12v Watermaker - Experiences for article?

[Tellie]

There is some truth to the fact that many boats are going to larger solar arrays and Lith batteries. BUT, you also need to take into account that people that are outfitting their boats like this are not cruising on 10ah a day. They need this large array because their energy demands are a lot higher these days, home sized refrigeration, ice makers, electric stoves, four AC units, etc. So efficiency does matter when choosing electrical drains. Sure there are also a lot more boats outfitted with diesel generators but a boat electrical system design solely around a generator can be a mistake with these modern high amph boats. If you have designed your electrical load just around a generator, if that generator fails (Never heard that ever happening before) you are stuck without the capabilities to charge even the best of Lith batteries unless you invest in larger alternators and large solar arrays, all which add to the hidden costs of inefficiency. This is a balance of what you desire and your boats capabilities, many times the two don't care for each other. These modern boats that put generators on board still need to be aware of their daily amph budget which most cruisers these days don't even consider. I hear it all the time on the docks that "I have a generator so I can have anything I want on my boat, I'm sure this 3KW I spent 10k buying and installing will do the trick. Daily amph budget? I don't need no stinking Amph budget." Finding the proper balance is an individual thing. Give me ten identical boats and I'll show ten completely different electrical demands.

[jmh2002]

Agreed, and even the financial budget is still a balancing act of different approaches, which will suit different boats and use cases.

Cheaper less efficient watermaker, but need to spend money on a genset and/or solar and batteries to run this... (might make sense, or might not)

And that can end up in quite a circular discussion.

Certainly it makes more sense of you can plan the whole systems approach at the start.

But in practice many boats are upgraded bit by bit which doesn't always result in the most optimal setup.

[SV THIRD DAY]

Originally Posted by 69Datsun510

I have the ability to do so with a Cat, add 4x 1000Ah Winston Thundersky cells batteries, about 3000Ah, inverters for the AC stuff, and DC from the batteries.

Which is easier to maintenance, install, get parts for, tear apart and rebuild? Which one is reliable if serviced regularly as need with filters? The best, most reliable HP pumps, will break down, if not looked after. Water keeps the pumps friction down and cools them, to keep the clearances correct.

You could have rulled out the Cruise RO too soon because with a LiFePO4 battery bank and that size of solar system you can swap out the AC motor with a DC motor on the high pressure pump and make water directly from your battery bank with one of the simplest, easy to repair and robust pumps in the market. Not to mention save thousands of dollars and get a system with no proprietary parts and makes 30 gallons per hour! If you are paying for the Winston batteries...you might as well take advantage of what they can do for you.

We have dozens of clients with No generator aboard but with large solar arrays and LiFePO4 batteries running the 30GPH water makers. Most run them through their 2000W inverter but some also swap to a DC motor. Personally I recommend staring with the AC Motor and going through the inverter since it is so easy and then makes the Honda as a back up for water making and charging simple.

You can (and should).still carry the Honda for cloudy days....you can never have enough power and Water on a cruising boat.

[mikedefieslife]

Here's my experience with a 12v watermamker.

Bought an Ecosistems Splash 25 in February direct from the Ecosistems in Barcelona.

The unit was commissioned in May/June and regularly outperformed it's 25l/h specs, producing close to 30l/h at roughly 12-13amps

It wasn't long before output began to drop. 20l/h, 15l/h to barely 10l/h. It had been flushed after every use and the filters were all changed.

I contacted Ecosistems about the problem, and they asked me to run some tests. Which I did. Then despite multiple emails, they failed to respond for a month. Turns out the whole company takes a holiday in August. When they did return, I was told the guy dealing with my enquiry wasn't available for another week.

A week later, still no word. "oh he's busy, he will get to you". He never did, so I had to take it to Facebook, where someone did respond. (probably the same guy but he doesn't put his name on the communications anymore).

They asked me to run the same tests again that I ran previously, then proceeded to tell me that the results I gave them were impossible since the low pressure pump cannot move the volume of water I had measured being rejected.

Weeks passed with me tell them to find a dealership I can take the unit to. Eventually they found one. Sure enough I turn up, the engineer does the same tests I've already done and confirms my figures.

Ecosistems suggest a full rebuild of the high pressure pump. Parts were ordered from them by the company carrying out the work. A month later, the parts still haven't arrived. They have blamed it on the unrest in Catalunya, but the parts were ordered weeks before the unrest broke out.

So far, the service for what is a €4000+ purchase has been abysmal.

When it was working though, the unit was fantastic, but poor customer service, and the fact that you can only buy membranes through them since they are special centre entry membranes, is upsetting. On the plus side, the membranes aren't expensive, and they do supposedly have a worldwide dealer network.

Of course, by the time the parts do arrive, the unit and membrane will have been sitting with fresh water in them for nearly a month in a workshop somewhere. Better than still being full of salt water, but ideally it should have been pickled.

