Renata SA 3V Lithium Coin Cells - DESIGNER'S GUIDE - Manual (Page 45)

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the swiss power source
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Influence of storage / ageing on electrical performance
Influence of contact material
Frequently Asked Questions (FAQ)
Which are the recommended storage
conditions for lithium coin cells?
The normal storage of lithium coin cells is made
at temperature between +10°C and +25°C,
never exceeding +30°C (also according to
IEC 60086-1). In this way the maximum shelf-life
(i.e. max. retention of cell performances after
storage periods) of lithium coin cells is achieved.
Storage temperatures above room temperature
will increase the rate of self-discharge, reducing the available capacity of the cell. Humidity above
95% R.H. and below 40% R.H. should also be
avoided for sustained periods, as these extremes
are detrimental to batteries.
Storing the cells at low temperature is also
suggested, but attention must be paid when
transferring the cells to warmer environments,
because of the possibility of having water
condensing on to the cells (risk of short-circuits).
Which contact materials are recommen-
ded?
Recommended contact materials:
• Gold plating – provides the most reliable metal
to metal contact under all environmental
conditions.
• Solid nickel – provides excellent resistance to
environmental corrosion.
• Nickel-clad stainless steel – performs almost as
well as solid nickel.
• Nickel plated stainless steel – also a reliable
metal to metal contact (also used for RENATA's
battery holders SMTU/HU series).
• Inconel alloy – provides good electrical conduc-
tivity and corrosion resistance.
Never use tin plated contacts since in high
humidity and polluted environments sulfides can
form on the material and creep through pores in
the coating.
Which contact force and design ensure
best electrical performance and reliability?
The contact force of the contacts should be
between 2 and 10N (ca. 200 to 1000 gf).
Contact design: It is important that contacts apply
sufficient pressure to hold the battery firmly in
place and prevent electrical disconnections (even
under shock conditions). Contacts must be able to
resist permanent set. Furthermore, two contact
points guarantee more reliability than only one.
Can batteries undergo washing proces-
ses?
Please use non-conductive cleaning solutions for
the PCB washing process. In conductive solutions,
the batteries are short-circuited, causing
discharge, voltage drop and possibly deterioration
of the cell performance. Use cleaning solutions
that do not attack the polypropylene cell gasket. Are Renata lithium cells certified in terms
of safety?
The safety of Renata cells is certified by
Underwriters Laboratories Inc., Northbrook/
IL/USA, under the file number MH14002. See
also:
www.renata.com/content/3vlithium/tech_
safety.php and the Safety Section in this Guide.
General FAQs