[time-nuts] Battery backup of frequency standards

Chuck Harris cfharris at erols.com
Thu Jun 9 12:08:17 EDT 2005

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.


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