[ANSS-netops] ANSS-netops Digest, Vol 59, Issue 7
John R Evans
jrevans at usgs.gov
Wed Jan 7 22:20:25 UTC 2015
Hi All,
Agreed — excellent discussion.
We (Dave Croker and I) will know more soon, but I certainly agree that more panel and battery and better controllers are a preferable solution in nearly all locations.
There are a few sites where cost (versus a load of 28 batteries via helicopter) or always-dark conditions (bottom of redwood-lined V-canyon in the PNW) might still argue for a few fuel cell in spite of the initial cost. Fuel is just methanol.
Suspect thermoelectric has too much fire potential for many locations (used them in Idaho in the way-back-when and they scared the heck out of me so near dry pines).
Anyone have specific experience with reliability of the SFC cells? Bob?
They are mil-spec for the German military (likely though, but even costlier), so might be better for those rare candidate sites if we know nothing else; might be worth one test anyway. Their contact info changed, by the way:
SFC Energy AG
Christian Böhm
VP Defense and Security Business
Eugen-Saenger-Ring 7
85649 Brunnthal/München
Germany
+49 (89) 673.592.364
+49 (160) 90.52.74.72 <Cell
+49 (89) 673.592.169 <FAX
Christian.Boehm at sfc.com
www.sfc.com
www.efoy-pro.com/page/efoy-proenergybox
Björn Ledergerber (U.S. Rep.)
Bjoern.Ledergerber at sfc.com
Dave and I will let you know more when we know it, including at least rough costs and fuel-use rates and costs. We will assume up to 0.6 W at 12 V (500 mA) if no one objects.
Cheers,
John
John R. Evans
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On 2015-Jan-07, at 10:40 , anss-netops-request at geohazards.usgs.gov wrote:
> Send ANSS-netops mailing list submissions to
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> than "Re: Contents of ANSS-netops digest..."
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>
> Today's Topics:
>
> 1. Re: solar power problems (Philip Crotwell)
> 2. Re: ANSS-netops Digest, Vol 59, Issue 6 (Greg Steiner)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 7 Jan 2015 12:32:48 -0500
> From: Philip Crotwell <crotwell at seis.sc.edu>
> To: Patrick Bastien <bastienp at ldeo.columbia.edu>
> Cc: "anss-netops at geohazards.usgs.gov"
> <anss-netops at geohazards.usgs.gov>
> Subject: Re: [ANSS-netops] solar power problems
> Message-ID:
> <CAGFrVcWYkYVwpZeZeamvSc_+vL91zN0gW3qoqGZntLXf+kgrWQ at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> We use the same batteries. But get the PVX-1040HT if you can as they
> have a (H)andle. Very useful! :)
>
> Philip
>
> On Wed, Jan 7, 2015 at 12:18 PM, Patrick Bastien
> <bastienp at ldeo.columbia.edu> wrote:
>> 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.
>>
>> 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.
>>
>>
>> Patrick Bastien
>> LDEO-LCSN
>>
>>
>> On 1/7/2015 11:06 AM, Meremonte, Mark wrote:
>>
>> Bob, May I ask the AH size of AGM batteries for an average TA station?
>> Thank you, Mark
>>
>> On Wed, Jan 7, 2015 at 8:29 AM, Robert Busby <busby at iris.edu> wrote:
>>>
>>> Hi Mitch et al.
>>> This is a good discussion of Power for seismic stations, thanks.
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> More complexity described below:
>>> 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.
>>>
>>> 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.
>>>
>>> Bob Busby
>>> TA Manager
>>>
>>> On 1/6/2015 7:36 AM, Kyle Persefield wrote:
>>>>
>>>> Mitch,
>>>>
>>>> My 2 cents worth
>>>>
>>>> Because of cost, we have found throwing on more solar panels to be the
>>>> cheapest and least maintenance intensive solution. Fuel cells and
>>>> thermoelectric generators are expensive and then there is the recurring
>>>> cost for fuel, getting fuel to the site, then monitoring of the fuel
>>>> supply level to consider, and the added required maintenance. We have
>>>> not
>>>> found a solution to use these devices as demand requires their use. Or
>>>> turning them on and off as needed. So long as there is fuel they are on.
