Charger detects a NiMH as Li-ion battery, why?

XTAR Light

Apr 26, 2010
Some users told their smart chargers detect a NiMH battery as a Li-ion battery. The charger should be able to differentiate between NiMH and Li-Ion batteries. So why? More infornations sharing below.

Please check the charger 's performance first. Try to charge different batteries on this charger to see any problem occurs. If everything is fine, your charger works well. Then, the biggest reason of misjudgment might be that the battery is too old. And it's related to the working process of the charger to detect the battery types.

When you put the battery into the charger, it will charge the battery with a very small current, such as 200mA. Due to the different characteristics of the battery, Ni-MH battery will not boost or only slightly boost the voltage under low current loading. For the Li-ion batteries, the voltage will boost is very fast. Then the charger uses a short time to detect it. If the battery voltage does not boost, it's judged to be a NiMH battery. If the voltage increases quickly, then it's a Li-ion battery.

For an old NiMH battery, it has high internal resistance. So it goes from a low voltage to a noticeably high voltage very quickly when charging. And because the voltage rises too fast, it will be mistaken for a li-ion battery by the charger. If this situation happens, please check your battery's status. And it's not suggested to use this kind of old battery.


Flashlight Enthusiast
Apr 19, 2005
Doesn't the charger realize that nimh do not go over 1.5V and li ions usually start from at least 2.5v. (I assume we are talking about chargers that charge single cells, not strings of nimh) I have half a dozen of different smart chargers from multiple brands, including yours, i can't say i ever encounter that scenario. If i ever have a charger do that i'll trash it right away, if it this simple voltage range test isn't written into its algorithm, what else is not written?