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The Concorde Sun Extender PVX-1040T has a nominal capacity of 104AH,
so 312AH for the northern TA stations and 208AH for the southern TA
stations.<br>
<br>
Beginning late last summer, the LCSN has begun to switch from older
PWM-style charge controllers to MPPT charge controllers. Although it
is too soon to say something definite, this is seeming to have a
larger effect on station up-time than just adding more panels or
batteries. Something I am doing that might be considered
non-standard is wiring each solar panel individually to its own
small MPPT change controller. This allows each solar panel to
generate the maximum amount of power regardless of the lighting
condition of the other solar panels. The several MPPT charge
controllers then feed a common battery bank. I then regulate the
voltage powering the sensor by using a small low-noise DCDC
converter imbedded inside a cable. The MPPT benefits might be
magnified for the LCSN because of the location of many of our solar
powered stations are in forests or forest-adjacent. <br>
<br>
<br>
Patrick Bastien<br>
LDEO-LCSN<br>
<br>
<div class="moz-cite-prefix">On 1/7/2015 11:06 AM, Meremonte, Mark
wrote:<br>
</div>
<blockquote
cite="mid:CAHnsS_C1y7dAHcPuJffQ=zDTZK8Mn=y7u+7hEXonyieD5e29kA@mail.gmail.com"
type="cite">
<div dir="ltr">Bob, May I ask the AH size of AGM batteries for
an average TA station? Thank you, Mark</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Jan 7, 2015 at 8:29 AM, Robert
Busby <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:busby@iris.edu" target="_blank">busby@iris.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Mitch
et al.<br>
This is a good discussion of Power for seismic stations,
thanks.<br>
<br>
In the Transportable Array deployment, all 1717 stations
operate(d) off solar power for at east two years. The
average current draw for a station is 0.5Amps on a 12V
system, but can vary from 0.4 to 0.6A depending on the
telemetry system. High current telemetry systems such as
VSAT are powered separately. We avoided AC power because of
the proximity of noise due to pumps, motors, etc.<br>
<br>
In general we use (2) 90W PV panels and (2) AGM Lead Acid
batteries for stations south of the Kentucky/Tennessee line
(row U in TA station codes) and (3) 90W PV panels and (3)
AGM Lead Acid batteris north of there. Shady or snowy sites
occasionally got more panels and batteries. For permanent
stations I'd go with the (3) PV and 3 or 4 batteries. We
prefer good quality batteries designed for solar
applications, such as the Concorde Sun Extender PVX-1040T.
We use PWM regulators with Low voltage disconnect at 10.8V.
A few more sophisticated options are discussed below.<br>
<br>
I would concur with the notion that the most effective way
to improve a marginal station power situation is to add 1 or
2 batteries, and often this can be done without much
infrastructure alteration. And the next option is to add a
panel. There is little concern about over driving the
charge controller with too much current from too many
panels. In Alaska, the "more batteries" approach is taken
to extremes in which stations have 24 batteries to float
through the winter. I would also concur that, to date,
neither wind nor fuel cells have proved reliable enough to
warrant their use, especially in permanent stations of the
Lower48.<br>
<br>
More complexity described below:<br>
Our system has, in addition to the main battery bank, a
small reserve battery. When the system switches to the
reserve, certain loads such as the telemetry radio and local
data storage are duty cycled at four hour intervals. This
reduces the power of the station to about 3W, yet still
provides complete telemetry (though with episodic latency)
and complete local storage. For us, this reserve power
serves to identify the source of the outage is clearly power
as opposed to a host of other possibilities. In the
original design this reserve battery was Alkaline Lattern
30AH batteries [(3) x 6Volts] (a primary battery, disposed
of after use). More recently, We have also used 100-300AH
rechargeable batteries that are then connected to the main
batteries using a battery isolator circuit-which connects
the reserve batteries to the charger only when the main
