Weak Batteries?

[Datenight]

Hello all. I just got back from a sailing the French Rivera on an Amel Super Maramu. My cousin bought the boat this spring. We went over in June for a two week shakedown and had a wonderful time. This trip was a boys week.

The boat has 300 watts of solar and a 400 amp battery bank at 24 volts. What ever amps we used overnight usually 40ish were back in the bank by 11:00 a.m. in June.

Last week things began to go south. on an overnight trip from St. Raphael (homeport) to Cavi, Corsica voltage went to 19 volts but the amperage never went lower than 360. We ran nav and instrument lights and very limited interior lights between watches.

On the trip back we had to run the engine for an hour three times to keep voltage up. Amps never went lower that 355. As soon as engine started voltage was up.

We suspect weak batteries but it seems so sudden. Batteries are 5-6 years old. Any suggestions?

Thanks,

Rob

 

[menzies]

Could be just one battery. How is the charging set up. Most charging system tackle the weakest battery first, then when that is fully charged moves to the next weakest. If the weakest battery has a bad cell it will never charge and the charger will keep on trying. Meanwhile the other batteries are depleting and not being charged.

 

[Datenight]

Thanks Menzies. I thought of load testing but of course did not have my load tester with me! I should mention the batteries are sealed and all showed a green light so I assumed they were charged.

Still I agree that testing would be a good idea and will pass it along.

I don't know how the charging is routed.

Rob

 

[RT Firefly]

Greetings,
Mr. D. Mr. m could be correct. Could be just one battery. I've experienced a 12v car battery become inoperable from one start to the next. Almost instantaneous.