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The engine doesn't need the battery to run, the spark comes from the magneto. The battery's only purpose is starting the engine and lights if so equipped. When running you should see 13.5 volts at the battery. If not, it isn't charging.
How come we are to page two and some are still posting other eyederz about what might be wrong. As said by taxman any 12 volt system needs more than 13 volts to charge effectively....However as flamed hatch points out the battery also needs to be good to test the charging system.

The magneto could care less about the charging system.
 

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Discussion Starter · #23 ·
Its got 20 yrs of grease and grime built up on it so I'm going to pressure wash it tomorrow.

I'll take some pics and post them up once its cleaned up.

Appreciate the help!

How about some pictures? So we can help better.
 

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Discussion Starter · #24 ·
I appreciate your input and it possibly could be the battery, that's what I'm trying to pinpoint.

The battery is only about a year old and tests decent with a regular automotive load tester.

As mentioned, it will run with the battery disconnected so the magneto part must be O.K. ?

I assumed the magneto also is the charging system so need education there.

Where does the battery charging approx 13.5 Volts come from??

The battery shows 12 Volts, running or not.

Valve adjustment was done a while back and made a big difference.

Starter is old for sure but works well when the battery is up.

I don't mind buying a new battery if it needs it but I'm not yet sure.

I'm trying to figure out where my 13.5 Volts are and how to get them!!

Most of the wiring is going to be in the back sorta under the seat. Check all that to be sure first. But as stated good possibility its the valves! Starter could be going bad too... Id bet your battery is the problem myself!
 

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I appreciate your input and it possibly could be the battery, that's what I'm trying to pinpoint.

The battery is only about a year old and tests decent with a regular automotive load tester.

As mentioned, it will run with the battery disconnected so the magneto part must be O.K. ?

I assumed the magneto also is the charging system so need education there.

Where does the battery charging approx 13.5 Volts come from??

The battery shows 12 Volts, running or not.

Valve adjustment was done a while back and made a big difference.

Starter is old for sure but works well when the battery is up.

I don't mind buying a new battery if it needs it but I'm not yet sure.

I'm trying to figure out where my 13.5 Volts are and how to get them!!
Have you been reading the responses? Good god!
 

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Lights and battery charging are run off a lighting coil that is separate from your ignition coil. Ac current comes out and passes through a rectifier to cross to dc. The coil that fires your spark plug makes it’s own power and does not require any battery to work. You could actually remove the battery while it’s running and would be able to use the mower all day without it until you shut it down and go to start it again.
 

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you've got to get a volt meter on the 2 yellow wires going to the rec and check for AC voltage at wot.
or just buy a new rec/reg. and try it!
 

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Appreciate the info, is the capacitor/diode under the flywheel or somewhere visible??
Battery voltage is 12 Volts whether the Engine is running or not.
Trying to locate the rectifier, regulator, diode whatever it has??
As has been said - the engine runs off a coil that does not need battery voltage to run, and this is separate from the charging system.

The charging system is magnets inside the flywheel, and the stator is under it. You haven't said how the deck engages, since as I mentioned earlier, determines what type of charging system it has.
If it has a manually engaged deck, it only needs to charge a couple amps, so there will be a 2 wire plug that usually comes out under the fan shroud by the starter. The black wire feeds the key switch with A/C current for the headlights, and the red lead with the lump under the shrink wrap is the 12v D/C feed to the key. Unplug the connector - the red wire should show voltage with the engine running. If not, either the capacitor or the stator is bad.

If the deck engages with a button - it gets more complicated, because there are several variations of the systems to get the necessary amperage to run the deck clutch. Too many variations to cover here. Here are a couple links link to good troubleshooting guides.

1-7 (smallenginesuppliers.com)

How do I check my alternator & battery? | Briggs & Stratton (briggsandstratton.com)
 

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Discussion Starter · #31 ·
Bingo !!!

That's the part that I didn't know, they're probably both under the flywheel?

Machine has been trouble free so I've never had anything apart or had to learn anything.

I appreciate your helping me understand they are separate systems.

As mentioned, I'm an electrical dumdum.

Thanks
Again

PS: 440cuda could learn some civility from you, and others.

Lights and battery charging are run off a lighting coil that is separate from your ignition coil. Ac current comes out and passes through a rectifier to cross to dc. The coil that fires your spark plug makes it’s own power and does not require any battery to work. You could actually remove the battery while it’s running and would be able to use the mower all day without it until you shut it down and go to start it again.
 

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Bingo !!!

That's the part that I didn't know, they're probably both under the flywheel?

Machine has been trouble free so I've never had anything apart or had to learn anything.

I appreciate your helping me understand they are separate systems.

As mentioned, I'm an electrical dumdum.

Thanks
Again

PS: 440cuda could learn some civility from you, and others.
Well, that was actually said in yesterday’s conversation. Under the flywheel.
 

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Most brigs motors actually have the coil on the outside of the flywheel if I remember right. Makes setting the gap properly pretty easy. Lighting coil/stator are always on the inside for the most part. Need to remove the flywheel to get to them.
 

