wrote:




That applies pretty much only to NiCd (nickle/cadmium) batteries that
will get a 'memory' if not fully discharged with each use. That memory
can be dispersed with care, but it can be a real PITA...



** The so called "memory effect" in NiCd batteries is basically a myth.

https://en.wikipedia.org/wiki/Memory_effect


However, loss of capacity of a NiCd pack is very common and caused by one or more of the following.

1. Over-charging so the cells get hot.

2. Over-discharging so some of the cells go to zero or reverse voltage.

3. To fast discharging so the cells get hot.


Each of the above damages cells so some or all of them have reduced capacity or develop a fault condition where the cells discharge themselves in a much shorter time than the others - ie days instead of months.

Since all the cells in a pack are charged in series, the cells that contain more charge than others soon become over-charged and heat up while others remain less that fully charged. Such a pack will show low capacity as one or more cells goes flat early.

Such a pack can usually be fixed by discharging each cell individually to 1V, but if any cells have developed high self discharge then even this does not work.

The term "memory effect" is regularly trotted out when one of the above scenarios needs explaining.


..... Phil