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RE: [solectria_ev] Cold and Thundersky cells

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  • Gerry Gaydos
    Hi Chip,Thanks for sharing this with us. This is the kind of information that helps us all have a better understanding of real world performance of Thundersky
    Message 1 of 8 , Feb 14, 2013
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      Hi Chip,Thanks for sharing this with us. This is the kind of information that helps us all have a better understanding of real world performance of Thundersky prismatic LiFePo modules, and have a more satisfying experience with EVs.

      Reading your description of how you're measuring the temperature of the pack, I wondered why your temperature sensor wasn't located where the module(s) would be warmest, between modules and on the broad sides of the modules, not on the tops?

      This issue, collecting battery temperature data, is one on which I received some valuable input from Warren Winovich, a retired Nasa physicist (aerodynamics and thermodynamics specialist) in the Silicon Valley Chapter of the EAA. It might be worth investigating this point, for the sake of gathering the most accurate data possible.
      Thanks for the work you're doing.
      Gerry Gaydos

      "Internal combustion is so last century"... Funkymoto�, Electrifying Cars! 250 598 3100

      To: solectria_ev@yahoogroups.com
      From: cchandler66@...
      Date: Thu, 14 Feb 2013 15:18:26 +0000
      Subject: [solectria_ev] Cold and Thundersky cells


























      Cold and Thundersky



      This data is from August-December 2012 in 1997 Force with Elcon PFC 4000 charger, 49 160Ah Thundersky cells, miniBMS, 4210 test miles, 115 separate trips/charges on average 36 miles/trip in central Maine. This data is from one probe between the top of two cells in the middle of the rear pack under 1 inch of foam touching the cell top edges under a 2" air space and the plastic battery cover. The Force was driven mostly at the Normal setting (120 -130 amps, depending on pack temperature). Charging at both 110 and 220 volts, didn't seem to be any difference in cell temperature rise. There were three trips of about 70 miles.



      Data below is: average ambient temperature at trip start, average pack temp at start, Ah/mile, average temp rise during trips, average temp rise during chargings, total temp increase for trips plus chargings. All in degrees F.



      Aug: 75 degrees, 78 degrees, 1.2 Ah/mile, trips-6 degrees, charges-7 degrees, total-13 degrees.

      Sept: 62 degrees, 71 degrees, 1.25 Ah/mile, trips-10 degrees, charges-5 degrees, total-15 degrees.

      Oct: 56 degrees, 65 degrees, 1.28 Ah/mile, trips-8 degrees, charges-7 degrees, total-15 degrees.

      Nov: 40 degrees, 53 degrees, 1.4 Ah/mile, trips-9 degrees, charges-4 degrees, total-13 degrees.

      Dec: 34 degrees, 38 degrees, 1.5 Ah/mile, trips-13 degrees, charges-7 degrees, total-20 degrees.



      Extremes:

      July 28: 33.2 miles, 1.21 Ah/mile, starting ambient temperature-72 degrees, pack start temperature-88, pack end temperature-93, charge end temperature-102.

      Jan 2, 2013: 31.6 miles, 1.72 Ah/mile, starting ambient temp-16, pack start temp-10, pack end temp-35, charge end temp-45.



      Performance: I noticed only a slight decrease in power in November when the pack start temperature was below 50 degrees. The January 2nd trip was dramatically sluggish at first. The car wouldn't accelerate above 35 mph on the level, however after 8 miles of driving, the performance improved to the November level. Others with smaller capacity packs have reported poorer performance in cool temperatures, so perhaps a larger capacity pack performs better in the cold.



      As the pack got colder, the start voltage at full throttle sagged from a normal of 165v (80 degrees) to 134v at the coldest. My only voltage readout is on a CleanPowerAuto EV display and it doesn't seem to record below 134 volts at its current settings. At the start of trips with a cold pack, the low voltage alarm on the miniBMS often sounded at full throttle. The alarm should sound at about 132 volts at nominal temperatures to signal charging is needed.



      While driving in temps below freezing, it wouldn't be difficult to keep the pack internal temperature above freezing, helped by charging soon after driving. Any insulation (or heating) surrounding the battery packs would be helpful and benefit performance, but it my case doesn't seem necessary. I've parked the car until March; the diesel heater is inadequate below freezing and there are occasional blizzards and salt on the roads.



