Batteries (Yes, I know, I have searched the archive... :-)

[KenMcCulloch]

Here's the story. Main battery bank is 2x110Ah 'sealed' lead-acid batteries, reserve battery is 100Ah. Isolated through a 1-both-2-off rotary switch, charged by a 90A Alternator with a Sterling external regulator, and by 24 hrs of mains power through a permanent 30A charger every few days when the boat is in use. A Pulstronic Battman monitor on the main bank gives readings for V, A, and Ah consumed. We rarely discharge the main batteries to lower than about 75% of nominal capacity, i.e. showing say -50Ah on the monitor. The batteries were apparently fitted in 2007 and up until this season they have done all that we needed of them.

During the later half of this season we have had a couple of incidents where the main batteries have had insufficient oomph to turn over the engine, while discharged to something like -50 Ah, suggesting they are failing. Charging the batteries to show them as fully charged on the monitor, left to rest overnight and they show 12.8v which is a little lower than I think we were seeing a year ago but not by much.

We were starting to think about replacing the batteries anyway, and will certainly be doing so for the start of next season. 7 years seems like a reasonable lifespan. It would be informative however if someone who really understands these things could offer some explanation as to what might be going on?

 

[cliff]

7 years is not too bad a life span but like us your batteries are getting old and decrepit - change them but get flooded cell so one can top them up. You will find after 7 years the electrolyte is low and the Sterling external regulator does not help conserve water - I go through 10~15 litres / year over 5 batteries when fast charging via the Sterling. The last set of batteries were changed after ~ 9 years of getting abused.