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RE: [force_ev] Battery equalization story

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  • BECKETT,WILL (HP-PaloAlto,ex1)
    Were the temps on the batteries you measured all the same? My Force has maintenance free batteries and there are 13 so it is difficult to compare the other
    Message 1 of 11 , May 23, 2001
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      Were the temps on the batteries you measured all the same? My Force has
      maintenance free batteries and there are 13 so it is difficult to compare
      the other data in your message. How many miles on this set and how old are
      they?

      -Will

      -----Original Message-----
      From: umarc@... [mailto:umarc@...]
      Sent: Wednesday, May 23, 2001 4:54 PM
      To: force_ev@yahoogroups.com
      Subject: [force_ev] Battery equalization story


      Recently 1992 Force has begun to get sluggish and my range is limited to
      about 15 miles tops. I took some hydrometer readings (all the cells seemed
      to measure about 1.250 at full charge) and some battery pack voltage
      measurements.

      My batteries are Interstate SRM-27's; according to Interstate the
      open-circuit voltage of this battery is supposed to range from 12.65 at
      full charge down to 11.89 at 0% charge. Multiplying by 12, that means I
      should measure just under 152 volts at full charge, 149.4 at 75%, 146.9 at
      50%, and 144.7 at 25% charge (I would not attempt to run it down to zero).

      After driving six miles to work (5 - 6 amp-hours down from full charge), I
      was down to 149.5; returning home (6 - 7 more amp-hours) brought me down
      to 147 volts, and beyond that I did not attempt to go since the car was
      already starting to feel sluggish.

      I decided to try equalizing the batteries. I got an old brainless charger
      capable of 190 volts (unloaded) and a string of 10-ohm, 18-watt power
      resistors with which I was able to keep the current at a pretty constant
      0.7 amps over 24 hours. At that time I found that the voltage on the
      battery pack wasn't increasing, so I stopped equalizing and let the car
      sit overnight.

      The next day I drove it to work. The open-circuit voltage measured 152. On
      returning home (having driven 12 miles on just over 11 amp-hours), it was
      down to 150. Without charging, I opened up the battery compartments and
      started taking hydrometer measurements. I found that some cells were up at
      1.270 or so, but others were down at 1.250. That surprised me; I thought
      the equalization should have made them all pretty much the same.

      Based on performance so far, my range is better than it was, but it's
      still disappointing. Does anyone have any suggestions as to what I should
      try next?


      Rob Landry
      umarc@...


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    • David Roden (Akron OH USA)
      1.270 is not bad for old batteries. 1.250 is not so good. Low voltage and SG are symptomatic of sulfation and/or positive grid degradation. How do those
      Message 2 of 11 , May 23, 2001
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        1.270 is not bad for old batteries. 1.250 is not so good. Low voltage
        and SG are symptomatic of sulfation and/or positive grid degradation.

        How do those cells look inside? (Wear safety glasses when you peek!) Is
        the electrolyte greyish when you suck it up in the hydrometer? Do the
        plates look like they have mold growing between them, sort of spreading
        them apart? Are the ends of the batteries bulging very much?

        When you have the eq charge running, are the cells with low SG gassing
        just as liberally as the ones with higher SG? If so, you may have gotten
        about all you can get out of them.

        If not, maybe you didn't equalize long enough. It can take several
        ~days~ of equalization to bring up chronically undercharged cells.
        Unfortunately you have to keep overcharging the fully-charged ones in
        order to keep enough current flowing through the undercharged cells.

        If you have some batteries in which ~all~ the cells are at high SG, it
        doesn't make sense to keep cooking them. I would try equalizing the
        batteries with lower cells separately with 12 volt chargers. You can
        keep poking at them that way for several days if you hold the current
        down to perhaps 2 amps and keep the electrolyte level up.


        David Roden - Akron, Ohio, USA
        1991 Solectria Force 144vac
        1991 Ford Escort Green/EV 128vdc
        1979 General Engines ElectroPed 24vdc
        1974 Honda Civic EV 96vdc
        1970 GE Elec-trak E15 36vdc
        = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
        Thou shalt not send me any thing which says unto thee, "send this to all
        thou knowest." Neither shalt thou send me any spam, lest I smite thee.
        = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
      • Tom Hudson
        What s the story with these cars with flooded batteries? Did they come with floodeds originally? I was under the impression that Solectria always used sealed
        Message 3 of 11 , May 23, 2001
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          What's the story with these cars with flooded batteries? Did they come with
          floodeds originally? I was under the impression that Solectria always used
          sealed batteries. If they originally had sealed batteries, did someone
          reprogram the charger profiles?

