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    What could I check

    Hi,

    I own an E-Solex (see here). This bike is powered by a 400 W hub motor feeded by a 36V / 15 Ah Li-ion battery. This battery has been refurbished four years ago (new cells, new BMS).

    A couple of wecks ago it happened, after this bike fell down from its stand, that the motor was unable to produce enough torque at starting or when climbing, even pedaling to help. It seems like there were kinds of vibrations transmitted all along the frame, making an awfull noise.

    I checked all connexions that can be seen and I tested battery voltage : open crcuit near 42 V, reducing to 38 V when climbing my uphill street witout any assistance .

    Sometimes the BMS cut off power but it's always a short while after the resistive torque decreased. I have to unplug and replug the battery in order to restart. Once the BMS went into security mode and I had to plug the battery to its charger to recover.

    I wonder where does the problem come from, cells, BMS, controller, Hall effect sensors ? What to ckeck and how ? I own a mulimeter and a scope but everything works fine when the bike is on its stand.

    I shoud precise that this awfull noise I talked about has always been produced when starting with 2 positions speed switch on low.

    Thanking you in advance for your help.

    Heffgé



    Last edited by heffge; 05-20-2020, 08:58 AM.

    #2
    Its very helpful that you checked voltage under load. That's good, so in one test, you showed your power system is delivering okay, you don't have excessive voltage sag from a bad connection or cell, if you can climb a hill at 38V, or only 4V sag. That is quite good.

    I should confirm, that you measured voltage as present at the controller, not inside the pack, am I correct in assuming this?
    *if at the pack, you could still have a bad wiring connection, check at controller end of harness.

    I think I'd look, next, at wiring from controller to motor. Especially phase wires. Maybe one is damaged. Could explain the starting noise, too.

    Or, maybe its a sensor or it's wiring, as you noted.

    Showing good voltage at controller input is a great start in narrowing things down.
    Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

    Comment


      #3
      Thanks for having paid attention to my problem. I'm sorry to answer so late but I h'd been quite busy those last days (grandson at home).

      What I cheked today.

      No difference if voltage measurement is made at the pack (on the charge socket wich is connected internally to the output) or at controller connectors.

      Motor phases disconnected from the controller, ohmmeter shows 0.6 Ω for any of the three combinations. Coils seem OK.

      Bike on its stand I measured 28 V AC at full speed beetwen phases. When a load is simulated with brakes (levers switches unplugged) this voltage goes down to about 15 V except for one combination where it goes up more than 35 V, ( I didn't want to insist too much) when the wheel is about to stop. I don't know if that means something.

      There are five wires for the sensors. That puzzles me and I dont know what kind of measurment could be made.

      I hope these poor indications will lead you to suggest more investigations.

      Comment


        #4
        Hi heffge,

        This post (#2) should give you some insight on the motor's hall sensor testing.

        https://electricbike.com/forum/forum...864#post101864


        Does the wheel turn with any resistance (magnetic braking type) at any time, or does it change between when the controller is connected or disconnected from the phase wiring?
        See the phase wiring test to induce resistance for a feel of it.



        Regards,
        T.C.
        See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

        Comment


          #5
          This post (#2) should give you some insight on the motor's hall sensor testing.
          Thanks for the link. It gave me the key about the 5 wires connected to the sensors.

          I tested them as suggested with a 6 V DC power supply and a 10 kΩ resistor. For each sensor, when turning the wheel, the voltage goes from 5.99 V to 0 .02V every 30° rotation (12 magnets on the rotor ?). That's lead to think the problem is somewhere else.


          Does the wheel turn with any resistance (magnetic braking type) at any time, or does it change between when the controller is connected or disconnected from the phase wiring?
          No change.

