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/* Written  9:24 am  Mar 19, 1990 by adam@cbmcats.UUCP in m.cs.uiuc.edu:sci.electronics */
/* ---------- "Why can't this bicycle light use Ni" ---------- */
>I just bought a CatEye taillight for my bicycle.  It states on the box
>that it requires two 'C' size batteries.  Inside the battery compartment
>is a label which warns against using NiCd batteries, but doesn't tell why.

(Some text deleted)

>Adam Keith Levin  --  CATS     Commodore Applications and Technical Support
>1200 Wilson Drive / West Chester, PA  19380                  (215) 431-9180
>BIX: aklevin             UUCP: ...{amiga|rutgers|uunet}!cbmvax!cbmcats!adam
/* End of text from m.cs.uiuc.edu:sci.electronics */

I suspect that this recommendation has nothing to do with the way the
circuit is wired, but rather that nicads put out less voltage than
dry cells, so the bulb will produce less light.

The dry cell puts out 1.5 volts, when fresh, and so with two, you would
use a 3 volt bulb.

The nicad puts out max 1.3 at top charge and has a nominal voltage of
1.25. At the point on the discharge knee, where the nicad is considered
"dead", it puts out 1.0 volts, just before it caves in and gives up the
ghosts. With two nicads, you could be as much as a volt low, 2 volts
for a 3 volt bulb.

I would think that nicads would be ok in the light, if you can find a
2.5 volt bulb to use in it in place of the 3 volt one. Other than that,
I see nothing wrong with using nicads. The way the circuit is wired
will not make any differance as per your schematic you provided in
your base note, the end result is the same.

Al Irwin
Univ of Illinois
Dept of Comp Sci
Urbana, Il
irwin@m.cs.uiuc.edu