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Author Topic: Field Day Power Suggestions  (Read 11785 times)
N3YZ
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Posts: 49


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« Reply #15 on: April 27, 2011, 04:55:11 AM »

The information provided by CT Solar may answer many of your concerns.

http://www.ctsolar.com/solarpowerforamateurradiofaq.aspx

73! John
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N7VEA
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Posts: 48




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« Reply #16 on: April 27, 2011, 10:01:43 AM »

Thanks John, that was very useful, and oughta give me a good starting place.  I hadn't found that website before.   Appreciate the help from everyone!

73 -Bill N7VEA
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AE6ZW
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« Reply #17 on: May 02, 2011, 12:34:04 AM »

I have 60 watts ( 17 V ) panel I got on ebay including shipping for $160 and $20 charging controller shipped from China for $20, it is charging 70 AH walmart deep cycle marine battery.  that power my HF and VHF radio completely.   duty cycle low however,  VHF radio is on all the time 300mA, HF radio several hours a day, AA battery charger,  60 watts panel generate about 400 WH here in Orange county , CA.  I get 6 hours of sun light due to wall, building shade etc in apartment yard.
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NA0AA
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« Reply #18 on: May 07, 2011, 01:33:26 PM »

Some other practical matters:

I'd not bother with Harbor Freight solar panels.

You need to realistically evaluate your operation - Field day is rather atypical in that in MOST emergency operations, you won't be transmitting nearly as much as you would for field day.

A lead-acid battery will give you about 1.3 amp/hours per pound.  A 100 amp hour battery is about 80 lbs, and is heavier than you will want to carry very far.

There are advantages to larger sized batteries IF you are not going to move them.  Trojan batteries come in convient sizes with 6 volt configurations starting at around 225 amp/hours, put two of 'em together and you have a LOT of capacity for a 100 watt radio.  I currently run a 100 amp/hour 12 volt deep cycle, but my primary radio requires 120 volts so I don't need as much storage as I used to.

In a real emergency, you would hopefully have a very low current draw receiver you can leave on to monitor, OR you turn your radio on by the clock to save power.

Once you know your consumption budget, you can calculate your solar needs if you want solar.  Keep in mind that with a battery bank of 250 amp/hours, you will have days of normal operation w/out any sunlight.  But if it were me, I would assume 6 hours of sun a day and derate my panels by 30% to allow for seasonal variations.

Let's put this into some perspective:

Your shack draws an average of 1.5 amps per hour, over 24 hours.  That's 36 amp/hours.  Allowing for recharge inefficiency, add 20%, so you need 43 amp/hours per day input to break even.  In six hours that's 7.16 amps of solar panel.  That is roughly a 120 watt solar panel to cover all the fudge factors.

Drop your hours of operation to a more rational figure like 6 to 8 hours and you can see that you would save a lot in panel size, although in general, your battery bank is sized on your estimated days w/out significant sun, assuming you won't just switch on a battery charger.

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KD8NGE
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Posts: 35




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« Reply #19 on: May 09, 2011, 08:46:47 PM »

Here is how mine is set up:
I have two deep cycle marine batteries powering my shack.
A third deep cycle marine battery starts my generator.  Over kill, yes, but it's on a trickle charger and also connected to my two shack batts. Each batt has a DPDT knife switch to cut each battery out if need be.
My shack has 12 volt LED lighting and a 110V inverter which allows me to charge the HT via wall wart or 12 volt plug as I choose.
Was I to participate in Field Day it would be with one of the deep cycle marine batteries, preferably with a built in handle.  Those suckers are not light.
One additional advantage to the marine batteries:  they often have threaded posts and wing nuts for connecting a 12 volt trolling motor, and are just dandy for connecting your power lines:  drop the ring terminal over the bolt, tighten the wing nut, you're on!
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KE4DRN
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« Reply #20 on: May 23, 2011, 08:53:59 PM »

hi,

here is an article in QST, Jun 2006 -  (Pg. 44)
about using a Hydrogen fuel cell for field day.


73 james
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K1CJS
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Posts: 5884




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« Reply #21 on: May 27, 2011, 11:39:39 AM »

Just for general consumption here, even if you have a deep cycle battery without wingnut posts, or if you have a regular car battery, there are terminal connectors made that clamp over the regular post and have a short stud with wingnuts on them.  

I have an older APC 800RT backup system for my computers, and I've modified it so I can use a couple of older car batteries for the backup power source.  Those terminals are what I used to connect them up.
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W6RMK
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Posts: 649




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« Reply #22 on: May 27, 2011, 02:35:31 PM »

<quote>I have an older APC 800RT backup system for my computers, and I've modified it so I can use a couple of older car batteries for the backup power source.  Those terminals are what I used to connect them up.</quote>

Might want to do a test and see if it overheats when run for a while.  A lot of UPSes are designed for 20 minutes of run time, and then they get too hot. Particularly the inexpensive ones you see at the bigbox stores, because they're very price sensitive, so they don't spend any more on heatsinks and/or fans and/or overtemperature shutdown circuit parts than they have to.

