My battery problem - I am barking up the wrong tree?

[PEJ]

10.00 Sunday at OV: Port engine battery dead. Link it to Stb, starts OK.

Run to Hamble

16.00 Sunday: Port engine starts OK without link.

17.00 Monday: Port engine battery dead.

I leave my fridges on and the battery charger running off the shore power.

I thought the problem was a dead battery but now I wonder if the problem is the battery charger not working.

Where you you be looking?

 

[Hurricane]

When were the batteries last changed
I never changed them when we had the boat and they were good when we sold her on - I suspect that Brian didn't change them either.
So maybe they are the originals - in which case they probably need changing.

 

[VicS]

10.00 Sunday at OV: Port engine battery dead. Link it to Stb, starts OK.

Run to Hamble

16.00 Sunday: Port engine starts OK without link.

17.00 Monday: Port engine battery dead.

I leave my fridges on and the battery charger running off the shore power.

I thought the problem was a dead battery but now I wonder if the problem is the battery charger not working.

Where you you be looking?

Check output of the battery charger. You dont say what type but presumably a triple output ( one output for each engine battery and one for the house battery ?) charger so check all outputs.
Initially check the volts but then check the current ( clamp type ammeter useful for this) to each battery after discharging a little.


Check batteries.

Ideally check with a hydrometer but if sealed types charge independently then measure the volts of each after resting with no further charging or load for 12 hours. Expect to get around 12.7. 12.8 better, 12.6 minimum ( double of course if you have 24 volt systems ).

Check batteries retain their charge, for a couple of weeks if possible , if not for as many days as possible. The volts fall quickly at first but then more slowly, a good battery taking several weeks to fall below 12.5

Even if volts measurements are good get suspect battery professionally tested by the modern equivalent of a "drop test" for high current capability.