[time-nuts] Battery backup of frequency standards

Brooke Clarke brooke at pacific.net
Thu Jun 9 15:48:31 EDT 2005


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.

Have Fun,

Brooke Clarke, N6GCE


Chuck Harris wrote:

> Brooke Clarke wrote:
> 
>> Hi David:
>>
>> You might consider getting a BA-5590/U military battery, see:
>> http://www.pacificsites.com/~brooke/BA5590.shtml
>>
>> These are really two seperate batteries, each one made up of 5 LiSO2 
>> cells, 15 volts per battery, 30 volts if connected in series.
>>
>> These are primary (not rechargeable) batteries with a shelf life well 
>> in excess of 10 years.  (I have some 14 year old units that test at 
>> 100%) Between 170 and 210 Watt hours depending on which manufacturer 
>> and date you get.  You need to be extremely careful NOT to charge them.
> 
> 
> You must also be extremely careful NOT to fully discharge, or short
> circuit them.  If you do, explosion, or explosive outgassing of Hydrogen 
> Sulfide
> gas is a very real failure mode.
> 
> There are very good reasons why LiSO2 batteries are never used in 
> commercial,
> or consumer equipment.
> 
> -Chuck
> 
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