          Then check resistance between each phase wire at a time and a metal part of the motor. It should read infinity or open circuit.
          No short circuit.

          tie two phase wires together in different combinations at a time for a total of three tests. At each combination, a similar magnetic resistance (also known a "cogging ') should be felt while trying to turn the wheel.
          As I turned it the wheel seemed strongly braked and resistance got up to about 200 Ω and was ... negative (no matter multimeter polarity). Because of the difficulty to turn the wheel I can't say il the values where identical on each of the 3 tests.

          Checking the phase connectors I discovered one might be the culprit. The lug was not firmly crimped and wire could slip in it. I replaced it with a new one but without any change to the problem. And from a few days it goes worse and worse.

          Now the BMS switch off power after riding a quarter of a mile, sometime less. I have to unplug/replug quickly the pack 3 or 4 times in order to restart.

          So is the result of my checkings and the situation today.

          Hoping you can help me further.

          Regards.

          Heffgé





          Comment


            #6
            Originally posted by heffge View Post
            Sometimes the BMS cut off power but it's always a short while after the resistive torque decreased.
            Can you explain this statement to me?



            Does the wheel have resistance to turning by hand at any time? (excluding brakes or other mechanical interference.)

            Are you able to check the battery's current output while riding?

            Did the wiring going into the axle for the motor sustain any damage from the fall? (scuff, pinch, scrape, cut, ETC)
            See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

            Comment


              #7
              Can you explain this statement to me?
              I meant that BMS switched off power after clambig not while. Actually, after a few trips, I have now a more accurate appreciation of what happens.

              It works for the first half a mile then the BMS switches off. Then il switches off after fewer and dewer distances. Each time I have got to proceed as I explained in my last message. It seems like the BMS protected itself from a too high temperature.

              Does the wheel have resistance to turning by hand at any time?
              Yes but a slight one and it has been so from the biginning.

              Are you able to check the battery's current output while riding?
              My multimetrer can't measure over than 10 A DC. I'm afraid more would destroy shunt. And I haven't got any clamp ammeter to measure phase currents.

              Nethertheless I tested phase voltages beetween them : 30 V AC for each of the 3 cases at full speed and 27 when braking but the rear brake is quite inefficient. And 45 V beetween any phase and the negative terminal from the pack.

              Did the wiring going into the axle for the motor sustain any damage from the fall? (scuff, pinch, scrape, cut, ETC)
              The 8 wires are enclosed into a sheat, the same type as used for brake cables. Near the wheel there is a metallic casing to protect the sheat where it's right-angled to enter into the axle. The fall might not have any impact.

              From my point of view this awfull noise might indicate that there is not enough current to feed the motor but which is the culprit, the controller or the BMS ? This one is the result of a long history. To say it briefly I had to purchase this model and mount it by myself because the one installed by the shop which refurbished the pack didn't feed the controller requirements (it acts as a 2000 µFcapacitor leading to an initial current over 1000 A when pack is plugged on).

              Hoping these indications can give you some idea about the origin of my problem.

              Regards

              Heffgé

              PS : Please be indulgent with my english.


              Last edited by heffge; 06-09-2020, 07:15 AM.

              Comment


                #8
                Originally posted by heffge View Post
                From my point of view this awfull noise might indicate that there is not enough current to feed the motor but which is the culprit, the controller or the BMS ?
                If this is the same noise as noted when the motor was always started in low speed? Is it possible the two speed switch was damaged with high no longer working?

                As a BMS is a protection device, I doubt that it would be the source of the problem. With it reacting to an over current issue, or under voltage problem. As you've seemed to have eliminated a voltage problem. (Full voltage after charging, and maintaining voltage under load.) A current issue would be suspect. As it doesn't seem to have a temperature sensor, or specs to that effect. I don't see that it has over temperature protection. But having current capabilities of almost 4 times what would be required by your motor. The current would have to be quite excessive.
                It would be helpful if you would consider installing a current and voltage monitor device such as this...
                A Bayite DC 6.5-100V 0-100A LCD Display.



