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Do de-sulphation devices work?

I seem to have to replace my leisure batteries too often. Although they are on a three stage charger on my mooring, when cruising it is not always possible to keep them fully topped up and incremental low charging takes its toll. I have seen these devides advertised, you seemingly leave them connected to the batter bank and they help to prevent build-up. What do you think?

Asked by: Nigel Scott  | 5.22pm, Monday 30 April

WW says:

The formation of lead sulphate within a lead/acid battery is a normal part of the charge storage/release process, it dissolves when the battery is charged. Sometimes with time and less than ideal usage the lead sulphate will crystallise on the plates, reducing the capacity as it stops the acid acting on the plate surface.
Electric de-sulphation devices connect to the battery concerned using power to feed high frequency pulses into the battery to dislodge the lead sulphate crystals from the plates. The battery needs to be trickle charged at the same time to ensure the sulphate recombines with the acid. The process is gradual and can take several weeks. If the battery is not charged at the same time, the lead sulphate crystals could drop to the bottom of the cell and short out the plates, ending the useful life of the battery.
They work as battery life extender, and to resuscitate a damaged battery, but need to be used carefully. Some battery chargers have a built in de-sulphation cycle.

Rupert Smedley  | 6.47PM, Monday 30 April

It depends what you consider 'too often'. Given the sort of use you describe, I would have thought your batteries should last somewhere between four and six years.
If the batteries are maintenance free, are you over-cycling them and evaporating off the electrolyte? If they are not maintenance free, are you keeping them topped up regularly? If they are gel batteries, are you charging them at too high a voltage?
Is your charger really three stage or does it have a fourth stage which gives it an occasion short blast of higher voltage to remove the sulphate as Rupert describes? If it is only three stage, it might be worth considering upgrading to a four stage and seeing whether that solves the problem.

Graham Booth  | 10.26AM, Tuesday 1 May

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