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Re: [IP] battery storage question

On Jan. 24, 2001, Andy said:


The way I read the chart "Projected Percent Service Maintenance", it looks
like storage in the fridge is VERY worthwhile -- it *better than doubles*
shelf life compared with storage at room temperature.

Let's look at loss of 10% of the initial charge. At 20 deg. C (68 deg F),
that takes about 4 1/2 years. At the fridge temperature, 0 deg C (32 deg
F), that's off the chart, but it looks to be about 11 years.

My batteries will stay in the fridge. Thanks for the info!

regards, Andy


 I, too, will continue to keep batteries in the fridge.  The reason that I
stated that it doesn't seem necessary is that I incorrectly figured that
most folks don't keep batteries stored for 4-11 years.  After two years in
the fridge (personally, a long time for batteries, though short for some
condiments), the batteries would have about 98-99% of the original charge.  
During the same time period at room temp, the batteries would retain about
95-96% of their original capacity.

If battery use in a pump is approximately equal each day, and brand new
batteries last six weeks (42 days), two year old refrigerated batteries
would last last about 41.5 days, and two year old batteries kept in a
drawer would last about 40 days.

Since the rate of self discharge is linear (or nearly so), storage
temperature becomes more important with increasing time.  As you mentioned
the shelf life, the loss at room temp. (just over 2% orignal charge/yr) is
about 2.5 times faster than that in the fridge (just under 1%/yr).  So if
you buy in huge bulk and keep them for several years, it pays to
refrigerate.  But if you buy a blister pack that will be used in less than
a year, it doesn't matter too much.

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