Vanguard 16 amp Alternator Check

[Panhed66]

Is there a way to check the amperage output on a 16 hp v-twin vanguard motor with a 16 amp regulated alternator without using the DC Shunt? I downloaded the B&S Digital Multimeter instruction Manual but it requires the use of the shunt... I just want to be sure the motor is charging while I'm still in the fabrication phase.

[sho305]

I don't know how without loading it. You can use anything you know the load, for example 55w lights take 55w, so that would be about 55w/12v=4.6amps each if they are 55w at 12v some things are rated at 13.8v or whatever. Note that most small engine stuff including stock golf carts only charge full rate at higher rpm. The easy way is just put a meter on the battery it should be around 12.5 at rest you will see it go higher if it charges running. If you ran it high rpm and turn on lights/etc and pushed the voltage back down to 12.5 then that would be about the max it can run. You can check ohms on stators and stuff to see if they are good, or look up the parts and see if that is rated for X output from the maker. I think a stock yamaha GC generator puts out 15A at max rpm 4K.

[Flintrock]

You can safely check the stator output without the shunt. Just disconnect the leads from the regulator, and insert your test leads into the either stator output lead pin receptacle. Output should be 30 amps on a 16v system. The shunt is recommended for safely testing the regulator/ rectifier output without blowing a fuse in your multimeter.
If you know the stator output is good now you can wait till you get everything else running and check the regulator output at the battery when running. If low you know you probably have a bad regulator if the stator output was good. When doing this if it tests low you can also check for ground on the regulator. It must be solid to the motor for it to work properly.

[sho305]

On an outboard with a stator you can usually test for AC voltage on it while running, and if you have that it is usually working but just a fast test.

[Panhed66]

Wow, you guys really know your stuff. I pulled the mortor out of the cart last night to do some final touch up on the fab work but should have it back in place by the weekend and will perform the tests you recommended. I'm getting excited to see how this thing is going to run. Thank you again for your help.

[Flintrock]

Originally Posted by sho305

On an outboard with a stator you can usually test for AC voltage on it while running, and if you have that it is usually working but just a fast test.

Huh?

[Flintrock]

Panhed66, all I'm saying is you can check the stator output on the bench to make sure it's functional before you put the motor back in with all the shrouds and accessories. The stator assembly is cheap and easy to replace while you have the motor out, the regulator/ rectifier assembly while more expensive can be replaced without yanking the motor.

and if you have a 66 panhead with a generator, well, you can figure this out......

and Yes, post some pics......

[sho305]

Originally Posted by Flintrock

Huh?

A stator makes AC power, the rectifier turns it into DC. Usually a stator works or it is shorted and does nothing. If you are troubleshooting and its on the engine and you can run it, that is a quick check that you have AC coming from the stator. Sometimes when rectifiers fail you will see AC in the DC, then you know the stator is working but the rectifier is shorting AC to the battery. Normally you would see very little AC at the battery.