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| Quick Note:
approximate charge time of a fully discharged 1400 mAH NiMH pack and 300
mA charger = 1400 mAH / 300 mA = 4.7 hours. This will vary depending on
the actual charge current, real pack capacity and the charge termination
method. Below is an extension of the NiCD charging explanation applied to NiMH charging. The pink plot is the NiMH battery voltage profile. It is very similar to the NiCD voltage profile. This similarity in voltage profiles is why most smart NiCD chargers can also charge NiMH batteries. Here, the termination is based on a voltage drop from the peak voltage. The blue plot is the battery pack temperature( the dip between 150 and 200 minutes was caused by me moving the temperature sensor). Charging was done at room ambient with the stock 300 mA wall transformer charger. Notice how the temperature increases throughout charge (exothermic reaction) unlike the NiCD battery which decreased in temperature near the beginning. Also, notice how the final NiMH temperature is many degrees greater than the NiCD.
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