battery has recharged to 13.2V. We add a 10A current limit
to the battery interconnection. The reserve power load
shedding can be thought of as doubling the capacity of the
reserve batteries, reducing the cost of overall power system
for this reserve capability. Without that sophisitication
of load shedding, adding more batteries is effective but
there is a cost in terms of station uptime. When a very
large, undifferentiated battery bank is depleted, it will
take a longer time for the batteries to reach the reconnect
voltage. In this time, the station itself could be
operating on the minimal power produced. We keep the main
battery bank fairly modest so it recovers voltage quickly,
and defer recharging the reserve pack until there is ample
power-sometimes weeks, or in Alaska, months later. Its
meant to get you through an ocasional bad spell. One issue
in this reserve battery switching is the dc currents can
introduce magnetic pulses seen on the
seismometer-particularly Trilliums within a few meters of
the switches.<br>
<br>
If you are plannning a Net-ops meeting in the future, I'd be
happly to elaborate on the power system for Alaska, which
uses a Genasun MPPT charge controller and LiFePO4 (Lithium
Ion) batteries and the same duty cycle loads, reserve
battery concepts. These significantly reduce the weight of
a 1440AH system to 420 lbs and do not require derating the
capacity for cold temperatures. They are very expensive,
but not as much as a helicopter trip.<br>
<br>
Bob Busby<br>
TA Manager<br>
<br>
On 1/6/2015 7:36 AM, Kyle Persefield wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
Mitch,<br>
<br>
My 2 cents worth<br>
<br>
Because of cost, we have found throwing on more solar
panels to be the<br>
cheapest and least maintenance intensive solution. Fuel
cells and<br>
thermoelectric generators are expensive and then there is
the recurring<br>
cost for fuel, getting fuel to the site, then monitoring
of the fuel<br>
supply level to consider, and the added required
maintenance. We have not<br>
found a solution to use these devices as demand requires
their use. Or<br>
turning them on and off as needed. So long as there is
fuel they are on.<br>
<br>
We have been very disappointed with wind turbines. The
smaller ones,<br>
which are designed for the consumer market, the bearings
always fail.<br>
Expect no more than 2 or3 years out of these "cheap"
units. Then of<br>
course there is the need for wind. No wind for extended
periods is just<br>
as bad as your overcast scenario.<br>
<br>
Kyle<br>
<br>
-----Original Message-----<br>
From: ANSS-netops [mailto:<a moz-do-not-send="true"
href="mailto:anss-netops-bounces@geohazards.usgs.gov"
target="_blank">anss-netops-bounces@geohazards.usgs.gov</a>]
On<br>
Behalf Of Mitchell M Withers (mwithers)<br>
Sent: Monday, January 05, 2015 7:12 AM<br>
To: Philip Crotwell<br>
Cc: <a moz-do-not-send="true"
href="mailto:anss-netops@geohazards.usgs.gov"
target="_blank">anss-netops@geohazards.usgs.gov</a><br>
Subject: Re: [ANSS-netops] solar power problems<br>
<br>
<br>
Here is a snippet from a recent report from a visit to an
example station<br>
with a reftek, three S-13's, and an episensor. Stations
vary of course<br>
and we do use low voltage cutouts at every station (fancy
ones that cut<br>
out the transmitter first, then the DAS and everything
else if the voltage<br>
continues to get lower).<br>
<br>
"The new battery banks, when installed were at 12.95 and
12.98. The total<br>
station draw is exactly 600ma (checked continuously for
about three<br>
minutes). I did a quick calculation of 4 batteries at 96AH
each, 384/.6 =<br>
640/24 =26.6 days. This calculation would assume no solar
charge, but does<br>
not take into account reduced battery capacity due to cold
temperatures."<br>
<br>
The panels at that particular station were supplying about
700ma together<br>
on an overcast day and are being replaced with bigger
panels this week.<br>
Of course one solution is more battery and more solar at
every station<br>
along with more frequent refreshing of batteries. But
that gets expensive<br>
and time consuming so I was fishing to see if anyone is
doing something<br>
creative. (e.g. wind or hamster wheels).<br>
<br>
Mitch<br>
<br>
Center for Earthquake Research and Information (CERI)<br>
University of Memphis Ph: 901-678-4940<br>
