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Power and lack thereof

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  • umarc@hippogryph.com
    Dear Solectrians, I was driving home from work the other day when on starting up a hill I found myself without enough power to sustain 30 mph (I was down about
    Message 1 of 5 , Oct 27, 2001
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      Dear Solectrians,

      I was driving home from work the other day when on starting up a hill I
      found myself without enough power to sustain 30 mph (I was down about 10
      amp-hours from full charge at this point, according to the meter).

      So the next day, after the car had charged overnight, I measured the
      specific gravity in all the cells in all twelve batteries, and they all
      measured about 1.265, which is what the manufacturer says they should
      measure fully charged.

      I wonder if I've got some sort of controller problem?


      Rob Landry
      umarc@...
    • David Roden (Akron OH USA)
      ... It could be a controller problem, or perhaps it was cutting back because the motor was overheating. Did you check the motor temperature? The most likely
      Message 2 of 5 , Oct 27, 2001
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        On 27 Oct 2001, at 11:59, umarc@... wrote:

        > I was driving home from work the other day when on starting up a hill I
        > found myself without enough power to sustain 30 mph (I was down about 10
        > amp-hours from full charge at this point, according to the meter).

        It could be a controller problem, or perhaps it was cutting back because
        the motor was overheating. Did you check the motor temperature?

        The most likely cause of this would be a failing battery. One cell with
        unusually high internal resistance will cause a large voltage drop. The
        more current that's used, the greater the voltage drop. One cell can
        actually cause far more than its own 2 volts of reduction because it acts
        like a resistor.

        Under normal circumstances, the controller tries to be kind to the
        batteries by limiting current to keep voltage above 1.75 volts per cell
        (126 volts for a 144v pack, or 136.5 volts for a 156v pack). Thus a low
        charge will cause a drop in top speed and acceleration rate. The same
        thing will happen in case of a failing battery which drags down the pack
        voltage under load.

        Ideally you should test the pack under operating load by putting a 50 amp
        (or more) dummy load across the pack and measuring each battery. This
        would quickly tell you which one is acting up. I use a dummy load I made
        from heating elements from derelict heat pumps, adding a fan and a spare
        contactor. This eats 100-110 amps at 144 volts (and as a cool weather
        bonus also warms up my garage nicely while I'm testing).

        If you don't have such a load, you may be able to determine the
        troublesome one by turning on the heater and all the accessories in your
        garage, and measuring the voltage of each battery in turn. Look for a
        battery that's about 2 volts lower than the others.

        Too bad Solectria didn't fit all cars with voltmeters. This was an
        option which should have been standard, as it alerts you to these kinds
        of problems.



        David Roden - Akron, Ohio, USA
        1991 Solectria Force 144vac
        1991 Ford Escort Green/EV 128vdc
        1979 General Engines ElectroPed 24vdc
        1970 GE Elec-trak E15 36vdc
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        thou knowest." Neither shalt thou send me any spam, lest I smite thee.
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      • Gordon Stallings
        ... I ve designed and built an instrument for the Force that monitors the voltage on each battery. The display fits into the blank spot in the dash. An
        Message 3 of 5 , Oct 30, 2001
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          At 15:15 10/27/2001 -0400, you wrote:
          >Too bad Solectria didn't fit all cars with voltmeters. This was an
          >option which should have been standard, as it alerts you to these kinds
          >of problems.

          I've designed and built an instrument for the Force that monitors the
          voltage on each battery. The display fits into the blank spot in the dash.
          An article about it is scheduled for publication in the next issue of
          Current EVents. The instrument clearly shows what happens if you
          regenerate hard on a fully charged pack -- uneven overvoltage -- not good!

          I'd be glad to provide advice or help to anybody who wants to do the same
          thing. Watch for the article!


          Gordon Stallings
          1999 Solectria Force
        • Tom Hudson
          I can t wait for the article, Gordon! I want one! -Tom (watching the mailbox for Current EVents)
          Message 4 of 5 , Oct 30, 2001
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            I can't wait for the article, Gordon! I want one!

            -Tom (watching the mailbox for Current EVents)

            > -----Original Message-----
            > From: Gordon Stallings [mailto:grs@...]
            > Sent: Tuesday, October 30, 2001 9:31 AM
            > To: force_ev@yahoogroups.com
            > Subject: Re: [force_ev] Power and lack thereof
            >
            >
            > At 15:15 10/27/2001 -0400, you wrote:
            > >Too bad Solectria didn't fit all cars with voltmeters. This was an
            > >option which should have been standard, as it alerts you to these kinds
            > >of problems.
            >
            > I've designed and built an instrument for the Force that monitors the
            > voltage on each battery. The display fits into the blank spot in
            > the dash.
            > An article about it is scheduled for publication in the next issue of
            > Current EVents. The instrument clearly shows what happens if you
            > regenerate hard on a fully charged pack -- uneven overvoltage -- not good!
            >
            > I'd be glad to provide advice or help to anybody who wants to do the same
            > thing. Watch for the article!
            >
            >
            > Gordon Stallings
            > 1999 Solectria Force
            >
            >
            > To unsubscribe from this group, send an email to:
            > force_ev-unsubscribe@egroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >
            >
            >
          • Don Buckshot
            I want one to! Don Buckshot Kansas City 1996 Solectria Force NiMH
            Message 5 of 5 , Oct 30, 2001
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              I want one to!

              Don Buckshot
              Kansas City
              1996 Solectria Force NiMH

              Tom Hudson wrote:
              >
              > I can't wait for the article, Gordon! I want one!
              >
              > -Tom (watching the mailbox for Current EVents)
              >
              > > -----Original Message-----
              > > From: Gordon Stallings [mailto:grs@...]
              > > Sent: Tuesday, October 30, 2001 9:31 AM
              > > To: force_ev@yahoogroups.com
              > > Subject: Re: [force_ev] Power and lack thereof
              > >
              > >
              > > At 15:15 10/27/2001 -0400, you wrote:
              > > >Too bad Solectria didn't fit all cars with voltmeters. This was an
              > > >option which should have been standard, as it alerts you to these kinds
              > > >of problems.
              > >
              > > I've designed and built an instrument for the Force that monitors the
              > > voltage on each battery. The display fits into the blank spot in
              > > the dash.
              > > An article about it is scheduled for publication in the next issue of
              > > Current EVents. The instrument clearly shows what happens if you
              > > regenerate hard on a fully charged pack -- uneven overvoltage -- not good!
              > >
              > > I'd be glad to provide advice or help to anybody who wants to do the same
              > > thing. Watch for the article!
              > >
              > >
              > > Gordon Stallings
              > > 1999 Solectria Force
              > >
              > >
              > > To unsubscribe from this group, send an email to:
              > > force_ev-unsubscribe@egroups.com
              > >
              > >
              > >
              > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
              > >
              > >
              > >
              >
              >
              > To unsubscribe from this group, send an email to:
              > force_ev-unsubscribe@egroups.com
              >
              >
              >
              > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
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