voltage gauge pegged.

I have a 60hp Mercury outboard recently the voltage pegged to 18v on the gauge and stays there on just about anything above and beyond 2k rpms. I took a reading from the battery with a digital multimeter it was at 14.4 volts with the engine at about 3k rpms.

The gauge does drop to 0 when off and rises to about 12-13 when in the run position. Also rises a bit at idle 13-14v.


Should I assume Is the guage faulty or should I test it further? If so give me a hint on where to measure from, this my first Mercury. I was thinking right at the gauge.

Re: voltage gauge pegged.

This will take two people, one of you hold an accurate voltmeter across the battery and the other read your gauge on the boat. Compare the two readings thru a cycle of turning key on , starting and gradually going to WOT, then shut down. The voltmeter should be correct, any variance should be a volt gauge problem, expecially if the boat gauge is reading higher, if reading lower there could be resistance in the line that feeds its. Your motor might have unregulated power and high voltages can occur, this is not good over time. A fiend of mine got some big resistors and put them in the circuit to keep the vltage down. He uses a switch to add them and take them out of the cirtcuit. There probably is an aftermarket regultor that could be used also. Somebody else would have to address that solution. Good luck JH

Re: voltage gauge pegged.

Oh sorry I should have mentioned this motor is newer, it does have a voltage regulator. Im 90% sure it holds at 14.4 volts at the battery no matter how high the RPMS. Was wondering more along the lines if there was a seperate output to the gauge. That could read different than I am getting at the battery while testing or testing from the battery was just plain wrong.

Thanks!

Re: voltage gauge pegged.

The voltage gauge is just sampling the key'd power line to the dashboard.

If you'll notice, your voltage gauge doesn't start at 0. To get a wierd range like that, the gauge has circuitry in it that is nonlinear. Nonlinear meters can sometimes get...well......realy nonlinear.

Substitute another gauge. It's probably the problem.

hope it helps
John

Re: voltage gauge pegged.

j_martin said:

The voltage gauge is just sampling the key'd power line to the dashboard.

If you'll notice, your voltage gauge doesn't start at 0. To get a wierd range like that, the gauge has circuitry in it that is nonlinear. Nonlinear meters can sometimes get...well......realy nonlinear.

Substitute another gauge. It's probably the problem.

hope it helps
John

Click to expand...

Thanks for the info it helps a lot.

Re: voltage gauge pegged.

As long as you are satisfied that the voltage output is regulated and not actually spiking as you volt gauge says, then you can tinker around with resistors on the back of the gauge, between the positive and negative leads, to see if you can get a correct reading. If the guage was originally reading correctly and then started doing this high reading lately then my guess is that a resistor has gone bad inside the meter. Is it a sealed unit or can you get to the circuit board, if so check all the resistors and if one is bad solder in a new one of like resistance. Someone with more electronics lnowledge may chime in here and give more ideas. JH

Re: voltage gauge pegged.

jhodge said:

As long as you are satisfied that the voltage output is regulated and not actually spiking as you volt gauge says, then you can tinker around with resistors on the back of the gauge, between the positive and negative leads, to see if you can get a correct reading. If the guage was originally reading correctly and then started doing this high reading lately then my guess is that a resistor has gone bad inside the meter. Is it a sealed unit or can you get to the circuit board, if so check all the resistors and if one is bad solder in a new one of like resistance. Someone with more electronics lnowledge may chime in here and give more ideas. JH

Click to expand...

Actually, shunting a voltmeter doesn't do anything but consume power and generate heat.

The internals involve non-linear semiconductors, like zener diodes.