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Is it impoosible to charge NiMH batteries at rates of 0.1-0.3C?

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treez

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I am baffled at the sixth paragraph down of the following web page from batteryuniversity.com, which states that it is impossible to charge NiMH at slow charge rates...............



It is difficult, if not impossible, to slow-charge a NiMH battery. At a C‑rate of 0.1 to 0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full-charge state accurately and the charger must depend on a timer. Harmful overcharge will occur if a fixed timer controls the charge. This is especially apparent when charging partially or fully charged batteries.



.....surely this cannot be right?.......if charge is going in, even if only slowly, then surely the battery is charging up?
 

BradtheRad

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The first sentence must mean it is difficult to 'smart'-slow-charge a NIMH.

At a high charge rate, the cell will start to heat up when it is full. Or rather it will heat up more than it has until now. This is used in some smart chargers as an indicator that charging should stop.

At a slow charge rate, the cell does not heat up as much. The charger cannot use temperature detection as a reliable indicator when to stop charging.
 
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A good 0.1C NiMH charge method has been suggested by Panasonic.

 
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