some questions about li-polys

[Turbo Tax 1.0]

i have a couple questions about lithium polymer batteries
-can i use them while im charging them
-for people who have used them have you ever had any major problem with them and what charger would you reccomend

these are the batteries i am planning to buy and the charger i am planning to use

lipoly batt
charger

[demonofaj]

Well I used infolithium Sony batteries to power stuff like an led sign for my school, and they work good. Even voltage and a/h. While they charged they lit the led's. About my charger, I hooked them to some broken camcorder and charged it from there.

[nos_slived]

Lithium Polymer: I do not know too much about them, but they are supposed to be lighter, smaller, and last about as long. There are a few downsides to them. For one thing, they can catch on fire if they are not charged with a proper charger. Another problem with them is that they are pretty expensive.

[Reaperman@home]

I've used them in RC aircraft--and have been meaning to get more into them as far as micro cars. But there is some danger in them. As batteries discharge their voltage drops. But unlike most batteries, if you discharge lipos below a critical voltage, *serious* damage to the battery occurrs.

Usually you just ruin a battery, but if you do it badly enough, the case begins to swell until it 'can no longer contain its insides'. and you get a small explosion of unhappy chemicals.

If you notice, most lipo devices come with a handy LED--if that LED goes off (or stops blinking, or whatever it does), you stop using your batteries quick because you like your hands. Expect to be building something to indicate dangerous battery voltage. Some larger Lipos come with an auto cutoff--I'd find out by reading rather than discharging. Typically a lipo cell starts ~4.2 volts and is to be cut off from further discharge at 3.0 volts. Store them full (you'll notice they're shipped with at least 30% charge)

also charge them individually if you're using more than one. Unless you have a "good" lipo charger.

as far as charging any hobby shop will carry a charger for them--as long as they carry electric helicopters. I don't have a good one, just the 15-minute 'wall-wort' charger that came with my chopper. They have some budget combo chargers that will do lipo/nimh/nicd for $75+, but if all you need is lipo, you can get a slow one like mine for ~$15-20--it looks like what you linked to is fine.

[Turbo Tax 1.0]

sorry bout bringin this back up but on the protection pcb it says i need to connect COM what exactly is that? http://www.batteryspace.com/index.asp?P ... rodID=1342

[gannon]

COM is short for Common, which is Ground.

[timmeh87]

If you notice, most lipo devices come with a handy LED--if that LED goes off (or stops blinking, or whatever it does), you stop using your batteries quick because you like your hands. Expect to be building something to indicate dangerous battery voltage. Some larger Lipos come with an auto cutoff--I'd find out by reading rather than discharging.

if you have a properly set up protection circuit, you dont need to know close you are to empty, the protection circuit will shut them off for you. of course, it will shut hem off at like 2.7v or something, so if you can know the voltage and shut them off manually at around 3.0v it will extend the life of your battery.

also, i have sucessfully taken a li-poly back from the brink before (0.6v), but you have to be REALLY CAREFUL.

[Turbo Tax 1.0]

i connected the battery ground to the Com and i still get nothing. is there anything else that it could mean

Edit: what about this diagram it has
it seems like it could mean to connect were the batteries attach to eachother?
EDIT2:yup the diagram is right i just had something else wired wrong, thanks guys for the initial help