electricity table (Google Docs)

Edward Cherlin echerlin at gmail.com
Fri Jul 18 22:09:16 EDT 2008

2008/7/18  <mianeil2 at yahoo.com>:
> I've shared a document with you called "electricity table":
> http://spreadsheets.google.com/ccc?key=p6DRYWvC0_wbHL1-bzt-3Mw&inv=devel@lists.laptop.org&t=808765302247483981&guest
> It's not an attachment -- it's stored online at Google Docs. To open this
> document, just click the link above.
> Hi guys!
> I was also wondering if you could give me feedback on this table. The
> table shows how much kWh is needed a year to power a xo based on
> different scenarios. If you think I should add or change anything
> please let me know.
> Thanks a lot!
> Mia

I don't understand your calculations. Your table labels the power
column in kWh, which is the wrong unit. It should be W, so that you
get Wh when multiplying by hours. Thus, for example, if we have 6 W (
roughly the power used by a single XO) for 5 hours a day for 365 days
annually, it comes to 10950 Wh or 10.9 kWh.

You also don't give a formula for power generation time. The Potenco
site gives this information:

A minute of pulling the PCG generates enough energy for:

    * 20 minutes of talk time on a mobile phone
    * 1 hour of ultrabright LED flashlight use
    * 3 hours play time on an iPod Shuffle (about one pull per song)

If one minute of pulling gives one hour of use, this comes to 5
minutes a day in the case I considered above, and similarly for the
other possibilities given, from 2 minutes to 15 minutes daily. Your
table, unaccountably, gives well over an hour of pulling daily.

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Edward Cherlin
End Poverty at a Profit by teaching children business
"The best way to predict the future is to invent it."--Alan Kay

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