NiMH Self-Recharging Effect??? - RC Groups
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Dec 28, 2003, 06:08 PM
Trying to defy gravity...
jimsky's Avatar

NiMH Self-Recharging Effect???

OK, pulled off my first real day of flying today with my Slow Stick. I was able to run a Powerizer NiMH battery pack (8 cell @ 1100maH) down until the ESC shutoff. Must have flown for about 20 minutes with varying throttle settings.

Wanting to know what the actual cutoff voltage was I measured the battery voltage when I got home, but found the battery "self-recharged" and it read 10.38 volts using a high impedance digital handheld volt meter. I know some capacitors can have a self recharge effect, but is this behavior typical for NiMH batteries?
Last edited by jimsky; Dec 28, 2003 at 06:13 PM.
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Dec 28, 2003, 06:29 PM
Right Honorable Member
flatfour's Avatar
Yes, this is typical for NiCd and NiMh cells.
If you try to run the pack again without recharging, you will find it quite dead.

If you want to know the cutoff, you will have to connect a meter while the motor is running. The voltage will jump up quickly after the load is removed.
Dec 28, 2003, 07:08 PM
Trying to defy gravity...
jimsky's Avatar
Thanks, for the quick answer.
Dec 29, 2003, 03:31 AM
Registered User
It's not really "recharging" it's just that the high load current drags the battery voltage down. When the load is removed the voltage recovers but the battery still has very little charge in.

That's just one of the reasons why you can't tell how much capacity is left in a battery by measuring the voltage .