Hacker News Reader

Hacker News

Comment by scott113341 | Hacker News Reader

Full thread

scott113341

"I made 14 kWh more during lockdown"

https://secondlifestorage.com/index.php?threads/glubuxs-powe...

^ has a wild picture of full setup

View on HN

That fire extinguisher looks ridiculously useless for a setup like this. Good thing it's a separate shed, at least.

Not gonna do you any good if the batteries themselves start going off, but if something else has ignited in the cabinet and the batteries are not yet on fire... you'd be glad to have the extinguisher, I bet

The fire extinguisher is in the wrong place entirely. If the setup is on fire are you really going to reach _in there_ to grab the extinguisher?

There's no protection over the bus connections. Any falling conductive item is now a spark hazard.

Using spring loaded alligator clips as test leads apparently for monitoring. I hope that's not a permanent configuration.

Everything is bolted down and I see no inline disconnects or even any fusing except on low voltage sections.

There are exhaust fans but I can't tell if there's inlet fans.

From this one picture, which may not be fair, this is not a safe setup. I would feel uncomfortable with this on my property.

Let us hope that all the wires above the battery packs are of the same polarity. I can't tell for sure if that's the case but I hope the two that are closest together are just book-ended.

I experienced a 400v DC lithium ion battery catch on fire once, it was very scary. That fire extinguisher won't do much at all, even if it is placed in a more logical spot.

The firemen ended up putting the battery, half melted, into a big drum of water and it hook hours to cool off. The concrete was still warm to the touch where it burned for ~30 hours after the situation was sorted out.

The smoke was just absolutely unbelievable. Made me reconsider buying an EV. That fire was no joke.

The MV contactor wasn't even closed, it had 24v powering it for the internal cell balancer from the vendor, that was it.

Even though it might not seem like it because reporting on burning cars is very selective, EVs do catch fire a lot less than gar powered cars - even when adjusted for how many there are on the road. Additinally, many new EVs use cheaper LFP batteries now that are almost impossible catch on fire.

I hear you and appreciate your point, I just don’t think they’re for me. Maybe when my kids are grown. Scary does t begin to describe what happens, the amount of energy is mind-boggling.

What would be an appropriate suppression system here? That's a lotta batteries all arranged like a boy scout arranges kindling logs for a campfire.

A roof-mounted water tank with a thousand gallons ready to dump into the shed? A drum of baking soda?

Or maybe rebuild the shed out of cinder block and clear any overhanging vegetation?

Maybe this whole setup is on desert dirt with plenty of clearance. The fire plan is "run away and wait."

A ton of sand, but that's the main issue with those systems and why it's genuinely impractical as anything but a hobbyist project. They need constant monitoring as all of those cells are from laptop and risk thermal runaway at some point. Even with the best matching possible some cell in his configuration will have higher internal resistance and create heat. "Real" large off-grid systems all use LiFePO4 and are unlikely to just catch fire. That being said from the forum post he seems well aware and he probably has individual fuse for each cell.

You could also just bury it so that the worst of the explosion is mostly mitigated. I've also seen small container setup which would probably work better than his (seemingly) wooden shed.

I wonder if the correct solution here is build the shed far away from house and trees, on a cinderblock foundation filled in the middle with 8+ inches of sand, and you just stand back with the garden hose to keep everything around it moist.

You can see the shelter here [0] and it is apparently 50m from the house [1].

Would be better if the ground was paved around the shed, but it seems to be far enough from other free standing structures.

[0] https://secondlifestorage.com/index.php?threads/glubuxs-powe...

[1] https://secondlifestorage.com/index.php?threads/glubuxs-powe...

The only purpose of a fire extinguisher is to allow you to get out. They do not contain enough water to adequately put out any real life fire (especially not an electrical one like this).

If he can't reach to grab it because it's too hot, he should have already left.

I hope it doesn't contain any water at all!

Dry Powder or CO2 is what you need for energized electrical equipment. And considering there's potential lithium involvement, you might want something more specialized (e.g. F-500 Encapsulator Agent). I agree anything more than a small-scale incident you're just getting the heck out of dodge. I'd have built something along the lines of a concrete bunker, with an automated suppression system to buy time.

I think I'd rather have the extinguisher near the door.

If you are outside, it does not tempt you to cross the room. If you are inside, you run for the door, and then turn around and decide if maybe you should just keep running.

It's definitely now in the wrong spot. I assume that once upon a time there was one rack against the wall, and it was only slightly irresponsibly placed, and now there are two racks and hey kids, heat rises.

The extinguisher should be directly inside the door so as not to attract someone to traverse farther into the building without an escape plan.

Of course if he did so then there would be no extinguishers in the picture and then we would also bitch about it.

Everything worth doing is worth over-doing. He should start doing mad scientist experiments and produce ball lightning, the amperage could be sufficient.

Reply on news.ycombinator.com