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Q & A

Replacement Batteries

I know you are generally very unenthusiastic about sealed leisure batteries. Would you consider them if accessibility is a problem?
On our boat two of the three batteries are easily accessible but third one, requires the disconnection of the batteries and removal of one of the other two batteries to shuffle the third battery into view. Although the third battery does get maintained, this tends to guided by the state of the accessible two. The current wet batteries have done eight years so do tend to recommend themselves.

Asked by: Clive Dutson  | 11.38am, Thursday 29 January


WW says:

You're right about my lack of enthusiasm for sealed batteries if they are the type that cannot be topped up at all.
It's an easy thing to say but is it possible to reposition the batteries, or perhaps make some structural alterations, so that you can get to the third battery more easily?
If not, you might consider something like Banner batteries which are maintenance free under normal conditions but which can be topped up if, for any reason, the electrolyte level drops. This might, at least, reduce the number of times you have to disconnect the two accessible batteries.

Graham Booth  | 3.00PM, Thursday 29 January

Instead of conventional sealed batteries (which often don't have as good quality thick plates as open-cell batteries) would be AGM (absorbed glass mat) or gel batteries, although the price for these may well be prohibitive. They are certainly very low maintenance, but any charging system would have to be adapted to suit. Also, some do not like taking fast charge from alternators, quickly building up internal resistance, which raises the cell voltage, kicking the regulator on the alternator into low-current output trickle mode.
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However, they may be worth a look at.
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An alternative would be to fit a (auto)top-up system to the battery bank so that you can easily keep the levels correct in an open cell bank, even if you can't get to them (and makes it almost impossible to overfill them).

Mark Langley  | 1.42PM, Friday 30 January


Readers say:

I priced a watering system but at £254.00 + Vat it seemed prohibitively expensive. In the end, I went for the maintenance free batteries that can be topped-up as I was able to get these for a very competitive price. I think the extra life I would get from batteries with a watering system would take a few decades to recoup!

Clive Dutson  | 3.29PM, Tuesday 12 January

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