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NX5MK
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Posts: 65




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« Reply #23 on: May 28, 2011, 08:33:43 AM »

Has anyone researched the options for hand crank generators, which (theoretically) provide a never ending power supply, are truly independent of any sunshine or wind power and have the added benefit of keeping us fit?
All I found was some website with a Chinese hand crank generator and I know that Barrett offers one, they are certainly no-nonsense products.

Is there anything a scale smaller, meaning - weighing less than 20 pounds plus?

Does anyone have an idea of a fair price for one of these hand crank generators?

73, Marcus
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W3LK
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Posts: 5644




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« Reply #24 on: May 28, 2011, 12:12:29 PM »

Has anyone researched the options for hand crank generators, which (theoretically) provide a never ending power supply, are truly independent of any sunshine or wind power and have the added benefit of keeping us fit?
All I found was some website with a Chinese hand crank generator and I know that Barrett offers one, they are certainly no-nonsense products.

Is there anything a scale smaller, meaning - weighing less than 20 pounds plus?

Does anyone have an idea of a fair price for one of these hand crank generators?

73, Marcus

And how many hours are YOU willing to crank one of them? I've done it and my arms were toast after an hour. Last ditch emergency power is one thing; Field Day is another.
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K7RBW
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Posts: 386




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« Reply #25 on: May 28, 2011, 06:31:41 PM »

It seems like a more practical option would be to make it "Foot cranked" like a stationary bicycle. That would keep your hands free to work the radio (and keep you in shape, too!)

I can just imagine how an EOC so equipped would look like the spinning class at the local gym Smiley
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WB6BYU
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Posts: 13029




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« Reply #26 on: May 28, 2011, 07:35:34 PM »

An exercise bicycle (or standard bike with the rear wheel elevated) and the wheel driving a roller on
the shaft of a 24VDC motor does the job.  You also need a shunt voltage limiter for when the person
pedaling gets too enthusiastic at the very beginning (it doesn't last long!)  We've used it a few times
for "natural powered" contacts driving a QRP rig directly, but a better approach is to use it to charge
a battery.  Seems to me with an appropriate gear ratio we could get 2A or more out of it over a
reasonable period of time (or about 5A max), which will keep the station on the air for quite a while
if it doesn't draw excessive current.

Whether it makes sense for Field Day depends on the physical condition of your club members.  But
for emergency backup, where a few hours of pedaling can provide a day's worth of power if you
are thrifty with it, it's not a bad approach.  Especially for something like a shelter where there are
lots of people without much to do anyway.
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NX5MK
Member

Posts: 65




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« Reply #27 on: May 29, 2011, 02:01:35 AM »

Thank you for your replies!

Yes, I am most certainly willing to crank one of the generators, we have a far too sedentary lifestyle anyway. Additionally, I would not be dependent on any other power sources.

The only bicycle powered generator I have found until now is:
http://www.econvergence.net/electroacc.htm

Any other suggestions?
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W3LK
Member

Posts: 5644




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« Reply #28 on: May 29, 2011, 01:47:00 PM »

Thank you for your replies!

Yes, I am most certainly willing to crank one of the generators, we have a far too sedentary lifestyle anyway. Additionally, I would not be dependent on any other power sources.


Obviously, you have never actually done it, then. <g>
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KB1GMX
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Posts: 714




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« Reply #29 on: May 30, 2011, 10:20:27 AM »

By shear luck I got ten 150Ah wet NiCd cells in excellent condition.  My 20W panel keeps them
up.  After heavy use a charger does its work.  The ten of them are not portable though as single
units they are about 12 pounds.  Because they are units moving them is for short distances is
not outside the possible.   They give the home station main and emergency power.

For field use I generally use a 30AH tractor battery and if sun is available 4 of the "Volkswagon"
3W panels in parallel (measures out to 14W in the sun).  The goal with solar is to offset receiver
drain and maybe a bit more.  This has worked very well for field day use running my Tentec 6&2
(6&2M 20w TX).  IF I run amps at 100W or more then the battery need grows greatly as those
suck down 15-20A on peaks plus the radio.  The use of solar to offset receiver (typical 1A at 12V)
makes the panel size manageable from a a cost perspective yet allows whatever battery chosen to
give far better life as TX support.  An additional advantage of small solar that is sized such is that
a charge controller is not required, though battery metering (Voltage, Current) is advised as over
current on charge is bad for the battery (14W of solar and a 8Ah gell cell for example) and running
the battery down below 10.5V (assuming the radio will still run that low) will excessively discharge
it.

I have experimented with Lithium based batteries and they give a great power to weight ratio
and a high cost to power figure.  Also charging them REQUIRES the proper charger regardless
of the  source (AC line, automotive or Solar).  However for frequent portable especially backpack
work where weight is everything this is the power of choice.



Allison
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