Lithium batteries – The ExhaustNotes Blog

By Joe Gresh

I was going to do a bunch of stories on my solar power system that powers my shed. I may still do that but this is more of an update on the batteries I use to store the solar power.

Small footprint means more energy density and hotter, more localized fires…

With solar, unless you plan on only having power in the daytime, you’ll need a way to store energy. The traditional way to accomplish this is with lead-acid batteries. I’m a lead-acid fan boy because they are so much cheaper than lithium batteries or a molten salt battery.

I should say, were cheaper…as of late lithium batteries have been dropping in price so much you can now get a 12-volt 100ah lithium battery for the same price as the cheapest Walmart lead-acid, deep cycle battery.

My solar system has been online since 2018 and in those years I’ve had to replace three Walmart batteries. The others are getting a bit long in the tooth, you know? Six years is a good service life for a lead-acid battery. Walking by the battery bank a few days ago I smelled the telltale odor of sulphur. This meant another battery had given up the ghost. It’s usually easy to find the bad battery in a bank. It will be hot to the touch, or in this case the filler caps had blown off. Kind of obvious.

The lithium batteries seem fairly even voltage wise at 100-amp load.

Looking at the average age of my battery bank I decided to bite the bullet and buy a new lithium set up. Getting in just under the tariff wire, so to speak.

My new bank will be 12, 12-volt, 100ah lithiums. Wired in series/parallel to produce a 24-volt, 600 amp hour storage capacity. That’s theoretically 14,400 watts of storage if you could squeeze every bit of juice out of the batteries.

By contrast, the existing 12, 12-volt 100ah battery bank only has 7200 watts of usable storage capacity due to lead -acid batteries dropping voltage below 50% capacity. The same total amount of juice is in the lead-acids but it’s at a voltage too low to operate equipment.

I use an old, analogue battery load tester to establish baseline numbers for future troubleshooting.

In addition, the lithium batteries have a smaller footprint so I’ll be able to rig the new bank on a single shelf instead of two shelves like the set up is now. This will cut down in battery cable length and by extension, voltage drop. Less cable is always good with electricity.

All in, I’ll nearly double my solar storage capacity in less square footage for less money than the old style lead-acids. This seems like a win-win.

Lots of important information that I will ignore is printed on the battery.

Now for the downside. These generic lithium batteries claim a 10-year life span but since the Chinese manufacturer’s keep changing brand names like I change underwear the likelihood of the same battery company being around a decade is slim. And then there’s that small detail of the fires.

Lithium batteries don’t like cold weather so that could be an issue. We do get some 20-degree nights at the ranch. I run pipe heaters at night so maybe that bit of drain will keep the batteries snug and warm.

Ah well, it’s not like lead-acid batteries don’t catch fire or explode occasionally.

I’ve had good luck with my Walmart lead-acids, no complaints, and I’m hoping these lithium replacements hold up at least 6 years. 10 years will be great and if they last look for an exhaustnotes long term review in 2035.

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Unlike motorcycles, I’m not fixated on doing things the old way for electrical energy storage. I run a lithium-polymer battery in the Husqvarna that has exceeded all my expectations. The thing never goes dead (no trickle charger needed) it has tons of cranking amps (no need to use the compression release to start the bike) and it weighs nothing. You can install the thing in any position and nothing will leak out. The only drawback to the lithium-polymer battery is cost.

Battery technology is advancing rapidly with so many new combinations of lithium with something else, molten salt or rare elements only found in war torn areas. It’s hard to know which technology will win out in the end but for now, in my solar-powered shed system, lead-acid still offers the best electron storage option.

Lead-acid batteries are messy, inefficient and half their capacity comes at a voltage too low to run your equipment correctly. They are heavy as hell and the cable connections are always corroding from the acid fog and hydrogen fumes escaping from the fill caps. You’re lucky to get 5 years service out of a lead-acid battery. The things are problematic in most every way.

But not in all ways: lead-acid is a completely mature technology. We’ve been building them since 1860 and there is a cradle-to-grave recycling system in place right now. Any auto store or Wal-Mart has the ability to take your old lead-acid batteries and deal with them responsibly. Unlike the new battery elements there are no ecological surprises with lead-acid: We know all.

Lead-acid batteries are available everywhere. Go to any town in the world with at least one gas station and you can buy a lead-acid battery. You don’t have to deal with Tesla or any of the high-tech battery startups that don’t actually have product. Your battery isn’t tracked online, the software will never need to be updated and your battery bank will never be monitored by anyone but you. Unlike most e-car and e-bike batteries, lead-acid batteries come in standard sizes (24, 27, 31, 4-D, 8-D) and for the most part are interchangeable unless you have a restrictive battery box or short cables.

Lead-acid batteries are tough. It’s hard to damage a clean lead-acid battery with tight connections. They put out gobs of amps on demand and as long as there is electrolyte in the cells they stand up to overcharging well. They’re even somewhat repairable: Go on YouTube and look up battery repair for ways to flush out debris from old lead-acid batteries to gain new life.

Lead-acid batteries are easily scalable and nearly any voltage or amperage desired can be achieved with large, simple jumper cables. I’m running 4, group 31, 12-volt batteries in my 24-volt system. My future plans are for 16 batteries total but there’s no rush. I can take as long as I want to get there or 8 batteries might prove to be enough for my usage level.

Most important for me: They are cheap! The four deep cycle marine batteries in my off-grid system @100 amp/hour each give me a total of 2400 watts of storage (@ 50% capacity) for 400 dollars. If I ever get to 16 batteries I’ll have 9600 watts of storage for around 1600 dollars. Compare that to 7000 dollars for 7000 watts of storage from Tesla’s Powerwall.

The newer Powerwall is AC-in, AC-out and comes with a built-in AC inverter which is a savings if you’re charging from the grid but you’ll need a solar AC inverter to charge the Powerwall from the sun so it’s kind of a wash for my set up. The lifespan/charge cycle of lead-acid batteries is supposed to be less, judging from the two-year lifespan of the lithium ion batteries used in my cordless tools, maybe not.

I’m not a Luddite when it comes to battery technology on motorcycles or power tools but for me the new designs and materials haven’t yet made sense for large, stationary storage banks at low cost. I’ll revisit the topic if Tesla reduces the price of their Powerwall by half or some new manufacturer comes up with a wiz bang combination of chemicals that outdoes ancient lead acid technology.