What is EDTA?

EDTA EDTA - ethylenediaminetetraaceticacid - tetrasodium salt to be more specific is the version in which we are interested.

How does it work?

I have absolutely no intention of attempting to explain this in anything other than in the simplest terms.

It dissolves lead sulphate that is the stuff that blocks the battery plates and causes the reduction in battery performance.

How to use it.

Essentially it is a dry white powder that dissolves relatively easily in water but not quite so readily in acid solutions. Thus do not add it directly to the battery as has been previously advised on at least one web site.

It should be dissolved in the minimum amount of DISTILLED WATER possible, warming the water will assist in this process.

It may not be necessary to use the EDTA solution in each cell. If you have a hydrometer you can determine the acidity of each cell that should indicate the extent of your problem.

For what it's worth I would only treat cells as necessary. EDTA will deal with your sulphation problem but will not restore your battery to anything like its capacity when new.

The sulphate bit which has deposited on the battery plates has come from the sulphuricacid in that cell and EDTA will not return this to solution.

Having determined which cells to treat carefully add the solution to the cell. It may be necessary to remove some of the electrolyte first, this point is not always made elsewhere. I say this because the process of adding the EDTA, the charging, the "gassing off" and heat evolution combine to cause the volume of cell fluid to increase.

Adding the EDTA solution to the cell will cause a visible reaction.

Opinion is divided on whether the battery should then be used as normal or thoroughly charged. My inclination is to apply an equalizing charge for say 48hrs before returning the battery to normal service.

As in the HomePower article it may be necessary to refill the affected cells with new acid (34% strength or 1.027SG). Getting hold of the acid is possible but not always easy.

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