? So others can add a few cents to it, and perhaps improve on the ideas?

I like my wheeler, it is very versatile. It can be used for porta-radio, a beer cooler, a seat, and even a pickynick! Would be great for those camping or fishing dudes that like to play radio too on their outings. Heck buy a few wheeled coolers!

Another idea would be to use a three wheeled bicycle with the big basket between the rear wheels for batteries and radio jazz. The antenner can be mounted to the bike frame, and radio can be mounted on the handlebars. If you're going downhill and have enough muscle power, you can use a bike generator to recharge the battery (just kidding). It depends on what you want porta-power for???

But the toolbox was heavy and flimsy for me, I also used a plastic file/record box once to contain the gel-cell. I agree that ONE battery is best. Like I said, those small deep cycle gel-cells (for Rascal scooters) wheelchairs are pretty good bang for the buck, good quality all around batteries.
 
Time for a New Portable Power Pack?  
by KX0R on June 8, 2007 Mail this to a friend!
I think the author did a great job on his battery pack, and it provides a good starting point for many similar projects.

This question of hooking batteries in parallel really deserves its own article. This is a controversial point. I want to throw some more gasoline of the fire by mentioning that I have examined commercial lithium-ion packs rated for about 6500 MAH (6.5 Ampere Hours) at about 14.8V. These packs contain 12 lithium-ion cells, arranged with four series groups, and each group has three cells connected in parallel. The parallel cells have straps spot-welded across their terminals, and there are no diodes, fuses, or other protective devices in the parallelling straps. These packs do contain protection PCB's for the whole pack. These protection PCB's treat each group of parallel cells as a single cell.

Clearly the manufacturers know that with matched cells, the lithium ion cells will charge and discharge evenly enough that direct parallel connections are OK. These cells have a very low series resistance and can deliver an amazing amount of energy if a fault occurs. These are the same kind of CGR18650 cells that are used in notebook computers and similar devices. They do use these cells in parallel without any special components to deal with differences among the cells.

It's obvious that if one cells shorts out, the other parallel cells will dump into the short. Perhaps the cells contain an internal fuse to protect against this unlikely possibility.

As long as the terminal voltage of a cell rises as it charges, and decreases as it discharges, cells with identical characteristics may be run directly in parallel. The cells are self-equalizing during charge and discharge, provided they are run according to recommendations of the manufacturer. Clearly problems could occur if the cells are overcharged, over- discharged, or otherwise abused.

There should be no problem with lead acid batteries in parallel, provided the batteries are from the same production line, built with the same chemistry, etc. Where all the problems occur is when you parallel a vehicle starting battery with another battery with different characteristics, like a typical deep-cycle storage battery. When this happens, one of the batteries will charge more than the other, and they never equalize, because their terminal voltages differ. During discharge, there will be serious problems. One battery may try to charge the other, resulting in overheating and damage.

Almost every manufacturer of batteries has recommendations about how customers should use their batteries in order to get the best performance. Read and follow the data sheets for the batteries you plan to use. Some of the choices you face are judgment calls - you have to weigh the risks and benefits for your application.

My favorite battery for QRP field day and home use is the 12V 17 AH sealed lead-acid battery. The Yuasa and Panasonic batteries are great. These batteries are about the right size for lots of jobs, yet you can move them with one hand, without hurting your back. They are overkill for most QRP rigs, even when they get old and lose some capacity. I've obtained several at hamfests or battery recyclers.

UPS batteries are a possible source of portable or emergency power. Large UPS units generally have a high-capacity sealed deep-cycle battery or battery set designed to be discharged at a high rate. Many of these batteries are rated to be dumped in only 15 minutes to one hour, so they have low series resistance and the ability to withstand deep discharge. These batteries sometimes show up at hamfests, and you may be able to find them used but OK, since operators of servers and networks replace them on a schedule.

Most of these sealed batteries lose ampere-hour capacity and show an increase in series resistance as they age. Nevertheless, many used batteries are still very good and will provide plenty of use in moderate-drain radio service.

Read up on batteries - there's tons of reliable information (as well as lots of bull) on the Internet.
Use common sense, and consider using protective devices where you need them.

My favorite device for QRP radios and battery packs is the PolySwitch. The is a type of resettable fuse. They are widely available in many ratings and styles, they're easier to use than fuses, and they are really low-cost. They're in many commercial battery packs, as well as automobile elctrical systems, etc. Consider using these instead of fuses in your homemade battery packs.

Here's a good place to start:

http://www.circuitprotection.com/polyswitch.asp

Mouser and other distributors have a large selection. These things work great and can save you a lot of grief.

