[Bodywerks]

So there's all this talk about "how do you know if your A123's have enough charge?". You also get the "I don't want to haul a battery to the field and fuss with hooking up a bunch of chargers" argument.
Well, what if you had a self-contained unit that is no more complicated that a field tote box to take to the field? And what if you just hooked your batteries up to a charge after every flight? Even at a 1C charge, we are talking about a 10-15 minute wait, here.
So let's say that this is starting to look like a solution, but you don't want to have to yank the charge-tote out of the trailer to hook the supply battery up to a charger - just another thing to deal with every weekend. This is a valid concern, and I may have come up with a solution: a solar-powered charger, deep-cycle battery, and battery charger all in one!
The panel works in clouds or clear sky, and puts a constant 1/2amp trickle charge to the battery, which is monitored by a solar charge controller to maintain the battery's charge. The monitor also has a power outlet port that is controlled by an on/off switch. I plugged a Fromeco IonCube directly to this so I can turn the charger on and off as needed.
The Ioncube is a multiple port battery charger, capable of charging all your aircraft batteries at the same time (it works with common ground systems), and has an output of up to 2.9 amps per port. It is also very small and fits snuggly into a small space.
So now, All I do is wheel this thing out to the field and put it in the sun whether I am using it or not so the battery can stay charged. After a flight, I roll it up to the plane, plug the leads in, and charge - no fumbling with 3 separate chargers and a loose 12V battery. Simple!

[In-N-Out]

Thats pretty cool. What did the solar panel cost? I thought they were pretty pricey.

[Gmoney]

JB and I were talking about that bery thing just a couple weeks back.. Man you are a MAN of action.. Maybe some more specs on what marine batt you used and some basic dimensions for others to build one.. I wonder If you could get a big enough batt and solar panel to keep up with 10S packs?

G

[Mithrandir]

I was gonna put the solar cells on the wings!!!

[Bodywerks]

Originally Posted by Gmoney

JB and I were talking about that bery thing just a couple weeks back.. Man you are a MAN of action.. Maybe some more specs on what marine batt you used and some basic dimensions for others to build one.. I wonder If you could get a big enough batt and solar panel to keep up with 10S packs?

G

You'd need about a 6'X6' solar panel and HUGE marine battery - would make for a pretty big tote box!
Once I decide that the thing actually works, I'll get more into specifics. I didn't really put anything down on paper, and I kinda improvised as I went. I posted this more as an idea/concept than a how-to.

[BBP]

Nick,

Cool box man!

I had a 1 1/2foot X 3foot panel on the roof of my trailer with a marine battery. Lets say over the period of a weekend I charge 3 flight batteries for a total of let estimate 5000mah including ignition and I fly the Heli 3 times and charge those batts and lets say the 3 lipos were 1600 mah each for a total of 4800 for a grand total of 9800MAH

Even with that larger panel it would take a week to get that battery back up to 14 volts

I am just wondering with the size of your panel which appears to be about 18X18 how it will keep up. Lets guess 400 mah for flight batts and 200 mah for ignition per flight lets say 10 flights over a weekend is 6000 mah not including charging lipos for foam and not leaving this cart in the sun for the week how this will work out for you. That is 1/2 the size of the panel that I had and that panel could barely keep up and it was in the sun all week long on top of the trailer.

I hope it works out, but what I generally had to do on those long weekends at Rabbit or Fresno...was start a generator and plug a charger in to charge the battery. Because even the larger panel could not keep up. I even did this at home sometimes because I used it more than usual. As my kids will sometimes watch a movie off of the inverter. This occurred a lot during the winter months as the days are shorter. It would be cool if you could monitor the mah that was being put back into the battery in the duration of time that you are at the field for the day, under perfect solar conditions I would be surprised if it was over 300mah over a 6 hour stay at the field.

I concluded for myself anyway that this was not worth the trouble, and I just plug the trailer in at night after flying with a regulated charger that cost about 30 bucks and not worry about it. Unplug the next day and go. However with your cart you can obviously wheel it into the garage and charge overnight.

Brian

[King]

You did a nive job constructing that Nick...keep us up on how well it works out....I keep two batts in the van all the time and recharge them every couple of weeks...I've all ways thought of a solor recharger for them, like form Harbor Frieght...

[Bodywerks]

BBP, Thanks for your experiences. I honestly don't know if my setup will be truly "self-sustaining". But I did plan it around a single 40% plane, charging for two flights a day during an IMAC contest, and maybe 3 flights a day when I practice.
Personally, the solar panel is not my main motivation for building this box. I really just didn't want a loose battery, or have to use 3 separate chargers that I have to clamp to the loose battery.
I like the fact that the Fromeco IonCube is a multi-port charger that is no bigger than about pint box of milk, and that it functions properly with common-ground power systems in our airplanes, so all batteries can be charged at once. I liked that I was able to fit all this stuff into a small, easily transported tote box, and all I have to do is plug the charger into the plane and press start.
The solar panel idea is a concept at this point. But I do like that the solar-charge controller has its own power output port with an on/off switch to control the power to the IonCube, as well as reverse-polarity and over-current protection
If the solar panel will not keep the battery up, it will at least keep pumping voltage into it, which will increase the life of the battery (my understanding is that you don't want to let deep-cycle batteries self-discharge).
I have a regular battery charger at home if need be. And I do already know that the 18ah battery is more than enough to support recharging two 40%ers over an entire weekend, which is really all I expected.
BTW, according to the solar-panel specs, it puts out 500mah at 14V

[Ground Pounder]

Just a comment on marine or deep cycle batteries. You should take a look a AGM (absorbent glass mat) batteries. They are designed for repeated deep cycle applications and are more applicable to both electric flight as well as field charging larger gas birds. I have used a 18 amp and a 35 amp battery for several months. A pro and con discussion on AGM v marine might be worth while.

[Ground Pounder]

Just as a FYI here is one sample of a AGM from BatteryPlus and a charger (solid state float charger that is sold under several brands).

www.batteriesplus.com/pc-30300-30300-PS-12180NB.aspx

www.batteriesplus.com/pc-36124-117-battery-tender-plus-12v-125ah-deltran-battery-charger-dbt021-0128.aspx