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adding batteries to an existing bank.

I am taking on a boat for the first time in Feb.The boat has a bank of three liesure and one starter which I presume is fine when moored and plugged into 240v . I am thinking of adding one possibly three for the purposses of having sufficient power whilst moving around the cut.Will this affect the existing setup or is this acceptable.There is a 2000 victrone invertor on the boat.And on the same vien is it possible for me to plug a generator straight into the system for power as required? Yeah I know lots of asks

Asked by: Andy Durler  | 10.19am, Thursday 2 January


WW says:

It is certainly possible to expand a battery bank, but it is best to do it when the existing batteries need replacing so that they are all the same type and age. Adding new batteries to an existing set up can cause problems, but with careful monitoring is possible.
It is also important to follow the BSS requirements for battery installation; either in a fixed box that comes at least halfway up the batteries, or in a metal tray with a strap to prevent movement. The terminals also need to be covered.
Connecting more than 5 or 6 lead acid batteries in parallel becomes counter-productive as the extra capacity becomes negated by the increasing self discharge rate. If you wish to have more capacity it is better to bite the bullet and fit high capacity traction cells.
When increasing battery capacity you will need to consider the charging capability of the existing alternator(s), and possible the capability of the engine to drive a higher output alternator. It is useless to fit bigger batteries and find that the alternator is too small to charge them fully in a normal days cruising.
If you have a 16A blue female inlet fitted to the boat, it is usually possible to connect a generator as you would shore power. The best place to use a generator is on the towpath, so that the exhaust gases are safely dissipated. When not in use any petrol (including the generator itself if there is any petrol in the tank) is not stored where vapour could enter the cabin. Petrol vapour is as dangerous as gas on boats, and has been the cause of several nasty explosions.

Rupert Smedley  | 2.24PM, Thursday 2 January

An additional thought; a way of effectively increasing the period between having to run the engine to charge the batteries is to fit a solar panel. This will povide a small trickle charge everyday often providing enough power to compensate for the draw of the fridge for instance.

Rupert Smedley  | 4.54PM, Thursday 2 January

Don't forget, if using a generator, then ensure that it is earthed- preferably with decent thick cable (at least 2.5mm) to a metal spike (like a mooring spike) into the ground. All generators have an earthing point, but often these aren't used. As Ruoert says, petrol is very dangerous aboard craft, but don't underestimate that portable diesel generators can cause fires from fuel leaks and are best used ashore as well.

Mark Langley  | 7.05PM, Sunday 5 January

If you are going for solar panels, then consider fitting a PWM charge controller as they are more efficient. Ditto for monocrystalline over poly crystaline and amorphous panels.
WW Has published articles on choosing, using and living with solar panels, which may be of interest to you. To find them, search in the box above. Otherwise, if you have any specific questions, then Rupert, Graham and myself will be pleased to help.

Mark Langley  | 10.36AM, Wednesday 8 January


Readers say:

Thanks for that info Rupert, great help and have taken all the advice on board(excuse the pun)

Andy Durler  | 4.49PM, Thursday 2 January

Yes I think I am erring towards solar Panels ,cleaner aswell as safer.

Andy Durler  | 6.01PM, Monday 6 January

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