Dead Batteries

[Chillmark]

Good Evening -

I went out to the boat yesterday and both my batteries were dead. Battery switch was on, but nothing on the panel was switched on.

So first issue, I'm guessing I have a short somewhere. Not a big deal if I remember to switch off the batteries when I leave, but not great news. Also, as far as I know, not easy to trace.

Second issue, I charged the starting battery, and it only went up to about 12.2 volts. I brought it down to the boat hoping I could start her up and use the engine to charge the house battery. She didn't crank so I brought the other battery home in hopes that BOTH will start it tomorrow.

The batteries are both about 5 years old so I'm assuming they just need to be replaced. While charging, neither of them are showing bubbles in the water holes. Is that a sign they aren't taking a full charge?

I'd also like to check the alternator just to rule that out as an problem. If I get the charger on the alternator, what should the output be from the alternator be? And If I remember correct, the positive lead of the multimeter goes on the alternator and the negative goes to ground...correct?

I realize this is rambling with a lot of questions, but thanks

-Chill

[99yam40]

Sounds like your batteries are shot, or your battery charger is not working.
Put a volt meter on the battery terminals before and while running the charger or the motor to see what they put out
Have batteries load tested

[Chillmark]

re: Dead Batteries

What should the output be at the alternator?

This is a C115txrt by the way...early to mid 90s

[99yam40]

around 14V

[Chillmark]

re: Dead Batteries

I load tested the batteries, and both came back done. $300 later I have two new batteries installed on the boat. I took it out for a spin, drifted for a bit and at around 1500 rpm I put the leads of my tester on the battery terminals and got 12.9 volts.

Sound OK?