Keep that expensive battery bank alive – It’s easy!


By Russ and Tiña De Maris

R&T De Maris photo.

Batteries are black boxes we don’t think about much. Not until the rueful day comes when they don’t respond as we want them to, and we’re off to buy new ones – and maybe driving 50 miles “out of the dingles” to do so. Maintaining your batteries saves money and frustration, and it doesn’t take much to do. While the suggestions in this article pertain to the common “flooded” or “lead-acid” batteries, the principles of safety apply to all battery types.

First, the requisite word of caution: Whenever you work with batteries of electrical systems, even “low voltage” ones, take off your jewelry! Watches, rings and bling-bling things. The potential energy in an RV battery is something to reckon with, and welding your ring to an electrical contact will ruin your whole day. Watch out with tools and other metals. The male of this writing duo once dropped a crescent wrench across a deep cycle battery – fortunately he was able to rescue it before it welded into place – narrowly avoiding a major fire.

Keep ’em charged: A battery left in a low state is one that deteriorates.

Keep ’em clean: That “little bit of dirt” across the top of the battery case can actually conduct electricity in the presence of moisture. A slight but real discharge of juice can occur.

Keep ’em filled: ALWAYS keep the top plates of “flooded” batteries covered with electrolyte. This means refilling to the “split ring” or about a half-inch above the separators. ONLY USE distilled water, NEVER tap water. And no, RO (reverse osmosis) water is NOT a substitute for distilled water. And when you fill, don’t overfill.

Keep out intruders: Don’t add “battery acid” or other additives. Thus far nothing has really proved up in the way of a miracle elixir that will give you more power, more potency or more life to your batteries. There’s no such thing as “Voltage Viagra.”

Another intruder is a physical one. Take a look at the first picture in this story. You’ll see two very large, deep cycle batteries – and in the same compartment, what’s that red thing? An inverter! Not a safe place for an inverter, as flooded-acid batteries give off hydrogen gas, and inverters can create sparks. It’s a lousy combination if you want to keep your RV in one piece. Keep inverters in a separate compartment far away from any explosive gases.

We found a great tool to help us keep our batteries filled up. We had very little “head space” in the compartment above the top of the batteries, and they didn’t easily come out for service. A solar panel retailer sold us a battery fill tool, the “filler part” of which presses into the battery cell and fills until the correct level is reached. It’s made of 3/4″ PVC pipe, and fits right into those tight spaces. Alas! The retailer went belly up, and we’ve yet to find somebody else that sells them. They were a lot less expensive than the automated battery fill systems being marketed today. If you know anybody who carries these great tools, please post a reply!


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Tom L Parrett
4 months ago

I use a plastic turkey baster…….distilled water !!!!!!

Tommy Molnar
1 year ago

I use an empty mustard dispenser (French’s yellow mustard) for my battery maintenance. Works great. The hardest part is removing my propane tanks to get to the batteries.

Vanessa Simmons
1 year ago

IGNORE this is just an adaptor to go on an item that looks like this! Been on Amazon for over a year like this with multiple complaints…seems the would correct it. The filler is linked at the bottom and is a black tube that looks like the yellow tube. I have no idea what an acid tube is that it attaches to!

Bill P
1 year ago

I hear and read all over the place about inverter placement with respect to battery location. If your battery is located in a location where hydrogen concentration causes you fire concern, it’s not the inverter that’s a problem, it’s the fact you’ve installed wet cell batteries in an improperly ventilated space. Concentrating gases, explosive or otherwise, presents an immediate danger to life and health.

Long runs of cable carrying high current loads are a bigger risk of fire. The longer the run, the better your chances are of chafing or kinking creating high resistance points and subsequent electrical fires. Most inverters these days don’t produce sparks. Magnetic relays have long been replaced by solid state relays.

Thomas Becher
1 year ago

Why would an inverter spark? Mines solid state,no relays,tubes or anything else to spark unless you connect wires with power or a load on. And the area where the battery is in should be vented. I know mine is. It has a black plastic hose running to the outside.

1 year ago

People often put the inverter in the battery bay because you need short heavy gauge DV wires between the inverter and battery bank. In my trailer, I put the inverter under the head of my bed inside the RV and only needed 18in to go through the wall to the battery bank that sits on the tongue.

1 year ago

Let’s see a picture of your inexpensive fill tool if you want the mob of us to track them down… I HAVE seen some much cheaper options than “the usual sponsor” on here, but not sure if it’s the same item you seek.

Earl Balentine
1 year ago
Reply to  Wolfe

Here is the battery water filler tool I use. It’s nozzle is spring loaded and will fill the battery cell to the correct level. when you hear the bubbling sound stop you know that cell is full. On amazon for about $7.50
Performance Tool W54274 Battery Filler (2Qt) with Auto Shut Off

1 year ago
Reply to  Wolfe

Or switch to agm or LiFePO4