Batteries

[chrishelen]

put a heavy wire breifly between terminala just like the garages used to do. if there is a bloody great spark it ok. if little spark but wire gets hot its flat, if no spark its dead. The garage has a more sophisticated device which measures the current while shorting the battery but basically the still short the battery. If both batteries ok individually, try shorting across the pair just in case crap connection between the two. If pair batteries ok check connection to starter. if connection to starter ok suspect starter.

I still think its possible you have defective cell in one of the batteries so you need to start bottom up and check each item in turn. If one cell was shorted you would have 22v for pair and it would probably still go. If one cell has high resistance however, then volts would be ok but it could deliver no current.

Its two 12V batteries connected in series.

 

[LadyInBed]

Its two 12V batteries connected in series.

That isn't a helpful statement.
Correct me if I'm wrong but I think we are all assuming that you have disconnected and separated the two batteries and only one of them is giving you concern.
Have you put the suspect battery on load and measured the terminal voltage yet, as I asked previously (around #23)?
It would then be a good idea to put the other good battery on the same load and compare the terminal voltage to the suspect battery then report back the results.

 

[chrishelen]

That isn't a helpful statement.
Correct me if I'm wrong but I think we are all assuming that you have disconnected and separated the two batteries and only one of them is giving you concern.
Have you put the suspect battery on load and measured the terminal voltage yet, as I asked previously (around #23)?
It would then be a good idea to put the other good battery on the same load and compare the terminal voltage to the suspect battery then report back the results.

Yes you did. I haven't had a chance yet. I'm quite busy at the moment. As soon as I get a second I will try it. I have already bought a new battery with is fitted to the boat and performs well. As you are aware, these batteries are very heavy and my old shoulder wound is still hurting after removing the 'dud' batt from its hidy hole.