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Error 30 apparently it's the dreaded error 30

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    Error 30 apparently it's the dreaded error 30

    What I know is I get Err 30 on the display (C961) connecting to my Luna BBS02 with upgraded controller. I had added an extension cable for the display. That extension cable is a high suspect since I had altered it by adding 3 inches in the middle. I took that extension out of the system (perhaps too late) and got the same error. I tested with an extra main harness that is brand new and got the same error. Also, I can't connect with the programming cable using either harness. So no contact with the controler. The bike had run properly for four short rides 1 - 2 miles each with the suspect cable.

    I am a newbie so I don't know how tough the BBS02 is but I don't think it was being abused. Running only 20 amps I was going up a gentle incline (3-5 degree) in a high gear but only after ascending through the lower gears and we were going over 20mph. I felt the motor housing right after and I figure it was about 120 - 130. It was hot but not so much I couldn't keep touching. The battery was not warm at all. I checked the voltage on the battery when I got home 52.6 * 20 = 1052 watts

    Also it had rained light and brief early in the ride but was dry when it cut out.

    Since I can't get through to the controller, I am afraid it's dead.

    My ideas on how this happened:

    1. My soldered extended cable might have shorted out the controler
    2. I cooked the controller riding uphill with 1052 watts
    3. Got rain water in a critical joint and shorted
    4. I don't know what I'm talking about and there is some other reason I don't know about and have not tested for.

    Does anyone have more troubleshooting ideas or thoughts? I don't want to have to buy and install a new controller but I will. While I have the case open, I'll install one of those temperature probe thingys.

    It sounds like the controller to me.
    How big is your chain ring?
    Sounds to me like you put too much strain on it using that higher gear.
    Kind of a Cardinal rule is to let the motor run fast using proper gearing.
    Also the BBS02 does not like steep or long hills from all I have read on them.
    I have BBSHD and regularly do 20mph up inclines in the 5 degree range; but I'm never out of the 1-3 gear range on a 10 speed cluster with a 42t chain ring when I do it.


      My chainring is 46t. I thought as long as I was putting in pedal power it would not strain too much. I'm going to ask the 30 minute tech for a second opinion and then order a replacement. In a way I'm glad to hear it's not necessarily my bad soldering but my bad behavior ;)


        750W “rated” kit I suspect above 1000W for “too long” might explain cooking the controller? How long is too long? Anything more than a quick burst across an intersection or a quick/short hill.

        There’s no free lunch - motors have “rated power” for good reason. Although bursts of “peak power” may be tolerable, no system can be expected to survive running excessive power levels for any length of time. Meaning sustained load/run.

        Another factor is electric motor RPM and efficiency. Bafang units become more efficient at upper RPM ranges. Trouble is, riders like to “feel” some pedal resistance at 25 MPH but if that’s happening, you’re probably wasting more electrical energy to heating the now inefficient motor windings than your legs contribute.

        46T front chain ring? Luna offers 30T for good reason.


          Well, the 46t is the smallest one that comes with the kit I bought. I did want a smaller chainring but every little bit costs. Of course now I'm ordering a new controller $. I followed the recommended troubleshoot process below and am sure enough it's the controller. Thought I was being conservative limiting the amps to 20. After reading so many posts about for sure you should set that amperage up to 25.

          Not sure I understand about people liking to "feel" the power. Yes, I love the feel of the power but not sure what the lesson was and I love to learn my lessons too. I've limited the throttle to 20 mph per California law and I have enjoyed the realization you can achieve 20 in all but the lowest gear and did so to keep the revs up. When pedaling along I can barely keep up with the cadence when I'm up around the legal limit of 28 (which is supposed to be achieved by pedelec) so if I get that smaller chainring will I never get up to that speed any longer?

