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Old Apr 10, 2007, 12:15 PM   #11
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Join Date: Jul 2005
Posts: 358

I would just like to point out that all of the battery manufacturers recommend charging NiMh batteries in the 0.5C to 1.0C range.

Cycle testing data from Sanyo and GP are obtained using 1C charging.

Some people suggest that this is a conspiracy to sell more batteries, but it really has to do with damage due to overcharging.

The end of charge signal that most chargers use is based on a drop in voltage as the cell is fully charged. When charging in the 0.5C to 1.0C range, that signal is prominent. At lower charge rates, it fades away and becomes difficult to measure.

If you want to give your batteries the best chance of obtaining 500 charge/discharge cycles, charge themat the 0.5C to 1.0C rates.

There is a recommended slow charge method. It involves fully discharging the cell, then charging it at a 0.1C rate for 16 hours. When the timer hits 16 hours, the charge is shut off. This is called a standard charge and is used when testing to determine the capacity of the cell. It does not work well with partially discharge cells, and it is rather time consuming.

To put some numbers to this, if you are using 2000 mAh cells, you should be charging at 1000 - 2000 mA. To charge a fully discharged cell will take from (actually a little over)1 - 2 hours.

If you are using 2700 mAh cells, your charger should be charging in the 1350 - 2700 mA range. Once again your charging time for fully discharge cells will be just over 1 - 2 hours.

Is it possible to charge at lower charge rates? Yes.

Is it recommended? No.

SilverFoxCPF is offline   Reply With Quote
Old Apr 13, 2007, 10:02 AM   #12
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Join Date: Nov 2006
Posts: 8

Maha C9000 refers to the charge rate that Silverfox posted as the "break in" mode.

It's also know as the BEC standard for measuring cell capacity.
vortex05 is offline   Reply With Quote

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