[ltp] bomb batteries

[Richard Neill]

Hamish wrote:
>  On 9/23/06, bhaskins@chartermi.net <bhaskins@chartermi.net> wrote:
>  > Well, we always can go back to NIMH batteries,
>  > not as long a run time though.
>  >
>  > I have never heard of a nicad or NIMH battery explooding
>  > and most Thinkpads will work with them.
> 
> I don't know about NiMH (Although I'd bet they can go up too), but NiCads were 
> notorious for exploding when charged too much. In fact years ago when I was 
> into model boats the boating mags were always showing pictures of peoples 
> creations in bits when they'd overcharged their NiCads that were still inside 
> the boats.
> They make a BIG mess when they go up... Explosively so. Not just burning.
> 

Agreed. I fly model aircraft, and the Nicads were regarded with much 
greater caution than the new Lions. BUT

a)The modellers used to abuse Nicads dreadfully. They'd charge at C4, 
and discharge at C20! Some home-made packs had the cells' venting holes 
blocked with solder.

b)The chargers were extremely crude - just connect a 7.2V pack to a car 
battery, via a 20minute clockwork timer, and a resistor. No 
peak-detection, nor temperature monitoring.

BUT Nicads almost never go bang on discharge(*), or when left unattended.

(*)except when shorted. An AA pencell nicad can generate about 90Amps!


Richard