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We couldn't find a wiring diagram so here goes. Need to make sure it is charging. There is a lose red wire coming from up. Around the flywheel and one unknown plug. How is the wiring setup for a low oil alarm? Thanks.

Model is 311777. 0209e.

Looks like someone has already hacking at the wiring. IPL says it has a dual circuit alternator stator so it will first need to be restored to the normal wiring then the red lead with the diode would be connected via one of three ways to recharge the battery.

1. via the ignition switch
2. via the starter solenoid
3. 0r via direct wire to the battery.

That looks like wires coming from the charging stator. That model has 3 different stators but, that looks like the Dual Circuit stator. It has DC volts going to the battery to charge it and has AC volts going to the headlights. They are notorious for over charging the battery though, that's why someone has disconnected the red wire, going to the battery....to try to keep from overcharging it.

If overcharging is a problem it is easy to add a voltage regulator but of course many users are too cheap to add one. The meters in the last diagrams are just for current and voltage tests.

So are you saying a wire with a diode needs to go from the red wire to the battery?

ba_50 said:

So are you saying a wire with a diode needs to go from the red wire to the battery?

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Who knows what has been chopped up and rewired, even under the engine shroud, so use a OHM meter to test the output of the wires coming down out of the shroud and use the chart StarTech posted in #5 to know what wires goes where.

It has never been rewired. Not sure how that happened. Only one red wire.

mower king said:

That looks like wires coming from the charging stator. That model has 3 different stators but, that looks like the Dual Circuit stator. It has DC volts going to the battery to charge it and has AC volts going to the headlights. They are notorious for over charging the battery though, that's why someone has disconnected the red wire, going to the battery....to try to keep from overcharging it.

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There is a black and red wire coming from the stator. If it was cut on purpose because of overcharging, does that mean it should be charging without them connected?

The stator wiring has been hacked. No diode so the red was connected it quickly burn out the stator; along with frying other parts and wiring too. The dual stator wiring harness needs replacing before you even try to reconnect the system.

ba_50 said:

It has never been rewired. Not sure how that happened. Only one red wire.

There is a black and red wire coming from the stator. If it was cut on purpose because of overcharging, does that mean it should be charging without them connected?

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I have one of these dual circuit stators at the shop, i'll be back at the shop Monday and I'll look at it and see what color wires are where.

Yep I am with Star on this
Rip the flywheel off and send a photo of the stator
Some thing very funny going on
There was a one wire stator fitted to some walk behinds but again the wire needs to have a diode in it or you are pumping AC into the battery which will boil the electrolyte and wreck the battery.

I think this is the alternator you have. You should have a connector with a red and black wire from the mower that connects to the regulator.

The only plug in is shown in the photo, one red/blue and one purple. The two loops in # post 5 must be the regulator.

If there is a regulator I don"t see one in the front or middle section
Is the Stator harness supposed to unplug on top?

The wires from the stator plug into the regulator. The regulator ia uaually attached to the engine shroud. I can't tell from the pic what wires are where. The plug with the black and white wire on the engine. Where do they go? Does the engine have a fuel cutoff solenoid? What is the make and model of the machine. Best i can tell someone has tried a bad attempt to bypass a bad voltage regulator.

I agree with Hammer....it looks like you have the 696459. The black wire is the AC source for the headlights. Measuring from the black wire to ground should yield 14 VAC at WOT(wide open throttle ~ 3600rpm). As you can see in the picture of the 696459, a diode is incorporated into the red wire to rectify the AC for charging the battery. This diode is a 'must have' in order to charge the battery. The replacement part number for the connector and diode is a Briggs 393456. This will splice to the red and black wires you have coming from the stator. I see in your first pic there is a connector there with a blue and red wire going up into a harness. This could be where the original plug from the stator plugs in. You should look at an electrical diagram for your machine to be sure but if the new stator connector mates up, it's pretty likely that's where it goes given its location.

If you want to skip the existing wiring and connect to the stator via the new connector/diode assembly, Briggs sells a mating connector to the 393456. It's a 691237. The red wire is the DC side to go to the battery and the white is the AC side to go to the lights(via the light switch). You can see that schematically in the diagrams posted previously.

Notice that Briggs does not spec a voltage at the DC connector. They only spec a charging current of 2-4 amps. It's easy to determine if you are charging without having to measure current. Measure the DC voltage at the battery with the engine off. After you have the stator properly wired back up(with Diode), start the engine and run at WOT. The DC voltage at the battery should be greater than voltage when off. It will likely be in the neighborhood of 13-15 VDC. [it goes without saying that since you are splicing in a new connector, you could easily measure the charging current in the red wire before making the splice!]

