reverse osmosis product water for servicing batteries ?

[Shala]

gday all
just wondering what the knowledge banks have to say about using r/o water to service batteries. i understand the common consensus is to use distilled water. it seems to me that reverse osmosis water that has almost all of the minerals and heavy metals removed would be just as effective. is this a flawed theory?

[robert sailor]

Personally I don't think it's flawed although I have to date only used distilled water for our batteries but if I ran out and the batteries needed water I wouldn't think twice about using RO water.

[Pitchondesign]

Distilled water has 0 ppm tds (total dissolved solids). RO water has between 100 and up to 500 ppm tds. Using RO water over time will have an effect on batteries. Having said that any water is better than having the plates exposed. Sparing use of RO water is probably OK, but I wouldn't make a practice of it.

[Gust14882]

RO filters general add minerals back into the filtered water for taste. Pure RO water without the additives would probably work at least for minor top offs. Pure RO water actually has a metal taste to it. Yuck!

[SteveInMD]

100 - 500? I'm getting around 5 ppm.

[Captain Bill]

Originally Posted by SteveInMD

100 - 500? I'm getting around 5 ppm.

That sounds a little too good for RO water from seawater. How are you measuring TDS? Has the meter been calibrated? Seawater RO membranes are rated at 99% efficient at best. 5ppm would require about 99.98% efficient and I have never seen one rated that efficient.

[belizesailor]

Originally Posted by Captain Bill

That sounds a little too good for RO water from seawater. How are you measuring TDS? Has the meter been calibrated? Seawater RO membranes are rated at 99% efficient at best. 5ppm would require about 99.98% efficient and I have never seen one rated that efficient.

Agree, never seen 5 even on a brand new membrane.

[senormechanico]

FWIW, my 15+ year old Spectra runs about 200 ppm after a few minutes when I shift to saving the product.
After running for an hour or so, I see a little bit under 100 ppm.
I have tested that with 2 different meters.

[old frog]

Originally Posted by belizesailor

Agree, never seen 5 even on a brand new membrane.

+1, even when using soft, carbon filtered, tap water as the input water.

[RaymondR]

You are adding water to compensate for losses in the cells from electrolysis of the water content. If you keep adding water with any salts or minerals in it, the mineral concentration in the battery acid will keep increasing. Don't know what effect this would have overall but since common practice is to add distilled or demineralised water it has probably been found to be detrimental.

[Dave-Zim]

I live in Africa and the quality of our shop bought distilled water is questionable. Once had algae grow in a bottle. So now i collect rain water and store it for use during the year. I don't collect rain water from the beginning of the season. I wait till we've had a few good storms first. I figure once it's been raining for a month or so. There will be less chemicals / smoke etc in the rain. I use this all the time and have never had a problem. Just make sure whatever you collect it from is clean. A big piece of plastic sheet draining in to a drum quickly collects enough water to last me a year.

[SV THIRD DAY]

Fresh water RO can get into the single digit ppm, but sea water RO wouldn't be lower than 100 ppm and I wouldn't put 100 ppm water in my battery unless it was an emergency.

[Pizzazz]

Another good source for "nearly" distilled water is a dehumidifier. Mine produces around 12 ppm, while the watermaker is around 200 ppm.

[GordMay]

Originally Posted by Pizzazz

Another good source for "nearly" distilled water is a dehumidifier. Mine produces around 12 ppm, while the watermaker is around 200 ppm.

Dehumidifier condensate can contain lead and other metal residues from the component parts of the dehumidifier; and stagnant condensate can harbor biological contaminants, including mold, mildew and algae, especially if the collection bucket isn't cleaned regularly.
Note that Pizzazz has tested his condensate, and uses it knowing what he's doing.

[senormechanico]

Originally Posted by SV THIRD DAY

Fresh water RO can get into the single digit ppm, but sea water RO wouldn't be lower than 100 ppm and I wouldn't put 100 ppm water in my battery unless it was an emergency.

Of course, neither one of us needs to worry about that, do we?


LiFePo4 has seen to that !