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In order to properly terminate a smart charger looks for a -dV signal from the cells. They only reliably produce this signal when charged at 0.5-1.0C.

The biggest mistake people make is charging at 0.1-0.3C, thinking this slower rate is "more gentle". The problem is, however, that most cells have almost no -dV signal at this rate, so the charger misses termination and you overcharge your cells, cooking them.

The default rate for the BC900(9) is 200mA, which is too slow for most cells. You have to make sure to change the rate to match the cells you are charging. Now, cells that are still in reasonably good shape can be charged a little slower, but without atypical "battery skills", that is hard to judge.

It's counterintuitive, but charging faster at 1C can actually be better for your cells, and they can terminate at a cooler temperature than at a slower rate that you think is "more gentle".

Once again, thank you for sharing your wisdom with us.

Figure 19, page 20
http://data.energizer.com/PDFs/nickelme ... appman.pdf

couple more:
http://www.aljaz.info/elektro/NiMH_bate ... aram-I.gif
http://www.thomasdistributing.com/images/Mhcharge.gif
http://www.candlepowerforums.com/vb/sho ... ostcount=1

isnt the 700 mah setting what you should use on the bc900 for charging duraloops?

Chads93GT wrote:isnt the 700 mah setting what you should use on the bc900 for charging duraloops?

I sometimes do with my BC900 because my cells are still in good shape, and the BC900 is a "hot" charger. It uses a linear constant current regulator which in turn uses PWM to adjust the "average" charge current on the cells. So for ALL cells the actual charge current is ~2A, but it uses PWM to average it down to the user selected value.

However, for AA Duraloops, 1A-1.8A would be the ideal for a charge current on the BC900. Since I am usually charging 3-4 cells, I typically use 1A (the max available).