Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 12-05-2021, 06:25   #1
Registered User

Join Date: Sep 2017
Location: East Coast US
Boat: Bayfield 36
Posts: 12
Large draw watermaker off batteries/solar/wind ... ok?

- I have 450AH battery bank, 390 watts solar, and a wind generator. I almost never have issues with keeping my batteries charged and they rarely drop below 80%.

- I have been looking at watermakers recently and have been strongly considering the portable rainman system that does 37gph.

- Its an AC powered watermaker which draws 1250 watts AC. So roughly it will roughly draw DC amps of 105 amps through my inverter.

Questions is ... will drawing ~105amps for an hour, once or twice a week be destructive to my batteries?

Thanks
SailingQuin is offline   Reply With Quote
Old 12-05-2021, 07:07   #2
Do… or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 12,000
Re: Large draw watermaker off batteries/solar/wind ... ok?

Quote:
Originally Posted by SailingQuin View Post
- I have 450AH battery bank, 390 watts solar, and a wind generator. I almost never have issues with keeping my batteries charged and they rarely drop below 80%.

- I have been looking at watermakers recently and have been strongly considering the portable rainman system that does 37gph.

- Its an AC powered watermaker which draws 1250 watts AC. So roughly it will roughly draw DC amps of 105 amps through my inverter.

Questions is ... will drawing ~105amps for an hour, once or twice a week be destructive to my batteries?

Thanks
Not if your batteries are lithium.
__________________
This is just an answer/comment; not interested in arguing or dealing with the trolls
s/v Jedi is offline   Reply With Quote
Old 12-05-2021, 07:09   #3
Sponsoring Vendor
 
Tellie's Avatar

Community Sponsor

Join Date: Oct 2007
Location: Hollywood, Fl.
Boat: FP Athena 38' Poerava
Posts: 3,645
Re: Large draw watermaker off batteries/solar/wind ... ok?

Why not look at far more energy efficient 12V watermaker? A 12V/14gph water maker run for three hours makes 42gallons at 19amp/hr or total of 57 amp/hr from your battery bank and skip the inverter altogether and use basically half the energy and gain more water production.
Tellie is offline   Reply With Quote
Old 12-05-2021, 07:29   #4
Registered User

Join Date: Sep 2017
Location: East Coast US
Boat: Bayfield 36
Posts: 12
Re: Large draw watermaker off batteries/solar/wind ... ok?

well, several reasons. the most important of which is portability.

- It doesn't increase the value of my boat to add it, so I'd like to have to ability to take it with me when/if I change boats
- non portable units are a reasonably large installation process (speaking from experience on a prior boat)
- space ... I have lazerette space, but don't have space where I'd need to mount a permanent unit, not to mention requiring access to through hulls... etc
- time ... I don't want to spend 3+ hrs ever 5 days making water when i can do it in one hour

Back to question at hand ... how does a large draw for an hour impact the longevity of deep cycle lead acid batteries?
SailingQuin is offline   Reply With Quote
Old 12-05-2021, 08:25   #5
Registered User

Join Date: May 2020
Location: Mediterranean
Boat: Feeling 44 DI
Posts: 16
Re: Large draw watermaker off batteries/solar/wind ... ok?

Good question, one that I've asked myself. I run a 12V Dessalator unit off 400 amps lead acid storage while the solar panels are performing at their best, with a net load of around 18 -22 amps. The research I've done indicates a net draw of 10% of storage is OK, and I don't seem to have any negative issues wirh the batteries.
Markb250 is offline   Reply With Quote
Old 12-05-2021, 08:32   #6
Registered User

Join Date: Aug 2019
Posts: 17
Re: Large draw watermaker off batteries/solar/wind ... ok?

We have a similar set up, but with lithium batteries. We use a seawater pro that makes 45 gallons per hour. Our 3K inverter works fine. The seawater pro ramps up electrical use as you increase the gallons per hour. If the rain man ramps up electrical use as you Increase GPH, I would expect that you’d be OK. The question is how much energy is required at the start up of the electrical motor. Once you’re running you should be fine, but requires much more energy then the operational load. We use 100 Amps to produce about 50 gallons. With lithium that’s not an issue. I’m not sure how good that is for your batteries.
cdcorl is offline   Reply With Quote
Old 12-05-2021, 08:33   #7
Do… or do not
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 12,000
Re: Large draw watermaker off batteries/solar/wind ... ok?

Quote:
Originally Posted by Markb250 View Post
Good question, one that I've asked myself. I run a 12V Dessalator unit off 400 amps lead acid storage while the solar panels are performing at their best, with a net load of around 18 -22 amps. The research I've done indicates a net draw of 10% of storage is OK, and I don't seem to have any negative issues wirh the batteries.
I agree. If OP has lead acid batteries then triple the capacity is needing for the continuous load he's looking for. A great moment to upgrade to lithium I think.
__________________
This is just an answer/comment; not interested in arguing or dealing with the trolls
s/v Jedi is offline   Reply With Quote
Old 12-05-2021, 08:43   #8
Registered User

Join Date: Sep 2017
Location: East Coast US
Boat: Bayfield 36
Posts: 12
Re: Large draw watermaker off batteries/solar/wind ... ok?

Interesting and thanks for the input ... do you know what would happen to my batteries with such a draw on it? Is sulfating the result from a large load on lead acid batteries?

Also, when you say 10% of storage ... so for my bank of 450ah ... i'd not want to exceed 45amps for any length of time?

Thanks.
SailingQuin is offline   Reply With Quote
Old 12-05-2021, 08:51   #9
Sponsoring Vendor
 
Tellie's Avatar

Community Sponsor

Join Date: Oct 2007
Location: Hollywood, Fl.
Boat: FP Athena 38' Poerava
Posts: 3,645
Re: Large draw watermaker off batteries/solar/wind ... ok?