                May help to troubleshoot, but is really nice also to just keep track of your battery state of charge and usage. (less than $20...) But you will need to wire in a rather large shunt...

                https://electricbike.com/forum/forum...6346#post56346

                Excessive current can be produced by bad phase to hall sensor configuration or damaged wiring to either. I would re-check the motor phase windings and wiring. Checking for shorts/opens.
                When resistance is mentioned in testing, while tying two phases together. This is the physical resistance to turning, not an electrical measurement.

                Does any component (motor or controller) get hot to the touch under load?

                Is this a geared hub motor?
                See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

                Comment


                  #9
                  Here a short video if you are interested about what this bike looks like and below a pic of the pack connector and an other sowing the messy wiring .
                  Click image for larger version

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                  Click image for larger version

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                  If this is the same noise as noted when the motor was always started in low speed?
                  Yes quite but il lasts longer, I mean until I reach 10 or 12 Mph.

                  I would re-check the motor phase windings and wiring. Checking for shorts/opens.
                  Thats's what i'll do.

                  Does any component (motor or controller) get hot to the touch under load?
                  The phase wires heat but it has always beeing tne case. Lugs isolation melt and I had to replace them a couple of times. From my opinion phase wires are too thin, thiner than those outcoming from the controller. I'm looking for a 3 pins connector like the one below but suitable with the diameter of my wires and hight current.
                  Click image for larger version

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                  I' ll chek for others other components.

                  Is this a geared hub motor?
                  I haven't got any idea about that. I h'd say no but you introduced doubt in my mind because it's a bit hard to pedal whithout motor working. But the most often you can't easily spin manually an electrical motor just as the front wheel of a bicycle.

                  I'll come back whith more details I hope.

                  Regards.

                  Heffgé
                  Attached Files

                  Comment


                    #10
                    Hi,

                    I'm not like giving up. This week I made my decision, I removed the wheel end extracted the left cover of the motor as I thought something might have move inside because of the fall.

                    I didn't see anything like that, just there are 40 magnets around the rotor. After having reassembling the motor and the wheel I tested. No more noise !

                    I'm just coming back from a 5 miles test ride and everything worked fine.

                    What hapenned, I'll never know.

                    Anyway, thanks to you I learned a lot of things about those motors and I did appreciate your help and your patience despite my approximate english.

                    Best regards.

                    Comment


                      #11
                      Glad to hear that you eliminated your problem. You sound as stubborn as me... ;-) Wish I had your magic touch though. Cheers!
                      See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

                      Comment


                        #12
                        The miracle didn't last a long time. No more noise but now it's like the pack is out of order

                        The bike doesn't run as fast as before even on flat streets and BMS switchs off power at the first hill. I have to unplug and replug the pack to restart and to do that again 3 or 4 times for a 1 mile ride.

                        There is a five leds charge indicator. I suppose it just shows voltage. Very quickly there are only two of them staying lighted. So I tighted my multimeter on the handle base to catch more informations when riding.

                        After full charge output voltage is almost 42 V at stop and drops when motor is running, and is only 34 V when the BMS switchs off. From specifications, the freshold for excessive discharge is 2,5V per cell !

                        Would that mind a whole rank of cells (7) is damaged ? I can't imagine it.

                        I suspected something wrong with balance connections so I opened the case but I didn't notice any damaged wire.

                        I am about to have this pack refurbished once again (for the equivalent of 600 $ !) but I wonder if I can be confident with my BMS. I'm afraid they install a new one witch would not fit with the very high instantaned current at connecting time. I'd like to keep mine but now I'm not so sure that it's safe.

                        From your experience do you think only the cells are unserviceable ?

                        Thanking you in advance for your opinion.

                        Heffgé

                        Comment


                          #13
                          One bad group, 2 poor groups, or several weak groups. Only way to check for sure is to check the voltages at the BMS connector.





                          Then decide what to do...


                          Still wish you had a amp meter on it so you could see both sides of the story. ;-)

                          Are the battery connectors clean and making good contact?
                          See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

                          Comment

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