>>>>
>>>> We have been very disappointed with wind turbines. The smaller ones,
>>>> which are designed for the consumer market, the bearings always fail.
>>>> Expect no more than 2 or3 years out of these "cheap" units. Then of
>>>> course there is the need for wind. No wind for extended periods is just
>>>> as bad as your overcast scenario.
>>>>
>>>> Kyle
>>>>
>>>> -----Original Message-----
>>>> From: ANSS-netops [mailto:anss-netops-bounces at geohazards.usgs.gov] On
>>>> Behalf Of Mitchell M Withers (mwithers)
>>>> Sent: Monday, January 05, 2015 7:12 AM
>>>> To: Philip Crotwell
>>>> Cc: anss-netops at geohazards.usgs.gov
>>>> Subject: Re: [ANSS-netops] solar power problems
>>>>
>>>>
>>>> Here is a snippet from a recent report from a visit to an example station
>>>> with a reftek, three S-13's, and an episensor. Stations vary of course
>>>> and we do use low voltage cutouts at every station (fancy ones that cut
>>>> out the transmitter first, then the DAS and everything else if the
>>>> voltage
>>>> continues to get lower).
>>>>
>>>> "The new battery banks, when installed were at 12.95 and 12.98. The total
>>>> station draw is exactly 600ma (checked continuously for about three
>>>> minutes). I did a quick calculation of 4 batteries at 96AH each, 384/.6 =
>>>> 640/24 =26.6 days. This calculation would assume no solar charge, but
>>>> does
>>>> not take into account reduced battery capacity due to cold temperatures."
>>>>
>>>> The panels at that particular station were supplying about 700ma together
>>>> on an overcast day and are being replaced with bigger panels this week.
>>>> Of course one solution is more battery and more solar at every station
>>>> along with more frequent refreshing of batteries. But that gets
>>>> expensive
>>>> and time consuming so I was fishing to see if anyone is doing something
>>>> creative. (e.g. wind or hamster wheels).
>>>>
>>>> Mitch
>>>>
>>>> Center for Earthquake Research and Information (CERI)
>>>> University of Memphis Ph: 901-678-4940
>>>> Memphis, TN 38152 Fax: 901-678-4734
>>>>
>>>>
>>>> ________________________________________
>>>> From: Philip Crotwell <crotwell at seis.sc.edu>
>>>> Sent: Monday, January 5, 2015 7:50 AM
>>>> To: Mitchell M Withers (mwithers)
>>>> Cc: anss-netops at geohazards.usgs.gov
>>>> Subject: Re: [ANSS-netops] solar power problems
>>>>
>>>> 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
>>>>>
>>>>> _______________________________________________
>>>>> ANSS-netops mailing list
>>>>> ANSS-netops at geohazards.usgs.gov
>>>>> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>>>>
>>>> _______________________________________________
>>>> ANSS-netops mailing list
>>>> ANSS-netops at geohazards.usgs.gov
>>>> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>>>> _______________________________________________
>>>> ANSS-netops mailing list
>>>> ANSS-netops at geohazards.usgs.gov
>>>> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>>>>
>>>
>>> --
>>>
>>> ============================================================
>>>
>>> Robert W. Busby
>>> Transportable Array Manager 508-801-7628
>>> USArray / EarthScope 37 Haynes Avenue
>>> www.earthscope.org/usarray Falmouth MA USA 02540-2312
>>>
>>> _______________________________________________
>>> ANSS-netops mailing list
>>> ANSS-netops at geohazards.usgs.gov
>>> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>>
>>
>>
>>
>> --
>> *********************************************************
>> Mark Meremonte Geophysicist
>> U.S. Bureau of Reclamation: Seismotectonics & Geophysics Group
>> Denver Federal Center Work: 303-445-3298 Cell: 303-808-3894
>> POBox 25007, 85-833000 Email: mmeremonte at usbr.gov
