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Li Poly battery resuscitated

My friend and I were out at the field when he tried to turn on his electric motor, the battery gave no response. Checking, the 3S Kokam had only about 2.0 V in it.

We had been admonished never run Li Polies below 9 volts for a 3S pack. Then the 2 V becomes about 0.7 V per cell. Way too low. He remembered that in haste because of a threatening thundershower, he neglected to turn off the battery and remove it from his airplane.

We tried to recharge the battery out on his open patio deck with a long extension cord. At first the Triton charger had the error warnings 2 - 3 times. We persisted and the battery began to come up to voltage slowly. Finally it was brought up to 12.66 V.

Took the plane out the next day for a couple of 12 minute test flights, battery OK. Remember, the battery was drained over a period of 2 days. Could this recovery happen if the battery was drained to such a level during flight?

Hope I'm not being long winded, Wan

Reply to
Wan
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One question, Wan. You say the resusitated battery gives 12 minute flights. How long was the typical run time before the 'incident'? I have a 2 cell pack that i inadvertantly ran down to

2.35V per cell, and now the pack is hosed, and gives roughly half the run time it did before.

Bill(oc)

Reply to
Bill Sheppard

Bill,

My friend's battery typically gave three 10 minute flights before the failure occurred. When he flew the plane for two 12 minute flights, it checked out to still have about 11.44 V, enough for another flight. We left because of gusty winds.

I am not an expert on Li Poly batteries, but perhaps your battery was run down during flight, a faster discharge, instead of a slow drain? That was my question. Would the recovery happen if the battery was overdischarged during flight?

Wan

Wan

Reply to
Wan

Ash, I'm almost certain the rate of discharge has something to do with the battery's recovery after it was drained below the recommended level. Because my friend took his plane for a few flights today, totalling about 25 minutes on the same battery.

Wan

Reply to
Wan

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