Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: Prev 1 [2]   Go Down
  Print  
Author Topic: Battery backup  (Read 45828 times)
W6EM
Member

Posts: 1705




Ignore
« Reply #15 on: August 31, 2013, 06:05:53 AM »

I have a UPS for my computer, and I ran my rig off of it for a little bit (just on RX) to see how it worked.  Unfortunately, it generated a lot of RF hash while in battery mode.
Yes, a UPS generates a series of positive and negative pulses when it is running.  UPSs generally run in "auto-bypass" mode, meaning they aren't producing the pulse trains when AC power is available.  They switch electronically within a fraction of a cycle on power failure.  So, as you experienced, best to test what it would sound like by unplugging the UPS and simulating an actual power outage.
Quote
  I like the looks of that product from West Mountain Radio.  I assume it doesn't generate RFI?
I don't own a Powergate.  However, from pictures in pop-up ads, it appears to be a matrix of P-channel Power MOSFETs inside a plastic enclosure.  Since it isn't a voltage converter, I don't think it would generate any wideband noise.

I didn't see any heat sinking in the picture and they look like surface-mount versions of MOSFETs.  Even with a Herculean device like the IRF4905, that has a maximum drain source current of 74Amps, they still do have drain to source resistance and will dissipate heat while under significant load.  As an example, a drain source resistance of 0.05 ohms at 20A will dissipate 20W, so heat sinking is probably necessary.......or, whatever is around it will get very, very warm...... 
Logged
AA4PB
Member

Posts: 14421




Ignore
« Reply #16 on: August 31, 2013, 07:11:51 AM »

Ultimately, a quieter and I think more efficient route would be to power directly off batteries in an emergency, rather than use a UPS which is basically converting the battery DC to AC, then my power supply converts it back to DC to run the rig.   

Absolutely running directly from the battery (rather than two conversions) will be more efficient. You could also consider running from the battery all the time and using a trickle or automatic charger to keep it charged when AC power is available. Then you wouldn't have to use any switch-over circuit. Typically you are in receive mode most of the time so the average current draw from the battery is pretty low so an automatic or trickle charger can easily keep the battery topped off between use.
Logged

Bob  AA4PB
Garrisonville, VA
AK7V
Member

Posts: 267




Ignore
« Reply #17 on: September 05, 2013, 09:28:59 AM »

Ultimately, a quieter and I think more efficient route would be to power directly off batteries in an emergency, rather than use a UPS which is basically converting the battery DC to AC, then my power supply converts it back to DC to run the rig.   

Absolutely running directly from the battery (rather than two conversions) will be more efficient. You could also consider running from the battery all the time and using a trickle or automatic charger to keep it charged when AC power is available. Then you wouldn't have to use any switch-over circuit. Typically you are in receive mode most of the time so the average current draw from the battery is pretty low so an automatic or trickle charger can easily keep the battery topped off between use.


Does anyone have a recommendation for a good, RF-quiet trickle charger that I can run off the AC mains to do as AA4PB suggests?

Thanks
Logged
KF7VXA
Member

Posts: 568




Ignore
« Reply #18 on: September 05, 2013, 10:11:30 PM »

I have used the "BatteryMinder" for about 6 years now as my trickle and maintenance charger.

