Love Joy coupling

[Geochurchi]

Hi, as stated load is 5 Amps with Amp at full volume, 2 LED head lamps, never thought of the Christmas lights, may be next year, no room for pulley or belt, if knew then what I know now I would have repaired the original, however the shaft on the armature was a bit beat up so a volunteer turned a new armature,NC.
Just curious! What happens if I remove the alternator and run with just the onboard charging system that puts out 16 Amps? Possibly even installing a larger capacity battery although this battery has a high RC of 35 minutes at 25 amps which seems fine to me.

[liveaboard]

If the alternator barely makes 12v, then there will be practically no current.

Changing the voltage regulator won't help I'm afraid; it will be supplying whatever voltage is available to the field coils already.
the "16A" alternator on the motor will probably not put out 16A at low RPM; but check it and find out.
Measurement is much more reliable than theory.

I've tested an 80A delco alternator to find the answers to those questions; it was a long time ago but I remember it made good current at around 1,000 rpm.
I made my own voltage regulators for them so I could tailor voltage to the battery and engine.

[Geochurchi]

What’s the best way to test output amperage from an alternator, use a clamp on meter?

[liveaboard]

If you have a clamp meter that does DC, it's definitely the easiest way.
Otherwise get a shunt resistor (they're cheap) and by measuring the output with a voltmeter you'll see the current.
Most handheld multimeters will do 10A directly through an internal shunt.
I've used a length of regular connection wire; by measuring the voltage drop across it's length with a known current, you can extrapolate higher current.
This works well because of the high sensitivity of digital voltmeters.

To measure what an alternator CAN produce at a given rpm, you'll need a load. I used a big resistor coil, but you can just turn everything on and connect a discharged battery.

[Geochurchi]

Thanks

[Bill Shields]

If the voltage just is not there...you could always (if you need it) move the alternator back a bit and put in a planetary speed increaser.

Or just go with the bigger battery and call it a day...taking the alternator space and dropping in batteries might be the most straightforward option