RE: TEK 1502 batteries

[Andrew Sandford]

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> -----Original Message-----
> Hi Andrew,
> 
> Thanks for your comments. I bet your right on with your ideas 
> of why the battery is there. Do you have a particular manufacturer/ part 
> # for the 3.6 volt batteries you use?

We have used several makes over the years, including Saft, Tadiran, Hawker.
The make is not so critical only the technology - Lithium Thionyl Chloride,
which works over the widest temperature range.   You need to select the size
of battery to match the carrier you have.


> I've noticed that the cost of TEK's original lithium battery have dropped
considerably, with 
> Mouser  electronics carrying them for around $7 each. Mouser also lists a
KeeperII magnum 
> battery which is 3.6 vdc, 1.6 amp/hr for $9 us.
> 

We were quoted around $25 some 10 years ago, this side of the pond.  The
battery was a MIL spec rated battery - which might have possibly justified
the cost. We have not checked since.

> You mentioned earlier that you used a battery with around 10X  the
capacity
> of the original battery which is about 750 mah.     

I seem to remember the battery we originally were asked to replace was
around 300 mAh.   I checked a recent unit and as you say is does have a
capacity of 750 mAh, maybe this was a design change in later units to try to
prolong the period between service. 

AA lithium batteries have a capacity in the range of 2-3 Ah depending on the
make and range. The cost around $6-7 over here.   As space is not limiting
you could even fit a "C" sized battery which has a capacity of 6-8 Ah, which
still only costs $15

> 
> To muddy the waters a little more, I've also considered 
> removing the pc mounted lithium battery, and installing IC contacts so
that 
> the battery can be unpluged when it needs to be replaced. This would keep
the 
> instrument as close to original as possible, while minimizing the effort
required to
> replace it.

This is possibly the simplest solution if you can get the batteries now at a
resonable price.  You may need to use a sticky foam pad under the battery
though to stop if falling out if the case is knocked/dropped.

Andrew Sandford