>> Denver, CO 80225 Web: http://www.usbr.gov
>> Ship: U.S. Bureau of Reclamation, DFC, Bldg. 67-10th Floor, Denver, CO
>> 80225
>> **********************************************************
>>
>>
>> _______________________________________________
>> ANSS-netops mailing list
>> ANSS-netops at geohazards.usgs.gov
>> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>>
>>
>>
>> _______________________________________________
>> ANSS-netops mailing list
>> ANSS-netops at geohazards.usgs.gov
>> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>>
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 7 Jan 2015 12:40:18 -0600
> From: Greg Steiner <vlf at cablerocket.com>
> To: <anss-netops at geohazards.usgs.gov>
> Subject: Re: [ANSS-netops] ANSS-netops Digest, Vol 59, Issue 6
> Message-ID: <54AD7D92.6020804 at cablerocket.com>
> Content-Type: text/plain; charset="windows-1252"; format=flowed
>
> Patrick, I'm curious as to how you get multiple MPPT controllers to
> charge a single battery bank. Are they inherently designed for this form
> of parallel operation?
> Greg Steiner
>
> On 1/7/2015 11:16 AM, anss-netops-request at geohazards.usgs.gov wrote:
>> Send ANSS-netops mailing list submissions to
>> anss-netops at geohazards.usgs.gov
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> https://geohazards.usgs.gov/mailman/listinfo/anss-netops
>> or, via email, send a message with subject or body 'help' to
>> anss-netops-request at geohazards.usgs.gov
>>
>> You can reach the person managing the list at
>> anss-netops-owner at geohazards.usgs.gov
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of ANSS-netops digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: solar power problems (Patrick Bastien)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Wed, 7 Jan 2015 12:18:20 -0500
>> From: Patrick Bastien <bastienp at ldeo.columbia.edu>
>> To: <anss-netops at geohazards.usgs.gov>
>> Subject: Re: [ANSS-netops] solar power problems
>> Message-ID: <54AD6A5C.6080608 at ldeo.columbia.edu>
>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>>
>> 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.
>>
>> 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.
>>
>>
>> Patrick Bastien
>> LDEO-LCSN
>>
>> On 1/7/2015 11:06 AM, Meremonte, Mark wrote:
>>> Bob, May I ask the AH size of AGM batteries for an average TA
>>> station? Thank you, Mark
>>>
>>> On Wed, Jan 7, 2015 at 8:29 AM, Robert Busby <busby at iris.edu
>>> <mailto:busby at iris.edu>> wrote:
>>>
>>> Hi Mitch et al.
>>> This is a good discussion of Power for seismic stations, thanks.
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> More complexity described below:
>>> 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.
>>>
>>> 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.
>>>
>>> Bob Busby
>>> TA Manager
>>>
>>> On 1/6/2015 7:36 AM, Kyle Persefield wrote:
>>>
>>> Mitch,
>>>
>>> My 2 cents worth
>>>
>>> Because of cost, we have found throwing on more solar panels
>>> to be the
>>> cheapest and least maintenance intensive solution. Fuel cells and
>>> thermoelectric generators are expensive and then there is the
>>> recurring
>>> cost for fuel, getting fuel to the site, then monitoring of
>>> the fuel
>>> supply level to consider, and the added required maintenance.
>>> We have not
>>> found a solution to use these devices as demand requires their
>>> use. Or
>>> turning them on and off as needed. So long as there is fuel
>>> they are on.
>>>
>>> We have been very disappointed with wind turbines. The
>>> smaller ones,
>>> which are designed for the consumer market, the bearings
>>> always fail.
