robert@fortune.UUCP (Robert Clark) (11/09/84)
Are there any consumer electronic devices that will not work properly, or
that will not work well using NiCad batteries due to the lower voltage
supplied by these cells? I have noticed that an FM walkman that I have
stops working suddenly at a certain point in the life of normal batteries,
even though the same batteries will still operate other devices ok for a
while longer.
Robert Clark
UUCP: {sri-unix, amd, hpda, harpo, ihnp4, allegra}!fortune!robert
DDD: (415) 594-2822
USPS: Fortune Systems Corp, 101 Twin Dolphin Pkwy, Redwood Shores, CA 94065bill@crystal.UUCP (11/11/84)
> Are there any consumer electronic devices that will not work properly, or > that will not work well using NiCad batteries due to the lower voltage > supplied by these cells? I have noticed that an FM walkman that I have > stops working suddenly at a certain point in the life of normal batteries, > even though the same batteries will still operate other devices ok for a > while longer. My Olympus "Quick 310 Auto-Flash" flash unit says (well, actually, the instruction book has printed in it) DO NOT USE NiCads!!! They will harm this flash unit. I have no idea why. I would appreciate MAIL from anyone who knows, or has tried (successfully or un-) NiCads in an Olympus flash unit. William Cox Computer Sciences Department University of Wisconsin, Madison WI bill@uwisc ...{ihnp4,seismo,allegra}!uwvax!bill -- William Cox Computer Sciences Department University of Wisconsin, Madison WI bill@uwisc ...{ihnp4,seismo,allegra}!uwvax!bill
hull@hao.UUCP (Howard Hull) (11/11/84)
Many battery-operated devices contain *switching regulators* which make up for
low supply-side voltage by drawing more current. This is in accordance with
the formula:
Power at the Load = Source Voltage X Source Current
Since, for any given instance of a fixed load power, the source voltage will
slowly decrease as the battery discharges, the source current will gradually
rise. At some point, the source current will increase rapidly and then become
so great as to exceed the maximum current specification of the regulator parts
and the regulator will burn out. Some manufacturers protect such regulators
by means of a fuse; however, replacing the fuse every time the battery gets too
low is inconvenient for most consumers. Using a low-value resistor in place of
the fuse is another technique, but that makes the regulator inefficient - and
efficiency is the primary reason for using a switching regulator in the first
place.
Instead, most manufacturers prefer to rely on the discharge characteristics of
the carbon-zinc battery. For such batteries, the resistance is low during most
of the battery life, but increases under heavy current draw - and does so to a
much greater extent at the end of battery life.
With Nicad batteries, resistance is uniformly lower during most of the battery
life. As has been pointed out, the voltage is uniformly lower as well. This
causes a uniformly higher current draw than would be experienced for a zinc-
carbon battery under the same load conditions. Then, near the end of a nicad
battery's life, the voltage sluggishly rolls off while the resistance becomes
only moderately higher. The switching regulator is thus subjected to a rather
longer period of greater input current stress, during which time it is more
vulnerable to even brief load surges.
Howard Hull, HAO.
> {ihnp4!stcvax | decvax!stcvax | seismo} !hao!hulljohnbl@tekig.UUCP (John Blankenagel) (11/13/84)
> > Are there any consumer electronic devices that will not work properly, or > > that will not work well using NiCad batteries due to the lower voltage > > supplied by these cells? I have noticed that an FM walkman that I have > > stops working suddenly at a certain point in the life of normal batteries, > > even though the same batteries will still operate other devices ok for a > > while longer. > > My Olympus "Quick 310 Auto-Flash" flash unit says (well, actually, the > instruction book has printed in it) DO NOT USE NiCads!!! They will harm > this flash unit. > > I have no idea why. I would appreciate MAIL from anyone who knows, or > has tried (successfully or un-) NiCads in an Olympus flash unit. > I can tell you what will happen. I did not put NiCads in MY Olympus flash but I saw the results of a flash into which someone put NiCads where the instructions said not to. NiCads have a lower internal resistance than alkalines or carbon-zinc batteries. The flash I saw was melted, including most of the case. It only contained two batteries too.