      Chip Chandler


















      [Non-text portions of this message have been removed]
    • Jeremy Smithson
      Hi Chip, Here is a dumb question: With 49 cells at a finishing voltage of 3.8V per cell you will be right around the 185V max for the controller, but what
      Message 2 of 8 , Feb 14, 2013
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        Hi Chip,

        Here is a 'dumb' question: With 49 cells at a finishing voltage of 3.8V
        per cell you will be right around the 185V max for the controller, but what
        if you had 52 cells and stopped charging at 3.6V? Then your operating
        voltage would be higher after it levels off.


        On Thu, Feb 14, 2013 at 7:18 AM, cchandlerc66 <cchandler66@...>wrote:

        > **
        >
        >
        > Cold and Thundersky
        >
        > This data is from August-December 2012 in 1997 Force with Elcon PFC 4000
        > charger, 49 160Ah Thundersky cells, miniBMS, 4210 test miles, 115 separate
        > trips/charges on average 36 miles/trip in central Maine. This data is from
        > one probe between the top of two cells in the middle of the rear pack under
        > 1 inch of foam touching the cell top edges under a 2" air space and the
        > plastic battery cover. The Force was driven mostly at the Normal setting
        > (120 -130 amps, depending on pack temperature). Charging at both 110 and
        > 220 volts, didn't seem to be any difference in cell temperature rise. There
        > were three trips of about 70 miles.
        >
        > Data below is: average ambient temperature at trip start, average pack
        > temp at start, Ah/mile, average temp rise during trips, average temp rise
        > during chargings, total temp increase for trips plus chargings. All in
        > degrees F.
        >
        > Aug: 75 degrees, 78 degrees, 1.2 Ah/mile, trips-6 degrees, charges-7
        > degrees, total-13 degrees.
        > Sept: 62 degrees, 71 degrees, 1.25 Ah/mile, trips-10 degrees, charges-5
        > degrees, total-15 degrees.
        > Oct: 56 degrees, 65 degrees, 1.28 Ah/mile, trips-8 degrees, charges-7
        > degrees, total-15 degrees.
        > Nov: 40 degrees, 53 degrees, 1.4 Ah/mile, trips-9 degrees, charges-4
        > degrees, total-13 degrees.
        > Dec: 34 degrees, 38 degrees, 1.5 Ah/mile, trips-13 degrees, charges-7
        > degrees, total-20 degrees.
        >
        > Extremes:
        > July 28: 33.2 miles, 1.21 Ah/mile, starting ambient temperature-72
        > degrees, pack start temperature-88, pack end temperature-93, charge end
        > temperature-102.
        > Jan 2, 2013: 31.6 miles, 1.72 Ah/mile, starting ambient temp-16, pack
        > start temp-10, pack end temp-35, charge end temp-45.
        >
        > Performance: I noticed only a slight decrease in power in November when
        > the pack start temperature was below 50 degrees. The January 2nd trip was
        > dramatically sluggish at first. The car wouldn't accelerate above 35 mph on
        > the level, however after 8 miles of driving, the performance improved to
        > the November level. Others with smaller capacity packs have reported poorer
        > performance in cool temperatures, so perhaps a larger capacity pack
        > performs better in the cold.
        >
        > As the pack got colder, the start voltage at full throttle sagged from a
        > normal of 165v (80 degrees) to 134v at the coldest. My only voltage readout
        > is on a CleanPowerAuto EV display and it doesn't seem to record below 134
        > volts at its current settings. At the start of trips with a cold pack, the
        > low voltage alarm on the miniBMS often sounded at full throttle. The alarm
        > should sound at about 132 volts at nominal temperatures to signal charging
        > is needed.
        >
        > While driving in temps below freezing, it wouldn't be difficult to keep
        > the pack internal temperature above freezing, helped by charging soon after
        > driving. Any insulation (or heating) surrounding the battery packs would be
        > helpful and benefit performance, but it my case doesn't seem necessary.
        > I've parked the car until March; the diesel heater is inadequate below
        > freezing and there are occasional blizzards and salt on the roads.
        >
        > Chip Chandler
        >
        >
        >



        --

        Jeremy Smithson

        Puget Sound Solar LLC

        immobile (206) 706-1931

        mobile (206) 669-7337

        jeremy@...

        www.pugetsoundsolar.com


        [Non-text portions of this message have been removed]
      • Chandler Chip
        Gerry: When I get the car back on the road, I ll do a comparison between the present location of the probe and one placed where you suggest, if I can get the
        Message 3 of 8 , Feb 15, 2013
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          Gerry:

          When I get the car back on the road, I'll do a comparison between the present location of the probe and one placed where you suggest, if I can get the second probe half way down between the cells. Then I can do a simultaneous readout. In any event, I assume no matter the location of the probe the interior cell temp would be somewhat higher than what any exterior readout would be. Others have taken temps from a single cell terminal with insulation over the top of the probe and terminal, perhaps a better location for reading internal cell temperatures. I'll do a temp comparison from a terminal, also. Thanks.

