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    First e-bike build

    Hi everyone, im new to electric bicycles but i recently returned from a vacation in Venice beach where they had powerful 16 mph scooters available to rent for $1+ 0.15/min and i loved it. I want to create a bike powered by a rear hub motor and 28x 28650 batteries at about 52v. I have bought nothing at all just yet, i want to make sure i don't regret my purchase within weeks. I was hoping since the people on here are presumably far more experienced than me, that i can learn from a few peoples mistakes and save myself the unfinished project.

    my list so far is:
    https://www.ebay.com/itm/IMax-B6-Dig...0/252047704675
    https://www.ebay.com/itm/26-1500W-Re...g/322269304808
    https://www.ebay.com/itm/Lithium-Bat...V/282802860786
    https://www.aliexpress.com/item/6pcs...30453c00EmYmok
    https://vruzend.com/product/vruzend_basic_kit/

    #2
    My two cents worth:

    The motor
    • That one is quite a powerful direct drive rear hub motor. It may be more power than you need.

    The battery solution:
    • If it were my 1st build I would not be building my own pack as you plan. I don't think you save a lot of money doing it that way and you may not get the result you want.
    • I would be buying a quality pack capable of delivering up to 30amps continuous if you want to drive that motor to its capability.
    • If you do ahead with the BYO battery:
      • Those are not 28650 cells; they are 18650 cells. I have never heard of that brand so have no idea of the quality.
      • That charger you point to would make charging very clumsy as you would have to charge groups of cells separately. You want a bulk charger to charge the whole pack through the BMS. (Most prebuilt packs come with a charger.)
      • Are you sure the Vruzend kit can handle 30 amps discharge?

    Comment


      #3
      I think i would rather the motor be more powerful than less, if there was a more powerful rear hub motor option that i can afford, i would get that. Especially since the kits are $160-$250 there is no changing my mind if i i want more power( i will).
      Yeah i looked at so many batteries, i must have missed that it is a 18650 not 28650, my mistake. I don't know anything about 18650, but those are re-branded LG batteries that presumably have failed testing.

      14 batteries with 3ah each would give 42ah of battery life and cost around $30, Wouldn't a similar pack be $200 or more?

      Yeah amp bottlenecking is an issue with the Vruzend kit, but there are a few ways to minimize this such as using multiple stripson top of each other and even a wire jumper if necessary. I copied what they said about amp limits below. According to their logic, 14 batteries x 3.5 can handle 49 amps. Unfortunately there's no way im getting my hands on a spot welder, so it will have to do.

      "We recommend that for best results, you limit the current draw of the battery pack you build with Vruzend battery caps to approximately 3.5 A continuous per cell. Current bursts of up to 7 A are acceptable, but for periods not exceeding 10-15 seconds. Higher current results in more waste heat being generated which can rob your pack of performance. That means that if you build a battery with six cells in parallel, you should try not to exceed about 20 A continuously with that pack, though bursts of higher current are ok. We’ve had some people do tests with higher current, but it usually isn’t worth the extra waste heat. Extremely high current can even be dangerous. Please be safe and don’t try to pull too much current from your battery cells – this is true with any battery building project, not just with Vruzend kits."

      For the charger yes i have a few bulk chargers, but i was under the impression i would have to use the iMax B6 to discharge and test cells before assembling the battery.
      Last edited by valueseek; 09-28-2018, 07:29 PM.

      Comment


        #4
        My 2 cents on power level: my first ebike was 250W. Not surprisingly, I sold it off in order to build an ebike with more power.

        My second ebike was 4kW, and that was too much (scary!). I dialed down the power so that I ride around now limited to 2900W. My cruising power is about 2300W, but I will push it to 2900W while accelerating. These power levels are the highest at which I feel safe.

        I have one battery which is ill so that battery can only support a max power level of 2kW. I rarely use that battery because 2kW feels like too little power.

        In short, my sweet spot is 2300-2900W for street commuting for a 240 pound rider, 95 pound bike and 10 pounds cargo.
        Last edited by commuter ebikes; 09-29-2018, 05:26 AM.

        Comment


          #5
          Originally posted by valueseek View Post

          14 batteries with 3ah each would give 42ah of battery life and cost around $30, Wouldn't a similar pack be $200 or more?
          Not really.

          A 14s2p config with 3Ah cells would provide 6Ah capacity at 52V. And the max continuous current draw for the pack would be twice the max continuous current draw for each cell as there are 2 cells in parallel. A 1500 Watt motor running flat out will want 1500/52 = 30 amps.

          As I say, just my 2 cents worth. It's your build.

