12HP Briggs Overcharging Battery

[Pat the RiverRat]

I installed a new 12HP Briggs on my old Craftsman II rider. My problem is it is overcharging the battery. Everything is hookup up properly are far as the 3 wires off the motor. If I leave the AC and DC circuit wires unplugged everything is fine except after awhile I have to put the battery on a trickle charger. Any ideas on how to troubleshoot and fix this? The old engine never did this and I've never work on riding mowers before other than the basic repair and replace. Any help would be appreciated.

[suemarkp]

I would guess that your voltage regulator is shot or something is not connected correctly. Do you have a volt meter? If so, measure the voltage at the battery when its properly connected and the engine is running. If you get more than 14.4V, its overcharging. I'd even like to see that voltage be even lower, like 13.8 or so once the battery gets its initial recharge after starting.

It be the voltage sense wire going back to the generator is broken or poorly connected. This will make the generator think its not making enough voltage. Is this motor a direct replacement for what you had before? If not, the new generator may need to be wired differently than the old one -- depends on how its charging circuit works. If the charge voltage is too high and its connected properly, you can look to see if a voltage regulator is available for your generator (its probably inside it and part of the generator). If its not a separate part, you may need a new generator (which usually costs a lot more than just a regulator).