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Re: [solectria_ev] amp hour meter

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  • Charles Bliss
    I was wondering about the accuracy of the Brusa vs an Arduino. For a different project, I was capturing the current over time to get AH using an Arduino UNO.
    Message 1 of 8 , Oct 5, 2013
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      I was wondering about the accuracy of the Brusa vs an Arduino.  For a different project, I was capturing the current over time to get AH using an Arduino UNO.  The resolution is only 1024 bits on the analog inputs.  I am getting much higher resolution on voltage from the BMS [SPI] circuitry and close enough for providing pack capacity.  I haven't put it in anything yet but it seems to be working on the bench.

      Regrettably chips used in the BC29 are obsolete.

      On 10/5/2013 7:17 PM, Rex Allison wrote:
       
      The amp hour meter has four components to it:

      1. A very accurate V to F circuit something like a 25000:1 accuracy (250A to 0.01A). It uses a very low input leakage op amp and a trimmed RC. This requires a highly stable capacitor and 0.1% resistors.
      2. A counter
      3. LCD driver
      4. 5 V regulator

      An Arduino would be a great replacement, the real trick is to replicate the accurate V to F on an Arduino shield. The 10 bit ADC of a Mega wouldn't get you close to the accuracy of the Brusa BC29.

      Rex


      From: Charles Bliss <cbliss@...>
      To: solectria_ev@yahoogroups.com
      Sent: Saturday, October 5, 2013 4:30 PM
      Subject: Re: [solectria_ev] amp hour meter

       
      If you do get it working again, you might won't to clean thoroughly and conformal coat.  Moisture is the enemy.

      How many people out there have bad units?  The box is a counter that outputs to the display in the dash. I would think it could be replaced with an Arduino project.

      On 10/5/2013 2:45 PM, murugac@... wrote:
       
      my amp hour meter in 1997 keep blowing the fuse, found out that terminal #1 and #2 is shorted. wondering if anyone has amp hour meter for sale? i removed the#1 pin which is standing up with black bottom. i am planning to follow the amp-hourrepair.pdf and solder the backside. thanksfor the pdf.  

      -Muruga




    • Ken Olum
      Mine never gave any trouble after I redid the coating. There s a lot to be said for doing this before you have problems. At a minimum, cover over the
      Message 2 of 8 , Oct 6, 2013
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        Mine never gave any trouble after I redid the coating. There's a lot
        to be said for doing this before you have problems. At a minimum,
        cover over the openings so the board isn't exposed to condensation from
        the air.

        Ken
      • geo_homsy2
        Ditto what Rex said -- The V to F converter in the brusa is VERY carefully designed. You will have to really know what you re doing to get this from an
        Message 3 of 8 , Oct 8, 2013
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          Ditto what Rex said --  The V to F converter in the brusa is VERY carefully designed.   You will have to really know what you're doing to get this from an arduino -- you need to build a proper analog front end.


          That said, I did use an arduino to build a multicolor programmable bar chart display for my dash, to indicate SOC and current.  But I didn't build the front end -- I'm taking signals off my BMS.


          I do have very good familiarity with the Brusa front end, having repaired different parts of mine several times.  Willing to answer questions on repairs not covered by the "one thing that always goes wrong" problem.


          @Charles:  Some of the op-amps are obsolete, but there are FAR better pin-compatible replacements available in the same package.  I wouldn't let that stop me from repairing one.  And the 40xx series CMOS chips are still mostly available.


          //Geo



          ---In solectria_ev@yahoogroups.com, <kdo@...> wrote:

          Mine never gave any trouble after I redid the coating. There's a lot
          to be said for doing this before you have problems. At a minimum,
          cover over the openings so the board isn't exposed to condensation from
          the air.

          Ken
        • Charles Bliss
          I guess I gave up too quick looking for pin compatible replacement chips. I ended up pulling the guts out of my 93 and merging them into my 97. I spent a
          Message 4 of 8 , Oct 8, 2013
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            I guess I gave up too quick looking for pin compatible replacement chips.  I ended up pulling the guts out of my '93 and merging them into my '97.
            I spent a lot of time going through the old data books at Halted trying to figure out what was in them.  Along the way, I got permission to completely reverse engineer it from Brusa.

            If you want a bad main board with bad chips for spare parts, I could dig it out.  The board itself may be in fair shape.

            For the money, I think a Cycle Analyst is much better money spent as a replacement.  A lot more than an AH meter.

            On 10/8/2013 10:38 PM, geo.homsy@... wrote:
             

            Ditto what Rex said --  The V to F converter in the brusa is VERY carefully designed.   You will have to really know what you're doing to get this from an arduino -- you need to build a proper analog front end.


            That said, I did use an arduino to build a multicolor programmable bar chart display for my dash, to indicate SOC and current.  But I didn't build the front end -- I'm taking signals off my BMS.


            I do have very good familiarity with the Brusa front end, having repaired different parts of mine several times.  Willing to answer questions on repairs not covered by the "one thing that always goes wrong" problem.


            @Charles:  Some of the op-amps are obsolete, but there are FAR better pin-compatible replacements available in the same package.  I wouldn't let that stop me from repairing one.  And the 40xx series CMOS chips are still mostly available.


            //Geo



            ---In solectria_ev@yahoogroups.com , <kdo@...> wrote:

            Mine never gave any trouble after I redid the coating. There's a lot
            to be said for doing this before you have problems. At a minimum,
            cover over the openings so the board isn't exposed to condensation from
            the air.

            Ken

          • geo_homsy2
            Charles- how far did you get with the reverse engineering? I did a lot of it (without permission from Brusa -- didn t occur to me to ask), and I have my notes
            Message 5 of 8 , Oct 9, 2013
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              Charles- how far did you get with the reverse engineering?  I did a lot of it (without permission from Brusa -- didn't occur to me to ask), and I have my notes drawn up, but just in paper form.  Do you have anything formal that you've written up?


              //Geo



              ---In solectria_ev@yahoogroups.com, <cbliss@...> wrote:

              I guess I gave up too quick looking for pin compatible replacement chips.  I ended up pulling the guts out of my '93 and merging them into my '97.
              I spent a lot of time going through the old data books at Halted trying to figure out what was in them.  Along the way, I got permission to completely reverse engineer it from Brusa.

              If you want a bad main board with bad chips for spare parts, I could dig it out.  The board itself may be in fair shape.

              For the money, I think a Cycle Analyst is much better money spent as a replacement.  A lot more than an AH meter.

              On 10/8/2013 10:38 PM, geo.homsy@... wrote:
               

              Ditto what Rex said --  The V to F converter in the brusa is VERY carefully designed.   You will have to really know what you're doing to get this from an arduino -- you need to build a proper analog front end.


              That said, I did use an arduino to build a multicolor programmable bar chart display for my dash, to indicate SOC and current.  But I didn't build the front end -- I'm taking signals off my BMS.


              I do have very good familiarity with the Brusa front end, having repaired different parts of mine several times.  Willing to answer questions on repairs not covered by the "one thing that always goes wrong" problem.


              @Charles:  Some of the op-amps are obsolete, but there are FAR better pin-compatible replacements available in the same package.  I wouldn't let that stop me from repairing one.  And the 40xx series CMOS chips are still mostly available.


              //Geo



              ---In solectria_ev@yahoogroups.com , <kdo@...> wrote:

              Mine never gave any trouble after I redid the coating. There's a lot
              to be said for doing this before you have problems. At a minimum,
              cover over the openings so the board isn't exposed to condensation from
              the air.

              Ken

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