OT: Solar Panel Tests with K1 and A123 Battery

[WD6DBM]

Dear Gang:

I'm a newbie to solar power, but I ran some tests today that I think might be of interest to those thinking of solar operation in the field.

The story so far:  I converted to Buddipole A123 packs for portable operation more than a year ago and have been deliriously happy with them.  However, to my knowledge there were no solar charge controllers available for them when I bought them, and so last year, when I first used a solar panel for Field Day, I tried a using a small 5-watt, ancient glass panel I got at a flea market for $10 and plugged it directly into a gel cell. Though it could not keep up with the K2's power demands, it extended the discharge of the battery.

To the best of my knowledge, an undersized panel can be used directly with a gel cell.  I have read that you do not want to try this with an A123 pack, and I was not going to risk it.    

Buddipole now offers a solar charge controller for the A123 packs.  However, it is currently sold out.  I went with a Genasun GV-5 Li 14.2v controller (NOTE: these are offered at different cut-off voltages so make sure you order the correct one-- Li 14.2v for A123 packs).  The Genasun controller has the added feature of dropping the battery out from the load when it reaches 12v so you don't damage the expensive A123 pack. I much prefer fail-safe features like this that prevent me from doing stoopid (sic) things.    

Today I hooked up my K1 (as a pre-test for the K2) to a dummy load, and had it calling CQ from its memory constantly.  Using a 5w PowerFilm panel (these fold up small and are great for QRP operations in the field), it would not keep up with the K1's power drain at full tilt, about 7W out,as expected.  I then hooked up a 10w PowerFilm panel, and it did keep up with the power drain, essentially keeping the 4s2P pack fully charged as indicated by the Genasun's LED.   I disconnected the panel, and drained the battery a bit, then hooked it up again and it reached full charge as indicated by the LED, while still calling CQ. I confirmed this after the test by hooking up the battery pack to a Cellpro 10s charger which indicated the pack was at full charge.  

I further crash tested the Genasun by disconnecting it from the battery, panel, and load in random order to see if I could destroy it.  I repeated this in every different order I could think of, and still it soldiered on.  Better it get destroyed now than in the heat of the moment on Field Day.    

The 5w panel showed about 300ma of charging current.  The 10w panel showed about 600ma of charging current.  Put in parallel, for 15w, they showed about 850ma of current.  Note:  If you connect multiple panels in parallel you must use blocking diodes.  PowerFilm panels supposedly have these built-in.

The Genasun did its job, showing no current from the panel to the pack when the pack was fully charged.  

This was an "ideal" test, with the panels flat on the ground and near noon.  However, I won't be calling CQ continuously during Field Day, either, and so I think this setup with 15W of panel power may be able to keep up with the K2 at 10 watts, given time talking to visitors, eating, and goofing off.  Time will tell! Ultimately, having a fully-charged battery near the end of the day means night operations, too, but the need for enough excess panel capacity so that the pack will charge during the day even with the radio drawing power.  You'd need more capacity for something other than casual operation. 

If I had it to do over again, I would have bought a 20w panel for use with the K2 (and eventually a KX3), though they are expensive.  A 5w panel might be adequate for a KX1 in the field, but cloud cover, tree cover, limited charging time, and less-than-optimal angle between the sun and the panel all translate into the need for a bigger panel than you might think.

PowerFilm sells a daisy-chain cable for hooking two panels together.  It is expensive, but it does use their water-resistant connectors.

I'd appreciate hearing from others with more experience with portable solar power for the Elecraft rigs. 

I have no financial relationship with any of the companies listed, though I am still seriously in love with Elecraft :-)  

73,

Eric WD6DBM          
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[John King-10]

The connectors on the Powerfilm solar products are Delphi Weatherpack
connectors. They are inexpensive and  readily available.

One source:
http://www.hipoparts.com/weather-pack-2-pin-sealed-wiring-connector-kit/

The link above is for a complete male and female connector pair. The same
place sells the individual piece parts, and the pin extractor tool (handy to
have.)

I have no connection to the above company; Weatherpack connectors are
available from other sources as well.

73,
  john  WA1ABI

Eric WD6DBM said

> PowerFilm sells a daisy-chain cable for hooking two panels together.  It
is expensive, but it does use their water-resistant connectors.
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Barry K3NDM]

Eric,
Don't put a solar panel on a battery without a charge controller! I fried a few batteries on a boat I had by going without a charge controller, and all I had was a good 10 W panel.

I have been using 45-60 Watts of solar panels for the last few Field Days with 2 K2s, an FT-817, and a K1. The battery has been a size 24, ~85 Ah. On this operation, we have had charge controllers, and our battery has been useful for the entire time.

The company that I would have suggested for a charge controller is belly up, but there are a number of sources for marine and RV controller that will work. Additionally, you might try Harbor Freight. They are the folk we got the 45 W worth of panels from.

73,
Barry
K3NDM

----- Original Message -----
From: "eric norris" <[hidden email]>
To: [hidden email]
Sent: Sunday, June 10, 2012 7:18:24 PM
Subject: [Elecraft] OT: Solar Panel Tests with K1 and A123 Battery

Dear Gang:

I'm a newbie to solar power, but I ran some tests today that I think might be of interest to those thinking of solar operation in the field.

