Very simple question from a newbie. Is it OK to charge my batteries 100% or is it best to stop short of completely full? I have a 4% "buffer" on discharge.
Charging Batteries

Absolutely no problem charging to 100%, i do it every time.
In fact the advice from GivEnergy is that you should periodically fully charge and fully empty the battery.
The 100% we are given is not in fact the absolute maximum the battery can hold, rather it is a reduced ‘safe’ threshold that the battery operates in. Likewise the 4% reserve, there is still a bit more even when the battery is fully discharged,
The question makes no sense because 100% and full are not the same thing.
Batteries should be charged to 100% as often as possible, because only then is the cell balancing function activated which is important for the long term health of the batteries. On a correctly installed and working system it should not be possible to charge to full.
100% is typically a voltage between 55 and 57 Volts.
Full is 58.4 Volts.
Thank you for your advice everyone.