RPC battery replacement

Stuart

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May 14, 2013, 10:30:47 AM5/14/13

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Has anyone tried using one of the large memory back-up capacitors instead
of a battery. I see these can now be purchased as large as 22F at 2.3V or
1.5F at 5.5V

--
Stuart Winsor

Midlands RISC OS and Raspberry pi show, 13th July 2013

http://www.mug.riscos.org/show13/MUGshow.html

Dave Plowman (News)

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May 14, 2013, 10:51:38 AM5/14/13

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In article <534bbe8d...@argonet.co.uk>,

Stuart <Spa...@argonet.co.uk> wrote:
> Has anyone tried using one of the large memory back-up capacitors instead
> of a battery. I see these can now be purchased as large as 22F at 2.3V or
> 1.5F at 5.5V

Is the charging circuit compatible?

I'm not sure I'd want to change anyway - both of my RPCs are only on their
second battery in getting on for 20 years. ;-)

--
*Rehab is for quitters

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

Theo Markettos

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May 14, 2013, 11:28:36 AM5/14/13

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Stuart <Spa...@argonet.co.uk> wrote:
> Has anyone tried using one of the large memory back-up capacitors instead
> of a battery. I see these can now be purchased as large as 22F at 2.3V or
> 1.5F at 5.5V

I once tried a 1000uF capacitor on an A7000 board. It lasted about five
seconds... :)

The self-discharge is going to be what'll limit the retention time, and I
have no idea how good the supercaps are. They should be no problem for the
charging circuit (as long as the inrush current is limited, which I think it
is).

Theo

Stuart

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May 14, 2013, 12:19:23 PM5/14/13

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In article <m5f*jy...@news.chiark.greenend.org.uk>,

Theo Markettos <theom...@chiark.greenend.org.uk> wrote:
> The self-discharge is going to be what'll limit the retention time,

Unfortunately this is not specified in the data sheet.

My Kinetic spends most of its time powered. It's in use every day and left
on overnight for it to carry out its back-ups (unless I'm away on holiday
or something)