http://www.thomas-distributing.com/maha- educate-batteries.htm
Q: I have not used my NiMH batteries in
several months and they are not holding
their charge. How can I fix this?
NiMH batteries will self-discharge if left
unused. Generally, within 30 to 60 days,
batteries will become completely drained.
When using them, you will need to first
recharge them. After extended storage, you
may need to condition (using the
conditioning feature on PowerEx chargers
like the MH-C204F) the batteries several
times to regain nominal performance.
Q: I plan to use the MAHA NiMH batteries as
a backup power. How long will they hold
their charge?
This is commonly referred to as the "shelf
life" of batteries. For MAHA NiMH batteries,
the shelf life at room temperature is about
70 to 90 days (for those who are a bit more
technical, take a look at the charge
retention curve). If you are seeking for
longer shelf life, you may wish to consider
alkaline or non-rechargeable lithium
batteries, which are commonly used for
memory backups.