>>> Expect no more than 2 or3 years out of these "cheap" units.
>>> Then of
>>> course there is the need for wind. No wind for extended
>>> periods is just
>>> as bad as your overcast scenario.
>>>
>>> Kyle
>>>
>>> -----Original Message-----
>>> From: ANSS-netops
>>> [mailto:anss-netops-bounces at geohazards.usgs.gov
>>> <mailto:anss-netops-bounces at geohazards.usgs.gov>] On
>>> Behalf Of Mitchell M Withers (mwithers)
>>> Sent: Monday, January 05, 2015 7:12 AM
>>> To: Philip Crotwell
>>> Cc: anss-netops at geohazards.usgs.gov
>>> <mailto:anss-netops at geohazards.usgs.gov>
>>> Subject: Re: [ANSS-netops] solar power problems
>>>
>>>
>>> Here is a snippet from a recent report from a visit to an
>>> example station
>>> with a reftek, three S-13's, and an episensor. Stations vary
>>> of course
>>> and we do use low voltage cutouts at every station (fancy ones
>>> that cut
>>> out the transmitter first, then the DAS and everything else if
>>> the voltage
>>> continues to get lower).
>>>
>>> "The new battery banks, when installed were at 12.95 and
>>> 12.98. The total
>>> station draw is exactly 600ma (checked continuously for about
>>> three
>>> minutes). I did a quick calculation of 4 batteries at 96AH
>>> each, 384/.6 =
>>> 640/24 =26.6 days. This calculation would assume no solar
>>> charge, but does
>>> not take into account reduced battery capacity due to cold
>>> temperatures."
>>>
>>> The panels at that particular station were supplying about
>>> 700ma together
>>> on an overcast day and are being replaced with bigger panels
>>> this week.
>>> Of course one solution is more battery and more solar at every
>>> station
>>> along with more frequent refreshing of batteries. But that
>>> gets expensive
>>> and time consuming so I was fishing to see if anyone is doing
>>> something
>>> creative. (e.g. wind or hamster wheels).
>>>
>>> Mitch
>>>
>>> Center for Earthquake Research and Information (CERI)
>>> University of Memphis Ph: 901-678-4940
>>> Memphis, TN 38152 Fax: 901-678-4734
>>>
>>>
>>> ________________________________________
>>> From: Philip Crotwell <crotwell at seis.sc.edu
>>> <mailto:crotwell at seis.sc.edu>>
>>> Sent: Monday, January 5, 2015 7:50 AM
>>> To: Mitchell M Withers (mwithers)
>>> Cc: anss-netops at geohazards.usgs.gov
>>> <mailto:anss-netops at geohazards.usgs.gov>
>>> Subject: Re: [ANSS-netops] solar power problems
>>>
>>> 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 <mailto: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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>>>
>>>
>>> --
>>>
>>> ============================================================
>>>
>>> Robert W. Busby
>>> Transportable Array Manager 508-801-7628
>>> USArray / EarthScope 37 Haynes Avenue
>>> www.earthscope.org/usarray <http://www.earthscope.org/usarray>
>>> Falmouth MA USA 02540-2312
>>>
>>> _______________________________________________
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>>>
>>>
>>>
>>>
>>> --
>>> *********************************************************
>>> Mark Meremonte Geophysicist
>>> U.S. Bureau of Reclamation: Seismotectonics & Geophysics Group
>>> Denver Federal Center Work: 303-445-3298 Cell: 303-808-3894
>>> POBox 25007, 85-833000Email: mmeremonte at usbr.gov
>>> <mailto:mmeremonte at usbr.gov>
>>> Denver, CO 80225 Web: http://www.usbr.gov
>>> Ship: U.S. Bureau of Reclamation, DFC, Bldg. 67-10th Floor, Denver, CO
>>> 80225
>>> **********************************************************
>>>
>>>
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