          Just curious...

          -Tom

          Thomas Hudson
          http://portdistrict5.org -- 5th District Aldermanic Website


          > -----Original Message-----
          > From: David Roden (Akron OH USA) [mailto:roden@...]
          > Sent: Wednesday, May 23, 2001 10:34 PM
          > To: force_ev@yahoogroups.com
          > Subject: Re: [force_ev] Battery equalization story
          >
          >
          > 1.270 is not bad for old batteries. 1.250 is not so good. Low voltage
          > and SG are symptomatic of sulfation and/or positive grid degradation.
          >
          > How do those cells look inside? (Wear safety glasses when you peek!) Is
          > the electrolyte greyish when you suck it up in the hydrometer? Do the
          > plates look like they have mold growing between them, sort of spreading
          > them apart? Are the ends of the batteries bulging very much?
          >
          > When you have the eq charge running, are the cells with low SG gassing
          > just as liberally as the ones with higher SG? If so, you may have gotten
          > about all you can get out of them.
          >
          > If not, maybe you didn't equalize long enough. It can take several
          > ~days~ of equalization to bring up chronically undercharged cells.
          > Unfortunately you have to keep overcharging the fully-charged ones in
          > order to keep enough current flowing through the undercharged cells.
          >
          > If you have some batteries in which ~all~ the cells are at high SG, it
          > doesn't make sense to keep cooking them. I would try equalizing the
          > batteries with lower cells separately with 12 volt chargers. You can
          > keep poking at them that way for several days if you hold the current
          > down to perhaps 2 amps and keep the electrolyte level up.
          >
          >
          > David Roden - Akron, Ohio, USA
          > 1991 Solectria Force 144vac
          > 1991 Ford Escort Green/EV 128vdc
          > 1979 General Engines ElectroPed 24vdc
          > 1974 Honda Civic EV 96vdc
          > 1970 GE Elec-trak E15 36vdc
          > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
          > Thou shalt not send me any thing which says unto thee, "send this to all
          > thou knowest." Neither shalt thou send me any spam, lest I smite thee.
          > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
          >
          > 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/
          >
          >
        • David Roden (Akron OH USA)
          ... The very first Forces were fitted with flooded Sears Diehards (really!). I think they used various brands of flooded batteries through about the 93
          Message 4 of 11 , May 23, 2001
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            On 23 May 2001, at 23:28, Tom Hudson wrote:

            > What's the story with these cars with flooded batteries?

            The very first Forces were fitted with flooded Sears Diehards (really!).
            I think they used various brands of flooded batteries through about the
            '93 models.

            It appears that for the most part flooded batteries did not give very
            good service. In particular, the Diehards (built at that time by Johnson
            Controls) seem to have been a somewhat unfortunate choice. The paperwork
            that came with my '91 Force (the very first Force ever built) indicated
            that APS, the original owner, replaced the pack several times, with most
            packs lasting less than 9 months. Of course this was in hot Arizona,
            which may have had something to do with the abysmal cycle life.

            Most of those early cars used BC-1000 chargers, presumably set up for the
            correct batteries. BC-1000, BTW, seems to have designated at least two
            different types of chargers, maybe more. One of them I saw appears to
            use an external charge control gadget in a Radio Shack-type builder's
            box.

            The one that came in my car was a BC-1000, but was not the original; it
            was a replacement 230 volt charger, probably from or for an E-10 pickup.
            It has a microprocessor-based charge control and what is apparently an RS-
            232 port for reprogramming (though I don't know how to talk to it and
            haven't put much into it since I don't use it). It's set up for the
            Hawkers that were in the car when I got it, but probably was originally
            programmed for flooded marine batteries.


            David Roden - Akron, Ohio, USA
            1991 Solectria Force 144vac
            1991 Ford Escort Green/EV 128vdc
            1979 General Engines ElectroPed 24vdc
            1974 Honda Civic EV 96vdc
            1970 GE Elec-trak E15 36vdc
            = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
            Thou shalt not send me any thing which says unto thee, "send this to all
            thou knowest." Neither shalt thou send me any spam, lest I smite thee.
            = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
          • umarc@hippogryph.com
            OK. I ve done a little more checking, and I find that most of the cells in my car have SG in the 1.250 range, and some even a bit lower. A few are up around
            Message 5 of 11 , May 25, 2001
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              OK. I've done a little more checking, and I find that most of the cells in
              my car have SG in the 1.250 range, and some even a bit lower. A few are up
              around 1.270, but not many.

