lithium explosion

As the energy density of batteries goes up, failures will become more spectacular. It's not a good idea to store both oxidizer and fuel in close proximity in the same container. It's a recipe for an explosive.

Jeroen Belleman

LiFePo4 appears to be quite a bit safer than the other lithium ion types. Not quite as desireable as the flammable versions but quite a bit safer.

boB

This is a great idea:

Lithium batteries don't explode spontaneously.

The "explosion" is actually the last stage in a process that starts when the batteries start self-discharging more rapidly than they should, which warms them up a little.

Any properly designed battery management system monitors this self-heating, with temperature sensors at the core of the battery, and on it's surface.

If the battery gets hot enough, the higher temperature can lead to a higher discharge rate, and at a battery temperature between 130C and

Any properly designed designed battery management system would warn the user when this were incipient and would start discharging the battery if it had a safe place to dissipate the stored energy.

It follows that any lithium battery pack that explodes either didn't have a properly designed battery management system, or was being looked after by somebody who ignored the early warnings.

All this is too complicated for John Larkin to keep in mind - we've discussed it here often enough that he should know it by now.

John Larkin doesn't seem to read data-sheets all that carefully, and he doesn't expect the manufacturers of "electric scooters,surfboards, wheelie things, bikes, and motorcycles" to be any more careful.

Jeroen Belleman is effectively saying that they should be, but hasn't spelled out the advantage of using more careful design to cope with the known dangers of using lithium batteries.

What if it didn't?

That includes 99% of battery users who wouldn't know what to do it they noticed the warnings or wouldn't be able to do it anyway.

Or the battery wasn't attended.

Battery fires have happened when nobody was near the battery; maybe charging.

Here, several cities have prohibited personal electric things with wheels from entering the urban public transport system after a few fires.

Then it probably needs to include a louder hooter and brilliant flashing lights to serve the same purpose, if more slowly than a purpose designed dissipator.

A voice message could be pretty explicit. All the message needs to say is to move the battery outside to where it can't do much damage if it bursts into flames. EV car batteries are big enough that that's quite a way, but cars are designed to move appreciable distances.

Warning systems can be designed to be quite attention getting.

A proper battery management system wouldn't let you charge a battery that had got close to going into thermal runaway

A slightly better informed city administration could adopt a more sensible rule. Personal electric things with wheels can be designed to be quite unlikely to catch on fire. One's that aren't shouldn't be on sale in the first place, and would be prohibited imports in any sensible region.

And what if cheap Chinese batteries weren't all designed by geniuses like Sloman?

Or just parked somewhere, not charging. I wonder how long it takes a tiny separator defect to spread into an explosive meltdown. Some references suggest seconds.

The US is the kind of place that will instate outright bans on e bikes, vape sticks, and books with gay people in them, but in most states it's perfectly legal to buy crates of fireworks at at time with way more explosive power than that, on the honor system. Kaboom!

And fretting about the hazards of exploding batteries with 300 million guns floating around is pretty schizophrenic. Compared to being injured by an exploding bike (or shot by a stranger for that matter) your chances of being shot by a police officer are at least the same, or higher.

It's wild that stuff like that make the national news in the UK.

In the US if I had to pick between the hazard of exploding bikes and overpenetration I guess it would be a toss up. Glad I wasn't being treated in the next room for my e-bike injury:

About 1300 people were killed by police in the US last year, out of a population of 333 million, about 4 PPM. Cops rarely shoot polite law-abiding citizens; don't threaten people, especially cops, with guns or knives.

There were 617 homicides in Chicago last year. I suspect few were attacks by strangers.

NYC alone had 18 lithium battery fire deaths last year, something like

As are most cities with access to Amazon/eBay...(no regulations on what people can sell on these platforms)

...

Here in Canada the average number of people killed by police annually is just under 40 per year since 2011. Out of a population of roughly

Perhaps our gun laws do make a difference.

John :-#)#

Traffic accidents kill about 50k Americans per year, firearms in the same ballpark, and Covid is still dropping 500-1k per day.

These fashions of death have been re-categorized as "acts of God" in the public consciousness.

It's not really a very good selling point. "Oh, by the way, this model has the latest upgrade and tells you when it is going to explode, so you can get out of the way".

It doesn't take genius to design a decent battery monitoring system, and manufacturers who sell dangerous products get sued, and banned from selling into markets with even minimal consumer protection legislation. Even the US finally banned tetra-ethyl lead as a gasoline additive.

If US legislators could understand statistics they'd have introduced sensible gun control years ago. Finding a form of words that the US Supreme Court wouldn't object to might have been difficult.

And who thinks that separator defects lead to thermal run-away and battery ignition?

John Larkin does pick up on other people's silly ideas, and has a few of his own - not all that many or he'd have got himself a patent or two.