FWIW, prior to splicing in a new diode and connector, you could start the engine and measure the AC volts from the red stator wire to ground. It will likely be in the 30-35 VAC range. If you get this on the red and 14 on the black then your stator looks to be good.

I'm struggling a bit with the idea that it was hacked due to 'overcharging'. Anything is possible! Those diodes are rated at 6 amps continuous current. If you let your battery die completely to near zero, you might jump it to get the engine started but the charging current would be high and can be more than 6 amps for too long! That's usually when you let the smoke out of the part!

Let us know what you find!

It's worth noting that the IPL for the engine # provided does not call out a 790292 regulator. FWIW.

Telesis said:

Those diodes are rated at 6 amps continuous current. If you let your battery die completely to near zero, you might jump it to get the engine started but the charging current would be high and can be more than 6 amps for too long! That's usually when you let the smoke out of the part!

Let us know what you find!

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As said that is continuous current which is not the case. This a half wave circuit and diode is operated in pulsed mode which means that they can normally handle a surge current several times the constant current value. Sometimes as much 400 amps for a 6 amp version. I use 3A continuous with a 200 amp surge rating with 1000 PIV rating on most of these systems (1N5408-G).

I would need the PN of the diode (off the diode) to look-up it specs but I would it is only 3-6 continuous rated diode with at least a 100 PIV rating.

Keep in mind that your meter is reading basically an average value of current when you are in the DC amp mode. When the spec is 2-4 amps, that is essentially a continuous average, not a pulsed amount. A battery acts like a big electrolytic cap and if you put a scope on the battery, you won't see much ripple because it's acting like a filter(among other things, lol!). Likewise, if you measure AC volts across the battery, it will reflect this small ripple. The fact remains, if a 3 amp diode is run at a higher continuous/average current for an extended period of time(that's the key point here), as in the case of a very weak or dead battery, it's clearly being stressed. I realize this is under abnormal conditions, but let's face it, lots of customers let their gear sit and try to start with dead batteries. I should have clarified that the Tecumseh 3A charging systems use a 6 amp diode. I believe B&S use IN540X 3 amp ones(341507 part#) like you are using. I can tell you that as an engineer, I typically derate by 100% in my designs which is why I'd use at least one rated for 6 amps continuous with 200PIV rating.... but heck, that's just me! FWIW

Now that I can agree with as many of my personal designs also uses 2x rating. That just makes sense for durability. I got one 5A design 12 power supply that personally know as 30 amps peaks have been pulled through it when a 250 watt 11 meter linear amp operated in AB mode was powered by it.

Now Star, you aren't admitting to operating 245 watts above the legal limit on 11m are you? LOL! I'm sure you meant 10m wink-wink! [I'm more of a pair of 3-500Z's running 4,000 VDC on the plates!]

Some final comments on the charging circuit for those who may be unfamiliar. Current only flows into the battery when the rectified value of the voltage rises above the battery voltage. When the rectified AC voltage falls below the battery voltage, no current flows into the battery. While the AC voltage ripple at the battery is nil, the current can rise from zero to several amps during those times the diode is conducting depending on battery voltage, with the average being what we read on a ammeter. (that's the magic of the battery. even though the current is going from zero to a number of amps, the voltage remains flat, and rises slowly as the battery charges) It's that average value of current that's converted to heat and in time does the damage if it's more than the part is rated for.

Actually only 238 watts on SSB but that was only on a repair into a massive oil cooled dummy load. Actually was upgrading a 10M mobile amp which I still have. It originally was 140W unit but I redid the transformers and a couple new transistors. My mail carrier couldn't believe the cost of the package that I got in; just had see what was in the package. It is was very low power compared to the 1.5KW peak base amplifier that I repaired the was originally a 300W that had incorrectly wound RF chokes in plate supply line to the four tubes. Boy those tubes went from having cherry red plates to a nice blue glow. The owner was a little ticked off when he smoked his RG mini 8 cables but I warned him the those 800w cables wouldn't handle the amplifier.

And boy I haven't seen a pair 3-500 in years. But most of the amps I repaired were using horizontal TV tubes. I was looking into building an amp with a pair ceramic tubes but I got unemployed at the time then parts became nearly impossible to find plus running my own took more time so I had little time to experiment building an amplifier.

But you don't need that kinda power to talk to Australia as I talked to a few operators there using less than 1W but of I was using a modified 4 element Moonraker using CP mode. Most times I used RH mode but a few times LH mode worked better.

That antenna ripped through the blocking of an 8 element beam antenna 40 miles away. That guy was bragging he could be block anybody. Any ways I had more fun using QRP power as locals couldn't heard me but they could hear the Aussies talking to me. I even had one local try using a 3KW amp to contact them with no luck. About broke my receiving meter needle. Boy was I laughing my socks off that night as I was using using only 1W.