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Using lighting coil to charge battery?


rickpilgrim

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I'm using a Briggs 14hp Twin 2 on one of my machines with electric clutch.

It has one red and one white wire for the charging/lighting circuit, and I'm asking if you can put a diode/regulater in that white wire to help charge the battery when the 4 amp draw clutch is on.

Will that work?

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Best result would be connecting a voltmeter to battery circuit and with engine running WOT , engage the clutch and see how the existing charge maintains the battery.

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At 3550 rpm on the tiny tach 13.8v until you turn on the clutch and it drops to 12.5-12.7v. That's not horrible but I'd be happier with 13.6v or so. If I could get 1-3 amps out of the lighting circut that would be great

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Local Briggs shop said they could sell me a diode that they thought would convert the single white lighting wire to DC but said I'd have to check the voltage and possibly find a regulater.

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Rick,

There is no easy way to take the "white" alternator coil output (the other end of the stator coil/winding is grounded) and rectify it for additional +12V D.C. power. Putting a diode in series with the lead will only half-wave rectify it yielding ~~ 1/2 the RMS current and voltage; thus not useable on a 12V system. Unless you could isolate the grounded end of these stator coil(s) and run another wire to it, then you could full wave rectify it and indeed have another +12V DC charging/power source.

Tom (PK)

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Thanks for clearing that up. Today I'm off to the small engine pick a part to find a 16 amp stator to replace the dual voltage one. The twin 2 likely has the small magnet flywheel so doing this won't give 16 amps but should get me to the 7-10 amp range which will be good enough for that electric clutch and charging the battery.

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Found the 16 amp stator at the small engine pick a part for $10 today but am wondering with the small magnet flywheel what the output will be as anything over 12 amps will fry my current regulator. I don't think it will be that high as I have never tried this. Anybody have any ideas about this?

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You need about 28 VAC wire to wire WOT as when it is rectified, voltage drops to 14V DC of which it is regulated to 13.5-.7 VDC.

You still need to check the battery condition to see if you can maintain the regulated voltage. If it goes that high , forget the amp flow as it is maintaining a good charge.

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Thanks BLT! When I get the exhaust all fab up and oil in it will check all that. Seeing I got the stator changed I saw my flywheel has 2" magnets spaced 1" apart all the way around I likely will be at the 16 amp output so using the Kawasaki 10 amp regulator is out so I have to source the appropiate Briggs regulator in a day or so before any more testing. That's why I was concerned about amps, to see what parts needed.

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So I pick up a new 16 amp regulator ($72 ouch) with 3 wires. The 2 yellow plug in the engine harness while the red wire has an end that looks almost diode like with a single pin connector. Is it ok to just cut that end of the red wire off so I can solder it into my wiring harness?

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The red wire with the connector is just that. The reverse flow diode protection is inside the potted regulator/rectifier module. You can buy the connector w/wire from Briggs (PN 692306) but I can't see it being a close to $9.00 hunk of wire. That connector is very common on most every B&S engine with an alternator system. Why not check out a shop/ bone yard place and clip one off a scrap tractor/wiring harness? Personally I wouldn't want to hard wire anything an engine and not being able to disconnect it.

Connector type in question:

http://www.digikey.com/product-detail/en/1-480351-0/A1408-ND/15658

http://www.digikey.com/product-detail/en/1-480349-0/A1409-ND/15660

Tom (PK)

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For clarity what I'm doing here is replacing a rope start problematic Kawasaki FV451 on a Hustler 1537 walk behind mower. It had very little wiring to begin with, alternator directly to clutch switch and magneto to key on/off, that's it on the engine side.

They(Excel Hustler)must have tried different engines along the way as there are holes drilled everywhere to mount regulator/solenoid/ battery box etc that line up with Briggs components.

The regulator is mounted to the frame, harness to engine has 2 plugs in it so in high vibration things I solder and shrink wrap for lasting results.

I can wire thru the key to isolate the alternator from the battery with key off, not my favorite way but gets the job done.

Thanks everyone for the help on this!

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quote:Originally posted by BLT

I think that diode keeps the battery from discharging back thru the regulator.


id="quote">
id="quote">The diode in series with the red wire is a half wave rectifier that changes the AC to DC. As powerking pointed out, one side of the stator winding is grounded, the DC output does not need to be regulated as it's current capacity is so low that it cannot overcharge a battery. The diode also prevents the battery from discharing through the stator winding.John U
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Today I had time to hook everything up and at mid rpm with the electric clutch on voltage was 13.71v and 14.13v with clutch off.

Thanks everyone for pointing out using the lighting coil would not be a good option for this machine.

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With the single diode, you are only using half of the AC wave form. By using a bridge rectifier, you could use both half's and double the output current. You would have to disconnect the grounded side of the stator winding and add a wire from it to the bridge. The bridge may look like this. The – , negative goes to ground and +, positive to the battery charging circuit. Sometimes the AC has a little sine wave symbol instead of letters. The two ends of the winding on the stator are connected to the AC. If you hurry to Radio Shack, you can get a bridge for a few dollars. You need one rated at least for 50 Volts and 8 or 10 Amps.

RS-Bridge.jpg

RS-Bridge.jpg.3912ffd17270e4651797ec53aaed6372.jpg

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Finding the ground on the dual circut is easy once the flywheel is off. You can see a screw with 2 wires hooked to it. It's a regular Phillips screw, not the 4 mounting bolts.

Of course once I had the flywheel off its was easier to swap to the 16 amp stator and add a regulator to get the needed power( 6 amps clutch, 2-3 amp battery) to do what I wanted.

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