              On Wed, 23 May 2001, David Roden (Akron OH USA) wrote:

              > How do those cells look inside? (Wear safety glasses when you peek!) Is
              > the electrolyte greyish when you suck it up in the hydrometer? Do the
              > plates look like they have mold growing between them, sort of spreading
              > them apart? Are the ends of the batteries bulging very much?

              The cells look fairly clean as far as I can tell. The electrolyte is
              clear, there's no "mold" that I can see, and the batteries are not bulging
              noticeably.

              > When you have the eq charge running, are the cells with low SG gassing
              > just as liberally as the ones with higher SG? If so, you may have gotten
              > about all you can get out of them.

              That I can't tell.

              > If not, maybe you didn't equalize long enough. It can take several
              > ~days~ of equalization to bring up chronically undercharged cells.

              I've decided to try another bout of equalization using an old brainless
              Solectria charger and three 10-ohm resistors in series. The voltage drop
              across 10 ohms is 6.7 volts, so the inflow current is 0.67 amps. The
              votage across the pack is 165; as I understand it I'm supposed to
              discontinue charging when that voltage ceases to increase.

              Is there any other test I can use to tell when I've equalized enough? I
              gather that opening the cells and doing SG tests while charging is a bad
              idea, but I suppose I could temporarily unplug the charger, test a few
              cells, then plug it back in.


              Rob Landry
              umarc@...
            • David Roden (Akron OH USA)
              ... If that s voltage measured while on charge, it s quite low. On a brand new 144v flooded pack, you should get close to 180 volts while the charger is still
              Message 6 of 11 , May 25, 2001
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                On 25 May 2001, at 21:58, umarc@... wrote:

                > The
                > votage across the pack is 165; as I understand it I'm supposed to
                > discontinue charging when that voltage ceases to increase.

                If that's voltage measured while on charge, it's quite low. On a brand
                new 144v flooded pack, you should get close to 180 volts while the
                charger is still connected and still charging. An old pack should hit
                around 173-175v.

                To see what's going on, you need either a true constant-current charger
                or a variable output charger and an accurate ammeter. If you don't
                measure voltage with the current at a defined value (I recommend 3 amps
                for the typical group 27 battery), variation in your house's line voltage
                will obscure what's actually happening to the batteries.

                The classic variable charger is a simple variac (variable
                autotransformer) and a bridge rectifier. You check it now and again by
                calibrating it to the current you've decided on (say 3 amps) and reading
                the voltage.

                When it stops rising, that's about all you'll get. If you take three
                readings an hour apart and see essentially no increase, call it quits.
                If you get to about 180 volts, you have really good batteries. More
                likely you'll top out at around 173-175v.

                However -- keep the batteries cool! As they heat up, the on-charge
                voltage actually drops. This confuses things.

                If the cells are seriously out of balance, it may take a very long time,
                as much as several days, for the voltage to stop rising. The increase
                goes slower and slower all the time because as you continue, fewer and
                fewer cells are still accepting charge and rising in voltage. The others
                are just gassing and heating up.

                If at the end of this round you still can't read much above 1.250 SG in
                most cells and/or you can't get the voltage measured while on charge to
                go over about 170v, it might be getting close to time for a new pack.


                David Roden - Akron, Ohio, USA
                1991 Solectria Force 144vac
                1991 Ford Escort Green/EV 128vdc
                1979 General Engines ElectroPed 24vdc
                1974 Honda Civic EV 96vdc
                1970 GE Elec-trak E15 36vdc
                = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
                Thou shalt not send me any thing which says unto thee, "send this to all
                thou knowest." Neither shalt thou send me any spam, lest I smite thee.
                = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
              • umarc@hippogryph.com
                ... That was the voltage I measured just after starting the charge; this morning it was at 171, and the current had gone down below 0.5 amp, so I bypassed one
                Message 7 of 11 , May 26, 2001
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                  On Sat, 26 May 2001, David Roden (Akron OH USA) wrote:

                  > If that's voltage measured while on charge, it's quite low.

