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Proud Wheel Horse Owner
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3,212 Posts
Discussion Starter · #1 ·
Hi Guys,
I've got an 18hp Briggs 422707 0179 opposed twin with a charging system problem.

It's got the standard 2 wire (red w/ diode, and a white) alternator (stator) and the white wire feeds the headlights. The red goes to the ignition switch where it jumps inside the switch to the 12v-hot-all-the-time wire from the battery.

I've tested the diode in the red wire and it's good.

The problem is low voltage going to the battery. Running full throttle, I get 12.6v to 12.7v at the most. After a couple of engine starts, run it for a few minutes, shut it off, restart it............the battery is down to 12.2v, drops to 8.5v during cranking, and the engine will barely crank over.

Cranking speed is normal with a jump pack and the engine fires right up.

Headlights do get noticeably brighter with engine speed, as you'd expect.

Here's what's making me a little crazy, and before I spend $65ish on a stator, I thought I'd ask.

When testing the voltage output of the red wire from the stator all the way to the ignition plug, I get 13v and sometimes more. However, at the battery, sometimes only 12.3 or 12.4 and then it will slowly creep to about 12.7. I can run the engine for a few minutes at full speed, and being seeing 12.6-12.7v, and then on immediate restart, it's back to slow cranking speed.

New battery, new battery ground cable, new cable from battery to starter solenoid on firewall, new cable from starter solenoid to starter. Starter cranking speed is still slow even if the starter solenoid is jumped.

Anyway, based on what I've said, is this what stators do when they go bad?

Thanks for reading.
 

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Proud Wheel Horse Owner
Joined
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3,212 Posts
Discussion Starter · #3 ·
Problem solved

:fing32:Thanks for the quick response.

Yep. Engine mount bolts are tight......just checked 'em.

Had a thought after my initial post. "I wonder if the 2-4amps that this stator puts out is such a small amount of current that the "system" is sensative to battery voltage......and if I fully charge the battery, will the stator then be able to keep up?"

So....it's been on the "smart" charger at 12amps for a couple hours. Just went out and fired it up and put the volt meter on the battery terminals. Immediately got high 12's, and within a minute or 2 it was producing 15.5v at full throttle.

I've been doing a lot of starts and very brief runs for the past 2 weeks while I've been bringing this tractor back to life, and that drained the battery without giving it much recharge time.

The machine is a 1984 JC Penny Grass Handler by MTD that I rescued about 3 or 4 weeksa ago.....

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1,548 Posts
Good thinking! Remember that the 2 to 4 amps is also sensitive to pushing voltage through a series of painted metal-to-metal contacts with oxidixed bolts if your battery ground is mounted to the frame. I am in process of converting some of my tractors to a direct ground cable from battery to engine block. If it acts up again, put a jumper cable from battery ground post to engine and see what happens. Good luck!
 
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