Alernator?

[Bret4207 0]

My 312H is doing fine, except is doesn't charge. There's a tag on the tractor saying it's equipment with a 15 amp alternator. Is this the starter generator or a separate alternator. I don't see anything that looks like and alternator, so I assume if on the fly wheel?

[wilm169 1]

There is a diode box in front of the battery the handles the charging from the stater. It is alum looking.

[Bret4207 0]

Yup, I saw that aluminum finned box. Is there a testing procedure for testing things? Any fuses? Ammeter shows a bit of discharge I think. Not much movement there at all. I searched the FAQ but didn't see anything related to this set up. I have a very basic understanding of the charging systems. Thanks, Bret

[DMedal 1]

quote:

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Originally posted by Bret4207
Yup, I saw that aluminum finned box. Is there a testing procedure for testing things? Any fuses? Ammeter shows a bit of discharge I think. Not much movement there at all. I searched the FAQ but didn't see anything related to this set up. I have a very basic understanding of the charging systems. Thanks, Bret

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Start your test by measuring battery voltage with machine off and then while running with a fairly sensitive voltmeter. If your battery is half-charged you should see voltage increase a small amount with engine running and lights off. If you just charged it fully, leave the lights on some first. It sounds like you've already determined your not getting a charge, but do this test anyway. The aluminum finned thingie is both a diode (rectifier) and the voltage regulator. You test it by eliminating other possibilities and then substituting a known good part. To test the stator windings (inside the engine) - look for continuity of the coil. A failure will almost certainly be an open circuit. I don't find the schematic for your machine in the on-line stuff, I suspect it is in the service manual. -Don

[PhanDad 3,462]

I recently had the same problem with a newer Briggs 16HP with separate starter and alternator (not S/G). Problem was the voltage regulator. I would think the Kohler engine is similar. There should be two wires running from the stator (under the engine shroud) to the voltage regulator and a single wire that goes from the voltage regulator to the battery (could be via the ammeter, switch, etc). Disconnect the wires coming from the stator and using an AC volt meter, read the voltage from the stator - if memory is correct, the reading should be in the upper 20's and will increase some with engine rpm. If that's OK, then reconnect the stator wires and using a DC volt meter check the voltage from the regulator to the battery. First check the reading without the tractor running - reading should be 12 to 13 volts. When the tractor's started, the reading should drop some, then when the engine runs, the reading should go to about 14.5 volts if the voltage regulator is working and the battery system is in good shape. If the reading is just the baseline, there's a problem. If there's a problem, I test the voltage regulator without it being connected to the battery system (some say this could damage a solid state regulator, but it hasn't happened to me yet). Measure the voltage between the lead and ground. It will be 0 until the engine is running, then should increase to the 14.5 volts. If there's no voltage, or low voltage, the regulator is bad. If it's 14.5 volts or so, the problem is elsewhere. There a couple of posts about this subject somewhere on the site, but atm I can't find them.

[Bret4207 0]

Continuity through the stator checks out and so does the circuit breaker/fuse. I also have continuity through the rectifier. Still no charge. I assume that means replace the rectifier?

[BLT 716]

Make sure you have a good case ground. The Briggs repair manual makes mention to that. Brush off case at the mating point and then retry it. I would do that to all your connections from the regulator on back. This is a case where a volt meter would give you some indication on whats going on.