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Trickle charging batteries

My 10 amp Smart battery charger has just failed. I use it to keep my 3x110 amp domestic batteries trickle charged via a shoreline connection when at my home mooring. I am receiving conflicting advice on what I should buy to replace it. One view is that a charger rated at 10 amps is not adequate for the job and that I need at least 50 amps. The other opinion is that for a trickle charge, 10 amps should be adequate. Do you have a view?

Asked by: John Burt  | 2.27pm, Monday 3 September

WW says:

A 'smart' battery charger will charge at different rates depending on the state of charge of the battery to which it is connected. A 10A charger is suitable for charging a single battery, or two small batteries; to charge three 110Ahr batteries a charger of at least 40A capacity will be required. It is true that to trickle charge your set-up 10A is adequate, but the benefits of a 'smart' charger will be lost.
You only mention the 'domestic' batteries, it is worth keeping the 'starter' battery topped up as well. This helps considerably to extend the useable life of the batteries. It would be best to fit a permanent multi stage charger with several outputs. These usually have three outputs to enable Starter, Domestic, and Bow Thruster batteries can be kept in tip top condition when shore power is available. (Unused outputs can be connected to another, i.e. use one for the starter and two connected together for the domestics). The battery charger should be connected directly to the batteries, bypassing the isolators, with fuses as close as possible to the battery connections.

Rupert Smedley  | 3.06PM, Monday 3 September

Sterling Power springs to mind, but we do not recommend specific manufacturers.

Rupert Smedley  | 3.44PM, Monday 3 September

Readers say:

Many thanks for the helpful reply and for the suggestion to include the engine start battery. I am finding it difficult to identify a suitable charger and cannot see that these have been reviewed by WW. Are you able to suggest manufacturers who produce the type of unit I require, please?

John Burt  | 3.39PM, Monday 3 September

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