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From: liz@poppyrecords.invalid.invalid (Liz Tuddenham)
Newsgroups: sci.electronics.design
Subject: Re: lithium explosion
Date: Sun, 14 Apr 2024 07:38:53 +0100
Organization: Poppy Records
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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.  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.


-- 
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk