[time-nuts] Power Back-up

Poul-Henning Kamp phk at phk.freebsd.dk
Sun Aug 9 14:30:24 UTC 2009


In message <C6A429C0.99E5%James.P.Lux at jpl.nasa.gov>, "Lux, Jim (337C)" writes:

>Not only that, but because they're designed to run for only about 20
>minutes, their thermal design depends on mass as much as actual conduction
or convection.  At low load, they're not very efficient, either.  It's
>cheaper to just put a bigger battery in than to use more parts in the
>inverter (lead is cheap, apparently) and still meet the spec.

Seconded.

That is why I run my critical stuff (servers + timekeeping) of batteries.

When I designed the setup, I calculated that I got 15 *times* the
hold-over for the same money.

And yes, put a MorningStart Sunsaver MPPT and a couple of panels on
your battery, and you get close to "permanent" hold-over, unless
you live in Denmark.

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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