          Chip Chandler
          cchandler66@...

          On Feb 14, 2013, at 10:49 AM, Gerry Gaydos <gerry.gaydos@...> wrote:

          > Hi Chip,Thanks for sharing this with us. This is the kind of information that helps us all have a better understanding of real world performance of Thundersky prismatic LiFePo modules, and have a more satisfying experience with EVs.
          >
          > Reading your description of how you're measuring the temperature of the pack, I wondered why your temperature sensor wasn't located where the module(s) would be warmest, between modules and on the broad sides of the modules, not on the tops?
          >
          > This issue, collecting battery temperature data, is one on which I received some valuable input from Warren Winovich, a retired Nasa physicist (aerodynamics and thermodynamics specialist) in the Silicon Valley Chapter of the EAA. It might be worth investigating this point, for the sake of gathering the most accurate data possible.
          > Thanks for the work you're doing.
          > Gerry Gaydos
          >
          > "Internal combustion is so last century"... Funkymoto�, Electrifying Cars! 250 598 3100
          >
          > To: solectria_ev@yahoogroups.com
          > From: cchandler66@...
          > Date: Thu, 14 Feb 2013 15:18:26 +0000
          > Subject: [solectria_ev] Cold and Thundersky cells
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          > Cold and Thundersky
          >
          >
          >
          > This data is from August-December 2012 in 1997 Force with Elcon PFC 4000 charger, 49 160Ah Thundersky cells, miniBMS, 4210 test miles, 115 separate trips/charges on average 36 miles/trip in central Maine. This data is from one probe between the top of two cells in the middle of the rear pack under 1 inch of foam touching the cell top edges under a 2" air space and the plastic battery cover. The Force was driven mostly at the Normal setting (120 -130 amps, depending on pack temperature). Charging at both 110 and 220 volts, didn't seem to be any difference in cell temperature rise. There were three trips of about 70 miles.
          >
          >
          >
          > Data below is: average ambient temperature at trip start, average pack temp at start, Ah/mile, average temp rise during trips, average temp rise during chargings, total temp increase for trips plus chargings. All in degrees F.
          >
          >
          >
          > Aug: 75 degrees, 78 degrees, 1.2 Ah/mile, trips-6 degrees, charges-7 degrees, total-13 degrees.
          >
          > Sept: 62 degrees, 71 degrees, 1.25 Ah/mile, trips-10 degrees, charges-5 degrees, total-15 degrees.
          >
          > Oct: 56 degrees, 65 degrees, 1.28 Ah/mile, trips-8 degrees, charges-7 degrees, total-15 degrees.
          >
          > Nov: 40 degrees, 53 degrees, 1.4 Ah/mile, trips-9 degrees, charges-4 degrees, total-13 degrees.
          >
          > Dec: 34 degrees, 38 degrees, 1.5 Ah/mile, trips-13 degrees, charges-7 degrees, total-20 degrees.
          >
          >
          >
          > Extremes:
          >
          > July 28: 33.2 miles, 1.21 Ah/mile, starting ambient temperature-72 degrees, pack start temperature-88, pack end temperature-93, charge end temperature-102.
          >
          > Jan 2, 2013: 31.6 miles, 1.72 Ah/mile, starting ambient temp-16, pack start temp-10, pack end temp-35, charge end temp-45.
          >
          >
          >
          > Performance: I noticed only a slight decrease in power in November when the pack start temperature was below 50 degrees. The January 2nd trip was dramatically sluggish at first. The car wouldn't accelerate above 35 mph on the level, however after 8 miles of driving, the performance improved to the November level. Others with smaller capacity packs have reported poorer performance in cool temperatures, so perhaps a larger capacity pack performs better in the cold.
          >
          >
          >
          > As the pack got colder, the start voltage at full throttle sagged from a normal of 165v (80 degrees) to 134v at the coldest. My only voltage readout is on a CleanPowerAuto EV display and it doesn't seem to record below 134 volts at its current settings. At the start of trips with a cold pack, the low voltage alarm on the miniBMS often sounded at full throttle. The alarm should sound at about 132 volts at nominal temperatures to signal charging is needed.
          >
          >
          >
          > While driving in temps below freezing, it wouldn't be difficult to keep the pack internal temperature above freezing, helped by charging soon after driving. Any insulation (or heating) surrounding the battery packs would be helpful and benefit performance, but it my case doesn't seem necessary. I've parked the car until March; the diesel heater is inadequate below freezing and there are occasional blizzards and salt on the roads.
          >
          >
          >
          > Chip Chandler
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          > [Non-text portions of this message have been removed]
          >
          >
          >
          > ------------------------------------
          >
          > Yahoo! Groups Links
          >
          >
          >