          Comment


            #6
            commuter ebikes- thanks for the tip, i will strongly consider getting something in the 2000w-3000w range. I am coming from dirtbikes and 1000cc supersport bikes so the extra power would be very welcomed. Any motors i should consider in particular? I've been trying to research other motors but there's very little accessible information online to make a decision. The voilamart motors on ebay have 2000+ sales so im just going of that.
            Fred- I appreciate the 2 cents, it is my build but i am also very inexperienced so you all commenting here really does help a lot. I think i understand everything you said except for "A 14s2p config with 3Ah cells would provide 6Ah capacity at 52V". What i wrote was just for an example with only 14 batteries not in parallel. I think understand you are saying is my range is doubled and amp requirements halved when using 14s2p as opposed to 14s1p.

            Edit: i understand now, i read an equation to calculate amp hours and it was completely wrong. 6Ah is not a lot for 1500w motor. Im still leaning toward making the batteries, but it will take a lot more than i thought. On the plus side, max continuous current draw should be less of an issue with 14s3p(anything wrong with odd batteries in parallel?) or 14s4p.
            Last edited by valueseek; 09-29-2018, 10:00 AM.

            Comment


              #7
              Originally posted by valueseek View Post
              commuter ebikes- thanks for the tip, i will strongly consider getting something in the 2000w-3000w range. I am coming from dirtbikes and 1000cc supersport bikes so the extra power would be very welcomed. Any motors i should consider in particular? I've been trying to research other motors but there's very little accessible information online to make a decision. The voilamart motors on ebay have 2000+ sales so im just going of that.
              Fred- I appreciate the 2 cents, it is my build but i am also very inexperienced so you all commenting here really does help a lot. I think i understand everything you said except for "A 14s2p config with 3Ah cells would provide 6Ah capacity at 52V". What i wrote was just for an example with only 14 batteries not in parallel. I think understand you are saying is my range is doubled and amp requirements halved when using 14s2p as opposed to 14s1p.

              Edit: i understand now, i read an equation to calculate amp hours and it was completely wrong. 6Ah is not a lot for 1500w motor. Im still leaning toward making the batteries, but it will take a lot more than i thought. On the plus side, max continuous current draw should be less of an issue with 14s3p(anything wrong with odd batteries in parallel?) or 14s4p.
              I have hub motors, but if I had to do it over again, I would get a 3000W mid drive (e.g., a Cyclone). Mid drives are much better on hills, much easier to change a rear flat tire on, and you can have more many more gears.

              The only reason I would use a hub motor (again) would be if I was trying to hide my motor from LE. Actually, this is important to me. As if LE can't tell that the bike has a motor when I am going 25-35mph.

              I definitely would not buy a motor off of eBay! Buy it from Luna. Big difference there as far as customer service and backing the product.

              FYI my battery is 20s9p which is seemingly an arbitrary number of rows in parallel. It doesn't matter how many rows you have in parallel, but the more the better if you want to pull a lot of juice!

              Comment


                #8
                Commuter ebikes- "As if LE can't tell that the bike has a motor when I am going 25-35mph." That gave me a laugh. Hmm the luna 3000w mid drive is the one to get eh? I've been looking at the new leafbike hub motors for $179, but the luna kit isn't too much more money and is obviously far superior. Thanks for the tip, looks like i might have found a winner.

                https://lunacycle.com/cyclone-mid-dr...planetary-kit/

                Comment


                  #9
                  Picked up this old trek 4100 for $25 today, this will be the base for my electric bike.

                  Comment


                    #10
                    Originally posted by valueseek View Post
                    Commuter ebikes- "As if LE can't tell that the bike has a motor when I am going 25-35mph." That gave me a laugh. Hmm the luna 3000w mid drive is the one to get eh? I've been looking at the new leafbike hub motors for $179, but the luna kit isn't too much more money and is obviously far superior. Thanks for the tip, looks like i might have found a winner.

                    https://lunacycle.com/cyclone-mid-dr...planetary-kit/
                    That would work. I like 72V systems. I can get up to 46mph with 31.5" O.D. tires for short periods (no wind, flat ground, battery hot off the charger, no cargo) and I can travel at 40mph under any circumstances.

                    The Cyclone 3000W kit in the link quoted above is what I would recommend (common part, replacement parts and service easily available).

                    If it is the case that (1) there are just about no hills on your route, (2) you can live with a single speed (12-23T freewheels available, but only 16-23T if you want appreciable quality), and (3) you are willing to run flat proof tires (e.g., https://tannusamerica.com/), an easy hub motor build is http://www.qs-motor.com/product/1000...rop-out-150mm/ plus a Kelly controller such as http://www.qs-motor.com/product/kell...less-dc-motor/

                    QS Motors are wired to plug right in to a Kelly controller. I buy Cromotors and Lyen controllers and I have to solder my electrical connectors (which I enjoy doing!).

