**Friends, I’ve gotten myself into a pickle and I need some help.**
A few years back, I decided to get into solar power by building a complete PV system inside a mobile trailer. The rationale for this doesn’t matter for the current discussion, but for the curious, I wrote an article outlining the whole design and build process.
Briefly, though, the system has two adjustable PV arrays mounted on the roof and side of a small cargo trailer, with an integrated solar inverter-charger and a 10-kWh LiFePO4 battery bank on the inside, along with all the usual switching and circuit protection stuff. It’s pretty cool, if I do say so myself, and literally every word I’ve written for Hackaday since sometime in 2023 has been on a computer powered by that trailer.
I must have built it pretty well, because it’s been largely hands-off since then, requiring very little maintenance. And therein lies the root of my current conundrum.
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### Spicy Pillows
I generally only go in the trailer once a month or so, just to check things over and make sure no critters or squatters have taken up residence. Apparently, my inspections had become somewhat cursory, because somehow I had managed to overlook a major problem brewing:
*This is one of two homebrew server rack battery modules I used in the trailer’s first battery bank.*
The LG-branded modules were removed from service and sold second-hand by Battery Hookup; I stripped the proprietary management cards out of the packs and installed a 100-amp BMS, plus the comically oversized junction box for wiring. They worked pretty well for a couple of months, but I eventually got enough money together to buy a pair of larger, new-manufacture server-rack modules from Ruixu, and I disconnected the DIY batteries and put them aside in the trailer.
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### Glass Houses
As for what happened to these batteries (while not as dramatic, the case on the other one is obviously swelling, too), I’m not sure.
There was no chance for physical damage inside the trailer, and neither battery was dropped or penetrated. Whatever happened must have been caused by normal aging of the 28 pouch cells within, or possibly the thermal swings inside the trailer.
Either way, some of the pouches have obviously transformed into “spicy pillows” thanks to the chemical decomposition of their electrodes and electrolytes, creating CO₂ and CO gas under enough pressure to deform the 14-gauge steel case of the modules. It’s a pretty impressive display of power when you think about it, and downright terrifying.
I know that posting this is likely going to open me up to considerable criticism in the comments, much of it deserved. I was clearly negligent here, at least in how I chose to store these batteries once I removed them from service.
You can also ding me for trying to save a few bucks by buying second-hand batteries and modifying them myself, but let those of you who have never shaken hands with danger cast the first stone.
To my credit, I did mention in my original write-up that, “While these batteries work fine for what they are, I have to admit that their homebrew nature gnawed at me. The idea that a simple wiring mistake could result in a fire that would destroy years of hard work was hard to handle.”
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### The Bigger Picture: Safety Concerns
But really, the risk posed by these batteries—not just to the years of work I put into the trailer, but also the fire danger to my garage and my neighbor’s boat, camper, and truck, all of which are close to the trailer—makes me a little queasy when I think about it.
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### Your Turn
That’s all well and good, but the question remains: **what do I do with these batteries now?**
To address the immediate safety concerns, I placed them at my local “Pole of Inaccessibility,” the point in my backyard that’s farthest from anything that might burn. This is a temporary move until I can figure out a way to recycle them.
While my city does have battery recycling, I’m pretty sure they’d balk at accepting 90-pound server batteries even if they were brand new. With obvious deformities, they’ll probably at least tell me to get lost; at worst, they’d call the hazmat unit on me.
The Environmental Protection Agency has a program for battery recycling, but that’s geared to consumers disposing of a few alkaline cells or maybe the dead pack from a Ryobi drill. Good luck getting them to accept these monsters.
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### How Would You Handle This?
Bear in mind that I won’t entertain illegal options such as an unfortunate boating accident or “dig deep and shut up,” at least not publicly. But if you have any other ideas, we’d love to hear them.
More generally, what’s your retirement plan for lithium batteries look like? With the increased availability of used batteries from wrecked EVs or even e-bike and scooter batteries, it’s a question that many of us will face eventually.
If you’ve already run up against this problem, we’d love to hear how you handled it. Sound off in the comments below!
https://hackaday.com/2025/10/20/ask-hackaday-when-good-lithium-batteries-go-bad/