          [Non-text portions of this message have been removed]
        • Gerry Gaydos
          Hi Chip, If you can, contact Warren Winovich, a long time member of the Silicon Valley chapter of the EAA. he has a lot of knowledge and experience in the area
          Message 4 of 8 , Feb 15, 2013
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            Hi Chip,
            If you can, contact Warren Winovich, a long time member of the Silicon Valley chapter of the EAA. he has a lot of knowledge and experience in the area of thermodynamics from his work with NASA. I'm sure he'd be glad to share what he knows a out it.
            Good luck
            Gerry.
            Sent from my iPhone

            On 2013-02-15, at 5:33 AM, "Chandler Chip" <cchandler66@...> wrote:

            > Gerry:
            >
            > When I get the car back on the road, I'll do a comparison between the present location of the probe and one placed where you suggest, if I can get the second probe half way down between the cells. Then I can do a simultaneous readout. In any event, I assume no matter the location of the probe the interior cell temp would be somewhat higher than what any exterior readout would be. Others have taken temps from a single cell terminal with insulation over the top of the probe and terminal, perhaps a better location for reading internal cell temperatures. I'll do a temp comparison from a terminal, also. Thanks.
            >
            > Chip Chandler
            > cchandler66@...
            >
            > On Feb 14, 2013, at 10:49 AM, Gerry Gaydos <gerry.gaydos@...> wrote:
            >
            >> Hi Chip,Thanks for sharing this with us. This is the kind of information that helps us all have a better understanding of real world performance of Thundersky prismatic LiFePo modules, and have a more satisfying experience with EVs.
            >>
            >> Reading your description of how you're measuring the temperature of the pack, I wondered why your temperature sensor wasn't located where the module(s) would be warmest, between modules and on the broad sides of the modules, not on the tops?
            >>
            >> This issue, collecting battery temperature data, is one on which I received some valuable input from Warren Winovich, a retired Nasa physicist (aerodynamics and thermodynamics specialist) in the Silicon Valley Chapter of the EAA. It might be worth investigating this point, for the sake of gathering the most accurate data possible.
            >> Thanks for the work you're doing.
            >> Gerry Gaydos
            >>
            >> "Internal combustion is so last century"... Funkymoto™, Electrifying Cars! 250 598 3100
            >>
            >> To: solectria_ev@yahoogroups.com
            >> From: cchandler66@...
            >> Date: Thu, 14 Feb 2013 15:18:26 +0000
            >> Subject: [solectria_ev] Cold and Thundersky cells
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >> Cold and Thundersky
            >>
            >>
            >>
            >> This data is from August-December 2012 in 1997 Force with Elcon PFC 4000 charger, 49 160Ah Thundersky cells, miniBMS, 4210 test miles, 115 separate trips/charges on average 36 miles/trip in central Maine. This data is from one probe between the top of two cells in the middle of the rear pack under 1 inch of foam touching the cell top edges under a 2" air space and the plastic battery cover. The Force was driven mostly at the Normal setting (120 -130 amps, depending on pack temperature). Charging at both 110 and 220 volts, didn't seem to be any difference in cell temperature rise. There were three trips of about 70 miles.
            >>
            >>
            >>
            >> Data below is: average ambient temperature at trip start, average pack temp at start, Ah/mile, average temp rise during trips, average temp rise during chargings, total temp increase for trips plus chargings. All in degrees F.
            >>
            >>
            >>
            >> Aug: 75 degrees, 78 degrees, 1.2 Ah/mile, trips-6 degrees, charges-7 degrees, total-13 degrees.
            >>
            >> Sept: 62 degrees, 71 degrees, 1.25 Ah/mile, trips-10 degrees, charges-5 degrees, total-15 degrees.
            >>
            >> Oct: 56 degrees, 65 degrees, 1.28 Ah/mile, trips-8 degrees, charges-7 degrees, total-15 degrees.
