wrote:
Following on from the thread about second use for old electric car
batteries: surely as end of life is reached for any cell the self
discharge increases and thus a higher proportion of the charge gets
expressed as heat?

I need to provide hot washing water in one of our vans, about 10
litres is enough and these basin units are readily available for £250.

I can see a split charge system will only charge the second battery
when the main vehicle battery exceeds 13.5V, and even a facility I'm
told that will only charge it on overrun.


Really? Why? Surely it'll charge whenever the engine is running?

Tim