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Subject: Pause vs power cycle break-even point - 83.5 econds
From: Brent Geery (fasttimes_at_mochamail.com)
Date: 2003-08-22


(The following should be even less for the new RomBox.)

http://rockbox.haxx.se/docs/battery-faq.html:

12. I often need to stop my player for about 15 minutes or so, and
when I do it runs off it's batteries. I was wondering, which is best:
shutting the player down completely and rebooting it when I want to
listen again, or leaving the unit on? Which way does it draw more
power?

In our testing we found the following results:

         HDD off, backlight off, idle 94 mA
         HDD off, backlight off, play 97 mA
         HDD off, backlight on, idle 129 mA
         HDD off, backlight on, play 131 mA
         HDD on, backlight on, play 230 mA
         HD on, reading, backlight off ~ 600 mA
         HD spin up before read max 800 mA
 
Using the power draw measurements shown above, lets look at the
numbers: Power-down and restart vs. paused for 15 minutes.:

Pause for 15 minutes will draw: 94 mA / 60 minutes * 15 minutes = 23.5
mAh.

Power-down and restart will draw about (800mA / 3600 seconds * 3
seconds = 0.6666 mAh) + (600 mA / 3600 seconds * 6 seconds = 1.0 mAh)
+ (230 mA / 3600 seconds * 8 seconds = 0.5111 mAh) = 2.18 mAh total
used.

Thus, leaving it paused for 15 minutes draws more power (23.5 mAh)
than turning off and then on again (2.18 mAh).

So where is the break-even point?

Each second of pause will draw about 94 mAh / 3600 seconds = 26 ľAh.

2.18 mAh / 26 ľAh = 2180 ľAh / 26 ľAh = 83.5 seconds

Thus a shutdown and restart uses as much power as 83.5 seconds of
pause.

-- 
BRENT - The Usenet typo king. :)

Fast Times At Ridgemont High Info http://www.FastTimesAtRidgemontHigh.org Voted #87 - American Film Institute's Top 100 Funniest American Films



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