KX0R

 
Time for a New Portable Power Pack?  
by N2TMC on June 8, 2007 Mail this to a friend!
I use batteries from my power wheelchair. They have to be replaced in the chair every 12 to 15 months. However, I find if I wire them in parallel I can run my TM-2550A and my TS-430S in the house. I have a float charger to keep them up to voltage. I have 4 batteries that are 50 ah and they work great. I was able to operate for over 24 hours without charging.
 
RE: Time for a New Portable Power Pack?  
by N1EY on June 8, 2007 Mail this to a friend!
NX7B:
"I don't know. It never occurred to me to be operating mobile from a recharging deep cycle battery instead of directly from the truck electrical system. Why would anyone do that?"

Actually many people like to run off batteries in the car. They do not mess with their starting batteries at all.

I run a portable station with a deep cycle battery as well. It goes out side with a 33 foot mast.

I am now thinking of creating a portable 2/440 station with 800mhz for ATCS decoding. It would have to support a laptop in a car along with the radio.

n1ey
 
RE: Time for a New Portable Power Pack?  
by NA0AA on June 8, 2007 Mail this to a friend!
I've got a number of portable packs, a 24 amp/hour pack built into my VHF/UHF portable [composed of two 12 a/hr batteries in parallel], a 4.5 for my HT's, a 34 a/h for easy carry backup, or the big dog, 100 amp/hours [70 lbs or so] of AGM goodness for when I can drive to the operating location. This last one can be charged from the car using a simple current limiting device.

The difficulty is keeping the battery voltage drop in radios optimal operating range, which is why I'm planning to aquire a solid state battery booster so that I can use those amp/hours to best effect. Although it's a trade off since the overall draw is higher. Sigh. Nothing is perfect I guess.



 
RE: Time for a New Portable Power Pack?  
by W4SK on June 10, 2007 Mail this to a friend!
Lots of useful information, thanks, Guys.

-73-

W4SK
 
RE: Time for a New Portable Power Pack?  
by KC8ADU on June 12, 2007 Mail this to a friend!
i will add a few things here as i work with solar stuff,large ups systems,and wheelchairs.
the jump boxes that recharge from a cars lighter socket depend on the resistance in its wiring to limit current.
the li-ion cells mentioned in paralell are indeed protected.
if one shorts the others in the group will dump into it till the ptc on each cell trips.
this does not help the cell that developed a dendrite short at full charge though.one can only hope the seperator melts before the cell hits thermal runaway and goes off like a road flare.
if you look around at hamfests you will find lots of gel and agm batteries for sale.but you need to be able to test them as many sellers check voltage only.
these can be totally worn out and still read 12.8v
i keep a load tester on the table next to ones i sell.
i get lots of 1 year pulls from several sources and take them to hamfests.the common u1 32ah wheelchair battery makes a great portable power source.
i sell them for $20 and they have lots of life left.
they get replaced yearly in critical apps where downtime from battery death cannot be tolerated.
 
RE: Time for a New Portable Power Pack?  
by KC2PNF on June 13, 2007 Mail this to a friend!
Another battery misconception:
Deep Cycle doesn't mean you can discharge it further than a typical lead-acid battery. Deep Cycles have a longer shelf life because of lower internal resistance. Drawing them down below about 10v will wreck them just the same as any other.

Jon
KC2PNF
 
RE: Time for a New Portable Power Pack?  
by NA0AA on June 15, 2007 Mail this to a friend!
Good point. I understand that 10.5 volts is sort of the line of death for a "12 volt" battery. The problem is that most radios will have stopped worked before you reach that voltage.

Deep cycle means that the battery is designed to be cycled to it's performance limits without damage more times than an SLI [Starting, Lighting, Ignition] or 'car' battery. I've heard rumor that a conventional car battery is scrap if cycled to 10.5 volts more than something like 3 times, but I've no personal experience with that.

I do know that only a few manufacturers will claim more than 500 full capacity cycles on a battery, although in fairness, for radio backup use that's plenty, even for gel-cells in portable kits that's quite a bit of usage.
 
RE: Time for a New Portable Power Pack?  
by K1CJS on June 15, 2007 Mail this to a friend!
"I've heard rumor that a conventional car battery is scrap if cycled to 10.5 volts more than something like 3 times, but I've no personal experience with that."

Its not the cycling that kills it, it's what happens during the cycling--the chemical interaction between the electrolyte and the plates of the battery. When it is discharged that much, permanent changes occur to those parts. Charging reverses those changes, but it can't restore the original condition of the parts.