                  That was the voltage I measured just after starting the charge; this
                  morning it was at 171, and the current had gone down below 0.5 amp, so I
                  bypassed one of the series resistors, which brought it up above 0.6 amp.
                  A couple of hours ago the voltage was up to 174 and the current down to
                  0.58 amp; just now it was down to 173.8 and the current up to 0.6 amp, so
                  I stopped charging and checked the specific gravity in several cells; all
                  were up above 1.270 where before they'd been at 1.250. I've disconnected
                  the charger and will now leave the car alone for a couple of days --
                  Monday will be the first opportunity I have to drive it.

                  At some point I'm going to have to go through all the batteries and check
                  the water levels.

                  > To see what's going on, you need either a true constant-current charger
                  > or a variable output charger and an accurate ammeter. If you don't
                  > measure voltage with the current at a defined value (I recommend 3 amps
                  > for the typical group 27 battery), variation in your house's line voltage
                  > will obscure what's actually happening to the batteries.

                  With a 10-ohm resistor in series, all I had to do was measure the voltage
                  drop across it and divide by 10 to get the current in amperes.

                  Thanks.


                  Rob
                • Tom Hudson
                  I have the Solectria owner s website back up and running! The old web host is still offline due to problems getting their data line reconnected, so I decided
                  Message 8 of 11 , May 27, 2001
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                    I have the Solectria owner's website back up and running! The old web host
                    is still offline due to problems getting their data line reconnected, so I
                    decided to set up my own domain, http://portev.org It's the Port
                    Washington Electric Vehicle Association. Technically, since my wife and I
                    own both the EVs in Port Washington, Wisconsin, it's legitimate. :-)

                    Any of you out there who would like to be included in the Solectria Owners
                    Website, please email me off-list and I'll get you added. There's no cost
                    or obligation -- I just want to get everyone listed, it's an informational
                    site so people can see how EV owners use their vehicles. Check it out and I
                    think you'll want to be listed.

                    Thanks,
                    -Tom

                    Thomas Hudson
                    http://portdistrict5.org -- 5th District Aldermanic Website
                    http://portev.org/solectria/ho -- Our Electric Vehicles
                    http://portev.org/solectria/ho/pvs.htm -- Solar Power
                    http://portev.org/solectria -- Solectria Owners Website
                    http://portgardenclub.org -- Port Washington Garden Club
                  • Tom Hudson
                    ... Thanks for the update, Peter. True, the value should be tailpipe pollution-free miles -- I made a clarification on the index page of the website. Plus,
                    Message 9 of 11 , May 28, 2001
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                      > One small update for the blurb on my car on the owners website.
                      > I have now gone 12,000 miles. I don't think we can really say
                      > "pollution free" since there is pollution from the power plants.
                      > Perhaps that is another comparable phrase we can think up.

                      Thanks for the update, Peter. True, the value should be "tailpipe"
                      pollution-free miles -- I made a clarification on the index page of the
                      website. Plus, I now have a total of the miles on the index page. The
                      average fuel economy in the US is currently around 25 MPG, meaning on
                      average, for every mile driven by Americans, about a pound of pollution is
                      emitted. Presently, our small group on the website has 73,990 miles --
                      Eliminating almost 37 TONS of tailpipe emissions! Wow.

                      I'd like to get odometer updates from everyone on the website -- I don't
                      have any readings at all for some people and it would be cool to see how
                      many more miles we have logged.

                      -Tom

                      Thomas Hudson
                      http://portdistrict5.org -- 5th District Aldermanic Website
                      http://portev.org/solectria/ho -- Our Electric Vehicles
                      http://portev.org/solectria/ho/pvs.htm -- Solar Power
                      http://portev.org/solectria -- Solectria Owners Website
                      http://portgardenclub.org -- Port Washington Garden Club
                    • Gordon Stallings
                      ... I ve now driven over 5,000 miles in my Force. Gordon Stallings 1999 Solectria Force
                      Message 10 of 11 , May 29, 2001
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                        At 23:52 05/28/2001 -0500, you wrote:
                        >I'd like to get odometer updates from everyone on the website -- I don't
                        >have any readings at all for some people and it would be cool to see how
                        >many more miles we have logged.

                        I've now driven over 5,000 miles in my Force.

                        Gordon Stallings
                        1999 Solectria Force
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