Bouncing Tach Needle

[Florida Mike]

A long time ago a friend had the same problem on his sailboat. I solved it by jumping a small dash light bulb around the voltage regulator. This kept a small field current through the alternator. He reported back that it cured the jumping needle and did not cause excessive charging. Just my two cents, Mike.

[gettinthere]

The fix did not work, needle still bouncing.
I don't understand the bulb fix, please elaborate? Where did you wire it?

[Florida Mike]

The bulb was wired around the regulator. It came from the switch positive lead that fed the regulator to the field terminal on the regulator. What this accomplishes is maintaining a small field current to the alternator which keeps the alternator charging slightly as in 1 to 3 amps. In this particular case the voltage regulator with external. It happened to be an old Chrysler regulator running a GM alternator. Just my two cents, Mike.

[gettinthere]

Mike
It sounds like you needed the bulb to keep a small load on the alternator. I'm having this issue when the batteries are in need of charge, so there is a draw from the batteries? Plus, chart plotter, radio, etc are running, creating a draw.
wouldn't this negate your idea as a solution for me?
thanks

[tuberider]

balmar regulators have a spot where you run your tac wire thru the regulator. takes care of the problem

[gettinthere]

...But the system ran fine for a while as is. Then started this problem. I suspect it has to be a bad ground, just haven't found it.

[Florida Mike]

The light bulb act as a resistor to maintain a small field current so that the alternator never turns off completely. Remember that the positive input to the bulb does need to be switched with the alternator. Remember your charge controller told you that the alternator was not charging when the tach, was not working. What this will do is make it so that the alternator never completely stopped working. I hope this clears a little bit of the mud is not contact me off board and I can call you and explain better. Good luck, Mike.