Hi:

There's a fundamental chemical difference between Ni-Cad and Ni-MH in 
that the Ni-Cad does not generate anywhere as much heat at end of charge 
as the Ni-MH.  Also the minus delta V for the Ni-MH is smaller than for 
Ni-Cad.  So a charger designed for Ni-Cad batteries will not work on 
Ni-MH.  The military Ni-Cad BB-590/U battery just has standard 
electrical contacts that are used for operation and charging, but the 
newer Ni-MH BB-390/U has added thermistor battery temperature monitoring.

It also turns out the the "Burp" type chargers, like the battery space 
universal charger, that include a large current discharge pulse in the 
charge cycle do not heat up the Ni-MH batteries like a constant current 
charger does.  Alexander has uC code for their burp charger for 
different uC brands for license.  More on Burp chargers at:  
http://www.pacificsites.com/~brooke/BatChg.shtml#Burp

I think it might have been "123" LiMnO2 batteries that caught fire at 
LAX after they were unloaded from a flight from Japan.  The fire was 
started because the fork lift operator speared the boxes just above the 
skid (aircraft metal pallets are different than the wooden pallets used 
on land) crushing the batteries.  For more on this see the NTSB report at:
http://www.ntsb.gov/Recs/letters/1999/A99_80_84.pdf

For a video of a Li-Ion BB-2590/U after being shot with an M-16 where 
all the cells spit fire see:
http://www.valence.com/SafetyVideo.asp

Happy Holidays,

Brooke Clarke, N6GCE

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