          Well, I started this project with the intent to learn more. Now that I will have a junk controller, I'll be able to see if I can get it working again. I know I read an article on how to rebuild a burnt controller. So if (prolly when) I burn out the new one I'll have a spare :)


            error 30 is indeed the most dreaded error of the bbsxx....

            i guess it would translate to mean "critical error"

            that being said its usually a damaged wiring harness or wiring pin.... but other that that it can be a bad display, a bad controller or a failed motor.

            Its a pretty broad error that is the hardest to pinpoint the exact problem....


              Continuing troubleshooting. Because of simplifying the system and using an alternate harness I'm confident enough to have ordered a new controller. I checked the home-altered cable last night for continuity end to end and dis-continuity from pin to pin at one end. It passed just fine.

              What is confusing me is another test with the handy multimeter found here: The working theory is I burned the controller (a..k.a. the mosfets in the controller). It passed this test at least as far as I can tell. I got a voltage across the fets through the negative pole and no voltage across positive which according to the document means it passed. Is this not a good test for BBS02? It is for an outboard controller, not BBSxx. I tested with the connections still attached to the motor and without. The voltage on the negative side changed slightly but it was consistent and still infinite resistance across positive.

              Could the problem really be the motor side of the unit. That part is supposed to be much less vulnerable to burnout and the motor was not that hot when it happened. Should I wait to test with the new controller or just dive in to test the hall sensors? I'd rather not crack open the motor side. Anyone have thoughts?


              • ykick
                ykick commented
                Editing a comment
                I've tried that MOSFET test before using 3 different DVM's (ohm meters) and got 3 different results. Also, it doesn't need to be the power FETs blown to cause a controller to fail. Blown BBSXX MOSFETs usually exhibit extreme resistance when rolling the bike backwards with the chain attached. Be aware there's always a little resistance but I'm talking about so much that the tire might slip if it were on gravel or loose surface?

                You have a USB cable? Disco the dash/display and plug the program cable into that connection - put the battery pack in cradle and test if you get anything with throttle? The USB program cable powers the system and allows throttle and PAS to work without a display. Easy test to rule out the dash/display as an issue without ever connecting the USB side to a computer.

                What I meant by "feel" is that people want to input leg power at 20-30 MPH and I have never figured out a reliable way to do that. It's because of the way the unit is internally geared in relation to the electric motor RPM. By the time you slow the electric motor down enough to input anything from your legs at those speeds the electric motor is operating in horribly inefficient RPM range and wasting significant battery energy by heating the motor windings.

                That's ok at slow low wattage regions of operation but when you need to burn 500-1000W continuously to maintain a high cruise speed or long hill climb, it's better to let the electric motor wind up in RPM and at that point legs really won't add anything.

              "What I meant by "feel" is that people want to input leg power at 20-30 MPH and I have never figured out a reliable way to do that. It's because of the way the unit is internally geared in relation to the electric motor RPM. By the time you slow the electric motor down enough to input anything from your legs at those speeds the electric motor is operating in horribly inefficient RPM range and wasting significant battery energy by heating the motor windings."

              Ok, I understand what your saying now. So, not doubting at all, why does it not drive heat and not power in lower gears? The pedal cadence is still slow. The way it works when on my non-powered bike, my legs are delivering the same power at all speeds and all within the same general cadence. It's just the gears that change the speed or torque based on the ratio. Something here is not intuitive. I input power at those lower gears and the chainring spins at the same speed all through the acceleration. Maybe that is toxic and overheating too. It would make sense. Maybe that's why it burned....

              I've been thinking hard about this issue since I realized what you were saying. I'm thinking for sure I want to shrink the chainring. I have a chain-line issue and have been eyeing the 42t Lekkie ring to help with both issues. I was already planning to follow an article I read to separate and rearrange my cassette to present a tighter cluster of gears in a better chainline. The 30t rings have no offset so the chain-line would get worse. In the meantime I think I'll do that cassette switch and just get rid of the highest gears and keep the low ones. That will give an improved highest gear.

              You say at high cruise speeds it burns 500 to 1000 watts. Since the unit is rated at 750 could it sustain that level? I was trying to come up with an assist schema in the config tool where the top PAS level would deliver 15 amps or ~750 watts. I want to keep the throttle at full amps.

