"Cell 1 : 2.8v" ???

[bill91]

Just wondering if I've knackered 4 cell pack, Imax B8 is showing Cell1 as 2.8v and the rest as 4.2v, and that’s after a balance charge (quite a bit lower before hand) which would only get going after charging it straight for a couple of minutes (took several attempts to). I think the charger must have been sensing the packs low voltage and so kept cutting out while displaying 'voltage error' etc.

Anyway, not sure if I will finish it of by using it as is so what are the recommendations from those with more knowledge about this sort of thing please? Cycle it?


Thanks

[machasm]

Sounds Knackered to me.
You may find that using a cellpro 10S might breath some life back into it but I wouldn't hold my breath.
Ade.

[Downdraft]

Unlucky mate, sounds to me as if thats had it! If you plan to have a go cycling it be very careful and keep an eye on it at all times, Lipo's can go with a serious bang if overcharged and with one cell badly down on volts the others are going to try and make up the total voltage therefore making them over volt.
The only small chance of recovering the pack is to try a discharge balancer but if you let it get that low on volt's I'd say your chances are poor to none.

[bill91]

Damn, its only been used 15-20 times, Balanced every other charge, could it have come about from over draining it? After a DX6I timer cock up, I had no choice but to strech it to get my EDF back up wind in one piece.

I'll find something fire proof to put it in/on then

Cheers

[machasm]

Damn, its only been used 15-20 times, Balanced every other charge, could it have come about from over draining it? After a DX6I timer cock up, I had no choice but to strech it to get my EDF back up wind in one piece.

I'll find something fire proof to put it in/on then

Cheers

Could have been the case.
Over discharging is never a good thing with Lipos.

[Downdraft]

Damn, its only been used 15-20 times, Balanced every other charge, could it have come about from over draining it? After a DX6I timer cock up, I had no choice but to strech it to get my EDF back up wind in one piece.

Yep that will defo kill one, the rule is don't allow Lipo's to drop below 3.1 volts and they will serve you well.
You should'nt have to put back more than %80 of your total cell pack, so if it's a 4000Mah pack you should only be putting in around 3000Mah.

[express]

have a go at charging that cell as a single cell throw the balance lead
i did that on a 4 cell pack and it fine now

[bill91]

Could have been the case.
Over discharging is never a good thing with Lipos.

Thanks, thought so.

I do my best to avoid it, but it was either a 40quids worth of Lipo, or 250 of plane, quite a bit of wind to fight through to, still, my fault for not resetting the timer after the first pack was up.

[bill91]

Yep that will defo kill one, the rule is don't allow Lipo's to drop below 3.1 volts and they will serve you well.
You should'nt have to put back more than %80 of your total cell pack, so if it's a 4000Mah pack you should only be putting in around 3000Mah.

Its a 3000, 35c discharge. I usually put back 2000 +/- after 6 mins of flying

have a go at charging that cell as a single cell throw the balance lead
i did that on a 4 cell pack and it fine now

Thanks, I'll see what I can rig up for it.

[Mojo]

Could have been the case.
Over discharging is never a good thing with Lipos.

As Ade suggests.. Try a Cellpro, even a 4S.. Happened at my field to one of the club members and the 4S restored his discharged cell, when all other chargers would not.. And it was fine afterwards.. Worth a try

[bill91]

As Ade suggests.. Try a Cellpro, even a 4S.. Happened at my field to one of the club members and the 4S restored his discharged cell, when all other chargers would not.. And it was fine afterwards.. Worth a try

Last night I took a 4S balance lead extension and took some insulation of each wire, connected it to the packs own balance plug and using a crocky clip adapter from the B8 I was able to charge them all individually although they are all charged up to 4.2V now which seems a little high unless the chargers volt meter is a little of the mark (Skyrc, Imax).

Thanks for the help all, I may try it back in the EDF when the wind calms, I could also cylce it as a test before hand.

[unwind-protect]

4.2V is spot on. Take care when you next discharge it that the offending cell does not dip below 3.0V; IME once a cell's taken a beating it'll tend to discharge faster than the rest.