RO versus Distilled H2O

[BruceK]

...you can make a distiller with a jacketed exhaust pipe. It's what fishermen used to do before RO.

Might be better uses for a distiller if I had one.
When I had open FLAs I used "Demineralized Water" picked up at the supermarket, seemed to be ok. Wonder what the difference was to "distilled"?

 

[sunchaser]

I have 12 golf cart batteries in the engine room, they regularly consume a gallon and a half distilled water per month, your consumption does not sound unreasonable

I have 8 Trojan 105s. They regularly consume about two gallons per year.

 

[Chrisjs]

Single-pass desalination RO membranes alone can simply NOT produce water equivalent to distilled water. Residual TDS from a well engineered and performing single-pass desal RO is typically in the range of 0.5% or more of the original input TDS. So since "typical" seawater is about 35,000 ppm TDS that leaves about 175 ppm of TDS in the product water - and that is an optimistic outcome. The only way to achieve higher purity is to use 2-stage RO typically followed by ion exchange.
On the other hand, true distilled water should have a TDS of zero ppm, though depending on how it is manufactured there may be some minor entrained impurity TDS. Laboratory grade water 18 megohm/cm water is the purest water available, produced by multi-stage systems and should have zero ppm TDS, but the very act of transferring that water to a container can result in "contamination" because the water is so aggressive in "dissolving" ppt amounts of material from the container.
So long story short - using single stage desal RO water for batteries may be expedient, even unavoidable, but does not compare to using pure distilled water. However, since the remaining TDS in seawater RO water is primarily sodium chloride, it is better than using tap water which typically contains less sodium chloride but more of other materials such as calcium salts, which are more deleterious.
Lastly, if batteries consume much water it is likely caused by incorrect charging cycles or inadequate alternator regulation (need smart regulator). Best to address these deficiencies, but Water Miser battery caps can substantially reduce water evaporation.

 

[rslifkin]

Batteries in hot environments like an engine room will also tend to consume a bit more water, even with proper charging.

 

[bayview]

Now that you are down south, if you are running AC you would have a source of condensate that you could use for your batteries. You just need to capture the condensate from the AC units.

Bad idea. Condensate is full of airborne dirt and microbes.

 

[Chrisjs]

Also that condensate is flowing through various metallic parts and piping, so it is far from "pure".

 

[Codger2]

I retire March 2021 I’ll be there this time of year. A long ways to go from Alaska But warmth is calling my name.

Kevin, I know it's a long time before you head south but I invite you to call (PM) if you plan on stopping in San Diego. I've spent a lot of time in Ensenada (Corral) & I think it's a great place to hole up! Besides, I want to see that Bayliner of yours and the electronics you've added.

 

[Delfin]

RO water + Zero Water filter = cleaner than distilled.

 

[HeadedToTexas]

Zero water filter? Is that a deionizing bed? If so, that makes sense. Clean is relative as clean is not the same as low TDS.

 

[Delfin]

Zero water filter? Is that a deionizing bed? If so, that makes sense. Clean is relative as clean is not the same as low TDS.

https://www.amazon.com/ZeroWater-ZP-010-Filter-Pitcher-Quality/dp/B0073PZ6O0?SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-exp-a-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B0073PZ6O0

 

[HeadedToTexas]

Yeah, so Zero says "our filters use Ion Exchange Technology to reduce contaminants." It is making deionized water. Other filtration as well, but it's the ion exchange resin that removes the ions that contribute to TDS.

Topping off batteries involves a pitcher or something to pour from anyway, right? Looks like an excellent option.

 

[FlyWright]

The Rolls are huge batteries, 820 amps each. Which gives me roughly 400 Amps of use, but I try to limit draw to 275-300 max. These are the only batteries that are not sealed and are in the engine room, so they are susceptible to the engine room heat. They just took almost a gallon for both batteries, which is the norm over the last few years and was almost 110 days ago since last top off.

But thanks for the idea, ill put that task on the list with the other 40 items, LOL!

I would go back to one of the earlier questions asked about why the batteries need so much water.
I had 2 Rolls 8Ds as part of my housebank (plus 2 FullRiver 8D AGMs).
The Rolls batts did not need a lot of water. They were in the ER of a Selene 47, just like yours. I would check your charging system for overcharging, and consider fitting a smart(er) regulator. Worst case, try some Water Miser battery caps.

I've had good luck with Water-Miser caps to reduce the water loss over the past 5-10 years. I typically need to buy about 1-1 1/2 gal of distilled water per year to water my 6 GCs and G31 start lead acids. That's probably a 40-50% reduction from before the caps. I rarely take my batteries below 60%...can't even remember the last time.

I retire March 2021 I’ll be there this time of year.

A long ways to go from Alaska But warmth is calling my name.

Kevin, I know it's a long time before you head south but I invite you to call (PM) if you plan on stopping in San Diego. I've spent a lot of time in Ensenada (Corral) & I think it's a great place to hole up! Besides, I want to see that Bayliner of yours and the electronics you've added.

Same offer stands in the SF Bay/CA Delta area. Hope you plan to stay a while during the summer months to enjoy our warm, fresh water gunkholing in the California Delta. No jackets, air conditioning and bug screens required. There are several spots I know you'd like.

 

[JDCAVE]

How is distilled water 120 ppm? It can’t be. It’s either not distilled or you have measurement error going on with your instrument.

Jim

 

[fractalphreak]

How is distilled water 120 ppm? It can’t be. It’s either not distilled or you have measurement error going on with your instrument.

Jim

That would be my thought. I don't buy it or test it, but by definition distilled is evaporated and pure of any dissolved solids, if the label is honest...

All this talk of 100+ ppm gives me the willies. (even though the government tells me its safe to drink water that is up to 500 ppm.)

I am still dirt based, and have an RO/DI system at home that really does pull out nearly all TDS, I see about 1-2 PPM with all new filters, starting with local river-fed reservoir municipal water that is 40- 50 ppm. I'm using the RODI for my make up water in my saltwater aquarium and my boat batteries...

I've been wondering if anyone making water on board has gone to the trouble of adding the RODI type system on the boat, or if its just too wasteful energywise...they are really like a second watermaker, generating 2-3 gallons (or more) of wastewater for every gallon of RODI made, but man its good stuff.