Rethinking Batteries and Power

Two weeks ago, I was promoting the use of deep cycle batteries, so that School Servers could run 24 hours a day.  As I’ve thought more about living with rolling load shedding, and expensive power, I realized that I needed to rethink my assumptions.  What really matters is that the school server, and the internet be available during the school day — say from 7am to 5pm.  So the battery needs to be big enough to last 10 hours per day.  Each area needs to decide whether more than one day of charge is advisable, given the probability of an outage lasting more than 24 hours.

I just learned of a feature that has been a part of linux since kernel 2.24, where the system can be waked at a given time from a suspended state by the bios. If we can use this feature, we’ll be able to use smaller backup battery and save initial investment in battery and ongoing power expense. I discussed it with Lloyd, and he has seen bios documentation which talks about wake from timer.  The literature I read said that computers manufactured since 2001, have had this feature.


About George Hunt

Retired electrical engineer and programmer, enthusiastic about OLPC as a vehicle for gathering together volunteerism, mine and so many others', for helping education in developing countries.
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