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Battery blues

On my narrowboat I have been charging my batteries through a RAC car battery charger. I'm sure this is foolish but I am not a boat expert and it seemed to keep everything working for the past four years. No so anymore. If I disconnect the charger the lights go dim, the water-pump stops pumping and now, even when plugged in, the engine won't start and just clicks at me. I'm guessing my cheap charging solution has wrecked my batteries so its probably time to start from scratch...but how should I approach this electro-overhaul? Yours hopefully, RF
PS. I am (clearly) a boating electrics novice.

Asked by: Robert Fresson  | 7.43pm, Monday 2 March


WW says:

Your car charger probably didn't wreck the batteries but it didn't stop them ageing prematurely either. Depending on the quality of the batteries and how well they have been looked after, four years may be all you could expect.
When batteries are left uncharged, or insufficiently charged for long periods, sulphates build up on the plates and this prevents them from taking as much charge. Over a period of time, this becomes a vicious circle and the batteries eventually become unusable.
Start off by buying some reasonable quality lead acid batteries. Try to avoid maintenance free batteries that cannot be topped up. If the batteries are overcharged at any time and the electrolyte drops below the top of the plates, you need to be able to add distilled water to cover them or the whole battery bank may need to be replaced.
Then buy a four-stage marine charger that will charge the batteries quickly and keep them at the optimum voltage to resist sulphation. These chargers can charge both the starter and domestic batteries so that both banks are kept in good health.
Finally, assuming that you manage to buy fillable batteries, check the electrolyte levels regularly and top up with distilled water if necessary.

Graham Booth  | 5.56PM, Tuesday 3 March

Your car charger probably didn't wreck the batteries but it didn't stop them ageing prematurely either. Depending on the quality of the batteries and how well they have been looked after, four years may be all you could expect.
When batteries are left uncharged, or insufficiently charged for long periods, sulphates build up on the plates and this prevents them from taking as much charge. Over a period of time, this becomes a vicious circle and the batteries eventually become unusable.
Start off by buying some reasonable quality lead acid batteries. Try to avoid maintenance free batteries that cannot be topped up. If the batteries are overcharged at any time and the electrolyte drops below the top of the plates, you need to be able to add distilled water to cover them or the whole battery bank may need to be replaced.
Then buy a four-stage marine charger that will charge the batteries quickly and keep them at the optimum voltage to resist sulphation. These chargers can charge both the starter and domestic batteries so that both banks are kept in good health.
Finally, assuming that you manage to buy fillable batteries, check the electrolyte levels regularly and top up with distilled water if necessary.

Graham Booth  | 5.57PM, Tuesday 3 March

Your car charger probably didn't wreck the batteries but it didn't stop them ageing prematurely either. Depending on the quality of the batteries and how well they have been looked after, four years may be all you could expect.
When batteries are left uncharged, or insufficiently charged for long periods, sulphates build up on the plates and this prevents them from taking as much charge. Over a period of time, this becomes a vicious circle and the batteries eventually become unusable.
Start off by buying some reasonable quality lead acid batteries. Try to avoid maintenance free batteries that cannot be topped up. If the batteries are overcharged at any time and the electrolyte drops below the top of the plates, you need to be able to add distilled water to cover them or the whole battery bank may need to be replaced.
Then buy a four-stage marine charger that will charge the batteries quickly and keep them at the optimum voltage to resist sulphation. These chargers can charge both the starter and domestic batteries so that both banks are kept in good health.
Finally, assuming that you manage to buy fillable batteries, check the electrolyte levels regularly and top up with distilled water if necessary.

Graham Booth  | 5.57PM, Tuesday 3 March

Sorry about the answer in triplicate but the first two attempts to post it seemed to fail. Then, like the buses, three came along at once.

Graham Booth  | 6.00PM, Tuesday 3 March


Readers say:

Thanks for all the info Graham! I will look into one of these four-stage chargers. RF

Robert Fresson  | 8.00PM, Wednesday 4 March

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