About rebuilding the battery. I have no idea what the inside of the Metz battery is like, if and how it can be rebuilt/recelled. I usually make that decision after opening the battery case and studying what is inside. Then determining it it can be rebuild/recelled and what replacement cell I can use. Sometimes I have changed cell chemistry, sometimes not. Charging is a matter of process. After a shoot, I charge the batteries. So they are put away fully charged. Prior to a scheduled shoot, my SOP is to charge my flash batteries a few days prior to a scheduled shoot. When I shot more randomly, I did a top off-charge every other month. With NiMH batteries you can charge them at 0.5 to 1C, so all you need is a n hour or two before the shoot, and you can top up/charge the battery. Make charging a standard routine, and it stops being an issue. You can also look for tabbed low discharge NiMH batteries.