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48V Battery charging using Luna 1-5A / 80-90-100% - What should it be?

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    48V Battery charging using Luna 1-5A / 80-90-100% - What should it be?

    I decided to do some battery test charging at 80%, then 90% and finally 100%; all at 3A on my variable Luna charger. These are the readings I got when the charger shut off and on the display:

    80%-3A = 51.9V on charger / 51.8V on display
    90%-3A = 54.4V on charger / 54.2V on display
    100%-3A = 54.3V on charger / 54.1V on display

    Why doesn't the 90% and 100% have a difference? What should the readings be for each percentage level (80/90/100%) on a 48V Panasonic-Sanya GA 21Ah/1008Wh battery pack?

    Then I reduced the charging amps to 1A and left it on 100%. It did come back on. I left it there for 3-4 hours, but the voltage charge did not increase. I'm sure 3-4 hours on 1A with a full charge probably balanced out the battery pack nicely. Is that assumption correct?

    The end result was still ~54.3V on the charger and 54.2-3V on the display (kept switching the 10ths from 54.2-54.3-54.2-54.3V...

    I seem to remember that the 90% and 100% always had different charge levels in the past. One reason I did this is because I charged it 90% and noticed the level seemed to be at the 100% level on the prior charge. I'm wondering if I got one of those bad Luna variable chargers and it just started acting up???

    Did you leave it unplugged from both pack and wall for a minute between changing settings?

    The voltage/charge percentage charts are on hard and soft pack documentation pages.


      I unplugged the charger from the wall, then took the charger display reading. While still plugged into the charger, but with the charger NOT plugged into the wall I turned the bike display on and took that reading. Next I clicked the percentage charge switch from 80% to 90% and plugged the charger back into the wall socket for the next charge level. Repeated for 100% charge...

      Thank you for the link! For whatever reason I couldn't find those readings, even though I know I'd read them before. Here are the stated 80-90-100% readings from the chart in the above link for a 48V 13S pack:

      80% = 51.5V
      90% = 53.0V
      100% = 54.6V

      The issue appears to be the 90% setting charged to 100%. Don't know if anything in the procedure I did it makes a difference?


        It may vary somewhat depending on the model and revision but we usually recommend having the charger completely off when changing settings. As in, neither plugged into pack or outlet. Changing a setting may not register on all models if it's powered on at the time, and this could be from either wall outlet power, or power flowing backwards from the battery to the charger, or stored energy in the capacitors in the charger which takes about ten seconds to self-discharge fully. Not saying it will make a difference since it seemed to switch to the other setting fine, but it might.

        Hypothetically you could try adjusting the potentiometer in the charger. Not sure if it will work since it typically adjusts all of them, but it might be worth playing with if you want to see how it affects things.
        (do not leave battery unattended if experimenting with fine tuning the pots)


          I'm not going to open it up and change anything. It should work as is or be replaced!

          I think the 54.3V I'm getting at 100% charge on 3A is okay. The problem appears to be the 90% level; it's charging at the 100% level. The 51.9V I'm getting at 80% on 3A is okay too.

          Basically there is no difference between the 90% and 100%. I usually charge it to 80% shortly after I return and top it to 90% if the days ride doesn't need the full 100%, but just before this test I noticed the 90% was at the 100% level; thus the problem that appears to be verified in my test and the last charge below.

          Today the charger was unplugged from the wall and battery. I switched the slwly up to 100% one click at a time, then back to 80% one click at a time and finally one click up to 90%. It was already set to 3A. I topped off the battery before todays ride and it charged to 54.3V; same problem as before, and all switches were set with everything unplugged.

          Now what? I guess I'll try it a few more times to see if it resolves itself...


            Ok..I'm just giving general advice, I have no idea when it was purchased or anything like that if you are saying Luna should replace it. If you've already confirmed initial testing and you don't want to open it then yeah there's probably not much you can do. In any case what you are describing does not sound like clicking chargers, sounds more like the switch used on the knob isn't making proper contact in position 2.


            • Rider
              Rider commented
              Editing a comment
              Yeah, the 90% is the same as the 100%. It charged it 100% again when set to 90%. Kind of frustrating, but the 80% is working so that is my new charge level after a ride. I will keep flipping the switch around and stop on 90% to charge before each ride. That way I can see if it is sporadic or continuous.

              At least it isn't preventing me from riding! :-)