            >>
            >> Nov: 40 degrees, 53 degrees, 1.4 Ah/mile, trips-9 degrees, charges-4 degrees, total-13 degrees.
            >>
            >> Dec: 34 degrees, 38 degrees, 1.5 Ah/mile, trips-13 degrees, charges-7 degrees, total-20 degrees.
            >>
            >>
            >>
            >> Extremes:
            >>
            >> July 28: 33.2 miles, 1.21 Ah/mile, starting ambient temperature-72 degrees, pack start temperature-88, pack end temperature-93, charge end temperature-102.
            >>
            >> Jan 2, 2013: 31.6 miles, 1.72 Ah/mile, starting ambient temp-16, pack start temp-10, pack end temp-35, charge end temp-45.
            >>
            >>
            >>
            >> Performance: I noticed only a slight decrease in power in November when the pack start temperature was below 50 degrees. The January 2nd trip was dramatically sluggish at first. The car wouldn't accelerate above 35 mph on the level, however after 8 miles of driving, the performance improved to the November level. Others with smaller capacity packs have reported poorer performance in cool temperatures, so perhaps a larger capacity pack performs better in the cold.
            >>
            >>
            >>
            >> As the pack got colder, the start voltage at full throttle sagged from a normal of 165v (80 degrees) to 134v at the coldest. My only voltage readout is on a CleanPowerAuto EV display and it doesn't seem to record below 134 volts at its current settings. At the start of trips with a cold pack, the low voltage alarm on the miniBMS often sounded at full throttle. The alarm should sound at about 132 volts at nominal temperatures to signal charging is needed.
            >>
            >>
            >>
            >> While driving in temps below freezing, it wouldn't be difficult to keep the pack internal temperature above freezing, helped by charging soon after driving. Any insulation (or heating) surrounding the battery packs would be helpful and benefit performance, but it my case doesn't seem necessary. I've parked the car until March; the diesel heater is inadequate below freezing and there are occasional blizzards and salt on the roads.
            >>
            >>
            >>
            >> Chip Chandler
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >>
            >> [Non-text portions of this message have been removed]
            >>
            >>
            >>
            >> ------------------------------------
            >>
            >> Yahoo! Groups Links
            >>
            >>
            >>
            >
            >
            >
            > [Non-text portions of this message have been removed]
            >
            >
            >
            > ------------------------------------
            >
            > Yahoo! Groups Links
            >
            >
            >
          • d. Bouton Baldridge
            Jeremy, That could work, since especially with the older TS cells that sit at 3.3v per cell for most of their use as long as you monitor your charger to shut
            Message 5 of 8 , Feb 15, 2013
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              Jeremy,
              That could work, since especially with the older TS cells that sit at 3.3v per cell for most of their use as long as you monitor your charger to shut it off before it begins to rise. I have noticed that Elcon has lowered the end  voltage on its lithium algorithim, and since the voltage over the nominal is meaningless you could have a higher pack voltage that way which the motor and controller would like. Next time I change my pack hopefully not for a few more years after the 4 already, I will try it. Not a dumb question at all.
              Bouty


              ________________________________
              From: Jeremy Smithson <jeremy@...>
              To: solectria_ev@yahoogroups.com
              Sent: Thursday, February 14, 2013 3:03 PM
              Subject: Re: [solectria_ev] Cold and Thundersky cells

              Hi Chip,

              Here is a 'dumb' question:  With 49 cells at a finishing voltage of 3.8V
              per cell you will be right around the 185V max for the controller, but what
              if you had 52 cells and stopped charging at 3.6V?  Then your operating
              voltage would be higher after it levels off.