The great thing about the Batteryminder is that it puts out high voltage pulses that knock the sulphate off of the battery plates and sulphate is what kills most batteries. I don't use it when transmitting, so as far a quiet, I don't know, but ARRL has had some great articals on self built chargers that are quiet and pre drilled boards can be bought for most of them, that would be the way to go if you want a small charger while using your radio. Changing chargers during an outage would be no big deal, you'll have plenty of time to do it.
I have even brought batteries that were well on their way out back to at least 90% with the batteryMinder, they really work.
The small one I use can be had for $40.00. They also make higher wattage as well as solar powered chargers. I put them on my truck batteries for 3 weeks at a time and have yet to have replaced a  battery in over 4 years, they are all like new.
The little one puts out 1.3 amps max. and will charge up to 4 of the same kind of battery at once. When charging more than one battery, the positive from the charger goes on the positive lug of the first battery and the negative goes on the negative lug of the last battery.
I have yet to have a set of batteries go bad as long as I buy a matched set of new one's, all the same. If you add a new battery to a bunch of used batteries, that's when you start wrecking batteries, I have yet to lose even one when starting with a new matched set.
I use the battery charger, have a 1000 watt inverter generator, the 4K charger in my Toy Hauler and a bunch or solar panels and charge controllers. Between all of these, I can keep my batteries charged for a long time, even in an extended outage. Just having solar panels hooked up when there is sun as you use your radio extends the time you get out of your battery(s) before a charge is needed.
I also keep the 37 gallon gas tank in the toy hauler full with gas and gas saver and use it from time to time and replace it. My two trucks have almost 80 gallons of gas in them between the two of them and I never let them get below 3/4 full when driving. This way, I always have a good supply of gas.
Be sure to use gas saver and change out the gas at least every 6 months. I just pump the gas from the toy hauler into my trucks and then refill the tank with more gas and gas saver. I've never had a problem with rancid gas this way. The metal gas cans are far better than the plastic one's for storage also. A bottle of the stuff that helps the gas burn water from condensation is a good thing to run through from time to time, just don't use too much, it's not all that good for the fuel system.
I have a fair amount of wind where I live also and am building a wind charger also. Not a big one, maybe 500 watts, but that's enough. An MFJ battery voltage booster tops off the system, just don't run your batteries below 10.5 volts or you will greatly shorten their lives.  If you have enough batteries, set it to turn off at 11 volts for max. battery life.The voltage booster assures you always have 13.8 volts from a battery with less voltage.
You can set it at a voltage of about 12.5 volts and still have most of your radios work just fine and the batteries will last longer between charges. You might lose a little wattage output, but not enough to matter 95% of the time.
Also make or buy several solar chargers for AAA, AA and D cell batteries. The Sanyo EnLoop batteries hold their charge for a long time and seem to be the best rechargable's on the market today.
They work great in AA battery packs for HT's as well as flashlights and anything else you can think of, buy plenty of batteries, you'll use them.

73's John KF7VXA
« Last Edit: September 05, 2013, 10:30:25 PM by KF7VXA » Logged
KA5IVR
Member

Posts: 11




Ignore
« Reply #19 on: January 07, 2014, 06:27:38 AM »

The downside is you may have to tweak your power supply to supply a little more voltage depending on your station and your radios, to overcome diode voltage drop and keep the batteries up to full charge.

I just use Anderson power poles and disconnect and reconnect my station as needed, refresh charging the batteries when I use them or every few months if I don't.  It's a bit cheaper to do--but you have to remember to do it!

I found this out the hard way during the last power outage.
Logged
KF7VXA
Member

Posts: 568




Ignore
« Reply #20 on: January 28, 2014, 04:09:44 PM »

Just using the Anderson Powerpoles is the way to go.
Sure, your off the air for the 45 seconds it takes to change the connectors, but you have no loss of power that USP's and other equipment takes. You'll get more time from your batteries when run direct to your 12 volt equipment without running the battery voltage too low and killing your battery.

Best set up is to have 2 or 4 deep cycle batteries. Buy a couple of 75 watt solar panels and a charge controller. Either hook the charge controller to one or two of the batteries you are using or use two batteries while the solar panel charges the other 2 batteries. Does not work at night, but if you have decent sun, it's a fantastic set up. A back up generator and battery charger is the cheapest if you keep enough fuel on hand.
We tend to get a lot of wind during storms, so I also bought a small 600 watt wind generator for day and night use. Not the best return on your money, but if you have the wind, it's worth it. Make sure you have enough wind on a regular basis or when you have storms (seems to be the time the power goes off), that's when a wind generator shines. If you don't have the wind, don't bother, it will be a total waste of money. Many rural places can use the wind, but in town, you'll almost never have enough wind to turn a wind generator.

73's John
Logged
AE5JU
Member

Posts: 244




Ignore
« Reply #21 on: April 11, 2015, 06:26:36 PM »

In my latest portable kit I'm using the Samlex SEC-1223BBM.  It has extra terminals for battery, and if 120 vac
fails, it automatically switches to battery.  The radio never blinks, you never notice.

http://www.universal-radio.com/catalog/hamps/3382.html

When AC is restored, it switches back to AC and the 1223BBM also charges the batteries.

Samlex and Astron both have the modules to do this switching if you have a regular power supply.

http://www.universal-radio.com/catalog/hamps/6037.html

http://www.universal-radio.com/catalog/hamps/5603.html

There is also the Low Loss Power Gate from K10BK.  I have one of these, too.  Works well.

http://ki0bk.no-ip.com/~pwrgate/LLPG/Site/LLPG.html

I'm also using for portable an "Elite" series AGM battery, 55 AH, from www.gruberpower.com
In the shack I have a similar Elite, 80 AH, also from Gruber.

