Battery Watering Systems

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
After having read RC's treatise on AGMs, I'm much less enamored of them. In the new boat I need new batts, and was thinking of going with flooded. I don't have the height for golf car batteries, which would be my first choice. The batteries are tough to access, as it requires removing the aft cabin mattresses and some plywood boards. I'm afraid they wouldn't get watered properly.

I have done a brief search for battery watering systems. I've read mixed reviews on Hydrocaps and Water Miser caps, so I thought I'd just go for a watering system that allows proper watering without having to see the batteries.

There are many systems, mostly geared towards industrial applications. I found this: Flow-Rite Qwik-Fill marine and RV battery watering system.


https://flow-rite.com/battery-watering/marine-rv/qwik-fill

Not super expensive, at about $50 for a two-battery kit, squeeze bulb not included.

Supposedly fills to the correct level - I think it uses a float valve in each cap.

Anyone have any experience with or opinions on this or similar systems?

Thanks,

jv
 
Feb 10, 2004
3,918
Hunter 40.5 Warwick, RI
I bought a set of used BWT auto fillers that use a float to provide the correct level. I installed them and the first time I used them I thought that they overfilled. Maybe my batteries were always under-filled? Anyway I removed them until I could run some tests and assure myself that they were working properly. I have an extra fill bulb if you find that you need one.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Thanks, Rich! I'll let you know. Are you planning on re-installing them?

I looked at the website and can't figure out what kit is right. How did you determine this?
 

Kermit

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Jul 31, 2010
5,657
AquaCat 12.5 17342 Wateree Lake, SC
I use a turkey baster. I pour water into a blue Solo cup (we save the red ones for beer) and then suck it up with the baster and then squirt it into the cells. Probably takes more time than the system shown, though.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Makes sense, Kermit, but in the T3800 the batteries are in a really inconvenient spot, which is why I'm interested in a remote watering system.

I confess I'm still ignorant about the correct level, and when to water. My batts have a "cuff" or something that has slits in the sides. Should one fill 'til the water is to the bottom of the cuff? Or part way up the slit? Different when charged or discharged?
 
Dec 25, 2000
5,702
Hunter Passage 42 Shelter Bay, WA
Hmm. Spent several years using two Interstate wet 8Ds on our boat. Used a turkey baster to top them off every two months. Access on our boat is pretty convenient. Lasted maybe eight years. So about twelve years ago decided to replace our wets with Deka AGMs. Still going strong even after twice having their voltage dropped to eight the first time and six the second time due to a loss of shore power, another story. Different opinions about AGMs here, but they seem to have worked well for our cruising application and quite resilient to low voltage.
 
Feb 10, 2004
3,918
Hunter 40.5 Warwick, RI
Thanks, Rich! I'll let you know. Are you planning on re-installing them?
I looked at the website and can't figure out what kit is right. How did you determine this?
Regarding the BWT watering caps- I don't know anything about the other brands - you chose the cap based upon the particular brand and model battery. I had US Battery 2200 at the time and now I have Superior batteries. Both use the same watering cap. The differences are the battery opening and the depth of the electrolyte that determine the correct cap.
As for putting them on my 2 year old batteries- I'm not sure. I check the level about every 4-6 weeks and I add about 1 ounce a couple times per season. One thing I noticed when I bought my current set of batteries is that right from the distributor there were differences in the electrolyte level in all of the cells. Perhaps as much as 3/8-1/2 ", but most were within 1/4" or so. If the caps bring all the levels to the same point, does that mean that some of the cells are going to be over-watered? None of the levels were at the bottom of the fill tube with the slot up the side. I would have to look up the recommendation for electrolyte level, but I think it is about 1/8-1/4" below the bottom of this fill tube. What I do know is that I don't want to over-water my cells.
BTW, I used Water miser caps for years and felt that they did a good job.
I think that the amount of watering needed will increase if you charge aggressively (like C/6 or so), and if you always charge at rates that are C/20 or so the need for water will be less. I tend to charge aggressively to minimize generator run time and I realize and accept that this practice may shorten the life of my batteries.
 

