FW: Battery

[Joseph Bento]

On 1/28/2014 6:45 AM, John Teller wrote:
> Lithium ion cells are extraordinarily sensitive.  If you overcharge 
> them, they will overheat, catch fire or explode.  If you discharge 
> them past that magic number, they will undergo an irreversible 
> chemical reaction such that if you try to recharge them they will 
> overheat, catch fire or explode. If you discharge them too quickly, as 
> in short them out when fully charged, they will overheat, catch fire 
> or explode.  If you puncture a cell it is very likely to overheat, 
> catch fire or explode.  Monotonous, isn't it?
>
> Every cell that ends up in consumer service includes a fuse and a 
> small IC whose only function is to permanently short out the cell once 
> it falls below the minimum charge level. This isn't just lawyer stuff 
> - see Boeing's recent experience with the 787 for an example of how 
> hard it is to get this right, especially when the cells get really 
> big.  Tesla, Nissan, GM et. al. have done an amazing job protecting 
> their massive automotive lithium battery packs.  Each cell is equipped 
> with its own cell minder which can communicate with the charger to 
> provide all kinds of telemetry about the cell condition.  These packs 
> are also centrally located not only for CG purposes, but also to 
> shield them from collision damage.
>

It's so comforting that these virtual bombs are in everything. Equally 
comforting is that most are also manufactured in China.  It is not 
unheard of where one will spontaneously overheat, catch fire, or 
explode.  I believe most airlines now limit any spares you may carry 
either in carry-on or checked baggage.

Joe, N6DGY