Batteries don't hold a charge

[Chris Mead]

My 2 batteries are charged at the slip using a West Marine smart charger. Both batteries are in series...I start using the ALL switch and routinely rotate from 1 to 2 while sailing to power the radio, etc.Recently, they seem to charge only enough to barely crank the Yanmar diesel.I run the engine for a bit and they seem to charge up a bit more ... but still seem to rapidly lose power. Yesterday, they died completely while on the lake. Luckily I had a new battery charged and ready to go!I took both old batteries to Sears who pronounced one dead and the other okay. This means the charger and/or alternator must be bad, right? I purchased anonther new battery anyway with the intention of starting with TWO new, good batteries.How can I tell whether the charger is broken? Its lights flash while on, it says 'charging'. Its never been wet or abused.Help!

 

[Debra B]

12 volt or 6 volt (or 24V)

You don't say what you have for batteries. 12 volt should not be in series, but 6 volt should be in series. Batteries in series, add the voltage. Batteries in parallel, add the amp hours.I had a "smart charger" - not west brand - and it fried several 4D-s actually I replaced it once with the same model and it fried more batteries. Went to the Xantrex charger - no problems.Also make sure the charger is sized to the battery bank. Even a smart charger will overcharge a bank that is too small. This should be spelled out in the product literature. (Xantrex prints it on the box so there is no mistake.)If you have the 2 12 volts in series, then you are under charging - unless.... do you have a 24 volt system?

 

[Scott Wilson]

If the charger is working

my recollection is that voltage at the battary terminals (measured with a voltmeter) on a 12 volt system, should be in the 14 volt range.

 

[Pete]

batteries not holding charge

Your batteries will discharge to the lower of the two. so your charger and alternator can be fine and it is just a battery problem.I would advise that you replace both batteries at the same time (even if Sears said one is O.K.)This is standard practice with multiple batteries.Check charger and alternator but my guess is they are both O.K. and you need batteries.

 

[Leigh Fenneman]

BATTERIES NOT CHARGING

I had a similar problem; but both of my batteries were "new." It turned out that when the old ones were replaced, the new ones were not wired properly from the selector switch. Output of the charger was great, and seemed to be working, but one of the leads from the bank selector switch was not connected to the proper terminal on the battery.