I'm glad to find this forum as there seem to be many questions answered about the small Briggs engines. I am trying to track down a charging/discharging issue on Sears lawn tractor. Sears 917.256810; Briggs 28N707. I mowed with this for 2 years with no problems. It failed to start a few weeks ago, I put a new battery in it but it obviously didn't cure the problem. It starts fine with a boost from my portable battery pack, but often won't restart even after an hour of mowing. I could use some help in testing to track this problem down. I do have a multi-meter. There are 2 wires coming from under the shroud, red and black, and the red has a diode in it. I have the headlights unplugged and don't really need them.
Should I be getting about 13.6 volts at the battery when running?
What should I read at the battery when I have it on a charger, and what would be a good reading on the battery after charging, I had it on for 24 hours and it is reading 12.3?
What would be a reasonable reading a week later, assuming the battery has both terminals disconnected?
How do I test output of the alternator at the black/red wires? AC or DC? one test lead to the plug and one to the frame?
If I suspect a parasitic draw and want to stop a discharge, is it good enough to just take one lead off of the battery or should it be both?
Does this system have an actual voltage regulator, I can't seem to see one?
I got that one. This is pure gold, thanks. I got the battery charged up again, hooked the battery cables back up but unplugged the plug from the stator. I will monitor this for a week and see if the battery stays up.
#6
sgkent
we had the same happen in our Mercury Sable wagon recently. I spent a month chasing the drain only to find that the new quality battery had a intermittently bad cell in it from the factory. With the cables off that cell drained overnight. A battery will lose very little voltage in a week. Our new battery that works well in the Sable reads 12.45 V when charged. That said, this meter is calibrated and it is not uncommon for meters to be off a fraction. You leaving the plug off test should be a good test too.
