reverse osmosis product water for servicing batteries ?

[roverhi]

Catchment (rainwater) should be pure but not necessarily so. Used rainwater in a newly rebuilt engine. Took about 6 months for the acidity in the water to rust out the freeze plugs. May not be a problem where you are at but with our Volcano added a lot of sulphur compounds to the air which are acidic. Water looked fine but appearances can be deceiving. The acidity probably would have been a plus for a battery, however.

[CharlieJ]

My Village Marine RO WM included a procedure for using RO water as the feed stock and reducing the HP from the normal 800psig to a much lower pressure. The actual value escapes me but the current tech manual says to adjust the HP pump pressure so that product water does not exceed 120% of the nominal flow when using seawater as feed stock. With this process I made water at < 3ppm TDS.

[boatnerd]

From Village Marine manual. They recommend using filtered product water and lowering pressure to @200psi to produce " battery water". I haven't tryed it but in an emergency it's good to know. .

[thinwater]

Is Steveinmd possibly running brackish Chesapeake water instead of seawater?

If I were cruising, either filtered rainwater, AC condensate, or dehumidifier water. I've tested all 3.

But only RO from tap water. That will work too.