                    FYI the tallest geared (12T) single speed freewheel is found here: https://west-coast-electric-cycles.m...peed-freewheel. Not easy to find SS freewheels geared this tall. That freewheel is neither high quality nor able to be serviced. I use White Industries freewheels when I run a single speed and the tallest that they sell is 16T.

                    Continuing on with a hub motor setup, you can fit a 5-speed freewheel such as https://www.universalcycles.com/shop...s.php?id=87465 if you use a frame with 190mm dropouts. You can fit a 3-speed freewheel (not recommended as I have never seen any quality 3-speed freewheels for sale) if you use a frame with 170mm dropouts. But I see you already bought a bike with standard dropouts so that is one more reason to choose a mid drive so that you can have plenty of gears.
                    Last edited by commuter ebikes; 09-30-2018, 10:03 PM.

                    Comment


                      #11
                      So the hub motor info was probably a detour.

                      Getting back to the Cyclone, that really is a great choice. I really like the fact that it is a common motor. Like I said, I hope that you choose a 72V system so that you can get your speed on.

                      You can reap the benefits of the fact that the Cyclone is so common by Googling just about any questions that you may have about it (or post the questions on this forum).

                      The reason that I dogged eBay is that I have bought a lot of things on eBay and had so many problems. I still buy a lot on eBay, but only small items and usually from sellers that I am familiar with. I believe that many eBay sellers are so focused on keeping their costs down that the buyer often ends up with inferior products. This is okay for some things, but not for electronics that may leave you stranded and walking your bike home.

                      Sometimes I may sound like a shill for Luna, but I am not an employee (never have been, but I would apply if I my wife were willing to relocate). I have followed ebikes very closely for about 3-4 years, and it is my opinion that the Luna crew is very enthusiastic about getting riders on ebikes and I understand that they have a small profit margin/high sales volume strategy.

                      Luna helped me out a lot by creating this forum. This is a very friendly forum. I want to thank all of the members for being so polite and respectful.

                      Riding bikes is fun!
                      Last edited by commuter ebikes; 09-30-2018, 10:21 PM.

                      Comment


                      • xcnick
                        xcnick commented
                        Editing a comment
                        Originally posted by commuter ebikes View Post
                        I want to thank all of the members for being so polite and respectful.
                        Oh bite me! Time for you to do a cyclone and come up to the mountains and ride with me.

                      • commuter ebikes
                        commuter ebikes commented
                        Editing a comment
                        That’s funny!

                      • xcnick
                        xcnick commented
                        Editing a comment
                        Valueseek, I have 5 running BBSHDs and one coming today in the mail. Never done a cyclone because the HD is just too damn easy. I need to do a cyclone too. I wonder if Commuterebikes will like shifting. I am over it. An electric motor can be designed to do the job without shifting. Gimme one of dem. I would say BBSHD to start, then a Ludi if you can get one. The next power step would be ERT or Grin for a Phaserunner controller and 72 volts so it is not so peaky. At 150lbs and unlimited funds for drivetrains I don't need more power than the Ludi to get the job done, stock leaves me short on hill climbs over 30 degrees. Peaky is what two stroke guys say when the usable RPM range is only double digits. To know when to shift my HD I make sounds like my Yamaha mini enduro of 50 years ago. ring a ding ding, shift, reeeee, shift, reee, shift, re, shift. r, shift times ten. Commuterebikes and I need to work out the math for big guys. I have a guy who weighs twice what I do and the stock HD performs for him about like the least powerful Focus I tried. It only weighed fourty pounds so it was fun, if under powered. I only hope my buddy finds his 55 pound bike as fun. But he needs more power. He has to pedal steep hill climbs which if funny as hell for me. With the seat up climbing, the crashes are spetacular! When he loops out there is no catching it and on his back he goes. With the seat down I can just stand up and let the bike crash without me when it loops out. That was wordy.
                        Last edited by xcnick; 10-02-2018, 07:00 AM.

                      #12
                      I decided the cyclone 3000w kit will have to wait, i'm not ready to invest the amount of time and money needed to install it. I got the hub motor and it has been working great so far, however i need to make a larger battery to try the full 35a the controller can push. I also bought a second motor for the front to help the rear not heat up during heavy use. The most annoying issue i've had is not being able to test cells because the fake imax b6 i got only works at 0.5a for some reason; and the Opus BT i got drains them all the way down to 3.3v which is too low for me. Still haven't found a way to test cells, maybe ill try to find a real imax b6 after i return the chargers i bought. Update with pictures coming soon.

                      Comment


                        #13

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                          #14
                          front controller is 26a rear is 35a to make 61a 2,928w total

                          Comment


                            #15
                            valueseek, so what battery did u end up connecting to your rear and front motor? The pic of the bike battery bag looks small to be running 61A .

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