Electric Tote/Field box options and charging lead batteries?

Does it have to be an actual "Flight box"? A couple of years ago I went to Orchard Supply Hardware and purchased a plastic stacking toolbox with wheels. In the bottom I installed a Die Hard lawn tractor battery. I had a second 7Amp flight box battery installed also but removed it later. I mounted several pairs of power outlets (banana plug type) into the side of the box to allow for multiple chargers to be used at once. The box has enough room with the different stacking trays to carry chargers, various leads and adapters, flight packs, tx, video receivers, small B&W 12v TV, butane soldering pen, and plenty of other crap.

I'm not sure what ya mean by actual flight box? For a 3200mah battery pack (say 3.2 amps).. is it reasonable to assume that if completely depleted (which lipos never are).. a 7amp battery (lead acid calcium) would only be able to charge it about 2.1 times or so, but probably alot more in reality? (Debating whether to go bigger batter or just do a PSU and hook up to the car battery while the car is running. I dont really want to touch the car, but I'm not sure, I'm also thinking i probably wont charge more than maybe one or two times at the field anyway)

I ended up picking up the Ultra Tote, as its smaller and i figure i can line one of the drawers with ceramic tiles for fire proofing the drawer that ill use to charge the lipos in at the field or at home on the kitchen counter. I'm also betting i can easily throw a fan in there to keep things from getting hot in the sunlight.

Cheerio

Why not save the drawer and just charge the lipo's outside of the tote? A small Pyrex bowl/measuring cup or a piece of the foil backed insulation used to build furnace ducts can safely hold the battery while charging.

I've been looking at the same solution too.

For me, 20aH would be ideal for a field charger battery.

If you go the Tower route, you can do 2 7aH batteries and get 14aH fo a decent price.

If you do the math though, 14aH ain't much.

The other question I have is how to properly keep the field box o float charge so it is always at the ready

-- stone_ax

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Harbor Freight sells a float charger, #42292.

To me, the gel cell batteries have such low self discharge, charge them after you get home, and if you want that extra 1/2 amp hour, then you can put it on charge a half hour before you leave. Really, that is all it takes.

Is it not safe to put a lead calcium battery on its say 600mah to

Are you saying the gel cell batteries are better suited for continuous charging?

"markm75" wrote

I would not consider 600 miliamps a trickle charge, at all, for a 7 amp hour battery. 7 milliamps would be a trickle charge.

No, not at all. You are not understanding what I am telling you, or I am not understanding what you are asking.

It is safe to charge with an AC adapter, as long as you stop it after the correct time. Not continuously, at the rates you suggested, though.

That is the trick; knowing the correct time to stop the charge. If you guess wrong, overcharging it will kill it dead as a doorknob. No joke.

If you charge it at one amp, and it is drained, it will take a hair under 8 hours. Figure capacity x time, or a 7amp hour battery charging at one amp =

Now, let's say your battery is not completely dead. How much capacity is left in it? You have to guess. If you guess it is half dead, and charge it for about 4 hours at one amp, no problems. If it was only a quarter dead and you charge it for 4 hours, it has taken one more step into the trash can.

That is why you need a float charger; so the charger can read how the charge is progressing, and then stop the charge at the appropriate time.

I think there is still a problem with your understanding. You do not need to continuously charge it to keep it ready to use. If you fully charge it when you get home from the field, and let it sit for a month, it is not going to be discharged enough to even be able to notice. Really. Even for two or three months. They hold a charge while sitting around, even better than a car battery; much better. If you want to put that last little bit back in, put it on charge for a half hour, but not much more, or else you are over charging it, and it has taken that first step into the trash can, again.

Long to short, go buy a float charger, and keep from killing your batteries. You will end up killing them (multiple batteries, if I remember correctly) if you do not use a float charger. Pretty foolish to save the 20 bucks or less for the float charger, and instead buy twice as many batteries over a period of time, don't you think?

