13.5 hp wiring for battery charge

[bertsmobile1]

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.

 

[Hammermechanicman]

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.

 

[ba_50]

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?

 

[Hammermechanicman]

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.

 

[Telesis]

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!

 

[Telesis]

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

 

[StarTech]

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!

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.

 

[Telesis]

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

 

[StarTech]

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.

 

[Telesis]

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.