Hitting the chemical limits of the batteries is what causes 1/ rapid aging and 2/ catastrophic cell damage and/or short failure and runaway, so if what you say is true (I don’t think it is) then the other manufacturers have implemented poor state of function control (SOF) and it would be a good idea to avoid.
Proper SOF control is loosely required for ECE R100 which most manufacturers would have, but OTOH I am convinced that it’s possible to fudge that certification.
Yes, it is an inherently unsafe battery chemistry. And they're everywhere. I really hope we find a better replacement soon, there are already some promising contenders but none that meet-or-exceed on all specs.
It's also quite unsafe to run lithium ion batteries in series with different levels of wear / charge state, the old ones can easily be pushed too hard and fail (spectacularly).
That is because of the current lithium chemistry batteries. A more stable battery that wont blow up so easily after some damage wont have the same restriction
We don't accommodate it because various makes of batteries have wildly different characteristics and applications, but all of them have a bad safety profile. For us, it's fine. For the general public, not so much.
This is good, I agree, but I have one major criticism: no mention of safety concerns for running non-rechargeable lithium batteries like the CR123 in series.
There are some true horror stories out there from people who have suffered chemical burns and permanent lung damage, even hydrogen fluoride poisoning just from operating those normally, with a manufacturing fault in one of the cells.
Yeah I think these batteries aren’t uncommon, as far as the voltage and form factor goes. My understanding is the biggest risk is safety. There’s a lot of junk out there, whereas Rad did a good job ensuring it’s supply chain on these. My battery is nowhere near any noticeable capacity loss so I haven’t really looked hard at batteries yet.
The article implies the issue was caused by indefinite high temperature, and the heat sinks performed correctly. I'm no battery engineer, but I assume the temperature spec is only for some finite interval.
Batteries are bags of scary-sounding chemicals. I do not trust them.
Those cells are very dangerous to use. stick to LiFePO4 or LTO. Cobalt based chemistries can experience and awful thermal runaway when over charged. This can occur if you have a shorted fet in your BMS. Which can happen from inrush current or high voltage.
How safe is this? Having more efficient batteries seems to imply more risks of spontaneous exposions, as we've seen in various phones, cars, and computers.
> Lead-acid batteries cannot sustain high amps for a long time, so they are less dangerous in that regard.
The specific hazard discussed above was about overheating a wedding ring or a watch. With 100 A, you'll reach that point in around 100ms. No need for long time at all, and a lead battery poses the exact same risk in that regard.
Yes, 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!
I had an internship at a company that made lithium battery packs. The control boards on the packs have primary cell protection provided by a specialized micro controller that monitors cell voltages and prevents over/under charge levels and monitors current, however they also have secondary protection ICs that are hardware based that will shut down the pack should the cells reach dangerously high levels, as well as fuses to prevent dangerous levels of current.
Net result, changing battery firmware can reduce usefulness of battery (higher charging degrades cell life, blow fuses etc) but the packs should have hardware based protection from being a safety hazard
I could understand this for larger batteries, I'd hate to see the damage a Powerwall or something similar could do when someone lets the work experience kid do QA for a few hours.
Proper SOF control is loosely required for ECE R100 which most manufacturers would have, but OTOH I am convinced that it’s possible to fudge that certification.
Source: battery controls engineer.
reply