JRacer

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Aug 9, 2011
1,331
Beneteau 310 Cheney KS (Wichita)
Calders book, Boatowner's Mechanical and Electrical Manual, says " you should see a tube going down toward the plates having a slot in it. Wet cells should be maintained at the base of the slots or if the tubes and slots are not present, at 1/4 to 1/2 inch above the top of the plates but no higher'
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
I think the H-34 batteries may be the most inconvenient to reach of all boats in the world.. In late 2005, I installed a Flow Rite system for the two 31 size batteries and have been really happy with it.. I had to remove/clean/reinstall it after 6 years to clean the algae out of the fill tubes, but other than that, it has been a real pleasure.. Attached picture is me going in to clean the battery connections.. not much access room, as you can see..
In Pit 2.JPG
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Thanks guys. I read in Crown's documentation last night that that thing I called a "cuff," with the slots in it, they call a well. They said the level should be no higher that the bottom of the well. They also said that if you find a battery with the plates exposed to air, you should fill with distilled or deionized water only until the plates are covered, no more, and then charge.
Rich, I'd be concerned, too, about the differential fill, and the chance for dilution, or 'differential dilution,' as it were. But that could just be my OCD, not based on knowledge or experience.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
I think the H-34 batteries may be the most inconvenient to reach of all boats in the world.. In late 2005, I installed a Flow Rite system for the two 31 size batteries and have been really happy with it.. I had to remove/clean/reinstall it after 6 years to clean the algae out of the fill tubes, but other than that, it has been a real pleasure.. Attached picture is me going in to clean the battery connections.. not much access room, as you can see..
View attachment 143451
Thanks Kloudie. Which Flo-Rite system did the get, the RV one, or the "Pro Fill?"
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
When I bought mine at Bass Pro, there was only one “double 12v” available. I don’t know which of the two available today it is equivalent to.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
In Pit 3.JPG Looking at the web site, I think mine is pretty much a ProFill.. The RV one is for the big 6V deep cycles.. The fill caps are not individual, they are ganged, so if ya have 12V size 31 and below, the ProFill looks right. ?? Bass Pro had a special where they included the fill bulb kit with the Pro Fill when I bought it way back when.. I like the little "quick connect" with cap.. Other than growies in the tubing, I've had no problems.. Battery life went from sub 3 years to 7-8.. because it was such a pain to water them.. I think that you can get some dimensional info from them that will lead you to what ya need..
Picture is me in the cockpit locker "pit", batteries are down by my right hip.. and about at right knee.. A nightmare to access.
 
Last edited:
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
'nother note.. before installation, it would be good to sterilize the inside of the tubing to forestall the growies.. maybe straight bleach through there then a very thorough rinsing because any trace of bleach will kill a battery..
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Thanks. Yea, that's a tough spot for batteries.
I'm surprised about "the growies." I would think that sealed tubing that has only had distilled water run through it would be immune. Maybe you're right, maybe it was stuff in the tubing before installation.
 

Jeff

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Sep 29, 2008
195
Hunter 33.5 Carlyle Lake in Central Illinois
A few years ago I posted to a topic about water levels for batteries. I bought 4 new wet cell Group 31's for my boat. These replaced my 6 year old set of the same style. The battery warehouse I bought from suggested Thermoil (www.thermoil.com/) be added to each. They explained that it would minimize outgassing, water consumption and when heeled protect the lead plates. Well I bit the bullet. When I posted about my purchase many considered products like this snake-oil. The batteries are connected to an older Xantrex Truecharge 20 24/7/365. Before winter lay up last week I checked them again. In four years I haven't needed to add water. My old set did not have this additive. Water was needed 2-3 times a year. I have no connection with this company but will use this product with my next set of batteries in a couple of years.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
A few years ago I posted to a topic about water levels for batteries. I bought 4 new wet cell Group 31's for my boat. These replaced my 6 year old set of the same style. The battery warehouse I bought from suggested Thermoil (www.thermoil.com/) be added to each. They explained that it would minimize outgassing, water consumption and when heeled protect the lead plates. Well I bit the bullet. When I posted about my purchase many considered products like this snake-oil. The batteries are connected to an older Xantrex Truecharge 20 24/7/365. Before winter lay up last week I checked them again. In four years I haven't needed to add water. My old set did not have this additive. Water was needed 2-3 times a year. I have no connection with this company but will use this product with my next set of batteries in a couple of years.
I read their web home page. That is really very interesting!
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
O.K., I've read, and re-read the Thermoil website and accompanying documentation, watched the videos, and I'm sold! Wow. Makes complete sense to me. Of course, there's always the chance that I've been duped, and taken in by some snake-oil salesman. But it's a relatively low-risk thing to try. I'm interested in the De-Sulfater, as the batts I removed from the new boat have symptoms. And, the De-Mister, if it works as described, could get one on an annual watering and maintenance regimen. It should also just about eliminate corrosion issues, too.
Now I'm torn. I thought a watering system was the bee's knees, now I'm enamored of Thermoil. Jeez, what to do?

BTW, for Group 24, 27, and 31 batts, the dose of De-Sulfater is 1 oz. per cell; the De-Mister is 2 oz. per cell. 12 oz. bottles of each are $20 and $18, respectively.

There must be more to this topic. Watering systems apparently do a good business with industrial customers, as apparently does Thermoil. How do the customers decide?
 
Feb 10, 2004
3,918
Hunter 40.5 Warwick, RI
I very briefly looked at the Thermoil website, so I haven't been sold and I don't know all of the facts.
But consider this: Users have been watering their batteries since they were invented. Manufacturers are always looking to improve their products, show an advantage, and capture more market.
If Thermoil was as good as this thread would have me believe, then why hasn't even one manufacturer added it to their product at the factory? Or at least mentioned it on their own website?
Just askin'......
I would not want to risk $400+ on a set of deep cycles unless I had absolute proof that this stuff did no harm not to mention being beneficial. But that is me.
 
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