Quote:
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Originally Posted by Rinkerguy
"...I have a 2003 Rinker, Mercury 5.0 MPI motor, and dual batteries...While connected to shore power, batteries fully charge...While under way, volt meter registers maybe 12V..."
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Are the batteries as old as the boat? Most factory batteries begin to fail after 3 years.
Did the "electronic testing" include a load tester? That type puts a "short" into the circuit, heats up, and gives you a real idea of its potential.
A load-testing meter is available today for $10. I got mine (the same one) a few years back, for $30! Lucky to be you.
(And don't use one of those those
computrozed testers—they're no good
).
There's a chance that you have a leak while at anchor. Remove one cable and put a 12V light bulb between the battery post and the cable. With all equipment off, the light bulb shouldn't glow—even dimly.
Your voltmeter should show 14.7 volts at full charge.