B&S voltage regulator

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  #1  
Old 09-06-19, 04:48 AM
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B&S voltage regulator

B&S 18.5hp - model 31P7770348E1 - not charging battery...

Alternator (stator) putting out over 30 VAC (high RPM)
Voltage regulator only putting out 5.6 VDC with battery lead dis-connected, and 8.03 with battery lead connected.

Replaced voltage regulator - getting exact same outputs....hmmm...

Here's my question:

- The regulator screws to a plastic bracket, which in turn screws to the block. There is a ground wire (at least I think it's a ground wire) attached to the screw...HOWEVER...if it's screwed into plastic, doesn't that mean it's un-grounded? And doesn't the regulator need to be grounded?

As always, thanx for your help!

Wally
 
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Old 09-06-19, 09:53 AM
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Yes, I believe the regulator housing needs to be grounded. If the ground wire is touching the housing, it should be grounded. Check for continuity with your ohmmeter.
 
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Old 09-06-19, 11:59 AM
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Thanx Cheese!!

Since I made this post, I've searched the WWW from one end to the other, and I have found everything from 'absolutely must be grounded', to 'never, ever...' LOL.

It seems there's confusion on whether the 'housing' should be grounded...OR that the 'center' (for lack of a better term) where the mounting screw is...should be grounded.

I admit I only have a layman's understanding of how a voltage regulator works, but I believe ONLY the center mounting screw needs to be grounded...and NOT the outer casing - since is has no contact w/the inside. As a matter of fact, I saw a few cases of voltage drain when the case itself made contact with ground - so I believe the case actually should be isolated / insulated from ground.

All this is purely speculation, but there is (what appears to be) a black ground wire looped onto the center mounting screw, and I think that's where it's supposed to be getting it's ground. I'm not sure where that wire comes from / goes to...but I wonder if it's just not a good ground.

I'll play with it some more tonight.

Thanx again!

Wally
 
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Old 09-06-19, 04:01 PM
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Hi, if that regulator was originally mounted to the plastic maybe it should be left that way although everything I have seen it is grounded, is the base of the reg. Aluminum?
Check this link out.
http://www.briggsandstratton.com/~/m...eplacement.pdf


Geo
 
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Old 09-06-19, 05:33 PM
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Ok you have a different regulator than I was thinking. The more common one has mounting slots for two bolts and an aluminum housing surrounding it. I can't swear that it needs grounding but the type I referred to comes grounded and has no external wiring to ground it. I've seen the type you have but I don't know if it needs to be grounded or not. Easy enough to test. I doubt grounding it would cause discharge unless the unit was bad.
 
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Old 09-07-19, 09:16 AM
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Thanx folks! Unfortunately, I dodn't get a chance to play with it last night.

Geo: thanx for that link! Definitely some good info. The diagram on page 29 is what I have - 9amp system, and it indeed shows the regulator grounded (as Cheese pointed out). The case appears is aluminum, and the plastic it mounts to appears to be OEM, so I agree...this is probably how it should mount.

The black wire on the center-mounting screw must be the ground. I haven't looked closely so far - but I need to 1. clean the loop connection at the mounting screw to make sure there's good contact, and 2. find out where that wire goes to (i.e. where it's grounded to) and make sure there's good contact there as well.

That's gotta be the problem.

Thanx again! Wally
 
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Old 09-12-19, 05:42 AM
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In case anyone's following this...

I finally had a chance to work on this last night. I believe the the black grounding wire comes down from somewhere around the flywheel, not exactly sure where. Regardless, it is indeed a ground wire, and after a good polishing, it does provide good ground to the voltage regulator.

Unfortunately, still only getting 8.11VDC out of the regulator...grrr...

I suppose it's possible the 'new' regulator I got is defective, but it's odd that it's putting out the exact same voltage as the old one.

Still stumped...

Wally
 
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Old 09-12-19, 06:07 AM
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Hi, what color are the wires coming out of the stator?
Geo
 
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Old 09-12-19, 09:05 AM
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Geo:

One yellow (going to stator)
One red (going to battery)

Here's the one I bought:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
 
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Old 09-12-19, 10:10 AM
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Is your battery good in that it will charge fully off a wall charger?
 
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Old 09-12-19, 10:47 AM
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I looked at a mower with this regulator on it just a day or two ago and made note that the regulator was indeed mounted to the engine block in this application and grounded, which answers that question definitively. The voltage from your stator is appropriate, so I might be inclined to blame the aftermarket regulators.
 
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Old 09-12-19, 11:34 AM
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marbobj: Yup, battery was new last year. Will take and hold a charge fine.

cheese: I suppose I'll try to return the one I bought and try again. For what it's worth, local dealer wants $53 for one - presumably for an OEM B&S...yikes.

Wally
 
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Old 09-13-19, 02:22 AM
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Check out E Bay..................
geo
 
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Old 09-13-19, 11:04 AM
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Thanx geo: ordered a used one on eBay today. Supposedly, it's OEM, and tested to work. We'll see...

Wally
 
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