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BBSHD powers down at PAS level 5

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    BBSHD powers down at PAS level 5

    I just purchased a used fat tire (donor) bike with Luna BBSHD and a 52V 12ah (seller stated that is the battery size) that I will be switching to a GT Avalanche 29" mountain bike. I took the fat tire bike for a ride last night and had the whole system shut down on me every time I reached PAS level 5, which is over 1000 watts of power per the display. I am waiting for the programming cable to be mailed to me but am wondering if the display is causing the shut down or something else? The battery was charged to 80% prior to the ride. I had to unplug the battery connection each time in order to turn the system back on. Ideas? I am not very electrically inclined but have a friend coming up from the Bay area at the end of the month who is an electrical engineer. Thanks!
    Last edited by Tall Guy; 05-03-2021, 02:09 PM.

    #2
    Update: I rode the bike again after work and now it will randomly turn off even if I am only at PAS 2, using 600 or less watts. Still unknown reason as to why.

    Comment


      #3
      Does it do that if it's fully charged? How old is the pack, how many cycles? Is there significant voltage sag on it? Is your display set to read voltage, if not please switch to voltage not percent, percent is for 48v not a 52v pack like that one

      Comment


        #4
        It is currently 93% charged and I was told it only had 4 charge cycles since it was purchased. It is reading 52.6V but I didn't notice a voltage sag. Original owner bought everything a year or so again from Luna.

        Comment


          #5
          Year or so I think SO is the operative word, that is a V1 pack so I think its at least 2018 age wise. 4 cycles isn't much so its been sitting a long time and you have to wonder what sort of care or attention it got over all that time.

          If some sort of programming was shutting the system down the display would stay on. If the display is going dead its a connection issue or the BMS in the battery shutting things down because its sensing low voltage. My V1 pack will reset itself without having to connect to a charger so that does fit that you can get it back.

          If it was me I would be rigging up some way to slowly and steadily discharge the pack. This could be on the bike in a trainer or just raised off the ground or a larger old school light bulb or another member recently discovered an electric griddle is a great way to load a pack. Run it down slow and steady till the BMS cuts it off. Ideally you will have a volt meter connected to it during this process so you can monitor what is going on and when it cuts off. A $15 meter from Home Depot is fine for this, doesn't have to be fancy and will likely come in handy for other things on and off the bike later.

          After it discharges put it on the charger up to 100%. Repeat the discharge process. Repeat the 100% charge process. Maybe then try a ride again? The idea is with all that sitting the cells have likely got way out of balance. Most of the BMS's you find on e bikes don't balance till you are close to 100% so if you are not charging to 100% normally you need to from time to time to make sure you get them to balance. In this case you also want to do the slow steady discharge to help the balance too. They sort of balance as you discharge them as long as its slow and steady so we are just trying to even things out and hope there is no serious damage.

          Comment


          #6
          Thank you, 73 Eldo. I'll give that a shot. Downside is I just learned from Luna support I will probably not even be able to use this motor on my new bike as it is 120mm and won't work with a 73mm bracket.

          Hopefully I will be able to sell for what I bought it for to someone who wants a fat tire e-bike. Guess that is what I get for relying on the seller's assurances instead of doing more research myself.

          Comment


            #7
            Originally posted by Tall Guy View Post
            It is currently 93% charged and I was told it only had 4 charge cycles since it was purchased. It is reading 52.6V but I didn't notice a voltage sag. Original owner bought everything a year or so again from Luna.
            Just to be clear, when we refer to "sag" we are considering how much the battery voltage drops under load - how much voltage with zero load at rest then how much voltage when loaded significantly, that difference in voltage is "sag"... no offense meant if you already understand that

            Sag is greater at low SOC's (lower battery voltages)


            When I read your post the first thing that popped into mind was that you are getting excessive sag under higher loads and that is tripping an LVCO


            Like 73Eldo says I'd run it through several cycles of 100% charge and good steady discharge. the 200+W pan is good for this, will take 2-3hrs to discharge and is a light enough load to minimize risk of damaging cells that are terribly out of balance and high enough to be able to see some sag - and use some sort of meter, percent bars provided very low value regarding battery voltage and SOC

            Comment


              #8
              120 is a lot for a 73 bb. Thats pretty much 2 inches of extra space which all ends up on the non chain side of the bike. An extra inch isn't terrible, some actually like it because it gets the crank arms more centered and some people say that bothers them. Most people don't seem sensitive to that especially the typical E bikers that are not athletes. 2 inches is getting to stick out pretty far and would require a lot of spacers which would not likely be good long term for staying tight.

