[time-nuts] Battery backup of frequency standards

Chuck Harris cfharris at erols.com
Thu Jun 9 21:33:51 UTC 2005


Hi Brooke,

No, I'm thinking of LiSO2.  Early examples of the 5590 had what was
not so jokingly called a detonate lever on the top.  When the lever
was acuated, a short was put on the cells, and after a suitable amount
of time, the battery would belch forth a great quantity of H2S gas.  This
inerted the battery in a most dangerous and unpleasant way.  Every wonder
why that lever was there?  It's because the LiSO2 batteries are even less
safe when they still have some life left.

The Army guys out at Ft Monmouth have gone to great efforts to make
the LiSO2 battery safe, but I hear that one still goes off from time to
time.  As a result, all military battery compartments that are used with the
LiSO2 batteries, are required to have a screened vent on the side to
handle a destructive blow off of H2S.

Notice that all of the applications you have mentioned are emergency in
nature, and not intended for the unwashed masses.  You won't be finding
a LiSO2 battery for your laptop, or on the rack at Home Depot.... well,
you shouldn't.

-Chuck

Brooke Clarke wrote:
> Hi Chuck:
> 
> I don't think it's possible with a BA-5590.  There's circuitry inside 
> that limits the current draw with a dead short.  Fully draining the 
> battery is no problem, in fact there's a one way action switch on the 
> BA-5590/U that puts a resistor across each internal battery in order to 
> fully drain it.
> 
> You may be thinking about Li-Ion or Li-poly batteries where fire comes 
> out of the battery when it's mistreated (too much current either charge 
> or discharge, over or under voltage, or mechanical puncture).  Like the 
> video at:  http://www.valence.com/SafetyVideo.asp
> 
> Not true about LiSO2 batteries and commercial products.  The "D" cell 
> that's inside the BA-5590 is used in a number of products, medical 
> emergency equipment and head mounted flashlights come to mind.




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