What really happens is that the amp-hour capacity of the battery is diminished to the point it can't put out enough power all at once to start a vehicle engine in extreme conditions. Even though the battery is considered dead--it can still be useful as a source of low amperage 12 volt power for other uses.

Cheaper batteries can be 'killed' if extremely discharged just once. Better, more expensive batteries can take a few discharge cycles--as long as the battery is well maintained and fully charged if accidently discharged. Its life depends on the quality and purity of the parts used to make it, and how it is used--or abused.
 
RE: Time for a New Portable Power Pack?  
by KB0MJM on June 20, 2007 Mail this to a friend!
For what it is worth - I was working in a hospital recently and the Biomed tech had a box of gel batteries sitting on the floor. I asked what he was going to do with them and why he had so many. His reply gave me an oppourtunity to request that I get rid of them for him, which he was glad to do. They have a policy at the hospital to AUTOMATICALLY REPLACE all of the batteries in the IV pumps at a defined time each year or two. All batteries were rounded up and put in a box to be sent out. This may be a significant source for hams to get batteries which, although not new, now that I have 25 of them I can take more than needed to have some leeway. I plan to give some out at the next meeting of hams that I attend, radio club or hamfest. You might call the biomed folks at your local hospital and ask their policy, perhaps recommending that you have heard that for safety purposes many hospitals replace their batteries en bloc. smile.
 
RE: Time for a New Portable Power Pack?  
by K2GW on June 25, 2007 Mail this to a friend!
>>$85.00??? Deep Cycle battery works fine for me and is a sight cheaper.

After you spill the acid on yourself or ignite the emitted hydrogen gas indoors, it gets a lot more expensive. AGM or Gel Cells are much safer and more appropriate for Amateur Radio portable power sources.

Lead acid wet cells do have their place... in engine compartments or in fixed location outdoor vented battery bank "caskets". They do not belong in your house or being regularly transported in your car.

73

Gary, K2GW
 
RE: Time for a New Portable Power Pack?  
by W6EM on June 25, 2007 Mail this to a friend!
Yes, Gary, you are correct in your cautions. Commerical station battery installations all require complete air changes, per se, forced ventillation of some sort to rid the atmosphere of hydrogen from the charging process. Trying to use a vented LA battery inside one's home, or even the trunk of one's car, is a dangerous undertaking. Spillage of the sulphuric acid electrolyte is another worry.

As far as paralleling goes, its been mentioned lightly, but, here's the problem. There's no certainty that over time, the internal characteristics including each cell resistance, will remain all the same. Not too much of a problem for just seriesed cells. Commercial chargers have a feature called an "equalizing" charge rate. Its a high rate for a very short time that's designed to try to equalize all of the series cells. Try, is the keyword.

However, with unequal discharge and charge current distribution in a paralleled arrangement, you've got the possibility of excessive charge or discharge currents occurring through one of the paralleled batteries of the matrix. So, what's that mean?
Well, it doesn't even have to be enough to take out a fuse.

For so-called sealed, gel or mat electrolyte technologies, that can mean gassing. Oh, but they're sealed. Not quite. They have "valve regulated" technology that burps the gas out if gassing occurs at above design pressure. Gassing means ultimate loss of electrolyte and end of the cell life. So, just because its "sealed" doesn't mean it won't vent if gassing happens. Hopefully, they'll reseal when pressure is relieved. According to one reference text, gassing of LA cells usually begins when cell voltage exceeds 2.3 volts (13.8V). So, beware.

The advantages to gel cell or mat electrolyte types is that you can tip them over without spillage or weeping acid to contend with. That's important for us as we move them from place to place often on our person.
The disadvantages, such as freer flow and mixing of electrolyte aren't of too much concern for light discharge ham use.

And, for those touting other electrolyte technologies, find the 20AH or higher energy capacities at a reasonable cost and I'll listen....

One thing I didn't read was any mention of rating discussed. AH rating is an 8 hour discharge at a constant current which is one eighth of the Ampere-hour energy rating. At the end of that time, cell voltage will be about 1.75V (10.5V)

I've several older gel cells that are now approaching 15 years of age. Still going strong. I've not done an 8 hour rate discharge test on them, but I'd bet they'll still come close. I recharge at a fixed regulated 13.6V output with current limiting to less than 1.5A. I used a single 7AH pack Saturday and Sunday for a total of 4 hours FD operation with my FT-7 at 20W PEP. Of course, intermittent transmitting and replacment of all incandescent lamps helped. The puppy only demands 200mA on receive. Beat that with an FT-817!!

73,

Lee
W6EM


 
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