              I assume the fat bike is just too small for you? If it was a reasonable size then you could look at swapping on some 29" wheels since they are about the same diameter as fat 26's. There are also some more mellow tires that fit fat rims that can make them a little more decent on the streets but if its too small none of that will help. If you can afford it maybe keep it around for others to ride? Unless you like riding by yourself you will be trying to convert others to e biking and its nice to have an extra bike around to let them ride and hopefully get hooked so you have people to ride with. Having an extra bike that is smaller is usually good since it fits more people and even tall people that have not ridden recently tend to me more comfortable on smaller bikes. My other justification for having an extra bike is spare parts. Even if the BB with is different there are still a ton of parts that can swap between units. Just having the ability to swap displays and cables can be handy for if you have issues with one bike.

              Comment


                #9
                Thank you both. I am not versed in electrical stuff so learning more about voltage is helpful. Yes, I am 6'5" and the bike frame is definitely too small for me compared to my 29" tire 21" frame mountain bike. Hanging onto it for friends to ride is a good idea, but will limit my buying a new motor/battery for awhile until I have the funds again. I'll see if I can find a electric griddle at Goodwill or borrow a friends. :)

                Comment


                  #10
                  Great idea on the goodwill. I would guess they have a ton of them for cheap and since its turning into a shop tool don't really care if its a little crusty or is missing the cord or lid.

                  Now where to tell you to find alligator clip wires. Home depot seems to sell the clip part but not with the wires. They are easy to find online but 97.53% of them are total garbage that will never take the 5 amps we need here. I think I will jump back to that thread and claim your goodwill idea then ask if anyone knows an easy place to get the leads.

                  Comment


                  • AZguy
                    AZguy commented
                    Editing a comment
                    Frankly about anything will take 5A, it's not a big deal and even cheap alligator clip leads will work fine... like I mentioned I'm using 20AWG relatively cheap leads I picked up at Frys

                  • 73Eldo
                    73Eldo commented
                    Editing a comment
                    Last couple fairly cheap sets I have bought looked like maybe a 22 gauge but only had a single strand inside so maybe a 40 gauge? Also if you squeezed the them the wrong way you just crushed them. That quality and style seems to be sold under a lot of different names these days. They are the ones that come in multi colors in a set of like 12. I don't remember what I was doing with them when I discovered how bad they were, thinking it was using a 9v battery so not talking much current there.

                  • AZguy
                    AZguy commented
                    Editing a comment
                    I may be optimistic that the ones I'm using are 20AWG and wouldn't be surprised if they are thinner - it was just a WAG.. I still wouldn't worry, even 26AWG (or smaller) can carry 5A although if they are that small they may get warm - the ones I'm using aren't even getting warm that I can tell by touch

                  #11
                  I just talked to the seller and he graciously agreed to refund me my money. Now I need to purchase a new BBSHD mid-drive and battery. I'll open a threat on the bike build for suggestions on what I should get/need. Thank you again for your input! I'm sure it will come in handy in the future.

                  Comment


                    #12
                    Thats good to hear. Makes me think they guy wasn't likely out to screw anyone, he just doesn't understand that sitting for 2-3 years at least may have killed the pack.

                    I think I saw Pax say that they have a shipment of 73mm BBSHD's sitting at the LA port now so hopefully in the next week or 2 they will find their way into stock. You can go to that thread and ask to be notified by email when they do come in if you don't want to check every day. With items like the BBSHD kits they seem to get quite a few in with every order so they don't tend to sell out in hours or days like smaller quantity stuff like bikes do so you don't have to be checking the store multiple times per day to catch them.

                    Comment


                    • Tall Guy
                      Tall Guy commented
                      Editing a comment
                      The 73-100mm is in-stock right now. I know the 73 is right where I am at so I wonder if it would be a good fit or just wait for the normal size to come in.

                    • 73Eldo
                      73Eldo commented
                      Editing a comment
                      Dunno. The BBSHD has a little extra length on it to start with over the BBS02's so I don't think you will need the extra space on a 73. Going to the 100 is an extra inch you have to fill with spacers and that will be sticking out the non drive side, that's kinda a lot if you don't need it.

                    #13
                    Did you check your main power connections for quality, corrosion, or bends in the wire; all things that may increase resistance and lead to thermal system shutdown?

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