If you have wet-cell batteries, you know what fun it can be to check and water the batteries. You’re supposed to do it every month, but when you have to remove part of the batteries — disconnecting the wires, lifting at arm’s length straight in front of you — do you really do it that often?
I’m certain that the previous owners of our boat didn’t (evidence: the two hard-to-get-to batteries lasted about 15 months).
Even if you don’t have to move and disconnect the batteries, they’re usually still hard to get to.
So in the process of doing all our other battery work, we added a battery watering system. Since it’s hard to show here on our boat, I’ll use the artists’s rendition of the Qwik Fill system:
There are a couple of brands available, but they all work pretty much the same as least as far as the ones you’d use on a boat go.
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- You replace the vent caps with the special watering ones.
- Connect tubing from one set of vent caps to to another (generally two or three batteries can be connected).
- At one end of the “chain” connect the fill tube which has a quick connect on the other end.
- At the other end of the “chain” put an end cap.
- When not in use, the fill tube is just coiled up and left in place.
- To fill the batteries, you use a squeeze pump that’s similar to an outboard motor fuel line — connect one end to the quick connect, and put the other into the jug of distilled water. Squeeze a few times and you’re done!
The vent caps have a float valve in them that stops water flowing when the cell is full, so each cell gets just exactly the right amount of water. When the squeeze ball gets hard, all cells are full. Disconnect the pump tube.
Here is a short video fro Flow-Rite explaining the installation and use of the system:
There are fill systems made for most Group 24, 27, 29 and 31 batteries and also for 6-volt golf cart batteries. Typically you buy “battery systems” (the vent caps and tubing) for one or two batteries in a group (buying as many sets as you need — this is the part that stays permanently attached), then you need one pump unit for all and you simply connect the pump to each fill line.
The water does not stay permanently attached — it’s not a totally automatic battery watering system, simply one that makes it so that you don’t have to reach each battery. For us, it now takes about two minutes to fill our batteries, including the time to get the distilled water out, get the pump tube out and connected, and put everything away. But yes, we still have to do it every month.
It’s now this easy:
If you read the company literature and some reviews, some people talk about installing the system in just a few minutes. HA! Remember, this is a boat project. And nothing is ever easy.
Yes, it’s easy to make the actual connections (just be careful as you’re working around battery acid). But if you’re on a boat where the batteries are hard to get to, it’s going to take longer as you have to get to all the batteries and wind the connector tubing around the battery wires. It took us about 3 hours before we were totally happy with the installation and didn’t have any places where the tubing was pinched.
The two big companies offering battery watering systems are Flow-Rite and Trojan, and both offer systems for 12 volt batteries (as far as I know, up to Group 31 size) and 6- and 12-volt golf cart batteries. We went with the Flow-Rite because it was easy to order online from Amazon and I had problems making connections with the local Trojan dealer. However, from talking to some people with a Trojan system, it seems that Flow-Rite is also less expensive. One reader, Bill & Donna from Denali Rose used the Trojan system and wrote up their experience — read it here.
NOTE: Both companies also make systems for golf course operations and other commercial applications which will fill tens (or hundreds) of batteries with varying degrees of automatic operation — these are NOT suitable for a boat. You want the ones designed for boats and RVs.
Here are the links for the Flow Rite systems on Amazon. You need as many “kits” as you have batteries — that is, if you have three batteries, you need one 2-battery kit and one 1-battery kit; if you have four batteries, you’ll need two 2-battery kits, and so on). In addition, you need one of the pump assemblies, no matter how many batteries you have. Our total cost for the project (3 12-volt batteries) was about $120.
- Flow Rite Qwik-Fill 2-battery kit for Group 24, 27, 29 and 31
- Flow Rite Qwik-Fill 1-battery kit for Group 24, 27, 29 and 31
- Flow Rite Pro-Fill Golf Cart 2-Battery Kit
- Flow Rite Pump Assembly (one needed no matter how many batteries) — the same pump is used for both 12-volt and golf cart systems
This is one of those improvements that no one every sees, yet it makes life aboard so much easier. Doing the battery water is now such an easy job — we don’t even have to open the battery compartment, let alone move batteries or disconnect the wiring. Total win!
