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Old 23rd Oct 2020, 6:08 pm   #4
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Default Re: 18v Li Ion chargers and going quietly bonkers

LiIon cells are remarkably easy to charge properly and also easy to make a dog's breakfast of it. You apply a current limited voltage of 4.1 to 4.2V* per cell, the current can be almost anything as lithiums are nearly 100% efficient but I would not go much further than 1C**. then wait until the current goes down to about 5 to 10% of C** and stop charging.

Simple but needs good control to stop (full stop) charging at the end. The temperature sensor is there if it all goes tits up, such as one cell going bad and the other(s) getting hot, it is not an indication of being charged but a way of preventing a bang!

*4,1V gives many more charge cycles at the loss of a bit (10 to 20%) of capacity, the military do this a lot.
**C is the ampere hours ignoring the hours bit.