Charging problem

[SeaSteward]

I have a Balmar 80A on my yanmar with an external regulator. The output dropped so I checked connections and changed the belt. The output is down to 12.3 when charging and my house batteries are suffering. IM out cruising and need the alt. Any suggestions? Im pretty certain I have isolated it to the alternator.

thanks

[theartfuldodger]

check field plug if you can and be sure there is power on one of the two wires, have had trouble myself in this area, and have since change the design to correct the heat problem. You should be able to full field the alternator and check its out put as well, Balmar's website should show you how to do it.

[JohnRPollard]

Do you have the optional temp sensors at the alternator and/or batteries? Is it possible they are sensing a high heat or malfunctioning?

[camaraderie]

You need to isolate the problem to the alternator OR the regulator as well as check for common issues. Follow these steps:
Page64-troubleshooting

If it is the alternator, you can probably get it re-built at any auto shop wherever you are to get you through wherever you are. I am guessing it is the regulator since you seem to be getting some output...but you can have it diagnosed for sure in 15 minutes with the above guide.

[SeaSteward]

Thanks for the input- there is no magnetic field at the pulley shaft. The field test was tough- there is only a two prong plug not the harness shown. The reading from the pos post at the back opf the alternator is low- maybe its a brush issue.

thanks!

David

[Rockter]

To determine if the brushes are in trouble, pull off the field wire from the alternator and run an improvised positive wire from battery positive to the field wire terminal on the alternator. Do not connect it just yet.

Now start the motor, let it settle and you will see no output voltage at the battery. Momentarily touch the makeshift wire to the alternator field terminal. Be careful. There should be an audible whine as the alternator comes to full load. The belt will object too, and often it will slip and smoke, so make the touch momentary.

If the alternator does not respond to that, then I would suspect brushes or rotor. If it does respond, then suspect the regulator. You cannot fix them. You will need a new one. Check the terminals and the earth on it.

Stop the motor, and check for reasonable continuity between the brush terminals. The last one I looked at was open circuit, but if correct, expect about 8 ohms there. Open circuit was dead rotor for me. A broken brush, or broken brush terminal will be obvious.

This subject is topical for me just now. I have a Russian motorcycle, and the lights are flickering again tonight. That's after finding a shot rotor on the old alternator and putting a new alternator on there. It looks like the regulator has gone too. Either that, or I have a rogue earth. An analogue multimeter will betray it, in the moring, I hope.

[camaraderie]

David...glad you could narrow it down. Let us know how it all turns out and good luck!