charging issue - bad stator or bad battery or both

I bought a junk 1998 Murray at auction for about $50.  

murray model 38515x92B  man date: 98118

I fixed it by replacing the carb and hoses, doing the badly needed value lash, rewired a bit, replaced the starter relay which went bad after a while.  Plus, replaced the idler pulley and belt.  Plus, new battery, tire chains, and some tire tubes.  I have been using it steady for about nine months and it has saved me a ton of time and money.

I bought a new battery about 2023, a Duracell, but, upon getting it home from Batteries Plus, I realized it was dead at 12.15v.  I tried charging it, but, it self-discharges to 12.35 volts well within a week and about 12.15 volts after two weeks.  They scammed me on the battery because it was 17 months old when I bought it.  They refused to take it back.

I ended up putting it in the Murray because I was not going to put a junk battery that would be dead within a year in a mower I was selling to someone else.

My problem is the Murray running at 3180 RPMS is putting out 16.68 volts to the battery and at rest the battery is about 13.80v until it self discharges. It is not getting drained from the mower, I have left it out of the mower in a bucket and have watched it self discharge day by day.  I can not get an accurate reading on the A/C to the headlamps, but, it looks like it varies from 1.# to 2.# volts A/C.

I have a :

Engine: B&S 12.50 HP
model : 287707 type:1272-E1  code: 97091520

https://www.ereplacementparts.com/briggs-and-stratton-2877071272e1-engine-parts-c-16758_17347_19160_225651.html

I do not even see a voltage regulator on the motor or schematic, so, how can it be putting out 16.68 volts at 3180 RPMs unless the stator is bad?

I read almost all the other threads on electrical and starters.  The JD and Kubota replacement 15-20 AMP alternator and external regulators appear not to be reliable from Amazon or Ebay.  So, if I go with anything, it will be a Ford 40 amp alternator running upside down off the deck belt V pulley with probably an external Ford voltage regulator.

Though the 1 wire GM 10si looks better, I have doubts about fitting it.  Though the simply wiring with the internal regulator could be a plus.

Anything I can do to check the stator to determine if it is bad?  

Since it is not regulated, I do not see how it can be putting about 16.68 volts unless it was bad or the engine was running way over 4000 rpms.  

I do have a brand new battery I could swap in for a quick test, but, I don't want to smoke a new one.








Thanks.

16+ seems excessive.  I've seen 14 at most.  You have a 2 wire or 1 wire from your alernator?  If 2 wire, one of them should have a diode on it.  That is the regulator.  If one wire, there possibly should be a little box with 2 wires coming out, one from the alternator the other back to battery.

https://www.thepowerportal.com/ipls/ipl.htm?md=2877071272E1~_IPLURL_LO.pdf

Page 20.

Hi,

I will check tomorrow to see how many wires and if it has a diode. I did not know the diode was a regulator, I thought it was just a zener diode. This at one time did have a blown fuse, but, it was an ATO and was badly corroded so I thought that was part of the wiring problem before the relay died.


Thank you very much for the link.

I looked for a manual and the closest I could come with a listing was e-replacements. Though I did get an owner's manual that applies mostly to my version of Murray.

Hi,

Thank you for the manual link, that is what I needed.  I do not have a few things shown in the diagrams.

I have a dual circuit, two wire, unregulated, with the red wire having the diode. I tried finding out exactly how the diode rectifies the A/C current using a single wire to no avail.

I used a meter and watched it steadily climb from 12.50 to 16.2# as the engine got hotter before I shut it off. About 1/10 a volt every second. I figure whatever is in the red wire is toasted.

I wanted to order an updated alternator and regulator/rectifier box, BUT, my flywheel is good and stuck.  It did not budge at all using a steering wheel puller and I am not going to risk destroying a good 25 year old engine by pounding on it.  At the worse, I can apparently convert this to pull start quite easily, so, I can use it on one of my project Snappers that needs an engine.

So, I cut the harness off close to the connector and installed a couple of 1/4" connectors.  I ordered this :

Voltage Regulator Rectifier for Kohler 8-25 HP Engine 41 403 10-S 41 403 09-S US

https://www.amazon.com/dp/B01MXIV66T/

If I can not get something working for the $18, then I will just go with a small Chevy Alternator one wire running off the unused deck belt pulley.  I rather not fabricate anything right now.+

There are a couple of 20 HP engines for sale locally with 9-15 amp charging for $200. Except for the lack of a locking rear axle, the Murray has been a good yard machine with the worn tires and chains.  i do not really need 20 HP at the moment and the12.5 HP has been fairly good on gas. So, I rather keep the original engine if possible.

+ I have a CC2185 with what appears to be a locking axle to get up and running and a Yanmar  L100N clone engine I have owned for 4 months and never installed because I have come up short in the shaft driven GT department.

Not sure if that regulator/rectifier will work but perhaps it will, it designed to take 2 phases of AC and convert it to DC, maybe you can just run it on one side? Let us know! Check out the Briggs and Stratton 691188, it's one that should work for sure and it's in your price range.


If you would like to get the flywheel off there's some tricks to help, it could come up again in the future so here it goes.

With the puller on and tensioned nice and tight hit the end of crankshaft with a little heat then quickly for the next steps... spray it with lube, get a prybar underneath the flywheel and give the bolt on the puller a couple of good whacks with a hammer... it should pop free!

