18 January 2010

Prematurely failing batteries (AG13, LR44, ...)

Most toys at our home use either AA/AAA batteries or 3xAG13/LR44 button cells.
I had once bought them online and I was relatively satisfied with their quality. Then I had to re-supply at the local store and paid the incredible amount of 1.5€/cell. They had even more expensive ones!

Out of 4 batteries, one was dead. Other 3 lasted much less than those that came with the toy.

During a desperate need of one of those toys last night, I got hold of my DVM and measured voltages across those "exhausted" cells.

40% of them that had been marked as "unsuitable" for toys were at 0.5V or below. Way below: they showed polarity reversal! The remaining cells were measured to be 1.2 to 1.4V and, not surprisingly, when mixed with good cells, brought a couple of toys back to life.

You may have to do some interactions until you find a working trio, but don't throw them to recycle bin right away because the fault might be in just one cell, not in all of them!

Apparently they should have capacity in excess of 150mAh, I think that a simple testing clamp can be arranged with a resistor mounted on a clothes peg...