General Rule for Charging NiCd and NiMH Batteries

[Bones]

Assuming the battery is in a fully discharged state (1V per cell), calculate the charge time in Hours for a Nickel Cadmium (NiCd) or Nickel Metal Hydride (NiMH) battery pack using the following formula:

Charge Time Applicable in Hours =

Capacity (C) rating of battery in (mA) x 1.4
Output current in (mA)

​

In general, for standard charge you need to put up to 140% energy in to obtain 100% energy out of your batteries.

For fast & rapid charge techniques this figure of 1.4 (140%) may need to be reduced by up to 15%. This is dependant on your charging parameters and charger termination method.

Source =

http://www.master-instruments.com.au ... general-rule.html

 

[SilverFox]

Hello Bones,

The charge acceptance is related to the charge rate. 140% is good for low rates, but that drops to around 120% at 0.5C and around 105% at 1C. The "standard" charge at 0.1C needs 160%.

Given that most of the chargers they sell are slow chargers, it is pretty good information. The do offer a couple of chargers that are capable of 1 amp charging, so their 15% adjusted value is also good. So from their perspective and looking at what they offer, it is a pretty good ballpark estimate.

Tom

 

[Toohotruk]

I just bought some Titanium 6,000 mAh "C" batteries for my Malkoff equipped Mag and if I used your formula correctly, and I use my cheapie 130 mAh charger, I would have to charge them for 64 hours! Does this sound right to you? I had originally planned to charge them for about 24 hours for the initial charge, then after a couple of "break-in" chargings of the same length of time, drop the charge times to about 12 hours...bad idea? After reading this thread, I now have serious doubts as far as the best way to use (and care for) these high capacity cells.

I have no experience with larger NIMHs with this kind of capacity, and I have fairly limited experience even with 2,500 mAh "AA"s so any advice would be greatly appreciated!

 

[clintb]

I just bought some Titanium 6,000 mAh "C" batteries for my Malkoff equipped Mag and if I used your formula correctly, and I use my cheapie 130 mAh charger, I would have to charge them for 64 hours! Does this sound right to you? I had originally planned to charge them for about 24 hours for the initial charge, then after a couple of "break-in" chargings of the same length of time, drop the charge times to about 12 hours...bad idea? After reading this thread, I now have serious doubts as far as the best way to use (and care for) these high capacity cells.

I have no experience with larger NIMHs with this kind of capacity, and I have fairly limited experience even with 2,500 mAh "AA"s so any advice would be greatly appreciated!

You need a constant current charger that can handle at least 600 mAh to do a proper forming charge. You do not want something that relies on voltage termination for the first / forming charge. The only thing I know that comes close is the Ace Hobby DDVC, but it only goes to 500 mAh per channel (2 channels).

 

[Toohotruk]

OK, I'm convinced...I ordered and just received this charger:

http://store.batteryspecialists.com/ap20201.html

And my new Titanium C6000 batteries are charging as I write this.

Good choice? :shrug:

BTW...I odered this charger late Friday night and it was in my hands this morning! That's what I call FAST service!!! :twothumbs