adam@cbmcats.UUCP (Adam Keith Levin) (03/19/90)
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.
It certainly _works_ with NiCds, there is no reason it shouldn't.
I am cross-posting this to sci.electronics because I suspect that CatEye's
reason has to do with the electrical circuit used in the taillight.
Standard flashlights usually have circuits like this:
bulb switch
|---(*)-----_\---|
| |
|------ilil------|
+ -
batteries
Note that the positive terminal of the first cell is connected to one
lead of the bulb, the negative terminal of that cell contacts the positive
terminal of the next, (and so on for additional cells) and the negative
terminal of the last cell has a switch between it and the other lead of
the bulb. Whew!
The CatEye has a circuit like this:
bulb 1 C cell
+ -
|---(*)----i|i|---|
| |
|--|i|i-----_\----|
- +
1 C cell switch
Note here that the positive terminal of one cell and the negative terminal
of the other are connected to the two leads of the bulb, and the remaining
contacts are connected (by the switch) to complete the circuit.
While electrically there is no difference when the switch is closed,
does it change the amount of leakage(?) on (one or both) NiCds when
the switch is open?
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!adamzmact61@doc.ic.ac.uk (D Spinellis) (03/21/90)
In article <10245@cbmvax.commodore.com> adam@cbmcats.UUCP (Adam Keith Levin) writes: >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. > >It certainly _works_ with NiCds, there is no reason it shouldn't. >[Stuff describing the circuit deleted] One reason I can think of might be safety. The voltage discharge curve of NiCd batteries is extremely steep compared to the curve of conventional batteries. For the taillight application this means that the light will go from bright to dark in a few seconds. This can be dangerous since you might fail to notice it. Using conventional batteries you get an extended `grace' period where the light is gradually dimming giving you time to notice it change batteries. I find it conceivable that the company is trying to avoid product liability problems. Diomidis -- Diomidis Spinellis Internet: dds@cc.ic.ac.uk Department of Computing UUCP: ...!ukc!iccc!dds Imperial College JANET: dds@uk.ac.ic.cc London SW7 2BZ #include "/dev/tty"