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From: elec140@csc.canterbury.ac.nz
Newsgroups: sci.electronics
Subject: Re: Charging Nicads
Message-ID: <1991Jun28.114746.1220@csc.canterbury.ac.nz>
Date: 27 Jun 91 23:47:45 GMT
References: <51309@ut-emx.uucp>
Organization: University of Canterbury, Christchurch, New Zealand
Lines: 36

In article <51309@ut-emx.uucp>, CCEB001@utxvm.cc.utexas.edu writes:
>
> The discussion of charging nicads makes it sound as though a simple
> power supply regulated to about 1.4 volts would be an excellent
> battery charger.  Is that correct?

All the information I have seen about nicads indicates that constant current
charging should be used, not constant voltage. You could use a constant voltage
level cutoff, however the internal resistance of nicad cells varies with
different types, thus they will be fully charged at different terminal
voltages, and these voltages will vary with the charge rate.

> I have some GE Generator nicads that charge in one hour.  I am
> interested in constructing a 12vdc powered charger for use in a car.
>
> Can anyone suggest a resonable source of a simple schematic or
> current and authoritive book.  The GE charger has about six ICs,
> four power transistors on heat sinks, and an astonishing number of
> wires.

Check out electric model car magazines, they're right into fast charging
nicads off 12V (in about 20 minutes!). However a good charger for this type of
application is not simple to build, or cheap to buy.

*********************************************************
Chris Kaiser
Postgrad - Elec Eng Dept
Canterbury University
Christchurch, NEW ZEALAND

E.MAIL: kaiser@elec.canterbury.ac.nz
*********************************************************
	"When you're fresh out of lawyers
 	 You don't know how good it's gonna feel"
		- Al Stewart, 1988
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