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Discussion Starter · #34 ·
Right on, now I'm getting somewhere!!

I believe I posted earlier it's a very basic mower no PTO clutch or oil filter and totally manual deck.

Fortunately, it looks easier to diagnose according to your great instructions below.

4 questions if you could spare the time please:

1: The stator would be under the flywheel, correct??

2: How about the capacitor, is it under there too?

3: I hear mention of a diode, is that a capacitor?

4: Would this basic model even have a voltage regulator??

Again, thanks for your continued input!!

I'm old and dumb but not to old and dumb to learn.

As has been said - the engine runs off a coil that does not need battery voltage to run, and this is separate from the charging system.

The charging system is magnets inside the flywheel, and the stator is under it. You haven't said how the deck engages, since as I mentioned earlier, determines what type of charging system it has.
If it has a manually engaged deck, it only needs to charge a couple amps, so there will be a 2 wire plug that usually comes out under the fan shroud by the starter. The black wire feeds the key switch with A/C current for the headlights, and the red lead with the lump under the shrink wrap is the 12v D/C feed to the key. Unplug the connector - the red wire should show voltage with the engine running. If not, either the capacitor or the stator is bad.

If the deck engages with a button - it gets more complicated, because there are several variations of the systems to get the necessary amperage to run the deck clutch. Too many variations to cover here. Here are a couple links link to good troubleshooting guides.

1-7 (smallenginesuppliers.com)

How do I check my alternator & battery? | Briggs & Stratton (briggsandstratton.com)
 

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Discussion Starter · #35 ·
Please forgive my dumbness friend.

My old stroke ridden brain is doing the best it can to keep up.

Well, that was actually said in yesterday’s conversation. Under the flywheel.
 

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Stator would be under flywheel.

capacitor, diode, or regulator would be hooked up outside engine shroud. There should be a single red wire that will either connect to the terminal post on the starter that is hooked to the positive side of the battery or it will run all the way to the battery positive itself. It will be a smaller gauge wire about the size of the alternator wire on a pre 80s gm car.
 

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capacitor, diode, or regulator would be hooked up outside engine shroud. There should be a single red wire that will either connect to the terminal post on the starter that is hooked to the positive side of the battery or it will run all the way to the battery positive itself. It will be a smaller gauge wire about the size of the alternator wire on a pre 80s gm car.
No. There are at least 15 variations of small engine charging system stators, with variations in circuit counts, output amperage and polarity. The wires and plugs are color coded to help with stator I/D. This is why I provided him with the links to I/D and diagnose the charging system.

For GLHS60's questions:
1: The stator would be under the flywheel, correct?? YES

2: How about the capacitor, is it under there too? NO - usually a connector coming out from under the cover in the starter area.

3: I hear mention of a diode, is that a capacitor? YES - it changes the current from A/C to D/C.

4: Would this basic model even have a voltage regulator?? USUALLY NOT. Depends on the stator.

As I said earlier - most engines of this type that don't need the amperage to operate a clutch coil have a 2 pin plug by the starter coming from the stator. The black wire carries A/C current to the key switch to operate the headlights, which work on A/C or D/C. The red wire with the lump under it - the lump inside the shrink tube is a capacitor to turn the current into D/C - that wire usually goes to the key switch and charges the battery when the key is on and the engine running. They typically do not apply battery voltage to the stator at all times, only as necessary.

Hope this helps.
 

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No. There are at least 15 variations of small engine charging system stators, with variations in circuit counts, output amperage and polarity. The wires and plugs are color coded to help with stator I/D. This is why I provided him with the links to I/D and diagnose the charging system.

For GLHS60's questions:
1: The stator would be under the flywheel, correct?? YES

2: How about the capacitor, is it under there too? NO - usually a connector coming out from under the cover in the starter area.

3: I hear mention of a diode, is that a capacitor? YES - it changes the current from A/C to D/C.

4: Would this basic model even have a voltage regulator?? USUALLY NOT. Depends on the stator.

As I said earlier - most engines of this type that don't need the amperage to operate a clutch coil have a 2 pin plug by the starter coming from the stator. The black wire carries A/C current to the key switch to operate the headlights, which work on A/C or D/C. The red wire with the lump under it - the lump inside the shrink tube is a capacitor to turn the current into D/C - that wire usually goes to the key switch and charges the battery when the key is on and the engine running. They typically do not apply battery voltage to the stator at all times, only as necessary.

Hope this helps.
No way there is 15 variations on a briggs motor on an mtd mower. They are as basic and cheap as they get. Worked on em all though middle school and high school as a first job. And the charge wire after the diode or regulator is always red on them whether it’s wired through the key switch then to solenoid or which ever variation that mtd found cheapest to use at the time. All he needs to do is verify that wire is receiving power while it’s running. Probe the circuit from past the diode/regulator and work your way back through the circuit and you will find your problem. 13-14 volts is normal. I found 90% of the time the key switch was to blame for charging issues on mtds. They used a real pos switch.
 

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Never seen an mtd lawn tractor with electromagnetic clutches either. Like I said, they are the cheapest machines you can buy.
 
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