B&S charging voltage

[rglide]

I have a (c. 1990) B&S 12.5 hp engine that is going through batteries (U1-7, 230 amp) every several months. They used to last several years. The batteries will hold enough charge to start the engine if put on a trickle charger, but without the charger, will be dead in a couple of weeks.

The engine runs with the battery disconnected, and the voltage at the terminals is 12.8 vdc, which seems low. I've heard of stators failing but not dropping in voltage, from what I assume should be about 14 vdc.

Any thoughts on what is going on?
Thanks in advance for any help.

 

[EngineMan]

Check the stator and the reg/rec.

 

[pauly50]

pauly50
stator either 5 amp or 9 amp has black lead with green connector and regulator has green connector with yellow lead in and red lead out d/c
depending on your flywheel magnet size ie 5 amp small magnet and 9 amp large magnet the a/c output for 5 amp will be 28 volts a/c minimum and
9 amp system 40 volts a/c minimum thse are measured with engine running at 3600 rpm

check earths and measure voltage going into battery with engine running it should be between 1-2 volts above the voltage noted without the engine running
if this is not the case and battery is load tested and passes regulator is most likley the culprit , the part number for reg/rectifier for 5 or 9 amp system is 491546
the stators for both 5 and 9 amp are same part number 392595

replace the regulator / rectifier and check charging it should read about 14.2 volts if working correctly

cheers hope this helps