12 volt watermakers, which one?

[txg]

Originally Posted by a64pilot

I have 1000 W of Solar, and it is by no way even close to enough power to run a straight non energy efficient Watermaker, not even close.
A Spectra, yes, but not just a regular Watermaker with a DC motor, unless it’s a tiny thing.

Either something is wrong with your solar system or you have a very inefficient fridge/freezer or something else that draws way more than needed. Or you are sailing in a very cloudy area.



We have 490Wp of solar, a 100L fridge (no freezer) and contrary to you mostly retired people we work remotely from the boat, on some days it is two powerful laptops running for 10 hours or more which should use up at least as much power as a freezer.



Still, our batteries (Trojan L16, so 400Ah) get back to full on most days. Full meaning 14.7V and <5amps going in.


We need about 14L of water per day and we would have enough surplus solar power in the absorption phase to generate that with whatever watermaker. Right now we use the surplus power to cook or make coffee with an electric plate with 1500W running through an inverter. Pulls 130amps from the battery when on and takes about 25Ah for pasta and about 8Ah for coffee.

[john61ct]

Originally Posted by a64pilot

In my opinion you need to decide if you are going to have a generator or not, if you are, go with a high output AC Watermaker

I agree with everything you say, but want to point out that high current produced by an ICE does not need to be AC "mains style" power.

Yes that is how most larger boats go, but. . .

The essential choice is between AH per gallon efficiency, and high GPH output.

[newhaul]

Originally Posted by Falbala60

Thank you A64,
as I have not my Lucia yet my posts (but I am not the originator of this one) was to get opinions of actual users and help me in the decision.

Actually, from the money I think it is OK to spend for FRESH WATER FREEDOM, with our 530 li (140 gal) tank, you and others convinced me to get a smaller WM, like 25-30 li/h rather than the 60 li offered by FP at 12,000$. Having a smaller that runs silently for longer time should be OK and is much cheaper ... 50% less cost.

It will definitely be DC and with a need of about 10A I think the 1000W solar will drive that when nice weather 2 or 3 times a week . (Are you OK with that ?)

It will NOT be with a rotating pump because of the potential noise, because if you can enclose the booster pump in an insulated and fan vented enclosure, you can't with the HP pump, and the 80A at 12VDC.... I follow you.

It will be with easy access of replacement parts in Esat Coast and Bahamas.

So ACTUALLY IT COULD BE a Spectra Ventura 200T...

the next decision does it worth to have the FULL MPC control for an other 3000$ if the skipper is "quite a bit technical".

please tell me that your 1000w of solar is a typo when you say that 10 amps is about all you get from it . I have 400w of solar and I average 16 amps out of it daily. Ie; 16 amps x 5 hrs minimum charge or 80ah. Per day
With 1000w of solar you should be producing about 300 ah minimum

[mitiempo]

Originally Posted by Falbala60

So ACTUALLY IT COULD BE a Spectra Ventura 200T...

the next decision does it worth to have the FULL MPC control for an other 3000$ if the skipper is "quite a bit technical".

Look at the Spectra Cape Horn. 2 pumps so a choice of output as well as redundancy. Fully manual and not much more than the Spectra 150 Ventura.

[Falbala60]

Originally Posted by newhaul

please tell me that your 1000w of solar is a typo when you say that 10 amps is about all you get from it . I have 400w of solar and I average 16 amps out of it daily. Ie; 16 amps x 5 hrs minimum charge or 80ah. Per day
With 1000w of solar you should be producing about 300 ah minimum

Sorry maybe my bad English ? No I meant that 10A is very easy for a 1000W solar that will be able to supply fridge and freezer plus charge bateries at the same time.... on good days !

[Falbala60]

Originally Posted by mitiempo

Look at the Spectra Cape Horn. 2 pumps so a choice of output as well as redundancy. Fully manual and not much more than the Spectra 150 Ventura.

Thank you for the hint, as the noise is mainly from the feed pump 2X water 1/2 the time but 2X the noise ? I will think about ... We will have a Lucia and I don't know the available space.

