Weird battery stuff

[sneuman]

I am a liveaboard and so frequently charge my batteries and use them (in the winter, anyway) primarily for cabin lighting. Came back to the boat the other night and found my batteries were completely dead after just a normal day of being away. My battery monitor showed nonsense on all the displays. I proceeded to charge up the batteries (two banks, wired in parallel) and got a very odd mismatch on the meter. Bank 1 (nearest charger), gives me about 12 volts charged (though used to give me 13+) and bank 2 gives something like 18.75 volts! What's up with that?

[AnchorageGuy]

if your charger is putting out 18 volts there is definitely something wrong. disconnect the batteries and measure the voltage output on the charger. Should be about 13+. Disconnect all of the batteries and check each cell with a hygrometer. You may find you have a dead or shorted cell.

[noelex 77]

Originally Posted by sneuman

My battery monitor showed nonsense on all the displays. I proceeded to charge up the batteries (two banks, wired in parallel) and got a very odd mismatch on the meter.

Were you measuring the battery voltage quoted on the battery monitor, or did you use a separate multimeter?

[sneuman]

Originally Posted by noelex 77

Were you measuring the battery voltage quoted on the battery monitor, or did you use a separate multimeter?

Battery monitor. They are new batteries (purchased in spring).

[AnchorageGuy]

First and foremast you need to take measurements at the batteries. You may be chasing ghosts when the problem is the monitor.

[noelex 77]

Originally Posted by Chuck Baier

First and foremast you need to take measurements at the batteries. You may be chasing ghosts when the problem is the monitor.

My thoughts as well. Use a multimeter on the batteries and check the voltage.

[Cadence]

You may want to disconnect the batterties and use a load tester. They are relatively cheap. A vom would'nt necessarelly detect a bad cell in one of them.

[AnchorageGuy]

Originally Posted by Cadence

You may want to disconnect the batterties and use a load tester. They are relatively cheap. A vom would'nt necessarelly detect a bad cell in one of them.

A load tester at this point will give a little indication but for them to work properly and give you useful information the battery needs to be fully charged.