[jmh2002]

Originally Posted by SV THIRD DAY

We have dozens of clients with No generator aboard but with large solar arrays and LiFePO4 batteries running the 30GPH water makers. Most run them through their 2000W inverter but some also swap to a DC motor. Personally I recommend staring with the AC Motor and going through the inverter since it is so easy and then makes the Honda as a back up for water making and charging simple.

You can (and should).still carry the Honda for cloudy days....you can never have enough power and Water on a cruising boat.

Thanks Rich, that's good info regarding one of my questions.

On the other side, what benefits are people looking for when they swap to a DC motor? (in the context of the above type of setup).

Because the AC motors are normally also smaller, lighter, and cheaper, aren't they?

[SV THIRD DAY]

Originally Posted by jmh2002

Thanks Rich, that's good info regarding one of my questions.

On the other side, what benefits are people looking for when they swap to a DC motor? (in the context of the above type of setup).

Because the AC motors are normally also smaller, lighter, and cheaper, aren't they?

In terms of benefits from the 12v motor approach you get the simplicity of using battery power to run the motor/water maker directly without another piece of equipment (the inverter) in the loop converting DC power to AC power. You also use a bit less power because the inverter has a conversion "loss" in going from DC to AC. So for example the 1.0Hp DC motor would use 80A of DC power but if ran through an inverter to convert to AC, you would typically see 90-95A being pulled from your batter bank by the inverter to run a 1.0Hp AC motor.

AC motors are a bit cheaper and are more "off the shelf" than a DC motor so it's all about the trade-offs like everything in the cruising world.

[crayiii]

We have a Sea Recovery Aqua-Matic 30 gph AC Watermaker (130 hours) that we are scheduled to have replaced with a Spectra Catalina 12v system. You see, while the watermaker runs perfectly, our generator has not run properly for months and we haven't found anyone in the Windward Islands that can fix it.

We're on a cat with 900 watts of solar and 800 watts of wind. Our batteries are generally 100% by 2:00 yet we can't make water.

This was an expensive lesson for us but we've learned. Sometime in the near future, we'll those the generator and is a ton of storage space. We never win the aircons except when we needed to provide the generator with load while making water. If we need to charge batteries on cloudy windless days, we have two large alternators on the engines.

[jmh2002]

Originally Posted by SV THIRD DAY

In terms of benefits from the 12v motor approach you get the simplicity of using battery power to run the motor/water maker directly without another piece of equipment (the inverter) in the loop converting DC power to AC power. You also use a bit less power because the inverter has a conversion "loss" in going from DC to AC. So for example the 1.0Hp DC motor would use 80A of DC power but if ran through an inverter to convert to AC, you would typically see 90-95A being pulled from your batter bank by the inverter to run a 1.0Hp AC motor.

AC motors are a bit cheaper and are more "off the shelf" than a DC motor so it's all about the trade-offs like everything in the cruising world.

Thanks, understood.

The benefit of saving 10-15A seems to be less of an issue for the people with 1000W or more of Solar and using excess capacity to run the watermaker after most of the battery charging is already done.

But taking one more component out the loop (the inverter) is good in terms of failure proofing.

On the other hand, as you mentioned, if the inverter fails you should be able ti run an AC watermaker directly off the Honda.

This may also allows for some other failures in the loop too, such as the panels themselves, charge controllers, even batteries.

If I understand correctly?

[jmh2002]

Originally Posted by crayiii

We're on a cat with 900 watts of solar and 800 watts of wind. Our batteries are generally 100% by 2:00 yet we can't make water.

Why not? Is the boat not set up to run the watermaker from the inverter too?

[crayiii]

Originally Posted by jmh2002

Why not? Is the boat not set up to run the watermaker from the inverter too?

HP pump is a 3hp 115v motor. That plus the feed water pump is greater than our 2000 watt inverter can handle.

Plus that much draw on our batteries would be a killer.

[Tellie]

Amp hours is bit like money. A lot of people just wish they had a bit more of it. But if they are already living beyond their budget, you'll usually find that given a bit more, old habits die hard. Energy efficiency is like living a bit below your means with a bit left over.

[Pizzazz]

My approach is slightly different from the majority here. In my mind, power generation and power consumption are independent activities. The only reason they are getting mixed up here is when you think of a 25 gph watermaker that draws 90A and this is clearly difficult to achieve without a genset or lithium. The traditional watermaker design uses standard pumps and pressure regulators that are only efficient at a certain minimum volume, thus I understand this logic.

However, I think of the watermaker as another device on board, similar to the fridge or the autopilot. The fridge takes 50-60AHrs per day and most people are fine with this, as long as the draw is moderate at 5-10A per hour. Similarly with the autopilot, I budget 50Ahrs per day but usually it takes less. A watermaker is a lot more useful than these two devices. The key is to have low noise and low current draw. One good example is the PS35/40 which takes 4-5A and will make you 20 gpd (only switch it off at night) if you tuck it somewhere. Another example is a watermaker that I am building (but decided not to sell because there is not enough profit) built around a pumptec pump that makes around 3 gph at 11A - you can leave it running forever. If you want to spend the money, the Spectra is clearly the best choice but I find them noisy and as mentioned before, if you consume 10 gpd average, the difference between 15Ahrs on the Spectra and 40AHrs on the PS35/40 is not that critical today with the power generation options.

