What's Wrong With This Pack?

Seen… on the internet. Someone showing off their new, DIY, 48V, 200Ah LiFePO4 pack.

Count the problems. This is an arc fault looking for a day to happen…


Well let me be the first to say ‘Dear god what the hell is that!?!’

The bolts not tight stands out. Doesn’t look like the battery leads are equal length, although it’s hard to tell past the vision obscuring rats-nest of… I assume balance wires?

Are those terminals and leads on top just straight bolted to the wood?

At least it’s LiFePO4, so he might probably maybe be less likely to burn his house down in a thermal runaway? At least until that drillbit rolls somewhere it shouldn’t be.

I see foam in the verticals, that’s wonderful for insulation but poor for heat dissipation. And why does it look like the negative is using BLUE wiring to go to the BMS, and the positive (?!) is using BLACK. Or maybe I’m seeing it wrong. Anyway, VERY hard to tell what’s going on…I presume that’s the BMS at the top. Or at least it’s a balance, although doesn’t look like the main power in/out is tapped into using that.

Is there any thermal monitoring? Might be 1 or 2 I see, not sure. And just…WTF?! And looks like there’s some metal plate bolted or something onto the bottom right plywood piece. Is that holding 2 pieces of plywood together for the bottom? Or not? Or something else?

Oh wait! Are those metal ‘support’ rods that seem to be bolted top to bottom also on the back side of it? In that case, WHY IN ALL THAT’S HOLY IS THERE ANYTHING CONNECTED TO THE ONE IN THE UPPER RIGHT!!! Or are those meant to be rods that are hooked to ground, and then to actual ground?! And that one in the bottom left looks DANGEROUSLY close to contacting one of the terminals.

I can’t even.

Might as well do this, at least it’ll be fun and you know that you’re doing it. Otherwise it’s just probably going to happen anyway sometime. And I just hope there’s no kids around. Ever.
rm -rf

No, no, it’s cool man it’s cool. The vertical threaded rods got wrapped in electrical tape dontya know? :dizzy_face:

So… @Syonyk, just where did you find this? I’m in the mood to be simultaneously horrified and amused tonight.

Ehm. Ok, that auto-filled the image, not the link.


Try that…

I feel like lack of downvotes and/or sarcastic put-downs might be an indication of lack of technical knowledge of the solarDIY subreddit? Just a guess? Nobody on there really thinks that’s ok right?

Clearly they do, or they’d have said something.

There’s a reason I no longer post on Reddit (and have removed all my content, though not the user), and this sort of stuff is a reason. “Correcting abominations” is frowned upon in the mainline sections of the modern internet. Post about the hazards, and you’ll get told it’s fine, nothing’s wrong, it won’t catch fire, and besides, so-and-so on YouTube did it. I can’t decide if it’s the blind leading, the dumb leading, or the “I know better but this gets way more clicks” leading. In any case, I got tired of (among other things) arguments about soldering directly to recycled 18650s and such (any data sheet worth anything will have a section about that in there, saying “NEVER SOLDER TO TERMINALS”). But, hey, a $200 spot welder (which is what I’ve used extensively, and does 0.15mm nickel strip just fine) is apparently too expensive, so, thermally stress every single cell in the pack, then bundle them by color (not by capacity, by color…) on plywood. You know, so you can screw it to the wall and have it look good.

There’s almost no overlap between the packs I used to build and the crap that’s regularly shown off as “amazing.” If you want a short rabbithole, search for “DIY Powerwall” and follow a couple forum links. You’ll see no shortage of things that should worry you.

You’ve heard my comment about how the 787 lithium pack was a hack job that never should have flown. That pack is far higher quality than most of the “DIY” stuff involving lithium, and I’ve zero interest in even being associated with that sort of thing now. I don’t fear lithium, but I sure have a healthy respect for it, and “abusing already abused lithium” is the sort of bad idea I won’t go near.


On this pack, the terminals screwed through the plywood is cute. I’m sure those never get hot under load, or if a screw backs off or something… though I do note that locking nuts are being used. I’m not sure I’d trust a nylon lock nut under high thermal loads, but… hopefully that doesn’t happen.

The balance wiring is just a hot mess, though. That stuff should be cut to length and carefully routed to make sure it’s not going to get tangled/rub/etc.

The metal drill bit casually tossed on top, by the exposed terminals, is a nice touch too.

If you want some still decent batteries/cells, with some major DIY (as in usually need a BMS as well), greentec auto is a known, pretty cent shop. They at a minimum will give you solid specs, and solidly tested “these cells are in reasonably good shape”. Apparently their site store is basically 100% out of stock, but their ebay store has a bunch of stuff.

Like this one. They let you know EXACTLY what the situation is, and give you warnings. If you’re ambitious and have enough testing equipment and such you might be able to harvest those cells and get lots of useful life out of them. Then again, maybe not. But they do give you the real info.

I’m not that ambitious. I’d do something used but in good condition, ready for wiring up and hooking up to a BMS.

Reddit by definition amplifies the mediocre because that’s who is there.

Trying to be the voice of reason is pissing into a gale force wind.

1 Like

Yeah. So I learned… and even though it’s not as reorder-all-the-things-for-engagement as Facebook/Twitter, it’s still pretty bad about “NUMBERS! ARE YOU LIKED? CHECK YOUR NUMBERS TO SEE!” loopholes in human psychology.

Why haven’t you hearted my comment yet @Syonyk? Do you just not like me? Am I not worthy enough for you?

/s :stuck_out_tongue:

I found a really good use of those reaction-style things - in Microsoft Teams of all places - the thumbs up is a great way to let someone know you read it without having to actually reply.

I’ve gotten used to it (in Slack), but I still hate it. You can’t be bothered to do a simple “gotcha” or something? And I ALWAYS turn off emoji/animated crap. I hate the animations, because they always seem to constantly rotate, so if any of it is visible it’s a constant “Look at me! Look at me!” distraction. So instead of seeing an animated thumbs up, I see :thumbsup_all:. Which in my not humble opinion, is far better. Still annoying, but less so that emoji crap.

It helps in “group chats” where a thread would be filled up with “gotcha” as multiple people read it. And those who don’t want it can disable it.

The animated ones are cute for about ten seconds (the animations for certain emojis in Telegram is … NSFW).


I find it doesn’t help that much. At least in Slack, it only gives me the number of people, I have to hover over it to get names. Whereas if they just provide a message, it’s easy to see the names in the chat of who got/understand/whatever it.

But that’s all just me.