Bongo chugged and chugged then stopped .( IM ASSUMING YOU ARE ALL RIGHT





Pulled in tried to start it, no go . Went and toppped up the tank with 15 litres of diesel and ran the twin batterries flat. Put them on charge overnight fitted them this morning. when putting in the second one there was a flash of sparks, terminals not wrong but pulled that one anyway and tried to start with one. JUST TUCKED THE POS on the second bat terminal wire out the way. But battery weak after a few turns.
Took the good one to halfords and came back as over or under charged unservicable.
So i now want to know whats story with putting in a 90ah battery with 850cca. ANY PROBS WITH DOING THIS . The standard batts seem a bit weedy. If this is okay any recomendations on experience .
Sorry for not trawling through threads i have glanced at afew but im on my lunch break so dont have that much time.
IF I JUST FIT THE ONE BATTERY DO I JUST INSULATE THE POSITIVE WIRE OFF THE SECOND BATTERY WITH TAPE AND LEAVE OR IS THERE MORE TO REMOVING THE SECOND BATTERY?
Appreciate the help guys thanks.
Just a quick ps to this for further reference.
PS
The glow plug light had been staying on for afew seconds after start up the last few weeks, so i understand that this is a sign the battery could be on the way out as well