After a year and few months, my 70mai battery seem dead. It wasn’t remember date/time anymore. The battery is HMC1450 which is about 8-10 USD. However, I measure the voltage of battery and found that it’s slightly below 3V so It should be chargable.
I tried to charge it with my Li-Po charger with 1S (3.7V) but it refuse to be charged. Some Li-Po battery seems dead but doesn’t really dead. Here is trick, you could try charge it with over voltage for very short duration. In my case, I had it charged with 2S (7.4V@1A) for about a minute, 3 times. Then charged it with 1S (3.7V@0.5A) and it’s alive again.
IMO, I think problem caused by NTC (Thermistor circuit) as It’s summer now and I living in very hot place. And NTC prevents battery from charging as temperature is too high.
Tong's blog 
Hello. I have the same problem.. The problem is not the battery itself. I have cahnged twice the battery. I think the problem is the NTC as you said, but what can be done to fix it?
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The battery with NTC is about 8-10 USD in my country so I bought a new one.
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