The story so far: I converted to Buddipole A123 packs for portable operation more than a year ago and have been deliriously happy with them. However, to my knowledge there were no solar charge controllers available for them when I bought them, and so last year, when I first used a solar panel for Field Day, I tried a using a small 5-watt, ancient glass panel I got at a flea market for $10 and plugged it directly into a gel cell. Though it could not keep up with the K2's power demands, it extended the discharge of the battery.

To the best of my knowledge, an undersized panel can be used directly with a gel cell. I have read that you do not want to try this with an A123 pack, and I was not going to risk it.

Buddipole now offers a solar charge controller for the A123 packs. However, it is currently sold out. I went with a Genasun GV-5 Li 14.2v controller (NOTE: these are offered at different cut-off voltages so make sure you order the correct one-- Li 14.2v for A123 packs). The Genasun controller has the added feature of dropping the battery out from the load when it reaches 12v so you don't damage the expensive A123 pack. I much prefer fail-safe features like this that prevent me from doing stoopid (sic) things.

Today I hooked up my K1 (as a pre-test for the K2) to a dummy load, and had it calling CQ from its memory constantly. Using a 5w PowerFilm panel (these fold up small and are great for QRP operations in the field), it would not keep up with the K1's power drain at full tilt, about 7W out,as expected. I then hooked up a 10w PowerFilm panel, and it did keep up with the power drain, essentially keeping the 4s2P pack fully charged as indicated by the Genasun's LED. I disconnected the panel, and drained the battery a bit, then hooked it up again and it reached full charge as indicated by the LED, while still calling CQ. I confirmed this after the test by hooking up the battery pack to a Cellpro 10s charger which indicated the pack was at full charge.

I further crash tested the Genasun by disconnecting it from the battery, panel, and load in random order to see if I could destroy it. I repeated this in every different order I could think of, and still it soldiered on. Better it get destroyed now than in the heat of the moment on Field Day.

The 5w panel showed about 300ma of charging current. The 10w panel showed about 600ma of charging current. Put in parallel, for 15w, they showed about 850ma of current. Note: If you connect multiple panels in parallel you must use blocking diodes. PowerFilm panels supposedly have these built-in.

The Genasun did its job, showing no current from the panel to the pack when the pack was fully charged.

This was an "ideal" test, with the panels flat on the ground and near noon. However, I won't be calling CQ continuously during Field Day, either, and so I think this setup with 15W of panel power may be able to keep up with the K2 at 10 watts, given time talking to visitors, eating, and goofing off. Time will tell! Ultimately, having a fully-charged battery near the end of the day means night operations, too, but the need for enough excess panel capacity so that the pack will charge during the day even with the radio drawing power. You'd need more capacity for something other than casual operation.

If I had it to do over again, I would have bought a 20w panel for use with the K2 (and eventually a KX3), though they are expensive. A 5w panel might be adequate for a KX1 in the field, but cloud cover, tree cover, limited charging time, and less-than-optimal angle between the sun and the panel all translate into the need for a bigger panel than you might think.

PowerFilm sells a daisy-chain cable for hooking two panels together. It is expensive, but it does use their water-resistant connectors.

I'd appreciate hearing from others with more experience with portable solar power for the Elecraft rigs.

I have no financial relationship with any of the companies listed, though I am still seriously in love with Elecraft :-)

73,

Eric WD6DBM
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft 
Help: http://mailman.qth.net/mmfaq.htm 
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net 
Please help support this email list: http://www.qsl.net/donate.html 
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Ingo Meyer, DK3RED]

Hello Eric,

Like Barry wrote: Don't use your battery without a solar charge controller.
The only (!) situation for connecting the panel direct to the barttery is, if your
transceiver sucks more current in RX mode as your panel can deliver AND (!!!) you pull out
the panel, if you switch off your transceiver. In all other cases use a solar charge
controller. The reasons are following.

Foundation: A solar panel delivers up to 20 or 22 V if the current is low (or zero). Yes,
the voltage drops if you put on a transceiver which sucks a lot of current.

Case 1: But what is happend if you switch your transceiver off? Right, the voltage rise
step by step during charging your battery because the charge current drops slowly. Anytime
the voltage transcends the cut off voltage of the battery (13.8 volts) and the battery
begins to produce gas and/or loses water (also at SLA's). Any loss of water or acid will
reduce the capacity of the battery and will reduce the life time of the battery because
you can not refill water or acid in SLA's. Esacaped acid is visible as white sediment
around the small vents on the upper surface of the battery.

Case 2: If you use a high-performance solar panel, so the current from the panel is
greater than the current to your transceiver. So the battery will charge at all times and
transcends anytime the cut off voltage. Consequences: See case 1.

If you want to use your battery for a long time, please use a solar charge controller.

73/72 de Ingo, DK3RED - Don't forget: the fun is the power!
www.qrp4fun.de - [hidden email]
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[WB4SON]

It is hard to beat the BuddiPole change controller for folding type panels,
or rigid ones that are under 75 watts.  It won't overcharge your battery
and doesn't produce PWM noise, is small, lightweight, and has PowerPole
connectors.  Despite a price increase its still reasonably priced given
what larger/clunky charge controllers sell for.

http://www.buddipole.com/sobaco.html

73, Bob, WB4SON
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html