if you deep discharge your cells (to below say 5.4v for the whole pack) they will never recover.
do not discharge at below 0.9v per cell (5.4v per pack)
this is why its better to get an equalising tray that cuts off at 0.9v.
or if you know your circuits make your own with some 0.9 zenna diodes and a couple of resisitors/capacitors...what ever they are
