Hi,
While unpacking some old boxes in storage, I came across 4 NiMH AA batteries in a charger. The batteries were quite dead, reading only about 100mv each. The batteries had been in storage well over 18 months. When installed in the charger the "charge" lamp would not come on. I assumed they were toast.
So out of curiosity, I put the batteries in a battery holder and connected them to the bench supply with the current limited to 100 ma. Then slowly raised the voltage until the current was 100ma. As the current began dropping I continued the raise the voltage and so on until the voltage reached ~ 4.5V. I then left them there for about 10 minutes until the current dropped to 20 ma, and then removed them from the battery holder and installed them in the charger. To my surprise the charge lamp came on. Then after several hours the Ready Lamp came on. The batteries were quite warm, but not hot. After this charge the voltage across the 4 batteries was ~5.52 V. I have been using them to power a breadboard ( 10 ma average) for a day now and the voltage is around 5.14v
Questions:
1. Did the storage and resultant discharge of these batteries significantly reduce their capacity?
2. What should I expect from these recovered batteries?
They seem to be working fine. The reason I ask is that I have never use NiMH batteries before and found about 40 more of these in another box in the same condition and wonder it they are worth recovering in the same manner.
While unpacking some old boxes in storage, I came across 4 NiMH AA batteries in a charger. The batteries were quite dead, reading only about 100mv each. The batteries had been in storage well over 18 months. When installed in the charger the "charge" lamp would not come on. I assumed they were toast.
So out of curiosity, I put the batteries in a battery holder and connected them to the bench supply with the current limited to 100 ma. Then slowly raised the voltage until the current was 100ma. As the current began dropping I continued the raise the voltage and so on until the voltage reached ~ 4.5V. I then left them there for about 10 minutes until the current dropped to 20 ma, and then removed them from the battery holder and installed them in the charger. To my surprise the charge lamp came on. Then after several hours the Ready Lamp came on. The batteries were quite warm, but not hot. After this charge the voltage across the 4 batteries was ~5.52 V. I have been using them to power a breadboard ( 10 ma average) for a day now and the voltage is around 5.14v
Questions:
1. Did the storage and resultant discharge of these batteries significantly reduce their capacity?
2. What should I expect from these recovered batteries?
They seem to be working fine. The reason I ask is that I have never use NiMH batteries before and found about 40 more of these in another box in the same condition and wonder it they are worth recovering in the same manner.
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