Excellent point. Reason why I asked in such a way was because here in the house I will have my ultra tote with the lead acid battery and the cell pro charger.. Someone in another forum said they charged their lead battery while using the cell pro (off of the same lead acid battery) safely and all the time, this way they could charge their lipos in house and on the field have a fully charged battery ready for action, perhaps he left out the fact he was using a float charger :)

I checked on the float mentioned before and yeah.. its only $7 plus shipping.. very nice.

I wont be using a PSU to power the cell pro in house, hence all the questions.. I'm trying to keep things as simple/ready for action as possible.

So I basically wont need the existing charger I have.. the 600mah one.. unless I need fast charging and I check the voltage periodically to see if full (what would full be considered on a 12v battery.. ie:

Any idea how fast the float charger charges (i'm guessing over night, like 14 hours full charge?) The one from harbor freight doesnt list many specs on it. Although the speed with this one isnt really that important, as it will just remain plugged in 24/7 pretty much, unless I take the box out to the field.

Sorry for the misunderstanding.. I dont think I was fully explaining my "vision" of things either.

| It is safe to charge with an AC adapter, as long as you stop it after the | correct time.

To be fair, that's true of almost any charger. Even charging LiPos with a NiCd charger is safe if you pick an appropriate charge rate and stop it at the correct time.

The magic is in stopping at the correct time. Alas, even if you can do it 95% of the time, that still leaves 5% of the time that you ruin your battery (and maybe start a fire.)

| That is the trick; knowing the correct time to stop the charge. If you | guess wrong, overcharging it will kill it dead as a doorknob. No joke.

Well, it takes a lot of overcharging to burn off the electrolyte -- a little won't ruin it, just damage it a bit.

| Now, let's say your battery is not completely dead. How much capacity is | left in it? You have to guess.

No, you don't (have to guess.) You can measure it. Unlike NiCd and NiMH cells, you can determine the charge status of a gel cell battery by simply measuring it.

I forget the exact values, but I think it's around 13.0 to 13.5 volts for fully charged and 11.0 to 12.0 volts for mostly discharged. (These values are measured when the battery is not on a charger or load.) And it's pretty linear -- a voltage halfway between the fully charged and fully discharged voltages indicates a battery that is approximately half charged.

I'd have to take some measurements to know the exact values, however.

| That is why you need a float charger; so the charger can read how the charge | is progressing, and then stop the charge at the appropriate time.

Yup, you want a float charger. Or you can charge it with a charger like the Triton, if you have another power supply for the Triton.

But float chargers are cheap.

| Long to short, go buy a float charger, and keep from killing your batteries. | You will end up killing them (multiple batteries, if I remember correctly) | if you do not use a float charger.

I also forget the specifics, but gel cells are somewhat different than car batteries, and a float charger for a car battery may not be exactly right for a gel cell -- I think they'll charge it slightly too high.

"markm75" > wrote

Good plan, with using the extra power to the battery, only when you have high drain. As far as what the voltage should be, I don't recall. Perhaps someone can jump in with that, or go over to Red's battery clinic and ask.

Perhaps up to two amps, but you could check it pretty easily.

I would not leave it on all of the time, as it could still over charge, slightly.

Try charging it with the float charger, take it off the charge and check the voltage a couple hours later. Then wait a week and check the voltage. I'll bet it is high enough that you will not be concerned with having to keep it on charge all of the time.

After you charge it, get a 24 hour timer, (and plug the charger into that) and set it so it turns on once a day for one hour. That will be plenty long to keep it charged, and will not overcharge, that way.

| That is why you need a float charger; so the charger can read how th

charge | is progressing, and then stop the charge at the appropriate time.

Yup, you want a float charger. Or you can charge it with a charger like the Triton, if you have another power supply for the Triton.

But float chargers are cheap.

After reading around in other forums I am now confused on this whol float charger or not concept..

Other forums say its perfectly fine to keep the 12v lead calciu battery on an AC trickle charger (600mah on a 7amp hour battery continously.. in fact, the local hobby shop had no idea what a floa charger was and said that they always use the trickle charger even al the time.

-- markm7

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