              On Thu, Feb 14, 2013 at 7:18 AM, cchandlerc66 <cchandler66@...>wrote:

              > **
              >
              >
              > Cold and Thundersky
              >
              > This data is from August-December 2012 in 1997 Force with Elcon PFC 4000
              > charger, 49 160Ah Thundersky cells, miniBMS, 4210 test miles, 115 separate
              > trips/charges on average 36 miles/trip in central Maine. This data is from
              > one probe between the top of two cells in the middle of the rear pack under
              > 1 inch of foam touching the cell top edges under a 2" air space and the
              > plastic battery cover. The Force was driven mostly at the Normal setting
              > (120 -130 amps, depending on pack temperature). Charging at both 110 and
              > 220 volts, didn't seem to be any difference in cell temperature rise. There
              > were three trips of about 70 miles.
              >
              > Data below is: average ambient temperature at trip start, average pack
              > temp at start, Ah/mile, average temp rise during trips, average temp rise
              > during chargings, total temp increase for trips plus chargings. All in
              > degrees F.
              >
              > Aug: 75 degrees, 78 degrees, 1.2 Ah/mile, trips-6 degrees, charges-7
              > degrees, total-13 degrees.
              > Sept: 62 degrees, 71 degrees, 1.25 Ah/mile, trips-10 degrees, charges-5
              > degrees, total-15 degrees.
              > Oct: 56 degrees, 65 degrees, 1.28 Ah/mile, trips-8 degrees, charges-7
              > degrees, total-15 degrees.
              > Nov: 40 degrees, 53 degrees, 1.4 Ah/mile, trips-9 degrees, charges-4
              > degrees, total-13 degrees.
              > Dec: 34 degrees, 38 degrees, 1.5 Ah/mile, trips-13 degrees, charges-7
              > degrees, total-20 degrees.
              >
              > Extremes:
              > July 28: 33.2 miles, 1.21 Ah/mile, starting ambient temperature-72
              > degrees, pack start temperature-88, pack end temperature-93, charge end
              > temperature-102.
              > Jan 2, 2013: 31.6 miles, 1.72 Ah/mile, starting ambient temp-16, pack
              > start temp-10, pack end temp-35, charge end temp-45.
              >
              > Performance: I noticed only a slight decrease in power in November when
              > the pack start temperature was below 50 degrees. The January 2nd trip was
              > dramatically sluggish at first. The car wouldn't accelerate above 35 mph on
              > the level, however after 8 miles of driving, the performance improved to
              > the November level. Others with smaller capacity packs have reported poorer
              > performance in cool temperatures, so perhaps a larger capacity pack
              > performs better in the cold.
              >
              > As the pack got colder, the start voltage at full throttle sagged from a
              > normal of 165v (80 degrees) to 134v at the coldest. My only voltage readout
              > is on a CleanPowerAuto EV display and it doesn't seem to record below 134
              > volts at its current settings. At the start of trips with a cold pack, the
              > low voltage alarm on the miniBMS often sounded at full throttle. The alarm
              > should sound at about 132 volts at nominal temperatures to signal charging
              > is needed.
              >
              > While driving in temps below freezing, it wouldn't be difficult to keep
              > the pack internal temperature above freezing, helped by charging soon after
              > driving. Any insulation (or heating) surrounding the battery packs would be
              > helpful and benefit performance, but it my case doesn't seem necessary.
              > I've parked the car until March; the diesel heater is inadequate below
              > freezing and there are occasional blizzards and salt on the roads.
              >
              > Chip Chandler
              >

              >



              --

              Jeremy Smithson

              Puget Sound Solar LLC

              immobile (206) 706-1931

              mobile (206) 669-7337

              jeremy@...

              http://www.pugetsoundsolar.com/


              [Non-text portions of this message have been removed]



              ------------------------------------

              Yahoo! Groups Links



              [Non-text portions of this message have been removed]
            • Newton Hausermann
              Hey Chip, I can back that performance up, at school we ve done some testing on K2 s 26650P cells (2.6ah LiFePO4 s) and we ve found that freezing them results
              Message 6 of 8 , Feb 17, 2013
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                Hey Chip,

                I can back that performance up, at school we've done some testing on K2's
                26650P cells (2.6ah LiFePO4's) and we've found that freezing them results
                in poor current output until the cells heat up naturally. I've also noticed
                with my R/C cars LiPo's that they like to heat up to ~110*F and run at that
                no matter what the load/ambient temps. So it appears that the cold effects
                the chemical reaction within the cells, and the rate at which it occurs,
                therefore how much current the cell outputs. However we haven't noticed
                any degradation in capacity on that run, sadly we don't have the ability to
                continually freeze discharge and refreeze cells again. These are just my
                observations on batteries in general, hope this helps.

