Actually the battery is 5 years old and had a 4 year guarantee. I hardly use the car so after a week or so standing outside the battery is down a bit. just wondered if one could damage it by overcharging!
I haven`t seen a battery one could top up the electolyte for donkeys years. All the battery chargers I`ve had start with about 2-21/2 amps if the battery is flattish, then automatically go down to about 1/2 amp or less as full charge nears. I think you would have to leave it on charge for more than about 36 hours to damage the plates inside.