B&S voltage regulator location

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  #1  
Old 05-19-09, 09:19 PM
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B&S voltage regulator location

I'm trying to sort out a Mastercraft riding mower with the Briggs 16 hp intek. Model number of the engine is 311777-0120-E1. The tractor model is 13AE678G515. It was purchased in 2000 I believe and our trouble is overcharging the battery. I see the red and black wires coming from the alternator with the diode at the connector. I tested AC voltage here and found it to be about 30VAC at idle and 38VAC at full throttle. The connector here changes the wire colors to red w/black stripe and a white wire. They are wrapped from here but it looks like the red/black goes to the ignition switch.
The problem is at the battery I'm initially getting about 13VDC at start up but after about 2 minutes it starts to creep up slowly to 16.7 VDC in about 8 minutes before I decided to shut it down. Don't know if it would have went higher but I just bought the battery and don't want to toast another one.
Anyway, if there is a voltage regulator here, I can't find it. I see on my JD that it is mounted on the side of the engine with 2 yellow wires and a red wire. But I can't locate this one. I thought maybe under the panel with the forward/reverse but all I see here is the solenoid and leads to a couple of kill switches.

Any suggestions would be appreciated.
 
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Old 05-19-09, 09:48 PM
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If you get the serial number of the tractor along with the model #, you may find schematics and IPL here PDF Manual Web Archive
 
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Old 05-20-09, 12:37 AM
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It doesn't sound like you have a regulator. How are you measuring voltage at the wires from the engine? Does the red wire have a "lump" in it under the shrink wrap near the connector?
 
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Old 05-20-09, 05:45 AM
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The serial # is 1D110I30093. Both that and the model # match the format for an MTD search but nothing was found.

The "lump" on the red wire is on the upper side of the 2 wire connector. Red and Black in, Red with black stripe and a white wire out. It looks like the red w/black stripe goes directly to the single connect on the ignition with a group connector out.
Measured with a volt meter set to ac, probing the underside of the connector at the red w/black stripe and the white wire. This is how I got the 38 volts. Setting to dc, I think I was able to get about 17 off one of these two wires and the other probe to ground on the engine.
 
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Old 05-20-09, 08:34 AM
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Originally Posted by cjkennedy1 View Post
The serial # is 1D110I30093. Both that and the model # match the format for an MTD search but nothing was found.
This is why I stated "may" ...although I am not sure why. As you said the numbers match their format and I do believe you have an MTD product...
You might call the support numbers listed and see if they can at least lead you to a manual. It sounds like you have a grasp on what your doing and manuals are always good to have. For this problem you will want manuals for the tractor since it is their chassis wiring that is likely the issue.
Unfortunately I have not ran into your problem much if at all so have no memory to go from.
Cheese and the others most likely can fix ya up tho.

good luck
 
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Old 05-20-09, 07:36 PM
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Thanks for the responses so far. Here is more accurate voltage readings for anyone that might have a suggestion.

Voltage at the battery starts at about 14 volts and then over a couple of minutes creeps up over 17 volts. Voltages at the stator are 17.4VDC off the red w/diode tested to ground on the engine. The black wire is testing at 15.6 VAC. Is it odd that with the meter left on AC I register 37 VAC on the red wire? Should it register anything if it's meant to be DC?

So I have a dual circuit unregulated stator that I believe is outputting on the high side and it's cooking the battery.

Any opinions about a fix? I'm wondering aside from actually replacing the stator if I could install a regulator to save pulling the flywheel? How would I wire that with 1 AC and 1 DC off my dual circuit?


Thanks again.
 
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Old 05-20-09, 07:53 PM
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I don't think I have ever seen an unregulated stator overcharge a battery unless it was over-revving. Your system IS unregulated (the existence of the diode proves it). The fact that it is charging and that you do have AC on the unrectified leg tells me the stator is ok, so at this time I'm pretty much convinced the engine rpm is too high.
 
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Old 05-20-09, 08:35 PM
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Okay, thanks Cheese. Didn't think to pull the throttle back today and test at a lower rpm. I did on Tuesday but wasn't properly testing 1 wire and the other to ground. Will let you know.

Cory
 
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Old 05-21-09, 06:47 AM
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I thought you were on to something but reduced RPM's don't solve the problem. At idle I'm still getting 15.4VDC which from what I understand is still higher than I would want at WOT.

Also if it helps, I found on the Briggs site a DC amp test to perform, testing between the DC stator lead and + batt terminal. The range that was ideal for 3600rpm was 2 to 4 amps but at WOT I get 1.5A.
 
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Old 05-21-09, 07:15 AM
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Have you tried a different battery...?
Not sure of any logic to back up questioning the battery other than it is the load/resistance in the charging circuit...

 
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Old 05-21-09, 09:21 AM
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Was worth a try. Another battery gave the same result of about 1.5 amps. I noticed on the ammeter that it shows about 4 amps. Looking at the wiring diagram for another MTD (Murray), I see that the ignition switch and ammeter are within the circuit before reaching the battery from the DC out on the stator. So bypassing that by testing from the stator out directly to the + post on the battery shows 1.5 amp, but ammeter shows 4 amps.

Does anyone know what they test for VDC on the stator?
 
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Old 05-22-09, 12:37 AM
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I'm not sure I'd be worried about 17 volts at only 1.5 amps harming the battery. What is the original problem? Was it burning out batteries one after another? Was the old battery the original? If you've been getting more than 2 years out of your batteries, I wouldn't worry about a thing.
 
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Old 05-22-09, 07:01 AM
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It is only the third battery because they have been boosting it for years. Not sure what the original battery was but the one I replaced (the second) was only 160cca and it wouldn't get past the compression without assistance (possble valve adjustment). The third battery I just placed is 235cca and it's working fine right now. Could be that their rough yard was hard on the batteries and we're thinking overcharge when vibration is what the batteries aren't liking. Perhaps we are just missing the obvious point of failure.
The new battery has a 1 year over the counter replacement if it tests bad. I'm going to place a piece of foam below the battery for cushioning and see how we make out over the season.

Thanks Cheese and BFH for the help and suggestions.
 
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