                Newton

                On Thu, Feb 14, 2013 at 10:18 AM, cchandlerc66
                <cchandler66@...>wrote:

                > **
                >
                >
                > Cold and Thundersky
                >
                > This data is from August-December 2012 in 1997 Force with Elcon PFC 4000
                > charger, 49 160Ah Thundersky cells, miniBMS, 4210 test miles, 115 separate
                > trips/charges on average 36 miles/trip in central Maine. This data is from
                > one probe between the top of two cells in the middle of the rear pack under
                > 1 inch of foam touching the cell top edges under a 2" air space and the
                > plastic battery cover. The Force was driven mostly at the Normal setting
                > (120 -130 amps, depending on pack temperature). Charging at both 110 and
                > 220 volts, didn't seem to be any difference in cell temperature rise. There
                > were three trips of about 70 miles.
                >
                > Data below is: average ambient temperature at trip start, average pack
                > temp at start, Ah/mile, average temp rise during trips, average temp rise
                > during chargings, total temp increase for trips plus chargings. All in
                > degrees F.
                >
                > Aug: 75 degrees, 78 degrees, 1.2 Ah/mile, trips-6 degrees, charges-7
                > degrees, total-13 degrees.
                > Sept: 62 degrees, 71 degrees, 1.25 Ah/mile, trips-10 degrees, charges-5
                > degrees, total-15 degrees.
                > Oct: 56 degrees, 65 degrees, 1.28 Ah/mile, trips-8 degrees, charges-7
                > degrees, total-15 degrees.
                > Nov: 40 degrees, 53 degrees, 1.4 Ah/mile, trips-9 degrees, charges-4
                > degrees, total-13 degrees.
                > Dec: 34 degrees, 38 degrees, 1.5 Ah/mile, trips-13 degrees, charges-7
                > degrees, total-20 degrees.
                >
                > Extremes:
                > July 28: 33.2 miles, 1.21 Ah/mile, starting ambient temperature-72
                > degrees, pack start temperature-88, pack end temperature-93, charge end
                > temperature-102.
                > Jan 2, 2013: 31.6 miles, 1.72 Ah/mile, starting ambient temp-16, pack
                > start temp-10, pack end temp-35, charge end temp-45.
                >
                > Performance: I noticed only a slight decrease in power in November when
                > the pack start temperature was below 50 degrees. The January 2nd trip was
                > dramatically sluggish at first. The car wouldn't accelerate above 35 mph on
                > the level, however after 8 miles of driving, the performance improved to
                > the November level. Others with smaller capacity packs have reported poorer
                > performance in cool temperatures, so perhaps a larger capacity pack
                > performs better in the cold.
                >
                > As the pack got colder, the start voltage at full throttle sagged from a
                > normal of 165v (80 degrees) to 134v at the coldest. My only voltage readout
                > is on a CleanPowerAuto EV display and it doesn't seem to record below 134
                > volts at its current settings. At the start of trips with a cold pack, the
                > low voltage alarm on the miniBMS often sounded at full throttle. The alarm
                > should sound at about 132 volts at nominal temperatures to signal charging
                > is needed.
                >
                > While driving in temps below freezing, it wouldn't be difficult to keep
                > the pack internal temperature above freezing, helped by charging soon after
                > driving. Any insulation (or heating) surrounding the battery packs would be
                > helpful and benefit performance, but it my case doesn't seem necessary.
                > I've parked the car until March; the diesel heater is inadequate below
                > freezing and there are occasional blizzards and salt on the roads.
                >
                > Chip Chandler
                >
                >
                >


                [Non-text portions of this message have been removed]
              • d. Bouton Baldridge
                Hi Newton,  that is a great set of observations. I have found that the high temps, anything above 80 degress F is the best performance on my 4 year old  40
                Message 7 of 8 , Feb 17, 2013
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                  Hi Newton,
                   that is a great set of observations. I have found that the high temps, anything above 80 degress F is the best performance on my 4 year old  40 Ah TSs, in fact they provide impressive power for their size, but the cold is "not so much" I have to rewind my stop watch for 0-60mph acceleration readings, but the waterbed heater does just enough for our mild winters to keep most of those following me from giving me the finger in traffic. Just as you have discussed, since the controller prevents the voltage from going too low when the pack is cold there does not appear to be much degradation from the cold performance. I would love to see another 4 more years, but we are going into uncharted territory now.
                  Bouty 


                  ________________________________
                  From: Newton Hausermann <rclugnut@...>
                  To: solectria_ev@yahoogroups.com
                  Sent: Sunday, February 17, 2013 12:07 PM
                  Subject: Re: [solectria_ev] Cold and Thundersky cells

