7 ms·
This sounds like it could be rather dangerous, no? Connecting up a bunch of old lithium cells of unknown origin and using them hard. I'd also worry about an in
by ficklepickle 9y ago
This sounds like it could be rather dangerous, no? Connecting up a bunch of old lithium cells of unknown origin and using them hard.
I'd also worry about an insurance claim being denied if it burned my house down.
However, I very much approve of the DIY ingenuity and repurposing of old stuff.
- Baeocystin 9y agoKind of dangerous seems like quite the understatement, considering the nature of lithium batteries! It'd be fun to play with something like this for the learning, but I wouldn't actually run one unless it was in its own shed, many dozens of yards from the nearest anything else. Lithium fires are no joke.
- deleted 9y ago[deleted]
- princekolt 9y agoI've read claims (theoretical and practical) from both sides, so apparently the safety of lithium cells can vary widely based on manufacture quality and maintenance. But also, on the video, they shows each pack of cells he uses has individual over and underchange and temperature sensors, so the system is able to tell if any individual section is going bad. It's a pretty neat, and external installation, so I don't think it is very harmful on a "massive heat incident".
- dom0 9y agoA properly designed lithium ion pack with tested high-quality cells is a very safe thing in the environmental conditions it was designed for. Notice how many qualifiers are used in that statement.
- agumonkey 9y agoBTW I've seen lithium cell safety bags, that can hold the flame enough. I wonder how a case could be done in a similar way to at least contain the heat and gas. Also, could there be a thermoelectric powered fan to slow down the heat rise when cell(s) starts to fail or burn ?
- Baeocystin 9y agoYou absolutely can design a firewall system able to fully contain a runaway pack. They have small systems that look like briefcases to nab runaway laptops on planes, for example. But when a cells goes, it goes. No fan is going to remove anywhere near enough heat. And you wouldn't want it to spread the vapors, as HF is a genuinely dangerous byproduct. The only real solution is full containment. And being 100% confident in your containment solution would require a lot of destructive testing- it isn't a trivial problem.
- agumonkey 9y agoOk a fan was ridiculous, but I didn't mean to diffuse gaseous products; just tap into the heat to activate some endothermic reaction around the system to, well, delay or dampen the process. Thanks nonetheless for the return
- askvictor 9y agoIf they're from laptops the cells should be safe (as opposed to unknown new cells from AliExpress which may or may not be to spec); albeit not necessarily at maximum capacity. As long as appropriate protection circuitry is used, I don't see how using then hard would make any difference (laptops use batteries hard too).
- userbinator 9y agoopposed to unknown new cells from AliExpress which may or may not be to spec Many of those are actually recycled old cells, likely from laptop batteries, and could still have a lot of capacity left --- often, what happens is that one of the cells in the pack fails/goes out of balance and the protection circuit disables the whole thing, meaning the rest of them are still very much usable.
- monochromatic 9y agoLaptops catch fire sometimes.
- agumonkey 9y agoMost of the videos on the subject I've seen have a simple idea: depending on the battery, one cell could turn a whole pack off for safety. Pulling them apart, and rewiring them to a new (and probably better) Battery Management Chip, could make the N-1 pack working. They also often charge them a few times individually to assess their stability. [1] one bad cell could force too much current elsewhere or overheat IIUC
- extr 9y agoYes, this is extremely dangerous. I'm sure some of the people mentioned have the expertise to pull it off, but for most this is like building a massive bomb in your garage. There's a reason that 18650s aren't generally sold directly to consumers, in most applications they need dedicated circuitry to be used safely. And that's for brand new cells, it's another story entirely to be using random collections of "old" cells, at various points in their life cycles, different rated capacities, and subtly different chemistry. No thanks!
- hwillis 9y agoTheres no way to detonate a pack like this. 18650s have a pressure release, so the cstch fire but dont explode. In the very unlikely event that fails, a cell could burst, but it cant cause other cells to burst unless the entire pack failed to vent under extreme pressure.
- Reason077 9y agoYeah. It's a total misconception that Lithium batteries can "explode". Sure, there's a fire risk if you have faulty or unprotected cells. But there's no explosion risk unless there's something very wrong with the way they're packaged.
