What is the best way / rate to charge NiMH batteries?

[blue_collar2]

I just got a new MRC superbrain 989 so I can control charge / discharge rates.

I've read stuff suggesting charging NiMH at a rate of 1C (3 amps for a 3000MAh pack) but when I do this I get fewer flights per charge.

Ive read other stuff that recommends 0.1 to 0.5C.

What is the best rate for charge? discharge? What is the best setting for delta mv cutoff during charge?

Thanks much!

[Hughes500Bob]

http://www.powerstream.com/NiMH.htm

Here is a good source for understanding how to properly charge a NiMh battery.

LiPos charge on average 1C (1 amp for each 1000 mAh capacity. NiMh charge on average .1C (1/10th amp for each 1000 mAh capacity) for 150% time factor = 15 hours @ .1C for 1000 mAh capacity.

[ldp1078]

I race carpet cars and still use nimh, we charge at 6-7 amps for 4200 cells. Really puts strain on batterys, to get the maximum voltage.

For my heli I don't do anything like that, I charge at

1.5 amp with peak voltage detect. set @ 10mv. It seems to work pretty good and doesn't take to long to repeak the battery after a couple of flights.

[SilverFoxCPF]

Hello Blue_collar2,

GP has some 3000 mAh cells. They recommend charging at 1500 - 3000 mA with proper charge termination (negative delta V of 5 mV), or a timed charge of 300 mA for 16 hours.

Their specification sheet (http://www.gpbatteries.com/pdf/GP300schE_DS.pdf) is pretty universal for NiMh chemistry.

Tom