I use this solar charge controller with solar panels.

http://ki0bk.no-ip.com/~pwrgate/LLPG/Site/Solar.html

The solar panels I have (two 50 w panels) produce 22 v no load, 16-18 volts
under load.  I can use one or both panels in parallel, depending on usage.

I've tested and all this stuff is operational in my shack.
Logged
NA4IT
Member

Posts: 77


WWW

Ignore
« Reply #22 on: April 16, 2015, 05:06:08 AM »



Power supply / charger came from http://www.cascadeaudio.com/power_converters/power_converters.htm.
Logged
KI0BK
Member

Posts: 3




Ignore
« Reply #23 on: October 08, 2015, 06:26:14 PM »


Quote
I didn't see any heat sinking in the picture and they look like surface-mount versions of MOSFETs.  Even with a Herculean device like the IRF4905, that has a maximum drain source current of 74Amps, they still do have drain to source resistance and will dissipate heat while under significant load.  As an example, a drain source resistance of 0.05 ohms at 20A will dissipate 20W, so heat sinking is probably necessary.......or, whatever is around it will get very, very warm...... 

Just to correct the math, P=I*I*R
0.05 ohms at 20A = 8 Watts

The MOSFETs used in the LLPG have an R(on) of <0.002 ohms so power dissipation is 0.8W's
It only gets warm if pulling more then it's rated capacity.  (25 amps max)
The circuit board is ample heat sink in normal use.
Jim KI0BK
Logged
N9AVY
Member

Posts: 98




Ignore
« Reply #24 on: October 12, 2015, 01:03:08 PM »

You mentioned SLA batteries, but didn't mention the AH rating. If you try to run the HF radio from a couple of 12v  7 AH SLA's, it probably won't work well, if at all.  I work with SLA's in my job and I generally meter than with a meter that read voltage and AH.  If a 12 V  7 AH battery reads below 4.4 AH , it gets tossed.   Batteries in commercial service get replaced every 3 to 5 years.  Just replaced a couple of 12 v 17 AH batteries that read 13 + volts, but the AH was down to 1.69 AH.  They were installed 14 years ago; so they don't owe anyone anything.
Logged
W6EM
Member

Posts: 1705




Ignore
« Reply #25 on: October 12, 2015, 07:17:47 PM »


Quote
I didn't see any heat sinking in the picture and they look like surface-mount versions of MOSFETs.  Even with a Herculean device like the IRF4905, that has a maximum drain source current of 74Amps, they still do have drain to source resistance and will dissipate heat while under significant load.  As an example, a drain source resistance of 0.05 ohms at 20A will dissipate 20W, so heat sinking is probably necessary.......or, whatever is around it will get very, very warm......  

Just to correct the math, P=I*I*R
0.05 ohms at 20A = 8 Watts

The MOSFETs used in the LLPG have an R(on) of <0.002 ohms so power dissipation is 0.8W's
It only gets warm if pulling more then it's rated capacity.  (25 amps max)
The circuit board is ample heat sink in normal use.
Jim KI0BK

Perhaps you are so close to the forest that you can't see the trees. If you square the current of 20A, that's 400Amps-squared.  Multiplying that times .05ohms is 20Watts, not 8 Watts!!

If the RDS-On of your device is truly less than 0.002 ohm, it must be an amazing P-channel device as most sources don't indicate such low values in P-channel devices at reasonable pricing.  OK.  Here’s an interesting and new P-channel power MOSFET  from Infineon, the IBP180P04.  And, it has a really low, 2.4mOhm RDS.  So, yes, the state of the art would now allow almost sink-lessuse of one of these to switch 20A.  Worthwhile to note that this is a 180A device!!!  Available for just over $2 each from Mouser..

Here's something that I’ve wanted to ask of someone who’s actually used the high current rating of SMT power FETs…. Just how hot does the very small SMT rectangular D or S lead  (not the tab on top) get when you try to pump 20A or more through it?  I would guess at least a couple hundred degrees Celsius.  Seems to me that unless one is very, very careful, that the conductor temperature could approach the melting point of solder.  Especially if approaching maximum device current ratings.

Then again, you DO advertise "or" gating, implying diodes being used for automatic switching.  Which is correct, the advertising or your Herculean P-channel device comments?

  
« Last Edit: October 24, 2015, 03:18:27 PM by W6EM » Logged
Pages: Prev 1 [2]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!