Solar lead acid battery housing

I'd say it's the worst possible place to house them.
I'd be expexting an explosion from a spark or being gassed in my sleep apart from eye irritation and any form of clothing being acid affected.
Not only does it give off hydrogen gas but also the charge and discharge create an acid vapour which may need washing out from time to time..
Also do not store lead acid directly on contrete floor.
Find an external naturally well ventilated purpose made and secured enclosure and don't forget warning signs.

 

I have no disagreements with anything else you said, but that warning against storing lead-acid batteries on concrete is many decades out of date. Like many urban myths, it persists.
http://www.todayifoundout.com/index.php/2017/02/storing-car-battery-concrete-floor-drain/

 

I disagree.
Instructables supporter I take it...??

 

As a child I was always told NOT to sit on concrete floor for erm... medical reasons (piles).
Now I’m reading myths and old wives tales. Some are hilarious.

Martin

 

Actually, I never heard of Instructables before you mentioned it. I was drawing on my experience back in the 80's when I was fairly new in the security alarm business, which had/has a lot of lead-acid batteries, mostly sealed lead-acid (SLA), and had/has a lot of turnover of said batteries.

I read a lot of manufactures' material about care and feeding of SLAs, but the caveat about never leaving them sitting on a concrete floor came by word-of-mouth, the primary source of urban legend. Neither I nor any of my fellow techs could figure out how sitting on concrete could drain or damage a battery.

Finally one of my co-workers unearthed an article in one of our trade magazines about some misunderstandings of SLAs. When the author got around to the concrete floor myth, he began by saying, "Now this one is weird." He had no idea where that idea had come from. Remember, the 80's was before the internet, so tracking an urban myth was a lot harder.

The best speculation he could come up with was that maybe the reason a battery had been left on a garage concrete floor to begin with was that it "didn't work" for some unknown reason (i.e., too new to be dead from age, and hadn't been {knowingly} drained, so shouldn't be so low on charge..?), and was set aside apart from the other batteries of known potential---on a garage floor, which is usually concrete. So when the battery had sat on the concrete floor for six months in a discharged state and was then tested, it didn't hold a charge---not surprising, if it's left untended in its discharged state, not good for lead-acid batteries---but the concrete floor maybe got the bad rap for the dead battery, because the real reason it got discharged back in the beginning was lost to history.

All that was sheer speculation, of course, (and probably wrong) but prior to Internet, the best he could come up with at the time. 35-40 years later, and a few minutes ago, I spent a few seconds on the internet and found the article I linked in my earlier post. I really didn't search any farther, because I was satisfied with the aforementioned site's explanation of the myth's origin. Like many myths, it started as fact that got outdated with progress.

I should probably mention that in my line of work, we had to switch out a lot of SLAs that had been discharged but for logistical reasons we had to leave systems with charged batteries---but we couldn't wait for several hours for the discharged batteries to charge. So we were compelled to put fresh (new) batteries in the systems, and took the "old" batteries (of varying ages) with us. This left us with a lot of used batteries SLA batteries with a wide variety of ages--some virtually new---that couldn't be re-used in our commercial capacity. One other tech and I collected a pile of these used batteries to play with--the other guy was a radio ham--and we did a lot of charging and extensive testing of those batteries to determine which could be used reliably and which were too far gone to be trusted.

And from time to time, we both left some of those batteries sitting on concrete floors for extensive periods--weeks or even months--in both charged and discharged states, and never noticed that it made any difference. You can leave a charged SLA battery unattended for months without damaging it, even if it's partially charged (I've never taken the time to test what percentage of charge it has to have, nor for just how long), but leaving it very low or completely discharged for too long (maybe 6-8 months?) will probably kill it---whether it's left on a concrete floor has nothing to do with it.

Of course, that's my (and my mate's) personal experience, and we haven't documented it and had it peer-reviewed (except with each other), so I don't expect anyone on this forum to take this as expert opinion. I'm just telling you the reason I haven't questioned the aforementioned linked article, nor done any further research.

If you or anyone else here have a source that does give a reason that lead-acid batteries shouldn't be stored on concrete floors, I'm open to being enlightened.

EDIT: All that being said, I agree that while all that dead space in the OP's wall is tempting, it would be one of the worst places to leave lead-acid batteries, for most of the reasons you mention.

