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Keeping batteries alive

My narrowboat, infrequently visited in the winter months, has 2 starter and 4 leisure batteries which have all gone flat, and I fear that they will have to be replaced. How can I ensure that a new set will not perish in the same way? I have no access to mains power, so charging is done with the engine (BMC 1.5) alternator via a Kestrel regulator. Someone has suggested installing an inverter-charger, but how might this quite expensive item help? Have you any suggestions, please?

Asked by: Stephen C  | 12.10pm, Friday 23 January


WW says:

Batteries that are not used for long periods tend to self-discharge but it is unusual for all five batteries to go flat at once. If it were just the domestics, it could be that you had left a light on when you left the boat. It may be worth getting a qualified electrician to check the system for current leakage.

Whether the batteries need to be replaced or not depends on their age and condition. You could try removing them from the boat, charging them at home using a mains charger and seeing whether they hold their charge. If not, you should replace them. An inverter charger on the boat will not be any use if you have no access to mains power as it needs electricity to run it.

To prevent this happening again, you could keep the old or replacement batteries at home during the winter and charge them in turn. However, if you rely on an automatic bilge pump, one at least should be left in place on that circuit. Alternatively, you could visit the boat every three or four weeks and run the engine to charge them. The engine should be run for at least an hour to ensure that it gets up to a reasonable temperature. In between visits, the domestic batteries should be isolated from the system to reduce the risk of discharge.

Graham Booth  | 11.42AM, Tuesday 27 January


Readers say:

I am not an engineer so cannot offer expert comments on batteries like Graham but when I had a similar problem I cured it by buying a solar panel for each bank. I know we moan that we never see the sun but after installing the solar panels I did not have any more problems.

Ken Neale  | 7.03PM, Friday 13 February

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