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From: Paul Hovnanian
Subject: Re: Parallel Alkaline Batteries
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References: <3D9A6F8D.8FCFC12D@Hovnanian.com> <3D9B1A5F.27212DC@110.net>
Date: Wed, 2 Oct 2002 17:00:13 GMT
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Jeff Wisnia wrote:
> Sounds weird to me Paul.
> AFAIK connecting two fresh identical alkaline cells in parallel
> shouldn't discharge them.
> Didja try the obvious? (Does the booster pack continue to put out 1.5
> volts when there's only one battery in it - in either of the two
> And, if you want to go to the bother, try putting a current meter in
> series with each of the cells when the booster pack isn't in use and see
> what, if any, the leakage current is. Though, I can't think of any
> reason why there should be any designed in.
I'll try that, but I anticipate that the leakage will be low. I don't
think the leakage would be designed in, but a side effect of a very
mismatch between two cells.
> OTOH, if the booster pack plugs into the 3 volt DC input jack (You
> didn't tell us that specifically.) then maybe it *is* supposed to put
> out 3 volts and there's something wrong with it, like a bent battery
> terminal contact shorting one cell right out whenever it's plugged in.
The pack doesn't plug into the 3V input. It has a seperate set of
contacts. But given that this unit accepts 3V in, I can't figure why
they (Sony) didn't connect the cells in series. There isn't anything
or shorted causing this.
> Probably the reason the DC input is set to accept 3 volts is because 1.5
> volt wall wart transformer/rectifier DC supplies aren't that common,
> most likely because the forward drops of inexpensive rectifiers are so
> high and vary with temperature enough that it would be hard to keep the
> output properly close to 1.5 vdc.
Probably correct. When running off the wall wart, they probably use a
simple series type regulator and just live with the power dissipation.
Wall wart power is 'free' and plentiful.
> That's all the gas I can emit based on the info you supplied. I betcha
> the right person in Sony could tell you what you want to know....Once
> you locate him/her.
> Paul Hovnanian wrote:
> > I have a Sony Mini Disc player with an internal 1.5V NiMH battery
> > plus a detachable 'booster pack' that takes 2 AA alkaline
> > cells. Not paying much attention to it, I've been using the
> > pack from time to time (when the internal battery gets low)
> > but I've noticed that the alkalines don't seem to have much
> > life in the pack even when its not in use. Maybe a month or
> > so.
> > I got poking around with the pack and noticed that its output
> > is 1.5 volts with 2 fresh cells, not the 3 volts I expected to
> > see on its output. The AA cells are connected in parallel.
> > I'm guessing that the batteries probably aren't lasting
> > long because one is discharging via a leakage current through
> > the other.
> > Has anyone seen this sort of battery configuration before?
> > Why is it used? Is my guess about why the batteries don't
> > last long correct?
> > This setup is all the more strange because the player has an
> > input for a 3Vdc wall wart power supply. This means that the
> > player has power conditioning circuitry suitable to accept 3V.
Paul Hovnanian P.E. | (here) mailto:firstname.lastname@example.org
Software Conflagration | (there) mailto:Paul@Hovnanian.com
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A limerick packs laughs anatomical
Into space that is quite economical.
But the good ones I've seen
So seldom are clean,
And the clean ones so seldom are comical.
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