Household Batteries – Monthly Service

More and more, offgrid battery tech is moving toward batteries that don’t require topping off the electrolyte levels. Some day maybe lithium battery prices will come down to where penniless desert hermits can afford them – preferably without depopulating Africa or something – and on that day I’ll rejoice. Until that day I’ll probably stick with lead/acid golf cart batteries as the affordable – and really quite adequate – choice.

And I have to say, personally I prefer a battery that forces me to do monthly PM because it’s not just electrolyte levels that can go wrong with your batteries. Corrosion is a thing. Connectors can come loose for no apparent reason. Mice can build nests in the box. Shit happens – and when it happens to your batteries it will bring expensive and stressful things into your life. A “maintenance-free” battery encourages sloth, and that’s not called a deadly sin for no reason.

It’s September first, and I always try to do my battery rounds on the first of every month. Several years ago this was a big deal because I was caretaker for properties scattered all over the Gulch and some of them had really big battery banks. Now it’s just my and Ian’s places, but the principle is the same: Periodic Maintenance is good.

First, wipe off the tops of anything that might find its way into the wet cells when you take the caps off. At my place that’s mostly mouse crap: My powershed is a disaster area. Take off all the caps at once, shine your flashlight into each cell and make sure they’re all bubbling happily away and that no one cell’s electrolyte level is excessively high or low. Either condition indicates a problem.

When adding water to the cells, use ONLY distilled water. NEVER tap water. In a shortage of available distilled water I’ve been known to go to extreme measures to make my own. This is important. Thanks to a Generous Reader I now have a water distiller specifically for the purpose – but the process is so time- and fuel-consuming that I hope never to have to do it again. If I ever do, though, I’m ready.

Anyway: That jug above is your friend. I’ve tried adding water to the cells every way there is, got one of these like ten years ago and have never regretted it. Electrolyte level is very important: Never overfill, or you’ll spill acid out and reduce battery life noticeably or even disastrously.

Also, wear old clothes you won’t mind getting a bit holey, should they come in contact with battery acid which absolutely will dissolve them. Seriously, leave your favorite shirt in the closet.

Check all battery connections…

…for corrosion and tightness. I have much less trouble with corrosion since I got a small can of this stuff

…which was also recommended by a blog reader several years ago. Probably any specific anti-corrosion grease will do but this has never yet failed me. Frankly petroleum jelly never did me much good.

Through the whole process, disposable latex gloves are a good idea for fairly obvious reasons. Your last step, once the caps are back on, is to take an old rag and just wipe down the battery tops to get them as dry as possible. Most of the liquid that accumulates on the top comes from outgassing but some of it comes from the caps when you take them off and that’s plain battery acid. In extremely grody batteries you can actually get a discharge going between the poles across the top of the battery. Otherwise it’s just esthetics but wetness does attract grime which is never good. A clean battery is a well-maintained is a happy battery.


Don’t make the mistake I made a year and a half ago, and run out of distilled water during a widespread shortage. We got a taste of shortages 2-3 years ago and will probably get more in the future. Don’t run short of essentials while you have a choice. I keep mine in Ian’s powershed, which is buried in the ground and doesn’t freeze in winter.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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7 Responses to Household Batteries – Monthly Service

  1. Malatrope says:

    I don’t remember if I was the one who recommended that NOCO battery grease, but I have used it for many years now and it has completely ended any corrosion at the terminals.

    I would suggest on your last step that you sprinkle some baking soda on your old rag to help neutralize the inevitable acid.

  2. Robert says:

    “discharge going between the poles across the top of the battery”
    Which, silly me, I eventually figured out was the issue.

    “wear old clothes”
    Alas, Uncle Sam declared I would be delighted to move those oh so many tons of batteries while wearing my spanking-new Blue Jacket. It was never the same after that, what with disintegrating where the new clean batteries were hugged to my unsuspecting bosom. I really liked that jacket…

    “distilled water during a widespread shortage”
    Which is why this CPAP user completely ignored the taunts and jeers of the short-sighted when I stocked up. It pleases my shriveled soul to observe those naysayers have quietly adopted my so-called hoarding practices which I prefer to call “being prepared”.

  3. Ben says:

    I learned the hard way about battery acid in my high school days. Picked up a battery one evening without even thinking about the “rain water “ on top, which splashed on my pants. The next day (at school!) those same pants started to disintegrate, exposing my jockey shorts for the world to see. Had to get a pass in the middle of the day to run home to change pants.

    Lesson learned!

  4. Zendo Deb says:

    Lithium Ion batteries make little sense for applications that are not mobile. Your electric car struggles with batteries that are too heavy. Your home, not so much.

    Also lead acid batteries are much less likely to catch on fire. Lithium ion are getting better, but they still burn with some regularity. (The easiest way to handle that is to immerse them in water for a few days.)

    If you feel flush with cash, and want to upgrade the batteries, consider Iron Edison. They are wicked expensive but are supposed to last 20 years or more. Failing that, what cellphone towers use for backup are lithium iron batteries. (I think that is what they are called.) Also expensive, also heavy. Less maintenance than lead acid.

    There are automatic watering systems. I had some for a solar installation where it was tough to get at all of the batteries. There are also caps that are supposed to catch the distilled water that cooks off, and let it re-enter the battery cell. Don’t know if if they work. The automatic watering system wasn’t cheap, but worth it in the long run.

  5. Malatrope says:

    Lithium Iron Phosphate is the way to go. Very few people use Lithium Ion for house batteries because a) they are more expensive, and b) they can catch fire badly and irrevocably.

    Flooded lead acid batteries are way too much work to maintain, though they rarely explode (if you keep them vented). LiFePO4 is “set up and forget”.

  6. RCPete says:

    I got the distilled jug when I read about it here, and it makes doing the solar systems a lot easier. (Aside from the fact that the quasi-portable system’s battery cover is too close a fit to the panels.) I have a 48V system for the well, and battery fills are reasonably easy.

    I have hydrocaps on the portable system–IMHO, they’re medium useless, and you have to take them off to refill, and it’s a pain. I use a pair of grouting gloves, which work fairly well, but the fastening ring on the hydrocaps doesn’t play well with them.

    Back around 2000, I did a 300W system with a couple of 6V AGM batteries. It didn’t get used a whole lot, but the AGMs just kept working. They’ve been sitting idle for a couple of years; I need to see if they’re still alive. They were a year ago. OTOH, those suckers are incredibly expensive for the amp-hours. On the gripping hand, I could mount them inside a tent trailer without having to vent to the outside. It was worth it.

  7. Ben says:

    I remember fondly a pair of high-priced AGMs that my employer replaced based solely on age. I dragged them home and got at least another ten good years out of them!

To the stake with the heretic!