li-po Battery question

[jevyguy]

I use a have a mamba brushless system that I run li-po 2 cell 2100maH battery with and I can't seem to get it right.
I charged the battery and ran it until the ESP made the truck stop at 6volts. I waited for the battery to cool down before I tried to charge it, but now I get a battery fault signal from my charger (which also happend to me about 4 months ago). My question: Is it the charger or the battery? Does the battery need to be drained more then what the mamba kit will do, or do I need to get a better charger? Any help would be nice

[slobin3d]

over discarging you battery will cause the fault you might try going into the mamba settings and bump the minimum voltage up a notch or two up to 6.6 volts. i know a trick for revive a lipo (caution, though if the batt is damaged in any way dont try. and always keep a close eye on it as it charges) you can charge it as a 7.2 nimh for about 5 seconds to get the voltage back upt to minumum. but like i said be very carefull and watch your batt very close.

As a rule lipos dont like or need to be cycled like a micd/mh battery would they need to maintain a minimum voltage to prevent premature death of the cells as well extreme over discharging or improper charging can cause the pack to explode in this nice naplm like stuff

[slobin3d]

what charger is it and what do you have it set at?

[jevyguy]

Thanks for the info.
So you think that I am discharging the battery too much thus making the charger read batt fault? If I do use your little trick, how many amps do I charge it at for 5 sec?
My charger is a HECell Li-po/Li-on charger set at 2 cells charging it at 2 amps. Is that what I am supposed to charge it at running a 2100maH pack?

[slobin3d]

charger sounds good. if it discarges to exactly 6v then yes its going to far it should stay above 3.3v per cell. ive had it happen a few times with my thunderpower 2100 3c on my super rooster since it has no cut off for 10v

[slobin3d]

i was reading the specs again on the mamba and 6v should be right so double check your cut off voltage maybe if you have a voltmeter you could check it and verify that it stops at 6v. the easiest way to play it safe is, when the truck starts to lose power shut it off cause lipos run full juice right to the very end

[slobin3d]

i wouldnt push the batt over 2 amps with the revival trick

[jevyguy]

Thank you thank you. I will try to revive and then let you know how it goes.

Did you say that you were running lipo's with a Novak super rooster esp?? I didn't know you could do that, or are you really not supposed to because there is no cut off voltage?

[slobin3d]

yes i run lipo with a super rooster they're rated at 10cell 12 volt so that is ok but yes there is no cutoff so i have to watch my batt very close. when the power cuts off shut err down works everytime

[jevyguy]

Thats cool about the super rooster. So you drive until it cuts out and looses all power or just until it cuts out once?
Alright so I tried your little revive trick and the battery reads 7.4v, but still wont charge. I tried charging a 3 cell batt that I have and it won't charge either but the wierd thing is the charger lightes up the lights different with both batteries.. I am totally lost.

[slobin3d]

you run until you notice any power drop then shut down.

can you try the packs on another lipo charger to make sure the charger isnt defective? Or it could be that the pack just might be dead which really would suck cause there not cheap.

[jevyguy]

I really don't think that it is the battery because the charger has done this before, and I don't know anyone who has a charger to test my battery with so I will have to figure something out.

[slobin3d]

do you have a local hobby shop they might let you borrow one to test the batts. it it is the charger i would recomend this one http://www2.towerhobbies.com/cgi-bin...=LXCTZ5&P=MLit chargers 1-8 cell nicd/mh and lipo 2 at a time

[Trikster]

If you want to use Lipos on non adjustable cutoff voltages, check in the Parkflyer section of your LHS. You can buy external voltage cutoff systems. There is also a product called the ParkBEC that I think does both LVC and 3 or 5 amp BEC.

[Flash Burns]

Taking Li-Po's down to 3.0v per cell is the absolute minimum. Li-Po's will not last very long taking to full discharge like you are doing. I'd say your pack has cratered. Would not recommend attempting to revive pack via 7.2v charge as you might have a vigorous chemical reaction on your hands real quick. I you do or did already let me know how it turned out for you. Pics of the flames would be nice. LOL There are various batt cutoff devices available on most RC Aircraft sires I would recommend on of those.

[slobin3d]

Originally Posted by slobin3d

(caution, though if the batt is damaged in any way dont try. and always keep a close eye on it as it charges) you can charge it as a 7.2 nimh for about 5 seconds to get the voltage back upt to minumum. but like i said be very carefull and watch your batt very close.

As a rule lipos dont like or need to be cycled like a micd/mh battery would they need to maintain a minimum voltage to prevent premature death of the cells as well extreme over discharging or improper charging can cause the pack to explode in this nice naplm like stuff

like said be very careful, ive done it many times with great luck but like I said be careful cause lipos are very volitile when mistreated
those battery cutoff devices only work if your esc shuts off when minimum voltage is reached, which most car esc's dont shut off at any voltage at least my novak and tekin dont which kinda makes them useless I know ive tried them i have a fma batt guard but it doesnt work on either, but lipos are easy to tell when they are dead they drop power real quick and if you watch for it you should be safe