Briggs & Stratton v-twin not charging (lawnmower)

[Hurley]

The alternator quit charging on my lawnmower last summer. My original searching netted the attached pdf that contains the alternator and regulator testing procedures for my specific engine on pg 41 & 42. My regulator had no measurable current output, however the alternator AC output was within spec. So I replaced the regulator, and nothing changed. Luckily my dad has a mower with the same engine and charging system, so I tested his, and sure enough the alternator output and regulator output both were within spec - so this confirmed that I was at least testing correctly.

Thinking I got a dud regulator, I bought another regulator to verify, and of course I get nothing on the output side again. I also ran a jumper wire from regulator directly to battery, no difference.

Is there something that I'm missing, since my alternator output measures within spec?

This is a briggs & Stratton Intek v-twin, 20hp, with the 10A alternator and regulator

P.S. - Prior to this happening, I had replaced the battery thinking it was going bad (since it wasn't holding a charge....more likely it wasn't getting charged because of another issue)

 

[hunterdan]

Not sure if this will help but 2 yrs ago my zero turn with a Kohler v-twin motor started doing the same thing. I would charge the battery and it would run and cut until the charge was used (30 minutes) I checked starter and all the stuff you are checking to no avail. I eventually took it to a local small engine repair guy and it turned out that the magneto on top of the engine had slung some weights. I got lucky and he had a good used one from an MTD but new was like 300.00

 

[a_kelley]

Could be either. I've seen the magnets come loose as well as the regulator's be bad out of the box. Why not swap regulators with the two units and see if his charges with your regulator?

 

[maulcruiser]

Check ALL of your grounds.