How to tell if a lipo cell is dead without a balance lead

[Stanley Speel]

Hi,

I recemtly very stupidly shorted a tp 6s lipo by trying to use crocodile clips to connect it to charge, melting the deans connector, and then shorted it again by even more stupidly cutting through both wires at once - melting the pliers!

Anyway, I had just bought a tp to jst xh connector to charge the tewo of them, and the charger says that one cell is dead. I was almost expecting this due to me shorting it. However, the voltage was at 25v. Then I tried my other tp lipo, and it also lists one cell as dead, but still 25v. Is it more likely that both lios have a dead crell, or that the balance adaptor is faulty? If they are at 25v can one cell stull be dead?

Thanks

Stanley

[cjcj1949]

That lipo could be very badly damaged and dangerous, or it might be ok. You need to measure the individual cell voltages. You'll get the most accurate results with a voltmeter. As you have found it is easy and hairy to short out lipos. You'll need to use multimeter probes on the balance connector. It is easy if you don't use meters to allow the two leads to touch while connected to the balance connector. You can prevent this if you insulate most of the probe with sellotape or insulation tape and just leave enough metal to reach into the connector. About 2mm. You will then not be able to short out the cells. You may have a cell that is too low for your charger and it is possible to charge it and it may be ok. If you measure the volts I can give you further advice. Charging could cause a cell to get very very hot and most sensible people would not bother.
As most sensible people don't fly helis you'll probably want to save the cost of a battery. Even if one cell is dead you can convert a 6S into a 5S and still use it with slightly reduced performance. You must video anything you do for posterity.

[Mark_T]

All excellent advice and personally I wouldn't use the pack you've shorted twice.

It does sound like a faulty adapter though, if the total voltage is showing as 25V on a 6S pack then none of the cells can be 'dead'. If the same adapter shows the same problem on two different packs then it suggests the adapter is faulty or perhaps the charger.

[Stanley Speel]

Thanks - Ill get another adaptor as the charger worksfor other lipos.