                  Hey Chip,

                  I can back that performance up, at school we've done some testing on K2's
                  26650P cells (2.6ah LiFePO4's) and we've found that freezing them results
                  in poor current output until the cells heat up naturally. I've also noticed
                  with my R/C cars LiPo's that they like to heat up to ~110*F and run at that
                  no matter what the load/ambient temps. So it appears that the cold effects
                  the chemical reaction within the cells, and the rate at which it occurs,
                  therefore how much current the cell outputs. However we haven't noticed
                  any degradation in capacity on that run, sadly we don't have the ability to
                  continually freeze discharge and refreeze cells again. These are just my
                  observations on batteries in general, hope this helps.

                  Newton

                  On Thu, Feb 14, 2013 at 10:18 AM, cchandlerc66
                  <cchandler66@...>wrote:

                  > **
                  >
                  >
                  > Cold and Thundersky
                  >
                  > This data is from August-December 2012 in 1997 Force with Elcon PFC 4000
                  > charger, 49 160Ah Thundersky cells, miniBMS, 4210 test miles, 115 separate
                  > trips/charges on average 36 miles/trip in central Maine. This data is from
                  > one probe between the top of two cells in the middle of the rear pack under
                  > 1 inch of foam touching the cell top edges under a 2" air space and the
                  > plastic battery cover. The Force was driven mostly at the Normal setting
                  > (120 -130 amps, depending on pack temperature). Charging at both 110 and
                  > 220 volts, didn't seem to be any difference in cell temperature rise. There
                  > were three trips of about 70 miles.
                  >
                  > Data below is: average ambient temperature at trip start, average pack
                  > temp at start, Ah/mile, average temp rise during trips, average temp rise
                  > during chargings, total temp increase for trips plus chargings. All in
                  > degrees F.
                  >
                  > Aug: 75 degrees, 78 degrees, 1.2 Ah/mile, trips-6 degrees, charges-7
                  > degrees, total-13 degrees.
                  > Sept: 62 degrees, 71 degrees, 1.25 Ah/mile, trips-10 degrees, charges-5
                  > degrees, total-15 degrees.
                  > Oct: 56 degrees, 65 degrees, 1.28 Ah/mile, trips-8 degrees, charges-7
                  > degrees, total-15 degrees.
                  > Nov: 40 degrees, 53 degrees, 1.4 Ah/mile, trips-9 degrees, charges-4
                  > degrees, total-13 degrees.
                  > Dec: 34 degrees, 38 degrees, 1.5 Ah/mile, trips-13 degrees, charges-7
                  > degrees, total-20 degrees.
                  >
                  > Extremes:
                  > July 28: 33.2 miles, 1.21 Ah/mile, starting ambient temperature-72
                  > degrees, pack start temperature-88, pack end temperature-93, charge end
                  > temperature-102.
                  > Jan 2, 2013: 31.6 miles, 1.72 Ah/mile, starting ambient temp-16, pack
                  > start temp-10, pack end temp-35, charge end temp-45.
                  >
                  > Performance: I noticed only a slight decrease in power in November when
                  > the pack start temperature was below 50 degrees. The January 2nd trip was
                  > dramatically sluggish at first. The car wouldn't accelerate above 35 mph on
                  > the level, however after 8 miles of driving, the performance improved to
                  > the November level. Others with smaller capacity packs have reported poorer
                  > performance in cool temperatures, so perhaps a larger capacity pack
                  > performs better in the cold.
                  >
                  > As the pack got colder, the start voltage at full throttle sagged from a
                  > normal of 165v (80 degrees) to 134v at the coldest. My only voltage readout
                  > is on a CleanPowerAuto EV display and it doesn't seem to record below 134
                  > volts at its current settings. At the start of trips with a cold pack, the
                  > low voltage alarm on the miniBMS often sounded at full throttle. The alarm
                  > should sound at about 132 volts at nominal temperatures to signal charging
                  > is needed.
                  >
                  > While driving in temps below freezing, it wouldn't be difficult to keep
                  > the pack internal temperature above freezing, helped by charging soon after
                  > driving. Any insulation (or heating) surrounding the battery packs would be
                  > helpful and benefit performance, but it my case doesn't seem necessary.
                  > I've parked the car until March; the diesel heater is inadequate below
                  > freezing and there are occasional blizzards and salt on the roads.
                  >
                  > Chip Chandler
                  >

                  >


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