Here is an update with some pictures.  

The external rectifier did not work, basically I wasted $18, EXCEPT, it was worth wasting if I could have avoided taking the mower apart.  All the tricks did not work including drill out the key.

All prying did was break the PLASTIC gear ring teeth in two spots.  Hitting with the hammer method resulted in bending the puller bolts as the force screw had no way to properly center.

I was going to go with an external type of Chevy alternator and decided against it since if I am not around in 7 years, let us say, and my wife has to have it fixed, I can imagine the nightmare.

So, I decided to order this alternator from Amazon.

Hipa 592831 Alternator Dual Circuit with 845907 Regulator for BS 394890 393374 691185 797375 797182 and 696459 691063 393800 391735 393474 390185 390671 390693 391222 391520 Lawn Mower Tractor

https://www.amazon.com/dp/B08Q4D9P9B?psc=1&ref=ppx_yo2ov_dt_b_product_details

$45

After three hours of trying everything, what I did was this.  I found in my bolt/washer collection (I try to keep fully stocked on 1/4 through 1/2 bolts, washers, and lock nuts) a metric M12 washer that fit perfectly in the snout of the flywheel.  I put the force screw against that to put even pressure on the crankshaft so it would not slip off like it did on the bolt.  Then I hit it lightly with the 1/4" impact to put pressure on the puller.

Then I took my 25+ year old Craftsman heat gun, held it against the snout for 10 minutes (I timed it) until the whole flywheel was almost too hot to touch.  Then I hit the forcing screw with the 1/4" impact, and the flywheel popped off.

Despite missing teeth in two places, it starts fine and now charges at 13.18 idle and 13.48 at 3600 RPMs.

I picked Hipa because I have had good luck with  them in the past.  The replacement looks better built then the OEM alternator.  No way to easily hook up the headlamps to the A/C output as with the old alternator, BUT, at 10 amps I feel I can now go LED like I wanted to for headlamps and reverse and side lights.

NOW, I just picked up a Kohler 17 HP for $25 that I was going to put on a RER Snapper 1028, but, I think it is massive overkill. So ... I am putting the B&S on the Snapper which at 12.5 HP should be more then enough.

Then putting the Kohler on the Murray since it will be used off road for pulling carts, skidding small logs,  and maybe ground engagement equipment.  Reason being the Kohler has a screw on oil filter, so, I think the forced lube might be better in the long run going up and down inclines. Plus, the 17 HP gives me the option of a locking K62 or K72 in the future.

So, I basically spent three work days on it (10 hours over 3 days since i only work maybe 4 hours per day).  I tried to avoid that, but, I learned a bit about B&S, myself, and another technique I will probably take to the grave.  

Since none of my 5 kids have any interest in this kind of stuff even though they were taught how to use tools and cut down trees. If they did I would have gone external single wire alternator or one with an adjustable external voltage regulator.

Thank you for the help.

For anyone thinking about banging on the crankshaft to remove the flywheel, doing it to mine likely killed the engine.  

After the install, the fuel did not fill up the filter like before, it was hard to start, because it was not getting gas, and it appeared to run lean going by the sound. I checked the carb, removed the anti-fire valve, redid the valve lash.  It did start a few times, and that was it.  

Doing a compression check I got between 0-10 psi, if that.  Key way is not sheared. Valve lash is okay, engine freely turns with no noise. Push rods and rockers look okay. The crankshaft appears to be a bit wobbly on the PTO side, but, that might be the pulley.  I guess when I get time in the next couple of weeks, I will tear the engine down to see what broke.

Next time I have this trouble, I might just go with an external alternator.

$0.02

Sorry man I completely missed you last post! I've had tough times removing flywheels and such myself, sorry it gave you such a hard time...

You have to be missing something, a engine doesn't just lose all it's compression... a leak down test is a quick way to find out where the loss is and it can be done with nothing more than compressed air. All you need is a blow gun and a way to seal it at the spark plug hole just don't give it a full blast, regulate the air, I've used a rag as a seal in the past. With the engine at TDC and both valves closed take the oil fill cap off and lighty add some air to the spark plug hole, if you hear it in the crankcase there's either a hole in the pistion or worn/broken rings. Hearing it in the intake or exhaust either means a valve is not closing all the way, is bent or burnt.

The only other things I can think is that camshaft phasing is off a tooth (which is easy to check without tearing it down), the cylinder has become fuel glazed or the head gakset has a huge tear in it but that's something I would imagine would be obvious.

If your tractor has a fuel pump that would explain why the fuel filter didn't fill up as normal, it relies on crankcase pressure but if it's gravity fed then something else is going on.

I'm interested to know what the issue turns out to be.

Yes, I will do a leak down test before I tear the engine down.  Hopefully it is something cheap to fix.  I think it had about 100+ psi, I can not remember exactly what it was.  I usually write everything down for each engine so I know the specs before and after and what I added. That way whoever gets it after me, especially a modified 4x4 truck, is not searching for answers or parts.

I had planned on replacing it anyway, but, I wanted to use it in on a project RER Snapper.  On the positive side, I have a brand new regulator for the used Kohler I installed, in case it ever needs it :-D

I will try to take pictures or a video to post when disassembling it.

Thanks!

I've used the prybar and hammer method dozens of times now.  Cracked case?  Hope not.