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  1. T

    Motor controller with variable regenerative braking

    Hi, We are going to build 3 test benches for mid drive motors. My question is related to controllers with regen capabillity. I have used controllers from Sabvoton, Kelly and TIs Instaspin FOC development boards - most have been a simple coasting regen, where the instaspin board did full...
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    Lacing 13G spokes into 8G/9G/10G spoke hole

    Hi, Long story short. Bought motorcycle style motor, custom made. Spoke holes are Ø4,2mm in diameter. Going to lace in bicycle rim. Ordered to length 13G spokes. I want to do this somewhat the right way. Problems: 1. Spoke hole too big, nipple falls through 2. Spoke "neck" too short in...
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    Bafang communication protocol UART

    Hello, I'm interested to know if anyone has done any reverse engineering on the bafang controller - display communication protocol? It seems to be a relatively simple UART connection. The best would be to get the standard directly from Bafang, as there is sure to be some commands that are not...
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    E-Bike efficiency high inflated

    Tested one of our ebikes to 64% total system efficiency when going on a trip from about 0moh to a location known to be 520 moh. No human input. BBS02 around 500W, 1C discharge on ~3C capable battery. With 85% motor efficiency, 90% battery efficiency the system is already at 76% theoretical...
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    Battery mount brackets

    Hello, Just looked at these brackets at lekkie.bike. Is there other and cheaper sources for such clamps?
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    Vacation in America

    I’m just home from 10 days in Orlando, Florida. Went on vacation after working like mad for the last half year. I went with my GF and experiencing USA was different from what I expected it to be. Firstly, cars everywhere! Holy shit, crossing the street is easier in a car, then on foot. We...
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    Trike with all wheel drive?

    I've been fortunate enough to be able to build a cromotor powered hardtail bike this summer. With a kelly controller it behaves nicely at low throttle, but twist the throttle and it most certainly will try to throw you off. Now it looks as if I will have another chance to build something...
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    Smart BMS

    Hello Endless-sphere, I've been working on a better BMS and I'd like to offer some members of ES the opportunity to test the first revision. This first batch is scheduled to be done in September 2014. In general: Every feature you would find on a normal BMS and then some Key functionality (By...
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    Simulation of Bicycle Frame Deflection

    I've run a fair share of thermal analysis in Solid Edge, but recently I tried out features to optimize mechanical properties of parts. I guess more would like to see this intro to optimalization in ST6, here is a tutorial to how this goes down. SFE2i_fLUfM Solid Edge is free for students and...
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    High power battery tester

    Recently I was allowed to drop all my compulsary labs in a embedded design class, and develop a battery discharger/cycler. Delivery of a build report will be the substitute for the labs. Scope of project Research possible solutions and build an automated battery tester that can handle high...
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    Building a durable 40 MPH bike

    So, I'm building a bike for my own school. There are some challenges that needs to be dealt with, I hope you can help me with some input. 1. The bike needs to be unisex. 2. The motor needs to output 100Nm without saturating, up to 45km/h (37mph). I was initially thinking HS3540, but I don't...
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    Allegro ACS758 current sensor IC

    Hi ES :) I see quite a few diy inverters using Allegro ACS758 current sensor ICs for current sensing. I've used them myself, the last batch I received went into a high prescision test bench for BLDC motors. Their use is for sensing DC and AC currents. I tested the hall ICs against a meter...
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    Conclusive proof gearboxes are awesome.

    Gearbox, no gearbox has had a debate with little proof and a lot of anectdotes flying wildly. In this example I will show you how implementing a gearbox can increase system efficiency and power. First things first, some measures of energy, power and rotation. Disclaimer: I'm european so I do...
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    Controller builders: Truly optimizing MOSFETS.

    Earlier I believed advanced control algorithms could overcome running 'hopeless' motors in the sence that they're extremely low inductance and resistance - giving a high current ripple. As far as BLDC is concerned - only low load conditions significantily improve with exotic algorithms like FOC...
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    What would you pay for the different parts of a BMS?

    This might seem out of line for some of you, but I'm researching this idea. I've worked alot on motor controllers, hoping to be able to sell them. After much failure and the general complexity assembling them, that project is still under development. Early on I made my own, quite rough, battery...
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    Controller builders: I was not going to share this with you

    But now I'm doing it. One of the keys to handling high power is handling the thermal challenges with it. China controllers use silicon pads or polyimide (kapton) tape to insulate the mosfets from the heatsink. I've found the perfect insulator - aluminium oxide. By growing a oxide layer 30-50 nm...
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    Controller Builders: Why High Amperage Shunts Suck

    So you've got yourself a good understanding of a three phase bridge, controll methods and electronics 101 - but when trying to get a reasonable shunt feedback from your high-powered system at high speed, you only meet problems. Because of their inductance and very low resistance - getting high...
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    Viking Bike v0.90, HS3540, 18s Konions, fibreglass pack.

    My build is nearly done, after much testing and failing. At the start of my build I was thinking of bringing 2000whrs of juice. I build a temporary pack with 1500whrs, but was already doing 70kmh - so I decided to make a sleeker package. The temporary build soon killed itself anyway. I learnt...
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    Stator material, glass steel

    So, I've been wondering what way to go to reach extreme performance in e-applications. For me the logical way is a gearbox and some very high rpm's. I've found a material witch I think enables this performance. It has a permeabillity of 600k (normal electrical steel is around 4k), a core loss...
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    Dedicated small powerful charger, some development questions

    Hello. I've finished my first prototype, and some questions have popped up. This is a small smps charger designed for current controlled charging with power factor correction. It checks pack health via middle point balance, thermistors and ah-in - ah-out. 1. As of this moment I get 12 bit...
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    Reviving overdischarged lithium phosphates

    I found this topic on another forum I often browse. This is what the user said: I was intrigued by this, what mechanics kicked into action here? Electrolyte repair of some sort? And, his 4*capacity seems to be out of wack?
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    Two phase BLDC vs Three phase BLDC

    I've researched and have a working prototype of a controller witch drives a three phase motor with Field Oriented Controll. FOC allways keeps the magnetic field in the motor 90degrees compared to the magnets - to ensure that all force go to make spinning force and not waste any on linear. FOC...
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    Bicycle range extrender.

    I see range extenders being discussed loosly in different threads here on ES. I'm thinking about experimenting with a small two stroke motor, witch should be able to produce 2-3 kW. Parts would be sourced from the moped crowd. A cylinder, case, crank, exhaust and injection system with a rc...
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    Making the products we want, intelligent bulk charger.

    Hello, I've got a lot of projects going - and lately I've been looking closer into battery management and charging. I want the charger to be intelligent in the sense that it will charge it up to the full 4,2V prior to riding. Storing the battery at 4,2V is not optimal, so storing it at a lower...
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    Controller builders: a gem about shoot through protection.

    Since I do not have access to the wiki, I'll share my findings here. Setting shoot through protection is often looked upon as: "Increase dead time until power consumption goes down, and then increase this figure some - to be safe". The problem here is Qrr, or "Body diode reverse recovery...
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