              I tried the program cable test you told me about and still no joy. The controller is supposed to be here on Monday. Thanks for your help and advice.


              • ykick
                ykick commented
                Editing a comment
                True, for lower road speeds (10-15MPH) and the legs feel resistance the motor is still operating inefficient RPM range. But since the power levels are so much lower, it’s not a huge waste or even a noticeable problem. Those are the best speeds/conditions to get your workout, IMO. Not 20-30 MPH…

                Sounds like you're understanding the operating envelope better and if you work out the chain ring and rear cluster combo to something more reasonable you'll enjoy ample performance and long service life.

                BBSHD with 42T front ring turning large tires I rarely find much need for anything less than 14/16T rear.

              Whelp, I'm back on the road. The new controller came in after a seeming eternity. After getting the phase wires crossed the first time I plugged in (dark room green and blue looked similar) I got it installed and working. Of course I had to re-do my wire harness and essentially re-work everything. I'm getting better at it with practice.
              I hacked my cassette. I ground off the retaining rivets and re-arranged the sprockets. Now the lowest gear it can get is 14t in the back instead of 11t. I'm a geek so I plotted out a spreadsheet with the ratios and the hack I did is as effective as buying the 42t Lekkie ring I was looking at. The left column is my cassette before adjustments. It also has the effect of improving the chain-line.
              My altered cassette is the one to the right. I used the stop screws on the derailleur to limit what gears can be used. The ones highlighted in red are out of bounds and the derailleur can’t use them:
              Plate # Teeth Ratio v 46t Ratio v 42t Ratio v 30t Plate # Teeth Ratio v 46t
              1 11 4.18 3.82 2.73 1 11 4.18
              2 12 3.83 3.50 2.50 3 14 3.29
              3 14 3.29 3.00 2.14 4 16 2.88
              4 16 2.88 2.63 1.88 6 20 2.30
              5 18 2.56 2.33 1.67 7 23 2.00
              6 20 2.30 2.10 1.50 8 26 1.77
              7 23 2.00 1.83 1.30 9 30 1.53
              8 26 1.77 1.62 1.15 5 18 2.56
              9 30 1.53 1.40 1.00 2 12 3.83
              I reprogrammed the controller. The PAS I set to use a peak of 900 watts. I set the “Current Decay” to a low number so it will drop the current to a holding level of 550 watts at a high pedal cadence (with the new low gears I get there soon). If I just spin the cranks at a low cadence I guess I can “trick” it into keeping a high wattage over extended periods, but I could do that with the throttle much easier so I won’t.


                Super glad to hear you got it diagnosed right and fixed.
                Nice job with the cassette mods - that makes a lot of sense to me.
                I really like the idea of shifting the gears you want towards the center and improving the chain line.

                Does your shifter work well going to what you labeled as plate #7?
                I have a 42t 1st gear on next bike I'm almost done with, and would want to keep it if I did something like this; but I'm afraid my newer model shifter would not like it.
                You got me to thinking that it may be possible to modify the 11 speed 42t to something like a 5 speed with some spacer washers and then be able to utilize the thicker stronger 5 speed chain!
                If anyone has seen this sort of thing I would be interested in any details or links.
                Last edited by FatMarty; 10-07-2017, 02:49 PM. Reason: Ask question about shifter.


                • Joules
                  Joules commented
                  Editing a comment
                  Dang it has been a long time since I was here. Yes, the gears work well. It took some tweaking of the screws but that's probably because I'm an amature at being a bike mechanic. Shifting to the largest sprocket does not feel... sharp. It does stop but feels a little mushy. I guess it's because the stop screw is adjusted to a point the designers weren't expecting it to. That's what happens when you hack things. They often work but are slightly imperfect. I have been enjoying the bike since. I ride 22 miles without pedaling hard enough to sweat. Which is good cause I work in an office.