Right, bear with me...
My battery had been lasting a day, tops.
I spent £50 on a smartcharger which could apparently recondition my tired (although only 6 month old) battery.
I did it's rejuvinating thing all weekend.
Today it went flat at 1.30pm.
Now...
The best way to get power back up apparently is a slow charge.
So I set it to 2 amps, and it says it's full after only 9 hours.
Now an 85amp battery should take more like 40 hours at 2 amp! (I planned an 8amp boost later).
That means only 18 amps gone in, and it's full.
So...
My pump uses 6amps per hour.
Does this mean it will last 3 hours max tomorrow?
Bugger.