[ANSS-netops] solar power problems

[Philip Crotwell]

Hi

How did you come up with your 25 day figure? Can you put some numbers
on power input and output?

We use two 105 amp-hour batteries per station, where the load is about
1/2 an amp. That gives me about 17.5 days theoretically, but my
understanding is that you never want to discharge batteries anywhere
near their rating as they can be damaged by high discharges. So maybe
worry less about age and more about installed capacity, ie double the
battery and replace them half as often.

We also, because of the cell modems, can monitor the battery voltage
over time, we have a cron job to ping the cell modem once an hour and
ask it what the input voltage is. For example here is the last few
days at one station. You can definitely tell the difference between
sunny days and rain, and we get a heads up if the power is getting low
and can do something before the station goes down.
http://eeyore.seis.sc.edu/earthworm/status/HAW_last720.png

Here is another station that we are becoming worried about, looks like
I might get to go on a road trip soon!
http://eeyore.seis.sc.edu/earthworm/status/CASEE_last720.png

Philip

On Sun, Jan 4, 2015 at 9:07 AM, Mitchell M Withers (mwithers)
<mwithers at memphis.edu> wrote:
>
> Many of our stations run on battery and solar and that normally works well.  We have a routine battery replacement cycle to make sure they don't get old.  Theoretically, we should be able to run with zero solar for about 25 days.  But this has been an unusually dreary winter in the southeast and we haven't had much sun for the past two months or more.  I'm wondering what others do in areas with limited sunlight to power stations that don't have AC available?
>
> Mitch
>
> Center for Earthquake Research and Information (CERI)
> University of Memphis                Ph: 901-678-4940
> Memphis, TN 38152                   Fax: 901-678-4734
>
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