View Full Version : Volt meter readings

06-28-2007, 11:10 AM
I know this subject gets a lot of threads, but my searching has not found a thread that really talks about the following question. What is you volt meter reading when you are running accessories, and the boat is on?

I believe I have a weak alternator, which I'm going to pull and have tested, but in the mean time, I'm seeking confirmation that I'm on the right path. I'm at 12 1/2 when idling , and if I turn my heater fan on it drops to 11 3/4, if I turn on other things like blower, lights, whimpy stereo, I can acutally get the volt meter to drop below 11. If I rev up I see no increase in the volt meter. I haven't had my multi tester with me when I've been in the water yet, so I haven't been able to verify guage accuracy. I tested it static in my garage last night, and if I turn on every accessory, my volt meter in dash will drop to 10.8, but my tester at the battery will still be showing 12.2.

I had a dead battery last weekekend, and replaced it, but now I'm thinking that battery was giving me issues because my alternator is not putting out enough volts to charge my battery when I run accrssories, so I'm acutally discharging all day long instead of charging.

What does your volt meter show you at idle, at higher RPM's, and does it drop like mine when you turn everything on? Anybody been here before?

06-28-2007, 11:11 AM
Oh yeah, it's an older boat, an 88 PS 190.

06-28-2007, 11:42 AM

This is what helped me. I am absolutely no engine expert but I got mine worked out. Different issue. I never trust my voltmeter in the dash. I only use it for variences.

07-05-2007, 05:30 PM
Never assume the voltmeter in the dash to be accurate. MC is notorious for dash/gauge wiring that does not allow accurate voltage to show on the meter. It will always read low. The low volt meter reading puzzled me for years, until I found out from MC friends they had the same, and it was just wiring issues (never addressed from my '91 thru late '90's at least).