Hey guys,

Been chasing a problem for a bit. I have a split charge system on my car where there is a smaller battery in the back which powers the KITT dash etc. the rear battery charges when the engine is running only then isolates itself when off. It also stops charging if it detects less than 14v from the main battery too.

This is where the problem is. Ive fitted a new 200amp alternator earlier this year, new belt, all the wiring is good but when the car has warmed up the voltage drops, when i first start its charging around 14.5v which is fantastic, but as the car warms up the voltage comes down, its usually going between 13.9 and 14.0 which is really annoying as the rear battery keeps clicking off charge so it never gets charged properly !

I decided to take the main battery off the car last night and i put it on charge at the wall, my charger showed fully charged and on trickle charge this morning so i switched it off and went to work. now tonight ive checked it with my multimeter and it was sitting at 12.48v............. that seems a little low to me with it just being charged and not connected to anything ! its a 12v 60AH battery too so its quite a beefy one. Ive had it on the car about 4 years now so maybe its just starting to lose its charge ?

Its the only thing i can think of with the engine running and it wont go just above 14v