Re: lithium explosion

On 14/04/2024 4:38 pm, Liz Tuddenham wrote:

Bill Sloman <bill.sloman@ieee.org> wrote:
 

On 14/04/2024 1:14 am, Liz Tuddenham wrote:

Bill Sloman <bill.sloman@ieee.org> wrote:
>

On 13/04/2024 3:39 am, Liz Tuddenham wrote:

Bill Sloman <bill.sloman@ieee.org> wrote:
>

On 12/04/2024 6:55 pm, Liz Tuddenham wrote:

Bill Sloman <bill.sloman@ieee.org> wrote:
>

... if
it had a safe place to dissipate the stored energy.

>
What if it didn't?

>
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.
>

..was being looked
after by somebody who ignored the early warnings.

>
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.

>
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.

>
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".

>
You don't seem to have been paying attention. If you deal with the
warning by discharging the battery, and making it safe, it won't explode.

>
>
Who it the 'you' in that sentence?

>
You personally.
>

Do you mean the average user,  in
which case this is a hopeless scenario as most users of batteries
wouldn't have a clue.
>
Until recently batteries have been inherently safe: unless you did
something stupid they were unlikely to give any trouble.  You are now
supporting a type of battery that is inherently unsafe and will catch
fire or explode unless the user takes some positive action.

>
But happens to offer a much higher energy density.
>
It takes a long time to degrade to the point where it can catch fire or
explode, and the degradation is entirely detectable.
>

Even if the user delegates this action to an automated system there is
no guarantee that the action will be taken every time it is needed.

>
And the brakes on your car don't always work, but we do seem to be
willing to live with that.
>

'Safety' that depends on taking a positive action to prevent a disaster
is not safe at all.

>
But we live with that, when the advantages are proportionate to the risk.

 My van has dual hydraulic systems for the footbrake, a mechanical
handbrake and even gears that could slow it down in an emergency.  If I
park it somewhere, the chance of it crashing into something while I am
not there to stop it is very small indeed, I don't need to take any
positive action.
 I suspect the number of spontaneous fires of vehicles with lithium
batteries is far higher in relation to the number on the roads than the
number of spontaneous runaways and crashes of diesel and petrol
vehicles.

It isn't - the numbers are quite a bit lower. There have already been some insurance statistics accumulated and some of them have been posted here. Electric cars haven't been around for all that long so to some extent this is comparing relatively new electric cars with a populations of IC cars which includes some antiquated junk, but electric cars do seem to be quite a bit safer.
Newspapers don't emphasise this.

In addition there is the same risk of brake failure on an
electric vehicle - even more so if it has an electric parking brake
which is the driver cannot operate quickly in an emergency.

The point was not the efficacy of the brakes but the existence of a risk which we are willing to tolerate.
--
Bill Sloman, Sydney