Charging issues? or has the battery had it?

Blimey, okay. Sounds even more complicated than before!

Going to drop the Power Box & revert back to the original zener & rectifier to see how she goes.

I've done a lot of reading & can't make heads or tails of what the right thing to do is! All sorts or pros & cons for various equipment.. it's a minefield. Back to basics is the most attractive way at the minute.