Quote:
Originally Posted by SailingQuin View Post
well, several reasons. the most important of which is portability.

- It doesn't increase the value of my boat to add it, so I'd like to have to ability to take it with me when/if I change boats
- non portable units are a reasonably large installation process (speaking from experience on a prior boat)
- space ... I have lazerette space, but don't have space where I'd need to mount a permanent unit, not to mention requiring access to through hulls... etc
- time ... I don't want to spend 3+ hrs ever 5 days making water when i can do it in one hour

Back to question at hand ... how does a large draw for an hour impact the longevity of deep cycle lead acid batteries?
I agree with others above. The draw on a Lead acid/agm battery bank of that size will put a serious dent in you battery's and their life expectancy. Going Lith is great but the costs of going that direction for a watewrmakwer doesn't make sense financially. Go 12 volt and you can run it off alternators, genset, solar or directly from your battery bank at zero extra expense and twice the energy savings. It will be far more valuable on the re-sale than a portable unit will be. Go AC and you'll be tied to your genset.
Also, what is the rest of your daily amp/hr. budget for your other electrical needs?
Tellie is offline   Reply With Quote
Old 12-05-2021, 08:51   #10
Registered User

Join Date: Nov 2018
Location: San Diego
Boat: Shannon 50 Ketch
Posts: 56
Re: Large draw watermaker off batteries/solar/wind ... ok?

I am no expert at this, but I think it comes down to your charging regimen. If you draw down 100amps like that every 5th day, and then during the 5 days you bring the batteries back to 100% charge, and otherwise don't tax them greatly during that 5 days, you should be fine in my opinion.

However, if you never charge above 80%, you will be shortening the life if your batteries (by how much I could not tell you).
jordanbigel is offline   Reply With Quote
Old 12-05-2021, 09:02   #11
Registered User

Join Date: Nov 2010
Location: UK, Croatia
Boat: Fountaine Pajot Athena 11.6m Rapa Nui II
Posts: 642
Re: Large draw watermaker off batteries/solar/wind ... ok?

Given the infrequent use of the watermaker, if you choose times when the solar/wind plus the engine is running and also charging at a reasonable rate, then the net draw from the batteries would be say less than ~50A, so for 1 hour you would draw down of the order of 10% of the capacity. A C of 0.1 seems eminently doable to me. I routinely heat the water via the inverter drawing 100A for 20 kinutes or more on 360Ahr with 480W of solar without running the engine.
Rapanui is offline   Reply With Quote
Old 12-05-2021, 09:11   #12
Marine Service Provider

Join Date: Feb 2012
Location: Vienna, Austria
Boat: Vagabond 47
Posts: 664
Re: Large draw watermaker off batteries/solar/wind ... ok?

450-105 = 77% - House 20% = 57% = NO PROBLEM for good FLA.
Try to reduce House while you make water
moseriw is offline   Reply With Quote
Old 12-05-2021, 09:23   #13
Registered User
 
Nicholson58's Avatar

Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 5,262
Images: 84
Re: Large draw watermaker off batteries/solar/wind ... ok?

Quote:
Originally Posted by SailingQuin View Post
- I have 450AH battery bank, 390 watts solar, and a wind generator. I almost never have issues with keeping my batteries charged and they rarely drop below 80%.

- I have been looking at watermakers recently and have been strongly considering the portable rainman system that does 37gph.

- Its an AC powered watermaker which draws 1250 watts AC. So roughly it will roughly draw DC amps of 105 amps through my inverter.

Questions is ... will drawing ~105amps for an hour, once or twice a week be destructive to my batteries?

Thanks
Not if you run a generator
Nicholson58 is offline   Reply With Quote
Old 12-05-2021, 09:33   #14
Registered User
 
Cheechako's Avatar

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 23,801
Re: Large draw watermaker off batteries/solar/wind ... ok?

That's a big draw. On everything. You dont even remotely need that big a water maker. 37 GPH?
The simplicity of a smaller 12V or even AC system that you run when everything is charging well would be great. Those windy or sunny days you can run the low draw system and never even know it while keeping the tanks topped up.
I converted a 1.5 HP AC system to engine drive. I just filled the tanks when motoring.
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 12-05-2021, 09:34   #15
Registered User

Join Date: Sep 2017
Location: East Coast US
Boat: Bayfield 36
Posts: 12
Re: Large draw watermaker off batteries/solar/wind ... ok?

great information, like the folks who do the same thing.

on good wind and solar days, it's not uncommon to see 20+ amps going into the batteries coupled with a nice boost in voltage.

So on good wind and solar days, it seems very doable.

Boat does have a 100amp alternator with balmar regulator, so it does put out some serious charge as well for the not so sunny/windy days.

giving me stuff to think about.
SailingQuin is offline   Reply With Quote
Reply

Tags
batteries, raw water, solar, water, watermaker, wind

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Is high current draw bad for deep cycle batteries? Toys_with_time Electrical: Batteries, Generators & Solar 15 04-04-2016 20:34
.5 amp draw. All is off. mariner36bob Electrical: Batteries, Generators & Solar 39 06-05-2014 07:39
ICOM 802 Power Draw When Off SvenG Marine Electronics 36 09-12-2013 15:58
Watermaker osmosis draw-back S/V Tai Ann Plumbing Systems and Fixtures 2 01-01-2013 10:17
.4 amp draw on batteries w/ shore power AC on benjiwoodboat Electrical: Batteries, Generators & Solar 4 12-04-2011 13:18

Advertise Here


All times are GMT -7. The time now is 11:16.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.