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Charging Problems on B&S Twin I/C Engine

briggs and stratton b&s charging rectifier alternator stator

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#1 Utah Smitty OFFLINE  

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Posted April 30, 2015 - 05:29 PM

I sold my Dayton a couple days ago and was getting it ready to deliver to the buyer.  I noticed the starter running kind of slow and did a voltage check... Battery is only 11.6 volts

 

The PO had just used a toggle switch for ignition and a large pushbutton switch for the starter.  When I pulled them off, I found that he hadn't hooked up the charging system to the battery. 

 

The engine runs without the battery hooked up, so it must have just used the battery for starting.

 

This engine has a dual circuit alternator-- 3amps DC for charging the battery, and 7 amps AC for the lights.  When I checked the voltage, the reading fluctuated all over the place, with the highest reading about 12 v at full throttle.

 

The alternator must be working somewhat as the engine runs with the battery disconnected, so is this maybe just a bad diode??

 

Any help would be appreciated, I'm supposed to deliver the machine tomorrow and I don't want to lose the sale.

 

Thanks,

 

Smitty



#2 Bolens 1000 OFFLINE  

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Posted April 30, 2015 - 05:39 PM

If the tractor is run by coil with magnets on the flywheel the battery is not necessary for the engine when running, sounds like this is only battery operated for electric start and lights so essentially the alternator may not be rworking at all.

 

What kinds of readings are you getting when the machine is running? Should have around 13 to 14 volts on a volt meter if the alternator is running correctly.


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#3 Utah Smitty OFFLINE  

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Posted April 30, 2015 - 10:32 PM

If the tractor is run by coil with magnets on the flywheel the battery is not necessary for the engine when running, sounds like this is only battery operated for electric start and lights so essentially the alternator may not be rworking at all.

 

What kinds of readings are you getting when the machine is running? Should have around 13 to 14 volts on a volt meter if the alternator is running correctly.

When I measure with the engine running, using a digital VOM, the readings go from a low of 3 volts or so to a high of 12--and the readings change very rapidly.  The engine does run even when I had the negative battery cable disconnected, AND, the lights work--they're run off the 7 amp AC circuit from the alternator.

 

I checked it again tonight with a test light --test light doesn't glow when the engines off and I touch the probe to the red (DC) wire.  When the engine is running the light glows... so maybe it does work and it's just my cheap HF voltmeter...

 

Smitty



#4 glgrumpy OFFLINE  

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Posted May 01, 2015 - 02:15 AM

Put meter on battery when running and see if around 14 volts there. If yes, maybe batt is bad? Batt should read 12.3 or more when off.

#5 HDWildBill OFFLINE  

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Posted May 01, 2015 - 08:44 AM

If you are trying to take a reading from the engine plug using just the probes on the meter using your hands the voltage is probably jumping all over the place. It is hard to maintain a good contact doing it that way.  Since the charging circuit is disconnected go to an electronics store like Radio Shack and get a set of alligator clips that you can put on the end of your probes (they just slide on).  They you should be able to get an accurate reading. 

 

In your case a cheap fix would be to go to Walmart and get a battery tender.  Connect the tender to the battery when it is not in use and when you need it, it will be ready to go.  11.6 volts is not enough to turn that engine over.


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