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Old 09-21-2009, 12:47 AM   #4 (permalink)
NiHaoMike
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If the pack voltage is between about 140 and 370, the existing laptop power supply will work as the DC/DC converter. And if it's a recent one, it will also be surprisingly efficient.

Just make sure to set cpufreq or whatever to use power saving even on external power. Power management is often limited on external power in order to increase performance. In particular, it takes a short time for the PMS* (Power Management System) to sense the increased load and a little more time for the PLL to adjust.

*PMS has been referred to as "power management stress" due to the annoyance of the clock adjustment lag. My solution is to use a KDE applet (PowerDevil or something like that) to manually change the power management setting. It defaults to aggressive power saving on battery, normal power saving on external power, and I can manually force full CPU speed when I need it.
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