 

Yes, burg/fire alarm systems usually have the SLA/AGM batteries for the Control Panel (the system "brain" using the battery, not the keypad) inside a steel cabinet in some out-of-the-way place, e.g., an unfinished basement or utility area housing a water heater or furnace, or a utility closet. Generally installers try to avoid laundry rooms or any space where water condensation or excessive heat might occur. I've seen them installed close to furnaces, but never next to a fireplace. And be mindful of where your water pipes are. I've seen thoughtless installations where a leaking pipe joint trashed the system Panel.

SLAs do occasionally leak from overcharging or just age, but generally don't have that problem if they're well-maintained. Putting them somewhere accessible to inspection is a good idea, which argues for keeping them inside somewhere. (Right at this moment, it's below freezing outside where I am, which would discourage me from inspecting anything housed outside my warm walls.) Generally the slight venting of acid vapor only causes corrosion at the terminals over a long period. And of course, you won't need to put your batteries in a cabinet like I do.

 

Once, while I attended grade-school in the 1950s, our teacher asked us (the students in her class) to clip and bring to class for "show and tell" an article-clipping that said something about science. This was, IIRC, right after the Ruskies shocked the world by orbiting the first man-made satellite, Sputnik. All Sputnik ever did was emit beeps, but anyone in the world with a wide-band radio receiver could hear those beeps. Plus One for the Soviets. This event heated up the Cold War somewhat and briefly pushed Science to the forefront of the U.S. educational system. That's Science with a capital S for big science, since only governments could afford to do big science.

So, being innocent and eager to please my teacher, I found and brought to school this small advertisement for Preparation H (I didn't know then what that was) that shouted out in bold print: SCIENCE SHRINKS PILES WITHOUT SURGERY!

What's not to like about that, I thought? In one sentence my "article" managed to cover "science," "medicine," and a "discovery for shrinking piles" (whatever those were). For a short while I was the laughing stock of that class... maybe the whole damned school, because we lived in a rural to semi-rural area and everyone in class, except for yours truly, knew exactly what "piles" were. And the incident somehow got back to my mother, who eventually set me straight on the difference between a real science article and an advertisement that exploited the name of science to sell a product. Not a whole lot different from what we have today with infomercials and ads on the Internet disguised as news articles or real opinion pieces.

As for concrete floors... as a child, AFAIK, no one mentioned the dangers of sitting on them. However, Dad always told me and my brother, "Sh!t or get off the pot!" which may have had some relevance to the advice of not sitting on concrete.

@Ian Wallis: What power cuts are you expecting? Now that GB is free of European influence via Brexit, there should be smooth sailing for the rest of this century. Pound Sterling will once again soon be represented by real silver. Uh, about the same time the petrodollar is represented by gold instead of oil. And, say, aren't you the guys building windmills in the North Sea and the Atlantic Ocean to supply electricity to the mainland? And has anyone thought about a coalition among Canada, Australia, and India? Lots of things to think about, moving forward!

As for log-burning stoves... are there still trees left in England, Ireland, or Scotland? Coal-burning is much more efficient than wood-burning, and there should be some of that left somewhere. A bit messy though.

 

The (now) myth about not storing batteries on concrete floors goes back to when they had wood or metal rather than plastic casings. The moisture that could be present, could either conduct and drain the battery if metal, or swell the wood. Plastic has neither of these problems.

I don't think the spot you've chosen is a good one but some concerns would be reduced if you used both a vent pipe AND a fan forced airflow through it so the area is negatively pressurized to keep all fumes pulled outside. Keep in mind that your fan ought to be rated for this type of exposure, and you could even consider putting two in series so that if one fails, you still have airflow till you notice and replace it.

You will greatly reduce the outgassing of the batteries if your charge controller does its job well and does not overcharge them. However, I and many other people in my area, have basements and sumps and battery backup sump pumps with standard deep cycle wet cell lead acid batteries in the basement, no vapor barrier between this area and the rest of the living area, and have not experienced any corrosion, explosions, or any other ill effects. Granted that is just ONE battery, so if there is a trace amount of problem that I haven't detected in many years of service, multiply that by # of cells you are using, but still, I have bare metal objects pretty nearby, and zero corrosion on them or the battery terminals in the humidity and temperature controlled basement where it is.

That battery is a few years old and I did have to add, maybe 3 oz of water for the first time this year, so it is outgassing slightly, but as mentioned above, not enough to matter, IMO. Then again, I might not have checked the water level when it was brand new and hadn't checked that a single time yet, so it is possible it was bought already 3oz below where I thought it should be!