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    Q128H right-hand side outer bearing size?

    Anyone here happen to know (or have a dissassembled Q128H to hand) the size of the bearing on the right hand side, between the outer cover and the axle? If anyone knows (or can measure) it would allow me to order a new one and not disassemble until I got it. Thanks.
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    The ultimate torque arm (For <2kW and standard axles)?

    Made from 10 or 12 layers of laser cut annealled spring steel and tempered to ~50HRC, it requires drilling & tapping a M4 hole 30mm away from the axle center. (The dimensions are flexible; by adding a series of 4mm clearance holes, an appropriate position can be chosen (and any excess cut off...
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    Aluminium torque plates: your choice. (Corrected)

    Update: Math corrected. I'd made several mistakes, but the upshot is that once corrected, it makes the point even more strongly. (Why did I my errors earlier? My excuse it that it is the adversarial nature of this place, and certain member's predilection for using pedantry to score cheap...
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    End turns bad?

    First. I know this is (probably) wrong, but I want to understand why, so please bear with me :) The conventional wisdom is that the end turns on a stator are dead weight. A couple of the explanations for this I've seen go: 1) They are outside of the width of the magnets, so do not contribute...
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    Supercapacitors vs batteries. Capacity.

    Supercapacitors are sized in farads: batteries are sized in watt.hours. Can they be compared? Farad is defined as Coulombs/Volts; and has equivalences as Amp.seconds/Volt and Watt.Seconds/Volt^2. Watt.hours is Amp.hours*Volts. Amp.seconds is 3600*Ah. Watt.seconds is Ah*3600*volts. A 3.2V...
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    Would you charge a 4s LiFePo with a "15V" wall wart (intended for charging a 12V SLA)?

    The title says it all. I'm looking to replace a 12V SLA (portable vacuum) with Li***, and would like to reuse the existing charger, because it is a wall mount&charger with bespoke connectors, and to save money. 4 x 3.65 = 14.6; but the 15V is the OCV; once loaded it will inevitably drop...
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    Two parallel packs made from different C rate cells.

    If I parallel two 10s4p packs made from different cells, samsung 26H & 29F, which are max rated as 5.2Ah (x4=20.8 ) and 8.25Ah (x4=33) respectively, and I occasionally draw 25A for short periods; what happens? Update: With more reading and thought I now think that the instantaneous demand will...
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    Anyone actually used the Boston Power 5300mAh cells?

    I've seen a few samples tested, but no one actually using them, despite that they seem to be very competitively priced?
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    Using a 1000W DD hub motor as a generator?

    My idea is to use a small RC gas motor and the energy concentration of petrol(gas), to provide a range extender to an e-bike. Rather than anything complicated like a hybrid drive mechanism, the thought is to save the weight of a dedicated generator attached to a gas motor by using a DD hub...
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    What limits the no-load speed of a motor.

    Take any motor and run it at 36V with no load and it will achieve some speed. eg. 300rpm (~36kph for a 26" wheel) giving an kV of 8.33 Now apply 48V and run it no-load again and it might do 400rpm (48kph). So what stops us just continuing to up the voltage to achieve ever greater (no-load) speed?
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    Samsung ICR18650-26x -- small spec. differences; big price difference?

    I'm looking on NKON site at Samsung ICR18650-26x cells in order to build a second battery that is compatible for paralleling with my existing pack that uses ICR18650-26F cells. They offer 3 variations: ICR18650-26F @ €3.40 ICR18650-26H @ €2.55 ICR18650-26J @ €2.65 I went looking for...
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    Short throw thumb throttle?

    I currently have one of these throttles: But I find it has a much longer throw than I would like. Are there non-twist thumb throttles with a shorter throw? Say 30-40° rather than 80-90°. Unfortunately, they don't list this detail in the sales blurbs. Thanks.
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    Known good BMS (for 10s)?

    The Amazon 10s4p battery pack that I recovered thanks to the kind help if the guys here seems to be standing up well. However, one thing I've measured is the difference in voltage/capacity drop if I leave the BMS connected and without. If I just let the pack stand without the BMS connected...
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    Surface resistivity & volume resistivity?

    I have the data sheet(pdf) for some Kemtron conductive foam. The specs give two figures for the foams resistivity: Surface resistivity: 0.05Ω/sq Volume resistivity: 0.015Ω/sq I was trying to work out what energy would be consumed if this was used to connect to a 18650 battery, but the...
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    4-prong battery connector; identification?

    Hi, My searches to find out what type or brand this connector is have failed: Does anyone know what they are called; or suggest a search term; or the best place to look? Thanks, Buk.
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    v-brake front fork mounting points?

    Not strictly an E-bike question -- though my purpose is e-bike -- are there any standards defining the dimensions of front fork V-brake mounting points? Thanks, Buk.
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    Visually distinguishing screw-on freewheels from "cassette freewheels"?

    There doesn't seem to be one definitive description that identifies screw-on freewheels from cassettes, and some listing are downright confusing: eg. "SCREWS ON TO ALL STANDARD MULTI-SPEED REAR HUBS WE STATE IN THE HEADING " SCREW ON CASSETTE " BECAUSE SO MANY PEOPLE CALL THESE FREEWHEELS A...
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    Which spoke length calculator?

    I just got a new rim, measured the ERD and fed it into two different spoke length calculators: Sapin.be site gives: 210.7 & 209.7 ebikes.ca site gives: 207.2 & 208.3 And I get different results. They each ask for a slightly different set of input data, but I've tried very hard to supply...
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    2WD logic?

    If you put two identical motors on a bike, presumably, you gain in torque; thus climbing and/or load carrying ability, but you are stuck with the same top speed as with a single motor. What happens if you combine two differently wound motors, say a "201 wind" and a "328 wind"? Ie. Does the...
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    All turned around.

    Do these numbers of turns vs. rpm/v make sense as is: 48V 290RPM motor's winding is 19turns, 6.04kV 48V 320RPM motor's winding is 18turns, 6.67kV 36V 290RPM motor's winding is 13turns, 8.06kV 36V 320RPM motor's winding is 12turns, 8.88kV Or is the absence of any information regarding the wire...
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    Xiongda 2-speed data for ebikes.ca simulator

    Does anyone have the appropriate data for the XD2 (36v & 48v) motors to plug into the ebikes simulator? I'm still frozen in cursed indecision about which of these variants to purchase and I'm hoping plugging the numbers in and running them will push me one way or the other; as my enquiries here...
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    Can anyone identify this geared hub motor?

    It is described as "36V/250W brushless geared hub motor", and not much more. I have a few more images from different angles, but this is the only one that (sort of) shows the logo on the hub itself. Thanks.
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    Fixing a (new) dud 36V10Ah battery pack.

    I bought a 36V 10Ah rack-mount battery pack from (via) Amazon. https://www.amazon.co.uk/gp/product/B01NGUGEED When it arrived properly packed and sealed, it turns out to be a dud.That is, there is 0 (zero) volts available at the output wires. I've done the return thing, got a full refund, and...
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    E-bike conversion economics.

    The basic question is can a competent DIYer put together reasonably efficient, reasonably light, reasonably powerful(legal, or legal+ a little bit) from parts, significantly more cheaply than buying a low-end but reputable kit. (And yes, I'm aware that its a big, fluid and ill-specified...
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