My LiPo sucks, son (cell or connector issue?)

[The Notorious Flank Sucker]

Apologies for posting in this section, apparently I don't have permission to post it where I thought it belonged in the Doctor's Corner.

I have an 11.1V lipo that I can't balance charge. I got it second-hand and don't know anything about it's history. My Hitec X1 AC charger gives me a 'balance connector error' when I connect it and try to balance charge. I can normal charge it (non-balance), but the pack begins to swell pretty quickly so I have to stop.

I've put my multimeter on the end of the balance connector, with the ground probe attached to the pack's ground terminal and this is what I got:

Red wire (cells 1, 2 & 3): 9V
Blue wire (cells 1 & 2): 4.5V
Yellow wire (cell 1): 0V

I unwrapped the top of the pack to get at the wired connections on the PCB. Even touching the probe directly to the yellow wire's connection on the board gets a 0V reading.

So here come the newb questions:

- is cell 1 dead?
- …and if so, does it make sense that the other cells are reading 4.5V each?
(I originally assumed 9V across all 3 cells meant that each one was reading 3V, so the cells must be fine and there's just a connector or wire problem.)
- …and if not, what's likely going on?
- what's happening when I regular charge the pack - are the two 'good' cells getting overcharged and causing the swelling?

Any tips or guidance greatly appreciated!

[lurkingknight]

if one cell is reading 0v, the pack is dead. don't try to charge it normally without balancing it unless you want a fire. swelling is a precursor to possible ignition. the pack is garbage. use your charge to discharge to safe levels and dispose of it. You can't save this pack.

[The Notorious Flank Sucker]

Thanks for the advice!

I have no problem with tossing the pack, but I would like a better idea of what's happening so I can better understand what my troubleshooting is telling me.

Is one cell dead, or is there more to this story?

[RainyEyes]

Originally Posted by The Notorious Flank Sucker

Thanks for the advice!

I have no problem with tossing the pack, but I would like a better idea of what's happening so I can better understand what my troubleshooting is telling me.

Is one cell dead, or is there more to this story?

Cells 2 and 3 are probably around 4.5v each (maths how i loathe you).

Cell 1 is dead so that is why there's a 0 charge and also the reason why you're getting a charge error.

Was the one cell recently pierced, damaged, or somehow defective in some way?

I'm not an expert but there could still be a way to salvage the remaining 2 cells but the cost of labour by a hobby shop tech is probably not worth it since it may be cheaper to get a new one.

A sales rep at Pinnacle Hobbies said something about trying to connect them 3 times max and anything beyond that the cell is finished. Can't remember exactly what was said.

[ThunderCactus]

At $12 a battery, salvaging a damaged lipo isnt worth the risk of burning your house down.
Discharge it, safely dispose of it, and just get new batteries =)

[lurkingknight]

it's also possible the cell was never brought up to initial charge after it came out of the factory, which has happened before. I know of people who HAVE brought 0v cells to life, however the other cells in their pack were healthy, these people had precision tools and chargers to monitor everything, but they still ended up throwing the pack out after testing to be on the safe side.


The problem with THIS particular pack is that if those cells are at 4.5V that is grossly overcharged as 4.2 is the max safe voltage.

Originally Posted by RainyEyes

Cells 2 and 3 are probably around 4.5v each (maths how i loathe you).

Cell 1 is dead so that is why there's a 0 charge and also the reason why you're getting a charge error.

Was the one cell recently pierced, damaged, or somehow defective in some way?

I'm not an expert but there could still be a way to salvage the remaining 2 cells but the cost of labour by a hobby shop tech is probably not worth it since it may be cheaper to get a new one.

A sales rep at Pinnacle Hobbies said something about trying to connect them 3 times max and anything beyond that the cell is finished. Can't remember exactly what was said.

[SuperHog]

Assuming you don't know the history of that used Lipo, the owner dumped it because it no longer works for him.

Your Hitec charger is a smart charger, and chances the previous owner used a basic dumb charger which already damaged the cells.

If you are getting 3V, the battery are at the lowest point before recovery. Also if the previous owner could have discharged them below 3V many times will result in a junk pack now.

Best to toss it instead of risking burning down your house or gun.

[RainyEyes]

Originally Posted by ThunderCactus

At $12 a battery, salvaging a damaged lipo isnt worth the risk of burning your house down.
Discharge it, safely dispose of it, and just get new batteries =)

Please tell me where you buy said batteries because I just spent 90 cad importing them from hobbyking

67 for 2 butterfly lipos and the. Another 30 for brokerage because FedEx.

[The Notorious Flank Sucker]

Originally Posted by RainyEyes

Please tell me where you buy said batteries because I just spent 90 cad importing them from hobbyking

67 for 2 butterfly lipos and the. Another 30 for brokerage because FedEx.

I too would love to know this magical source of $12 batteries. The ones I need are PEQ-size, 11.1V units. Cheapest I've found is $30-35 through local or semi-local sources.

Regardless, since this post keeps getting resurrected I should probably put this to rest: the battery in question has been discharged as per lurkingknight's recommendation, and it will be recycled shortly.

Thanks to everyone for the insights. Although I know my way around a multimeter, how that knowledge applies to batteries is obviously something I'm just figuring out.

[ThunderCactus]

last time I ordered batteries from hobbyking I'm pretty sure my 3s 1200mah stick batteries ended up being like $15/each landed cost.
They're usually like $9.something USD on the site.

[cetane]

I've never paid a dime brokerage for FedEx from hobbyking orders yet... our peso just so low now :-/

[RainyEyes]

Originally Posted by cetane

I've never paid a dime brokerage for FedEx from hobbyking orders yet... our peso just so low now :-/

Total after shipping:


Customs/brokerage:


My face when I see my credit card bill this month:

[ThunderCactus]

fedex tagged me for brokerage on whatever I bought last, too. Think it cost me more than the item was worth.
Solution? Don't ship fedex.

[Datawraith]

UPS got their hand slapped for doing this. Hopefully they'll turn their attention to fedEx and other mailing services for doing this too.

[ThunderCactus]

by "hand slapped" I hope you mean a multi million dollar fine and class action lawsuit. Cause fuck those guys.