- extr 9y agoSemantics. Is a battery undergoing thermal runaway/venting "exploding"? Or merely "ejecting scorching hot gas and catching fire?" Maybe it's not blowing up like an IED, but either way I don't want it happening in my garage.
- hwillis 9y agoThe difference between "can be ignited" and "massive bomb" is not semantics. Even new pouch cells are way safer than they used to be. Unregulated 18650 cells are quite safe if the correct circuitry is used. The only dependable way to ignite them is to smash completely open them at full charge.
- drcross 9y agoCells are brought through charge and discharge cycles to test them individually before building a pack.
- stephengillie 9y agoThe hyperbolic response isn't warranted, as these are nearly identical lithium cells of known origin. Were they all different random cells, or if disassembly were required, then one might catch fire or explode like a small firecracker. This isn't much more dangerous than putting batteries in a toy car, or putting gasoline into a hybrid.
- gamad 9y agoI'm a EE, and a licensed PE. I wouldn't do this.
- stephengillie 9y agoPlease excuse my ignorance - what is a licensed PE? Edit: Thanks for the answers. 2 questions: 1. Why would you not do this? 2. Were you to do this, what precautions would you take?
- gtCameron 9y agoProfessional Engineer
- hwillis 9y agoProfessional engineer
- planteen 9y agoProfessional Engineer. There's an Engineer in Training certification first, typically gained by passing a Fundamentals of Engineering exam in college. Then you work for a few years under a PE and take an exam to become a PE yourself.
- gamad 9y agoSomeone licensed by their (US) state as an Engineer, and the only person (in most states) who can legally call himself an Engineer. https://www.nspe.org/resources/licensure https://www.nspe.org/resources/licensure
- jjeaff 9y agoLuckily, home owners' insurance covers stupidity as well as acts of God. So as long as there is no evidence of intentional arson, then insurance would have to pay.
- hak8or 9y agoThat sounds really unusual I feel, the insurance company should be within their right to deny a claim if the home was destroyed due to gross negligence, like someone deciding to make a pool on their roof without asking an architect, or throwing a raging party with 700 people and the floor collapsing.
- heartbreak 9y agoIf they can prove you knew it was an increased fire risk, they won’t cover it.
- sumoboy 9y agoIf it's not in the policy "we don't cover homemade lithium projects", your covered. Very few things a home policy won't cover like nuclear war, terrorist acts for example. If your operating as a home business building these then that could be an issue, otherwise you can be an idiot and build whatever you want and your covered.
- cat199 9y agoWe don't cover !@#$ing with the utilities in ways that are not standard is probably in there somewhere..
- Dylan16807 9y agoThe tie-in to the utility can easily be professional or professionally verified. That's quite separate from the battery bank itself.
- danesparza 9y agoIn the case of electrical improvements (like hooking your hacked battery up to mains power) your insurance company just needs to do a little digging. They just need to find out if there were improvements without permits or if those improvements weren't made to code. http://www.popularmechanics.com/home/interior-projects/how-to/a17687/7-building-code-violations/ http://www.popularmechanics.com/home/interior-projects/how-t...
- nine_k 9y agoCan this thing be put in a fire-resistant compartment outside house? Even a couple layers of drywall would probably be enough to isolate the fire. A design with inner fireproof walls would prevent one cell from lighting up most of the pack. All this is neither hard nor expensive, and would limit the consequences of a fire severely.
- UnpossibleJim 9y agoNo way I'd do this inside my house, either, but if you watch the video, the Australian fellow had his in two little aluminium sheds out back, set on concrete. Looks like, most likely, a catastrophic event would trip the wires and (at worst) burn down the sheds and couple computers/Arduino boards. Now, insurance folk will always fight a claim, but you might be able to get past... maybe =/
- susi22 9y agoVery much so, a very good read: http://www.candlepowerforums.com/vb/showthread.php?141137-Inhaled-vapors-from-battery http://www.candlepowerforums.com/vb/showthread.php?141137-In... And also: http://budgetlightforum.com/node/45314 http://budgetlightforum.com/node/45314