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The First Volt

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    The First Volt

    I joined the forum in May of 2016 and the forum had not been open very long. In fact I went back and read every post that was made before I joined. since then I have been keeping up fairly well with what is going on.

    Anyway someone somewhere mentioned that you did not get much extra out of your battery by charging it up to max voltage. So yet another reason not to charge to 58.8 or 84.0 if you have a 72 volt battery. I filed away that nugget and didn't think about it again until the other day.

    I was riding my Electra Fat with an Edge 1500 and Luna's 72 volt 100 GA cell triangle battery. http://lunacycle.com/72v-triangle-pa...ebike-battery/ I had just charged it to 100% or 84 volts and that is what my Cycle Analyst was reading when I started out. I rode from my house to the entrance of the bike path and noticed that I was down a volt. I even waited a minute to see if the voltage would recover a tenth or two. No, One volt gone in .55 miles.

    So I started thinking what if I charge to a lesser amount will that first volt go away in .55 miles? I have been using a Grin Satiator to charge my batteries lately and I have setup some custom charging profiles for my batteries. I charge to 95% now when I am not trying to balance the battery. Today I left the house with 82.4 volts and kept my PAS at 500 watts like the previous outing.

    Long story short, I went 5 miles on the first volt and nearly made 10 miles on 2 volts. The second 5 miles may have been a little more up hill. It is now painfully obvious to me that you get nothing out of charging to 100% except Balancing the battery.

    I think my speedo is quite accurate because I checked it over a 30 mile trip with GPS and I was closer than 1%.

    It would be nice to run a whole trip on the flat and see how the battery does. I even know a path in RI that is darn near flat for 20 miles. I wouldn't have the patience to do that though. You know while typing this I remembered that Grin has a data logger. I will have to check into that...………...calfee

    #2
    I have the worst habit. I charge overnight. As soon as I wake up, I unplug the charger. After about 20 minutes, I top off for another 60 minutes while I finish getting ready for work. I do this because my 19.8Ah battery and "29A max current" setting barely gets me to work and back. I have been doing this for two years.

    This has got to shorten the life of the battery. Next time I will get a 26Ah battery and do things right.

    Comment


      #3
      calfee20, right after the end of charge the voltage starts dropping. It's fair for any cell. You could have that 1V drop even without riding that 0.55 mile.

      Comment


        #4
        after 6-7000 miles on ebikes I came to the same conclusions, charging to 100% is really only for balancing. That first volt really disappears quickly and only shortens the life. Heres a graph showing discharge. Save your battery and only go to 90% max 90% of the time.

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          #5
          Originally posted by thunderheart View Post
          calfee20, right after the end of charge the voltage starts dropping. It's fair for any cell. You could have that 1V drop even without riding that 0.55 mile.
          I don't agree. I charge to 84 volts, disconnect the charger, check the voltage on the cycle analyst, and turn the system off. The next day when I leave the voltage is the same. This may be due to the Grin Satiator because they really charge to the specified voltage. Part of the charging cycle is a .2 amp charge at the end for all of the cells to even out.

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            #6
            calfee20, you can refuse to agree with me but it won't change the battery's behavior:) A single 4.2V cell after being fully charged and disconnected from the charger will have ~4.12 or even 4.05V in some 20 minutes (without any load being connected). I can suppose that your charger keeps on charging at a very low current but it would be useless and very harmful for the battery.

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            • calfee20
              calfee20 commented
              Editing a comment
              I am just telling you what I have experienced myself. If YOU don't want to believe me,,, fine.

            #7
            Nerd fight!

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