bustanut666

Hi,

One of my Turnigy 2c 5000mah lipos are no longer balanced. I always balance charge the batteries. One cell says 3.80 and the other at 4.2.. i tried balance charging it several times with my Thunder AC6 but it still not at 4.2 on both. I only put it for like 2 hours and its charging at small rate like 0.1A so then i turned it off.

My question is it safe to let the thing charge for like 10+ hours or how ever long it will take to hopefully balance out. This is my first lipo and i was told i should watch it like a hawk when charging before it blows up, etc... But keeping my eyes on it for 10+ hours is a challenge.. Or should i run the battery on the car and then try to recharge it? or should i just do a regular charge.. dunno.. HELP.. thanks..

huck1199

Why do you think it will take 10 hours?

bustanut666

well i charged it for 3+ hours and it only went from 3.80 to barely 3.82... its charging at low rate like .1a because i think it detected the other cell is already full at 4.2

huck1199

Are you sure you have the proper parameters set for your charger?  If you have a balancer try using it to discharge the high cell and then charge the pack.

bustanut666

there isn't many options.. you can choose how many amps to discharge and how low... but u can't individually select a cell (4.2)

i think the battery is gone.. i plugged it in again today and it went down to from 3.8 yesterday to 3.6 today.. just sitting there..

huck1199

Does the charger have a "balance only" option? If not a standalone balancer might come in handy.  How much use does the pack have on it?  It may have been a weak cell that went bad with use,

bustanut666

no balance only option... only had the pack for few weeks.. probably less than 10 charges..

also, FYI.. when i received that lipo.. when i plugged it into the car, it kinda sparked almost everytime.. but ran and charged fine... but kept sparking when it was plugged in initially to the car..

after that, i thought it was maybe a cheap chinese dean connector so i replaced it with an extra one i got... i have already re-solder the deans again to make sure everything looked good..

could the dean connector have something to do with it??

huck1199

I would try to find a friend with a balancer  to bring the two cells to 3.6 and charge it and see what happens.

bustanut666

yeah.. i am new to rc so i don't really know anyone at the track yet..

guver

My Feedback: (325)

The best bet (if the cell or connection isn't damaged) is to charge it to 4.2 volts. Battery is balanced. There's nothing wrong really with charging it for 10 hrs either if you go that way.

mehrshad

try to charge the 3.8v cell directly through the balance connector. (with 2 small needle and beware of shorting them)
go with 0.5C or lower.
sometimes these problems relate to balance cable and connector.(I experienced that)

bustanut666

hmm... i have no clue how to do that.. let me try to do some research on directly charging it...

guver

My Feedback: (325)

Probe the cell that has 3.8 volts thru the balance plug. Those are the two pins that go directly to that cell. One will be common to the main + or - lead. You can charge thru the balance pins if you are careful not to short them out. You can also use the center pin AND (either the + or - lead) depending upon which cell you want to charge, just use the center one and the one that reads 3.8 volts. When done the battery is full and balanced. Don't go over about 1 amp on the balance wires if using pins or needles.

bustanut666

i have a hardcase lipo..

http://www.hobbyking.com/hobbyking/s...dProduct=10098

do i have to open the case up to access the cells?? or do i just put like a paperclip/etc to the balancer plugs to charge the individual cell..

so should it be either the yellow and red wire OR yellow and black wire.. depending on which one is the 3.8 cell??????

guver

My Feedback: (325)

No, you won't have to open it up. You can probe the center (yellow) one with a needle or pin or clip and then the other connection should be just as you said (either the black or the red depending upon which is 3.8) Using the center yellow and then the main lead will prevent a short between two pins. When I use two adjacent pins I always stuff a piece of insulat in between them to keep them apart. I have good luck with large bent sewing needles.

ps mehrshad gives very good info. Be advised that a bad connection inside the battery will appear like a low cell so if you can do some wiggling without shorting out it would be nice to view the voltage while banging the pack on a bench. The imbalance you have is abnormal and very suspect. I would beleive that somethinjg more is going on than just a normal imbalance. Dropping voltage from 3.8 to 3.6 just setting is also very suspect. Be careful.

bustanut666

ok.. not sure if i wanna mess with these lipos as you guys stated.. getting scared they might blow up.. i am new to this lipo stuff and i've seen and read enough on these lipos.. i think i might just get rid of it....

bustanut666

yup.. gonna toss it... give it to radio shack to dispose.. because it keeps dropping cells by just sitting there.. went from 3.8 to 3.6 first day.. then check it again yesterday.. its at 3.4 now..

thanks for all your help everyone.. greatly appreciated..

guver

My Feedback: (325)

Yep, it must have a short inside. If it isn't the connection outside the cell tabs then it's a goner.

drobin

You can get a balancer called "Blinkie". It plugs into the charger plug and can be used charging or alone. It discharges the high cell(s) to the low cell.Cost about $25.