An other question ... why is the MPC so expensive ? 2000$ to 3000$
Is it because the valves are automatic ?

[hellosailor]

"We have 490Wp of solar,"
i never heard solar power measured in "Whoppers".
Or does "Wp" somehow mean "Watts"?

1000 watts of solar panels should give ~5000 Watt-hours per day in the southern US right now. With a nominal voltage rating of 18(?) volts, that should be 55 Amp-hours coming off the array every day. Could easily be off 10-15% for many reasons but if it isn't giving at least 45Ah per day...something is very not optimal.

[44'cruisingcat]

Originally Posted by Dulcesuenos

The village marine draw alot of amps, 25 to 30 and are noisy. The spectra are durable, quiet and last a long time with minimal maintenance

Our Village Marine draws less than 20 amps, makes 40 litres per hour, has made over 100,000 litres of fresh water for us. We did replace the membrane 5 years ago due to getting chlorinated water through it, other than that, utterly reliable.

The Parker Racor titanium pump has a lifetime warranty.

[newhaul]

Originally Posted by hellosailor

"We have 490Wp of solar,"
i never heard solar power measured in "Whoppers".
Or does "Wp" somehow mean "Watts"?

1000 watts of solar panels should give ~5000 Watt-hours per day in the southern US right now. With a nominal voltage rating of 18(?) volts, that should be 55 Amp-hours coming off the array every day. Could easily be off 10-15% for many reasons but if it isn't giving at least 45Ah per day...something is very not optimal.

5000wh at battery voltage not panel voltage ah after charge controller.
5000÷14 = much more like 350ah into the house loads per day.
I get 45ah out of my 400watts in the winter.

[44'cruisingcat]

Originally Posted by a64pilot

I have 1000 W of Solar, and it is by no way even close to enough power to run a straight non energy efficient Watermaker, not even close.
A Spectra, yes, but not just a regular Watermaker with a DC motor, unless it’s a tiny thing.

There's something wrong with your solar.

We have recently upgraded to just under 1000W of solar, and on sunny days, not only can we make plenty of water, but we can also make HOT water from the solar.

That's with a Little Wonder 12v watermaker, and running a 240 volt HWS through an inverter.

[laika]

Originally Posted by mitiempo

Look at the Spectra Cape Horn. 2 pumps so a choice of output as well as redundancy. Fully manual and not much more than the Spectra 150 Ventura.

+1

I don't have any personal experience with the MPC, but the added cost doesn't justify how easy it is to just run the WM manually. You turn it on, go about your business, and flush it when you're done. Not difficult or time consuming to do. And nearly twice the output means you're not sitting there listening to the thing run all day.

[ReneJK]

1000 wp not enough ?

Sorry to derail from watermakers to solar but these are our panels , 670Wp (not whoppers but watt/peak , which is the universal way to denominate solar )

Avg 3000watts per day @ 13.8 volts (the days when we were off shore power when i took this pic) is 217 amps for the day = approx 217/8 hours 27 amps per hour and I have seen close to 40 amps/hour
More than enough to run a 12volt watermaker and have amps to spare for fridge, freezer , equipment etc

[a64pilot]

There is nothing wrong with my Solar, I get over 300 AH per good day from it, but it’s not nearly that simple, it more than anything is the number of hours to fully recharge a bank exceed the number of Solar hours there are in a day, plus the closer you get to fully charged, the less efficient charging a lead acid bank becomes, above 90% or so charged, its way down only about 50% efficient, but mostly its the number of Solar hours there are in a day.

So let’s talk a little about average AC powered 30 GPH watermaker pulls about 1100 to 1200 W to make water. However it swaps efficiency for simplicity and cost, 1200 W is roughly a little more than 100 amps from a battery bank, don’t forget Peukert’s law. So you get less than 30gls of water for your 100 AH, less cause there is start up and a fresh water flush, so say 25 gls of water or 4 AH per gl.

I believe a Spectra will make water at the rate of 1 AH per gallon. That’s what they cost so darn much, cause they are worth it

So I’m not saying you can’t run a DC Watermaker off of your battery bank, just that you can’t run the average AC Watermaker off of your battery bank whether you put a DC motor on it or not.

