Re: [Thumbgps-devel] Article -- Macx-1: GPS receiver with standard USB connector and PPS support

[tz <thomas@mich.com>]

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For a given size (and circuit board footprint) a supercap will have much
less capacity and it has an exponential voltage decay curve, so it might
have plenty of charge but not at a voltage that will hold the data.  This
usually means hours, not days of backup.

A good rechargeable lithium will last several years, maybe longer as there
will be no charge/discharge, maintains voltage until it is nearly
exhausted, and can hold the data for days or weeks.

On Wed, May 9, 2012 at 12:55 PM, Dave Taht <dave.taht@gmail.com> wrote:

> On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond <esr@thyrsus.com> wrote:
> > Dave Taht <dave.taht@gmail.com>:
> >> What would be the change in cost and delay in manufacturing to switch to
> >> using a supercap, rather than battery?
> >
> > Why would a supercap be better?
>
> Effective lifetime of... forever. no need for replacement. insanely
> fast recharge. smaller (probably). What's not to like?
>
> I am not in a huge hurry to get into manufacturing, and I merely
> wanted to cost out what what it would do to the bom, any changes to
> the PCB, and get an estimate for the time it would take to do. I think
> it will bump the unit cost up slightly,
> but what price, forever?
>
> > --
> >                <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>
>
>
> --
> Dave Täht
> SKYPE: davetaht
> US Tel: 1-239-829-5608
> http://www.bufferbloat.net
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