Re: Running NEC UL on C-cell nicads

(no name) ((no email))
Wed, 21 Sep 1994 05:40:29 -0400 (EDT)


sugests using a lithium battery to directly replace the 5V nicad
ram back up battery in our Ultralites. This is a bad idea.
Lithium cells are not designed to be recharged... a serious fire
/ explosion hazard would exist if you put a standard backup
Lithium battery in the long slot. At the very least we would
have to have a blocking diode to prevent charging. The effects
of the diode voltage drop and the different voltage of Li cells
would have to be carefully considered before I'd try it.

Then again low voltage won't hurt the RAM you only lose the data
as the battery dies, so mabey someone who has a dead Nicad could
try it and report back if it works and how long the back up
battery lasts.

If you try be sure to have a low leakage diode in series to
prevent charging.

Steve F

<The two ground connections sounds very reasonable, but this does not mean
<that all 3 lead batteries are nessesarily made that way. But it sounds goo
<d to me. So, to me it looks as though a common lithium cell would fit the
<requirements for the Ul laptop, unless the current requirement is too high
<or something. Thanks for the info, it may help when the time comes to find
<an "off the shelf" replacement for what is becoming (and may already be)
<an obsolete part.
< Fran KM1Z