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'[EE]: Small batteries, again'
2000\12\04@221611 by Sean H. Breheny

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Hi all,

Just wanted to give an update on the "small batteries" thread. I got some
of the 12V lighter batteries (a little smaller than a AAA cell), as well as
some even smaller 9V and 6V batteries of similar design. I haven't done
that much testing yet, but one of the 12V ones started with an open circuit
voltage of 12.5V, and then when I placed a 510 ohm resistor across it, the
voltage dropped to 11.6V, and decreased at about 50mV per second for
several seconds (I didn't keep it hooked up very long). This drew about 22
mA. So, it looks like it will work reasonably well for my application (I
need about 20 to 30mA for 20 seconds). At this 22mA rate, the battery would
drop to 7.5V (minimum for a regular non-low-dropout 5V regulator) in 82
seconds.

I haven't tested the smaller ones yet, nor have I actually done a longer
discharge for the 12V ones. I will report back when I have a chance to do that.

The actual battery used was an L1028 made by Vinnic (can be had from
http://www.24hrsbatteries.com) It weighs only a few grams.

Thanks for the help,

Sean

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2000\12\05@025502 by Roman Black

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Sean H. Breheny wrote:
{Quote hidden}

Sean, we see a lot of these 12v batteries in RF remotes for home/car
alarms, you can get alkaline versions for a fraction more price with
significantly more storage. Don't have any mAh figures for you but
in remotes used every day the alkaline last twice as long. :o)
-Roman

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2000\12\05@032457 by Sean H. Breheny

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Hi Roman,

Thanks! Actually, the L1028 says on it that it IS alkaline.

Sean

At 06:53 PM 12/5/00 +1100, you wrote:
{Quote hidden}

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2000\12\05@115947 by Dan Larson

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On Tue, 5 Dec 2000 03:24:55 -0500, Sean H. Breheny wrote:

>Hi Roman,
>
>Thanks! Actually, the L1028 says on it that it IS alkaline.
>

Sean, perhaps the sample you had was well past its useful shelf life.
I don't imagine that anyone moves those batteries too quickly...

Dan

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2000\12\05@123046 by Sean H. Breheny

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Hey Dan! (Long time, no talk :-)

Well, I'm afraid I don't understand: Roman said that he didn't know mAh
figures, so how could he have known that my test showed that the batteries
were below spec? I took his comment to mean "make sure you have the
alkaline type, they are the best".

I was actually pretty pleased with the test results, because I have never
seen cells that small (mentally dividing the volume of the battery up into
8 1.5v cells) that can supply 20mA at all! Am I wrong to think this way?
Should I be expecting more from the cells?

Unfortunately, Vinnic seems to be one of those "generic" battery
manufacturers and I can't find a date of manufacture or a "best used by"
date anywhere. You may be right, then, about them being old. I don't know
of any other supplier of these batteries, thought. Does anyone else?

Thanks,

Sean


At 11:00 AM 12/5/00 -0600, you wrote:
{Quote hidden}

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2000\12\05@130340 by Dan Larson

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On Tue, 5 Dec 2000 12:32:09 -0500, Sean H. Breheny wrote:

>Hey Dan! (Long time, no talk :-)
>
>Well, I'm afraid I don't understand: Roman said that he didn't know mAh
>figures, so how could he have known that my test showed that the batteries
>were below spec? I took his comment to mean "make sure you have the
>alkaline type, they are the best".
>
>I was actually pretty pleased with the test results, because I have never
>seen cells that small (mentally dividing the volume of the battery up into
>8 1.5v cells) that can supply 20mA at all! Am I wrong to think this way?
>Should I be expecting more from the cells?
>
>Unfortunately, Vinnic seems to be one of those "generic" battery
>manufacturers and I can't find a date of manufacture or a "best used by"
>date anywhere. You may be right, then, about them being old. I don't know
>of any other supplier of these batteries, thought. Does anyone else?

Well, I was just acting on a hunch, but it sure seemed like they were dropping
too fast. I wonder how long they could go if you left your load on until the current
dropped out altogether. I bet they also have a lot of "bounce back".

Just MHO.


Dan
{Quote hidden}

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2000\12\06@025125 by Roman Black

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Sean H. Breheny wrote:
>
> Hey Dan! (Long time, no talk :-)
>
> Well, I'm afraid I don't understand: Roman said that he didn't know mAh
> figures, so how could he have known that my test showed that the batteries
> were below spec? I took his comment to mean "make sure you have the
> alkaline type, they are the best".

Sorry if I wasn't clear, I don't know the discharge rate, but
from experience selling these to customers I know that the "good"
brand alkalines from Eveready etc last about twice as long as the
cheap asian ones that come with the product. Any security alarm
retailer will have stocks of these batteries for the RF remotes.
I believe the official size is A23. (12v)
-Roman
PS. Prices can vary from ridiculous to quite reasonable.

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2000\12\06@181508 by Peter L. Peres

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>I was actually pretty pleased with the test results, because I have never
>seen cells that small (mentally dividing the volume of the battery up into
>8 1.5v cells) that can supply 20mA at all! Am I wrong to think this way?
>Should I be expecting more from the cells?

At least some of the L1028 12V batteries actually contain 8 AG10 button
cells stacked in an envelope. The power density/weight for the same
technology is higher for 9V (6F22) type cells because the cells are 'bare'
inside and it will also give much more current.

The short current of fresh good quality alkaline cells of AG10 size should
be around 80-100mA (for a few seconds). This corresponds to a Ri of about
15 ohms. A NiCd cell of the same size (like Varta AG50 f.ex.) will be 1 to
2 ohms, or less, giving Amperes. A Lithium Hydride cell will be even
better and might explode in the process of being dead shorted (so don't
do it).

For rechargeable power the best idea imho are battery packs for the latest
cellular phones and still electronic cameras. These are usually 3.6 or
7.2V Lithium Ion one or two cell batteries that pack up to 1200 mAh in
less weight and volume than a 6F22 battery. The idea is that (as a
hobbyist) you already own a device that uses these batteries and a
charger, and you make a cradle/holder to interface it to your project.

For throw-away use maybe try Zinc Air hearing aid batteries. These are
expensive but the performance is good imho. They can last surprisingly
long at 10-20mA. You need to provide a way to tear off the hermetic seals
on all the cells while they are mounted in the project, before use ;-)

hope this helps,

Peter

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2000\12\06@181512 by Peter L. Peres

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>suppliers

GP and Duracell make them for sure. Tons of others. These two have
websites but I did not try to find datasheets for them...

Peter

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