[ARC5] Bias Battery

[Dennis Monticelli]

The Lithium Manganese Dioxide primary cells (CR prefix series) possess the
right characteristics for use as a bias battery.  They are fairly flat in
discharge (have to be to power memory) and have a very low self discharge.
Diodes could be used to drop the voltage without introducing extra drain as
Scott Robinson has suggested.

You can buy coin types that are much thicker than the ubiquitous 2032 and
thus have more capacity.  The first two digits are thickness and the last
two are diameter.  For even more capacity the CR123 is easy to find and
still relatively small.  Same chemistry.

One caution if you're thinking about soldering directly to a coin cell
without the benefit of solder tabs.  It's Lithium after all. Leave an iron
tip on them for too long and the little suckers can explode themselves
open.  Get one with a tab or just buy a socket; they're cheap.

https://biz.maxell.com/en/primary_batteries/cr_coin.html

Dennis AE6C

On Wed, Feb 5, 2020 at 8:25 AM Bry Carling <af4k at hotmail.com> wrote:

> Those ole biads batteries were really somethinjg else. Seems like they
> didn't corrode as fast in the old days.
>
> I have seen some ancient bias batteries that still had voltage decades
> later. Two in fact, that I inherited in a junque box.
> One of them read 3.1V and the other was about 1 volt. I thought about
> keeping the 3V one and said, NAH and tossed it. I had no idea people
> actually rebuilt them.
>
> Sincerely - Bry AF4K
>
> ------------------------------
> *From:* arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> on
> behalf of Hubert Miller <Kargo_cult at msn.com>
> *Sent:* Tuesday, February 4, 2020 20:17
> *To:* arc5 at mailman.qth.net <arc5 at mailman.qth.net>
> *Subject:* Re: [ARC5] Bias Battery
>
>
> I tore apart a bias batt from a GRC-9, hoping to recover the case, but it
> was too decayed.
> Yes, it is 4.5 volt, but I don't recall it having distinct cells inside.
>
>
>
> I bought from a China a 3 – watchcell battery holder and sent it to
> Richard Brunner on the
>
> East Coast to try out. He describes it as the "elegant solution to
> replacing the GRC-9 bias".
>
> I am planning to write up this and the dial light improvement options for
> VMARS in the U.K.
>
> and maybe SRS in Netherlands, but right now other priorities come to the
> fore. That's
>
> also why I outsourced the experimenting with these items. I bought the
> pieces I thought
>
> would work out, and shipped them off to Richard to try out. Thanks,
> Richard !
>
> -Hue
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