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From: don@umd5.UUCP
Newsgroups: net.analog
Subject: RE: Electronics wearing out
Message-ID: <616@umd5.UUCP>
Date: Tue, 25-Jun-85 17:57:35 EDT
Article-I.D.: umd5.616
Posted: Tue Jun 25 17:57:35 1985
Date-Received: Sat, 29-Jun-85 03:01:25 EDT
References: <2663@decwrl.UUCP> <508@edison.UUCP>, <172@almsa-1> <221@unccvax.UUCP> <657@lll-crg.ARPA>
Organization: U of Md, CSC, College Park, Md
Lines: 33

>   What about replacing the 7 year lithium battery after 4 years by
> connecting a new battery in parallel and then removing the other.
> 
> Doug Manatt

*** REPLACE THIS battery WITH a new one ***
Doug, 
I don't think that would be too good an idea as lithium batteries don't take
kindly to being current sinks. One, the battery could explode; two, the
battery's life can be shortened considerably. The batteries we (APCOM, Inc.)
use even have warnings about too much heat just from the soldering operation
to install them on a PC board. The fresh battery would attempt to charge the
weak battery while they are connected in parallel. On the other hand, if there
is a diode in series with the battery (what we do -- battery back-up), you
could possibly do something like you suggested, but one would first need TWO
batteries. On battery one, connect a diode in series, and connect the cathode
end of the diode to the cathode end of the existing diode on the PC board.
Next disconnect the old battery. Now install a new battery in place of the old
one. Lastly, disconnect battery one and its diode. Voila !!


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