WHOA! battery did something REAL strange!

[A RC Dude]

ok, i was digging out some old stuff and i found my old 6 cell gp pack i used to run b4 i got 3800mah packs whitch was b4 my LiPo. so i decided to sell it but b4 i did i needed to be sure that it worked right first. so i go hook it into a 23T titan motor and it didn't even make a noise. then i hook it up to the super brain and it said that the pack had .50 volts in it! so i set it to charge and then 2 or 3 seconds later i looked at it and it was reading 8.95 volts!!!!! so then i think that couldn't be right!! so to be sure, i take it off the charger and hooked it into the motor agian. this time b4 the wire tuched to motor thare was a HUGE spark and the motor spead up like it was running off 14 volts like when in the e-maxx!!!!!

it was charging at 6.00 amps and for only about 2 seconds! thare's no way it could have gained 8.45 volts in 2 seconds at that setting!!!!!!! but somehow, it apeared that it did.

anyone have a clue how that could have happened???

[glassdoctor]

Might be a simple as a bad solder connection that "fixed" itself with the handling of it...

but more likely it's a bad cell (internal short that was blocking voltage) that woke up when you hooked up the charger, thus allowing the pack voltage to flow again.

I've seen old packs act a bit like this.. they have cells that drop voltage really low, but the voltage goes real high when charged... I can't explain why... only guess.

[BrianG]

Actually, that's normal. What you did was put enough current back in the cell (and it takes very little to do this) to bounce the voltage back up to the cells rated voltage. Sometime, put a pack on a discharger and watch the voltage as it gets near 0.9v/cell. Once it gets at or a little below that, the voltage will drop VERY quickly.. like falling off a cliff quickly.

Your motor spun up fast because a single unloaded motor doesn't have much load, so there is little current. If you were to somehow load the motor, you'd hear the motor slow down really quick.

That said, I would charge the pack slowly to recondition them. If possible, do each cell seperately n case you have several bad cells. Then I'd do a few charge/discharge cycles on the whole pack to get it back up to par. For the whole pack to be that low means it was probably stored for a long time almost depleted. Also, charging heavy currents in a pack that low can cause cell reversal (bad).

EDIT: GD beat me to it.

[jhautz]

Not unusual at all. I had some old GP3300 sitting in a box for the past year and decided I wanted to use them for a rotostart. They read virtually dead like yours when I tested them, but when hooked to a charger (I didnt go 6A right out of the box like you) they peaked very quickly only taking a couple hundered mah of capacity. But you can revive them....

You are best off if the pack has been sitting for a long time is to cycle it 3-4 times with lower than normal currents. Just completely discharge it down to .8 volts/cell and the slowly (like .25amps) charge it again untill it peaks. Then let it rest a bit to cool down and then do the same thing a few more times. The first few cycles wont take long as the capacity will be drastically reduced form sitting for so long, but the last couple you should be getting close to theier normal capacity again and they will take longer. After that you can go back to your normal high amp charging as you always did. You will get most of the pack capacity back by doing this, but an older pack like that usually looses some puch and capacity just from age. They will probably be good starter box or roto start packs now though.


EDIT: Damn brian... you responed while I was typing

[A RC Dude]

thanks guys! i figured it was something like that but i wasn't sure. and yea, it's been sitting for over a year.
EDIT: looks like everyone seems to reply wile the others are typing

[A RC Dude]

Originally Posted by BrianG

Actually, that's normal. What you did was put enough current back in the cell (and it takes very little to do this) to bounce the voltage back up to the cells rated voltage. Sometime, put a pack on a discharger and watch the voltage as it gets near 0.9v/cell. Once it gets at or a little below that, the voltage will drop VERY quickly.. like falling off a cliff quickly.

Your motor spun up fast because a single unloaded motor doesn't have much load, so there is little current. If you were to somehow load the motor, you'd hear the motor slow down really quick.

That said, I would charge the pack slowly to recondition them. If possible, do each cell seperately n case you have several bad cells. Then I'd do a few charge/discharge cycles on the whole pack to get it back up to par. For the whole pack to be that low means it was probably stored for a long time almost depleted. Also, charging heavy currents in a pack that low can cause cell reversal (bad).

EDIT: GD beat me to it.

well the motor did have a load on it. i had it sitting in a little 9.0v lego rc frame lol it broke the ca glue that was holding the lego gear to the shaft.

now, as for why i had it in a lego car, lets just say i got real bored one day wile i was waiting on a part or 2 to come in

[A RC Dude]

well i charged and discharged it about 3 times each. it seems to work fine now! i still haven't tested it in a car tho.

but yesterday i found another pack that has been sitting for probably close to 2 times as long as that one. it's my DTX shark 1500 that i bought 5 years ago! lol just for the heck of it, i hooked it up to my super brain to test it's voltage! it read about 7 volts at first and it started droping rapidly! with in 1 sec it was under .8 of a volt. so i waited and waited for it to ballance out. it got down to .23 volts then fell to .11 in 2 secs. then it started jumping from .11 to .23 then back down agian! it would pop back up to .23 about every 2 seconds or so. i charged it at 2 amps for a second or 2 and then stoped it. i then looked at it's voltage agian. it leveled out at about 6.72 volts and stoped.

I'm guessing it's the same thing as the last one?