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**Madehn** · 20-01-2021, 18:37

So as i am installing my new watermaker--i got one of those "flashes" wither the result of hitting my head on the hatch- again or perhaps just a new idea - I would love to have a source of distilled water on board to service my bank of FLA batteries (no i dont want to change lets not turn this into a battery thread

). i am thinking that i can add a tap to my present system and install a DI filter cartridge in line with that tap and have a source of water for my batteries at a pretty minimal cost as i already have an extra set of filtration cannisters including a twin setup - one for carbon filter then one for DI filter- that way i never have to worry about finding/carrying distilled water for the batteries- for the number of gallons that i would need both the carbon and the DI filter should last for a LONG time. What am i missing, this seems too easy. Has anyone done this?

**GordMay** · 21-01-2021, 07:57

The most common types of water used in batteries is distilled water, then deionized water, and water from reverse osmosis (R/O).
The water used for battery electrolyte preparation should be distilled, demineralized, or R/O, and have an electrical conductivity less than 10-5 ohm-1 cm-1, and pH between 5 and 7.
RO water is considered mineral-free, like distilled water. The process of reverse osmosis removes all kinds of unwanted impurities, salts and ions from water, making it fit for human consumption. Regular service and maintenance of RO keeps the hardness, pH and TDS under permissible limits.

“Effects of Impurities on Lead-Acid Batteries” ~ Trojan Battery
➥ http://www.trojanbattery.com/pdf/WP_...ities_0612.pdf

**Adelie** · 21-01-2021, 11:09

Quote:

Originally Posted by Madehn

So as i am installing my new watermaker--i got one of those "flashes" wither the result of hitting my head on the hatch- again or perhaps just a new idea - I would love to have a source of distilled water on board to service my bank of FLA batteries (no i dont want to change lets not turn this into a battery thread

). i am thinking that i can add a tap to my present system and install a DI filter cartridge in line with that tap and have a source of water for my batteries at a pretty minimal cost as i already have an extra set of filtration cannisters including a twin setup - one for carbon filter then one for DI filter- that way i never have to worry about finding/carrying distilled water for the batteries- for the number of gallons that i would need both the carbon and the DI filter should last for a LONG time. What am i missing, this seems too easy. Has anyone done this?

If you filter it’s not really distilled.

You want distilled heat water to make steam then run that they a cooling tube so it condenses.

sailorboy1 · 21-01-2021, 11:12

I used a DI filter to make battery water for years. It made 3 ppm tds water out of tap water.

thinwater · 21-01-2021, 11:20

The challenge is that the battery water spec is 5ppm chloride, and seawater RO water TDS is largely chloride. This is considerably more difficult than starting with typical tap water, but doable.

You can also get suitable water by carefully collecting rainwater. Also dehumidifier condensate.

CassidyNZ · 21-01-2021, 11:55

Quote:

Originally Posted by thinwater

The challenge is that the battery water spec is 5ppm chloride, and seawater RO water TDS is largely chloride. This is considerably more difficult than starting with typical tap water, but doable.

You can also get suitable water by carefully collecting rainwater. Also dehumidifier condensate.

That’s what I use mostly - dehumidifier condensate. My watermaker water generally has 250ppm which I don’t think is clean enough for my batteries. The condensate off my dehumidifier reads less than 75ppm and on a humid day I get up to 10litres in 24 hours.

In a pinch I take water off the watermaker after a 10 minute fresh water flush - ppm can easily drop below 100.

thinwater · 21-01-2021, 12:20

Quote:

Originally Posted by CassidyNZ

That’s what I use mostly - dehumidifier condensate. My watermaker water generally has 250ppm which I don’t think is clean enough for my batteries. The condensate off my dehumidifier reads less than 75ppm and on a humid day I get up to 10litres in 24 hours.

In a pinch I take water off the watermaker after a 10 minute fresh water flush - ppm can easily drop below 100.

Battery water is NOT as simple as TDS. Chloride is much more harmful than calcium or carbonate, for example. The dehumidifier water will contain different ions than seawater RO water, which is nearly all NaCl. The seawater RO, on a good day, is most likely 10 times the limit, and is more typically 20-40 times the limit. Ordinary tap water is probably several times better (and still is bad).

75 TDS is quite high for a dehumidifier. 20s is more typical, so I'm guessing the chloride in the dehumidifier is probably too high. Rainwater should be ~ 10 ppm TDS.

**GordMay** · 21-01-2021, 12:30

The previously linked, Trojan Battery White Paper, “Effects of Impurities on Lead-Acid Batteries”, includes Table 1, “Recommended Maximum Allowable Impurities in Water for Battery Use”. No need to guess, what’s acceptable.
Here ➥ http://www.trojanbattery.com/pdf/WP_...ities_0612.pdf

CassidyNZ · 21-01-2021, 12:35

Quote:

Originally Posted by thinwater

Battery water is NOT as simple as TDS. Chloride is much more harmful than calcium or carbonate, for example. The dehumidifier water will contain different ions than seawater RO water, which is nearly all NaCl. The seawater RO, on a good day, is most likely 10 times the limit, and is more typically 20-40 times the limit. Ordinary tap water is probably several times better (and still is bad).

75 TDS is quite high for a dehumidifier. 20s is more typical, so I'm guessing the chloride in the dehumidifier is probably too high. Rainwater should be ~ 10 ppm TDS.

When you say “tap water”, are you talking if municipal water? Because municipal tap water in our local town is chlorinated to a point where it smells of the stuff. Surely chlorine in batteries is not clever.

In my homes (past 3) we live on rain water. I must test again one day because IIRC our water is up around 50 or 60ppm, can’t remember it ever being anywhere near 10. Perhaps that has something to to do with our roofing.

How does one eliminate/reduce chloride in dehumidifier condensate? How do you even test for it? Maybe the condensate I use is no good for my batteries. Although I used it exclusively in my last bank which lasted nearly 10 years and included two or three “run dry abuses”.

**Madehn** · 21-01-2021, 15:12

Thanks for all of the replies- from reading Gord's article and Sailorboy1's response i am thinking that running my RO water through a DI filter cartridge should give me water suitable for my batteries. Thanks to all.

**Tellie** · 22-01-2021, 01:42

Shirly, it's much easier to store a gallon of distilled water on your boat.

Jdeuel · 22-01-2021, 08:35

Quote:

Originally Posted by Tellie

Shirly, it's much easier to store a gallon of distilled water on your boat.

My late dad would haunt me if I let that one pass. Happy Friday!

RiverRat37 · 22-01-2021, 09:51

Quote:

Originally Posted by thinwater

The challenge is that the battery water spec is 5ppm chloride, and seawater RO water TDS is largely chloride. This is considerably more difficult than starting with typical tap water, but doable.

You can also get suitable water by carefully collecting rainwater. Also dehumidifier condensate.

I'd be careful with "just rainwater". It travels thru the atmosphere, which these days can be loaded with lots of particulate matter not to mention the thought of "acid rain".
Dehumidifiers collect their condensation on cold pipes -- what are the pipes made of? Can they pass metallic 'stuff' along to the water? Like copper corrosion. And they need cleaning from time to time because they collect 'stuff' from the air too.

Why not go to local grocery store and buy a gallon of "distilled water"?