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Carolyn Shearlock has lived aboard full-time for 17 years, splitting her time between a Tayana 37 monohull and a Gemini 105 catamaran. She’s cruised over 14,000 miles, from Pacific Mexico and Central America to Florida and the Bahamas, gaining firsthand experience with the joys and challenges of life on the water.
Through The Boat Galley, Carolyn has helped thousands of people explore, prepare for, and enjoy life afloat. She shares her expertise as an instructor at Cruisers University, in leading boating publications, and through her bestselling book, The Boat Galley Cookbook. She is passionate about helping others embark on their liveaboard journey—making life on the water simpler, safer, and more enjoyable.
Candy Ann Williams says
Great post! This would be a great project for La Fiaca!
Mark Zalenski says
I used these on the 8 Trojan golf cart batteries on my last boat for 7 or 8 years and they worked great. If you have a high point above the batteries to put the jug of distilled water on, the system will fill by siphon after one or two pumps on the bulb.
Lex (Tanton43, Chesapeake Bay) says
Thanks. You guys come up with many good suggestions. I like this one. Using this may help avoid holes in my clothes from battery acid.
Tina Barnes-Weida says
We have battery watering system and it is wonderful, water both banks (8batteries) in 5minutes, with no spilling of water. 1St of every month with ease.
Tony Hill says
Have one as well, love it!
Carolyn Goodlander says
Unfortunately, it costs about $100 for two batteries and we have 8!
The Boat Galley says
You’ve got a lot larger bank than we do. We’ve got three batteries and without the watering system we’d have to have AGMs as there is just no way to get to them. The cost of the watering system is considerably less than AGMs around here.
Scott Berg says
We have the Trojan watering system for our 6 GC house bank, cost us about $200 and it’s been great…well worth it
James Montgomery says
Battery watering systems come up regularly on E-bay used. Save a ton of money.
I use an old juice jug for the filler with a 3/8″ hole drilled in the cap. The hoses are 1/4″ ID 3/8″ OD so the hose stuffs snug in the cap. All I do to top batteries is pour some distilled water in the jug put the cap on and tip the jug upside down. It pulls a slight vacuum, so I crack the cap a bit to relieve it now and then.
Cost less me than $50 and is much faster and easier than fooling with the squeeze bulb.
Darlene Moore Bak says
Previous owner had this on our boat. So easy ! 2 banks of 4 fill in no time. Can’t imagine having to fill 8 batteries each separately
The Boat Galley says
I love ours. There is no way we could get to all our batteries otherwise — you’d literally have to “unwire” them all and remove two to get to the third. With this, I water the batteries while waiting for coffee water to boil. 🙂
Tom Kober says
With out looking how do you know all the plates are covered?
Barry Ainsworth says
The caps have a float that stops the fill at the right level
Ted Reshetiloff says
We use watermiser battery caps. Have for 5 years now. We still water batteries but hardly have to add much each month.https://www.flowsystemsusa.com/water-miser-vent-cap.html
Kelly Jones says
Simon Jones
Anonymous says
Tim Nenne
Anonymous says
I like it!
Anonymous says
John….
Anonymous says
If most owners would only think of that let alone perform the task……
“ I don’t know what’s going on I have a really funny egg smell all of the sudden”
Anonymous says
Michael Baldwin check this out!
Dave Skolnick (S/V Auspicious) says
I think this is a great idea. As for the installation time estimate, I point out that if you have a proper battery box vented overboard you’ll have to account for the time to drill a hole for the water tube, seal that hole around the tube, and have an appropriate plug for the end of the water tube.
Captain Bazza says
We have LiFePO4 batteries, what’s this battery watering thingy you need?
John Qosmio says
only for flooded lead batteries