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Subject: RE: Good news and bad news - Q about power saver
From: c s (rb_dev_at_yahoo.com)
Date: 2003-12-18


--- TP Diffenbach <rockbox_at_diffenbach.org> wrote:
> c s wrote:
> > Also do you have a theory on why the recorder
> > graph
> > seems indicate that the batteries are drained
> > faster
> > during the first half of the run despite the fact
> > that
> > the power saving mode was always on? That doesn't
> > seem
> > right. Why would the batteries be depleted at a
> > faster
> > rate at any point on the curve for the "power
> > saving"
> > mode?
>
> If you mean the "S" curve, then yes. The battery
> seems too fall off faster
> the greater the charge. On the FMR, for instance,
> the battery falls from
> 4.25 to 4.2 volts about as quickly as it falls from
> 4.2 volts to 4.1 volts.
> As the battery charge decreases, the rate of
> decrease also decreases, and it
> plateaus. Then as the voltage level decreases still
> further, the speed of
> decrease again speeds up.

I wasn't referring to the S shape of the curve. I
understand why it would be that shape. I was wondering
why the for the first 5 hours of test data, the
recorder in power saver mode ("Test A") was
discharging the batteries at a faster rate than the
baseline.

If the Recorder ceased operation when the voltage
dropped below 5.2 volts, your graph would indicate
that the power saver mode causes the batteries to
drain about 25% faster giving you about 90 minutes of
operation vs. more than 120 minutes for a recorder
without the power saver.

I found it odd that the graph showed the power saver
mode initially draining the batteries faster than the
baseline and then later draining them at a slower rate
than the baseline.

It would be interesting to put am ammeter in series
with the battery supply and see if the power saver
mode is actually drawing more current than the
baseline during the first few hours as the graph
implies. I would do it but I don't have one that could
accurately detect the small difference in current draw.

=====
Craig

rb_dev_at_yahoo.com

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