Memphis, TN 38152 Fax: 901-678-4734<br>
<br>
<br>
________________________________________<br>
From: Philip Crotwell <<a moz-do-not-send="true"
href="mailto:crotwell@seis.sc.edu" target="_blank">crotwell@seis.sc.edu</a>><br>
Sent: Monday, January 5, 2015 7:50 AM<br>
To: Mitchell M Withers (mwithers)<br>
Cc: <a moz-do-not-send="true"
href="mailto:anss-netops@geohazards.usgs.gov"
target="_blank">anss-netops@geohazards.usgs.gov</a><br>
Subject: Re: [ANSS-netops] solar power problems<br>
<br>
Hi<br>
<br>
How did you come up with your 25 day figure? Can you put
some numbers on<br>
power input and output?<br>
<br>
We use two 105 amp-hour batteries per station, where the
load is about<br>
1/2 an amp. That gives me about 17.5 days theoretically,
but my<br>
understanding is that you never want to discharge
batteries anywhere near<br>
their rating as they can be damaged by high discharges. So
maybe worry<br>
less about age and more about installed capacity, ie
double the battery<br>
and replace them half as often.<br>
<br>
We also, because of the cell modems, can monitor the
battery voltage over<br>
time, we have a cron job to ping the cell modem once an
hour and ask it<br>
what the input voltage is. For example here is the last
few days at one<br>
station. You can definitely tell the difference between
sunny days and<br>
rain, and we get a heads up if the power is getting low
and can do<br>
something before the station goes down.<br>
<a moz-do-not-send="true"
href="http://eeyore.seis.sc.edu/earthworm/status/HAW_last720.png"
target="_blank">http://eeyore.seis.sc.edu/earthworm/status/HAW_last720.png</a><br>
<br>
Here is another station that we are becoming worried
about, looks like I<br>
might get to go on a road trip soon!<br>
<a moz-do-not-send="true"
href="http://eeyore.seis.sc.edu/earthworm/status/CASEE_last720.png"
target="_blank">http://eeyore.seis.sc.edu/earthworm/status/CASEE_last720.png</a><br>
<br>
Philip<br>
<br>
On Sun, Jan 4, 2015 at 9:07 AM, Mitchell M Withers
(mwithers)<br>
<<a moz-do-not-send="true"
href="mailto:mwithers@memphis.edu" target="_blank">mwithers@memphis.edu</a>>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
Many of our stations run on battery and solar and that
normally works<br>
</blockquote>
well. We have a routine battery replacement cycle to make
sure they don't<br>
get old. Theoretically, we should be able to run with
zero solar for<br>
about 25 days. But this has been an unusually dreary
winter in the<br>
southeast and we haven't had much sun for the past two
months or more.<br>
I'm wondering what others do in areas with limited
sunlight to power<br>
stations that don't have AC available?<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
Mitch<br>
<br>
Center for Earthquake Research and Information (CERI)<br>
University of Memphis Ph: 901-678-4940<br>
Memphis, TN 38152 Fax: 901-678-4734<br>
<br>
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<br>
-- <br>
<br>
============================================================<br>
<br>
Robert W. Busby<br>
Transportable Array Manager 508-801-7628<br>
USArray / EarthScope 37 Haynes Avenue<br>
<a moz-do-not-send="true"
href="http://www.earthscope.org/usarray" target="_blank">www.earthscope.org/usarray</a>
Falmouth MA USA 02540-2312<br>
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<div dir="ltr"><span
style="color:rgb(136,136,136);font-family:'Times New
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Roman',Times">***************************</span><br
style="color:rgb(136,136,136);font-family:'Times New
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<span style="font-family:'Times New Roman',Times"><font
color="#0000ff">Mark Meremonte</font><font
color="#666666"> Geophysicist </font></span><br
style="font-family:'Times New Roman',Times">
<span style="color:rgb(102,102,102);font-family:'Times New
Roman',Times">U.S. Bureau of Reclamation: Seismotectonics
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<div><span style="font-family:'Times New Roman',Times"><font
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<span style="font-family:'Times New Roman',Times">Denver,
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Bureau of Reclamation, DFC, Bldg. 67-10th Floor,
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