Now there are of course DC water makers out there, and of course they do work, but likely it makes the best sense to run them when your motoring ,unless of course they are as efficient as a Spectra is.

I am not bad mouthing AC watermakers, I have one, just I accept that they are enormously inefficient compared to a Spectra, but that’s OK with me, cause my generator has power to spare.

[a64pilot]

I cut not pasted this post by evm 1024 on the depth of discharge thread, to explains better than I can and is of course a much more reputable source than I am

Good discussion (when kept at a technical level).

There are peer reviewed papers out there that take a good look at FLA parameters under most all conditions.

In terms of charging efficiency it appears that the efficiency declines with increasing SOC. As noted in the paper charge efficiency vs SOC is non-linear and runs around 91% average for SOC between 0% and 84%. The charge efficiency is 55% with SOC between 79% and 84%. Clearly a decrease in charge efficiency with a higher SOC. Further the charge efficiency was less than 50% at SOC greater than 90%.

See:

A Study of Lead-Acid Battery Efficiency Near Top-of-Charge
and the Impact on PV System Design
John W. Stevens and Garth P. Corey
Sandia National Laboratories, Photovoltaic System Applications Department
Sandia National Laboratories, Battery Analysis and Evaluation Department
PO Box 5800, MS 0753
Albuquerque, New Mexico 87185-0753

https://xtronics.com/uploads/batpapsteve.pdf

Here is the clip:

CONCLUSIONS
A test procedure has been developed to allow the
examination of battery charge efficiency as a function of
battery state of charge. Preliminary results agree well
with established general understanding that the charge
efficiency of flooded lead-antimony batteries declines with
increasing state-of-charge, and that charge efficiency is a
non-linear function of battery state-of-charge. These
tests indicate that from zero SOC to 84% SOC the
average overall battery charging efficiency is 91%, and
that the incremental battery charging efficiency from 79%
to 84% is only 55%. This is particularly significant in PV
systems where the designer expects the batteries to
normally operate at SOC above 80%, with deeper
discharge only occurring during periods of extended bad
weather. In such systems, the low charge efficiency at
high SOC may result in a substantial reduction in actual
available stored energy because nearly half the available
energy is serving losses rather than charging the battery.
Low charging efficiency can then result in the battery
operating at an average SOC significantly lower than the
system designer would anticipate without a detailed
understanding of charge efficiency as a function of SOC.
During normal weather, capacity degradation will not be
evident, but it will manifest itself when the battery is
called on to provide the full purchased capacity, which
will be found to be unavailable. Extended operation in a
low SOC environment can also result in permanent loss
of capacity from sulfation if the battery is operated for
long periods of time without a sufficient recovery or
equalizing charge.
The impact of low charge efficiency at high states of
charge has the greatest potential impact on systems
where high energy availability is needed. Such systems
usually utilize large batteries to ensure energy availability
during the longest stretches of bad weather. This may
not provide the energy required if the PV array is
insufficient to provide a recovery charge for batteries at
90% SOC and above, where charge efficiency is very low.
Charge efficiencies at 90% SOC and greater were
measured at less than 50% for the battery tested here,
requiring a PV array that supplies more than twice the
energy that the load consumes for a full recovery charge.
Many batteries in PV systems never reach a full state of
charge, resulting in a slow battery capacity loss from
stratification and sulfation over the life of the battery

[john61ct]

Originally Posted by a64pilot

So I’m not saying you can’t run a DC Watermaker off of your battery bank, just that you can’t run the average AC Watermaker off of your battery bank whether you put a DC motor on it or not.
…
I accept that they are enormously inefficient compared to a Spectra, but that’s OK with me, cause my generator has power to spare.

Exactly. If GPH is what's important to you, then accept (just like aircon,) it's a load you want to feed from dino juice, just silly to pull your battery bank so far down in such a short time.

But by getting your 20-40 gallons in just an hour, you can then turn off both the ICE and the watermaker, and enjoy pure peace and quiet.

And all the above can apply to a setup with no AC power or devices involved, albeit it's true few boats are set up this way.