I think it really depends on how you use the boat. If you are making passages, sailing most of the time in clean salt water and moderate winds, then make water as you go, you will not hear the watermaker over the wind and you can keep it running as necessary. You can get a PS40, a Spectra or have rich build you one targeting 15A draw with a 2514 membrane.

If you spend most of the time in anchorages with dirty water and want total piece and quietness, then I see the point of having a high capacity watermaker for which you need lithium or a genset which allows you to go for a day sail, fill up the tabks then drop anchor again.

Lastly, someone complained about making 30 lph (=9 gph) at 15A and then the output dropping. I believe the issue is with a bad watermaker design. You need a minimum flow to prevent fouling of the membrane. Without energy recovery and with typical pump efficiency around 87% and electric motor efficiency around 70%, when you do the flow equations, you need around 3-4Ahrs per gallon. Rich mentioned his was running at 3Ahrs per gallon and I trust his is well designed. If you run your watermaker at lower amps (lower flow), you will foul the membrane quickly. Thus I believe the above poster needs a new membrane or a smaller membrane.

SV Pizzazz

[a64pilot]

Originally Posted by Paul L

T

Yes, a Spectra is typically about 2x the output per amphour than an average 12v DC system. It is many times more efficient than the typical AC units, as I showed above comparing a 20gph CruiseRo vs a 15gph Spectra.

The pricing for main stream models is higher for Spectra, but not really that much more. Compare a Village Marine vs a Spectra for example.

Problem with using a 20 GPH Cruise RO is it uses the exact same amount of power that the 30+ GPH Cruise RO does. The difference between the two is just the second membrane, it’s very easy of course to modify a 20 into a 30.
A 40” membrane max output is 20 GPH, adding a second membrane takes you to 30+ because now your pump limited, you can get to 40GPH with a bigger HP pump and of course motor to drive it.

I have heard that a Spectra can make a gallon of water per AH.

[a64pilot]

Originally Posted by crayiii

Plus that much draw on our batteries would be a killer.

To me, that is the reason not to try to run a non energy recovery watermaker off of DC. It takes 90 amps to run my Watermaker, add in my normal 10 amp or so house load and I’m hammering my bank with a 100 amp load.
Why in the world would anyone want to do that when a little Honda is $1,000 and has other uses, like cloudy days etc?

Now if you have almost 2000W of Solar and a huge battery bank I guess it’s fine, but why give up the flexibility of what an AC motor gives you as in multiple sources, DC means battery bank, buffered of course with Solar or an alternator, but you can do that with an AC motor too.
A big inverter is most often also a big charger, and if you have a big battery bank, than you want a big charger, and the best way to get that is a big inverter charger.
Once you have that high quality pure sine wave big inverter, you are living in a different world, it’s similar to the pre watermaker world and the post watermaker one.

That is why I believe the choice of a high output but inefficient AC watermaker or an efficient energy recovery DC one is driven by whether or not you intend to have a generator on board.

And an inefficient DC as in non energy recovery pump is non sensical except for very unusual conditions, those being maybe the 2000W or Solar and a monster battery bank.

However to not carry a Honda, even if you have a Diesel generator is in my opinion restrictive.

I know people have become used to saving power and live a life style that requires being power miserly, however it’s the 21st Century now, nothing wrong with deciding that you chose to not do that, and that 1 gl of fuel you’ll burn per week in the Honda isn’t going to wreck the world or your pocket book, but it may be the difference in being flush with water and power, or having to conserve.

[Paul L]

Originally Posted by a64pilot

Problem with using a 20 GPH Cruise RO is it uses the exact same amount of power that the 30+ GPH Cruise RO does. The difference between the two is just the second membrane, it’s very easy of course to modify a 20 into a 30.
A 40” membrane max output is 20 GPH, adding a second membrane takes you to 30+ because now your pump limited, you can get to 40GPH with a bigger HP pump and of course motor to drive it.

I have heard that a Spectra can make a gallon of water per AH.

You can adjust your figures anyway you like to reach a conclusion. Go up to the 30gph and you add a $1,000 to the price.

If you want an efficient, low energy system with good flexibility, get a DC Spectra unit. If you want a high output system that you don't care about efficiency, then get a large output AC system. Plenty to pick from.

We cruise fulltime and right now in about as hot as it gets area, sitting 20 miles north of the equator. Having a 15gph unit supplies more water than we need. I don't get the folks who say they want a high output system so they only have to run the unit once a week. That is not the way to maintain a watermaker. Run it at least twice a week, 3 times in the tropics.