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Leisure Battery Lifetime and replacement

We are into our 5 cruising year and the 4 NUMAX M 110 batteries do not hold charge so well these nights. We are plugged in via a Victron inverter when not cruising. Do you have any suggestions on the best batteries to buy as replacements?

Asked by: Rob Henry  | 4.01pm, Tuesday 28 June

WW says:

Five years is quite good going for a set of batteries!
Most "semi-traction" batteries will probably work- the ones you have used are fairly common, and quite price effective. Full traction batteries are very expensive and might not easily work with your inverter/charger.
As long as you regularly check the water levels, "leisure" wet-cell lead acid batteries are probably the best bet. The internal plate thicknesses are the main difference between manufacturers, but this can be hard to judge.
For value for money, most chandlers batteries (or, for that matter, those you might get from other suppliers) are usually fine. however, just avoid "dual purpose" starter/domestic batteries. They tend to have thin plates (to give higher output over a short time- more CCA- cold cranking amps) and do not fair well with domestic cyclce abuse.
Sealed batteries can be fine, but some chargers can cause them to gas (and so lose water) if the voltage rises too high.
The other options (AGM, etc) are probably not worth the expense in most narrowboats, though people have great success with them, overall their price/lifetime ratio is probably not much different (or maybe worse) than bog-standard lead-acid ones.
Paying more doesn't mean you get more, alas... Shop around, but sticking with the type you have now might work out just fine!

Mark Langley  | 11.52PM, Tuesday 28 June

I agree with Mark's comments but would like to add a few based on my own experiences. It seems to me that much depends on the amount and type of use the boat has, and how well you treat the batteries.
We do two or three trips a year lasting from one to four weeks. Having started boating in a glass fibre cruiser powered by an outboard motor with very little charging capability, I am well aware of the need to conserve battery power while cruising. I find that a battery monitor helps me to see the state of the batteries and discourages me from placing unreasonable demands on them.
When the boat is moored, the batteries are regularly checked and topped up. They are connected to a Stirling battery charger which keeps them at a constant 13.4-volts.
The three domestic batteries are the Elecsol carbon fibre open cell type and were installed in 1997! I realise that they will not last forever but I am reluctant to replace them with maintenance free batteries because, if these are overcharged and lose electrolyte, they have to be thrown away. Unfortunately, the equivalent size Elecsol battery is now maintenance free so I am keeping my fingers crossed until I can find a good alternative.

Graham Booth  | 11.07AM, Friday 1 July

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