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    Rheostat and adding another battery to ebike for more volts

    I don't think that is right. Adding another battery of equal capacity and voltage (in this case 48V 10ah SLA) in parallel doubles the Amp-hr capacity and current capability. There is no need to tie the individual cells together, as this is SLA chemistry and I doubt very much his bike has any...
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    Rheostat and adding another battery to ebike for more volts

    I think you are confusing parallel with series. Putting them in parallel would mean the same voltage, but double the capacity and double the battery current capability (but current is likely limited by your controller). You need to check your controller, but it is likely about 50-60V max...
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    Rheostat and adding another battery to ebike for more volts

    From your original post I gather your goals are primarily increased range, and secondly increased speed. Your idea of using a rheostat doesn't sound appropriate at all, even if you knew your controller could handle more volts. Also know that other systems on your moped are likely made for the...
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    19" Motorcycle Wheels vs 26" Bicycle Wheels (rim and tires)

    Thanks, Rix. 18x6.4mm nipples seems too small for my wheel. The nipple holes in the rim are 8.1mm diameter. I'm guess your ERD is about right though. I plan to buy the spokes from Buchanan and the aluminum nipples from either Buchanan or Prowheel (prowheel cheaper and they are available...
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    The Unofficial 'CroMotor' Owners Tech-Tips Thread

    I have no doubt that the cromotor is one of the best motors out there (that doesn't require extensive modification to use), but it is also one of the more expensive and there is a long wait to get one. I would like to compare it to others, and the only way to objectively do that is using...
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    The Unofficial 'CroMotor' Owners Tech-Tips Thread

    Does anybody have a performance test report for the cromotor at 72V (or so) they could post here? I see there is one for 48V posted early in this thread, but not sure how well that scales...current should scale linearly, and input power as V^2, but that isn't exactly true, since the magnetic...
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    Motor lifetime

    I disagree - I think it could possibly lead to problems. Not saying this is happening, but the shape of the hysteresis loop of steel undergoing flip-flops in magnetization polarity, such as the stator steel does in a operating motor, is very important in regard to energy losses. Any changes...
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    Motor lifetime

    Folks, after doing some reading, I think I have found the answer. The phenomena is called "magnetic aging". from wikipedia article on electrical steels: "...The presence of carbon has a more detrimental effect than sulfur or oxygen. Carbon also causes magnetic aging when it slowly leaves...
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    Motor lifetime

    I agree, so why would a vendor even bring it up? Usually people don't want to say their products will wear out in 3 years, especially if that isn't true. I am just wondering if we are missing something, or if the design or materials of the particular motors listed are problematic. It would...
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    Motor lifetime

    I agree with most of what you posted. As for hard/soft, sorry I should have made it clear that by "soft" steel, I mean't magnetically soft - which means it doesn't retain much magnetization (low remanence) and the magnetic orientation is easily changed (low coercivity). An example of a...
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    Motor lifetime

    I would add that a permanent magnet can be partially demagnetized by strong external fields. I don't have any idea if the fields from say putting 200a in the phase wires is enough, but I doubt it (although the demagnetization also gets easier with elevated temps). I agree though, a well...
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    QSMOTOR,0.5-12kW Electric Hub Motor & Mid Drive Motor Manufacture China

    Vito, I have questions about the 3-5 year lifetime. What steel are you talking about? Do you mean the permanent magnets? I don't want to hijack your for-sale posting with technical questions, so could you go to this thread and answer them...
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    Motor lifetime

    In the for sale new section, a guy that is selling QS motors is claiming that they only last 3-5 years before the "steel" "loses its magnetization" and the steel needs to be replaced to bring back efficiency. Since QS builds a large percent of the motors that are re-branded and sold for...
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    The Unofficial 'CroMotor' Owners Tech-Tips Thread

    I'm really getting confused now. Does anybody have a graph of the performance test curves of a cromotor? Looking at the the two QS motors I linked to in my post above, the v3 is only 5% better than the v2. But then I compared to another cromotor looking clone, the evel gt4000...
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    The Unofficial 'CroMotor' Owners Tech-Tips Thread

    Hi Cromotor guys, In the "for sale section" there is a guy selling QS motors that he says are identical to the cromotor, in both form and performance. http://endless-sphere.com/forums/viewtopic.php?f=31&t=65929 Is this true? He posts two performance curves, on for V2 and one for V3...
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    Tilt switch for master battery disconnect relay (contactor)

    Hi, I was wondering if anyone has played with putting a tilt sensor (few dollars from digikey) circuit in series with the master battery switch. The motive is to disconnect the battery in case of a crash. Two fears, the throttle gets stuck on, either mechanically our through a short and the...
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    DIY graphene high capacity supercapacitors -use a DVD writer

    Caps with energy capacity equivalent to SLA, if true, is impressive. Two points though: 1) Batteries tend to have all their rated energy capacity in the top 30% of voltage drop. Capacitors are energy rated all the way down to zero volts, and have only given half their energy by the time they...
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    Creating my own battery pack

    I agree, bolting prismatics is way easier, but you have less options and usually a higher price for the same performance as cylindricals. And prismatics have less flexibility in form fitting your battery space. I am still looking at that option As for cylindricals, specifically 18650 size...
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    Creating my own battery pack

    Yes that is true; many places will do a free spot welding service if you buy the batteries from them. I haven't ruled that out yet, as their equipment and technique is more dialed in, but there are three major drawbacks: 1) I want a high amp (150a) pack, and many of these battery places only...
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    Creating my own battery pack

    I would guess that surface prep is very important, as is clamping during curing. Cleaning the metal first is probably very important, and maybe fine scuffing. And of course, some epoxies are very sensitive to mix ratios and mixing thoroughness. But, that said, I don't want to be the pioneer...
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    Creating my own battery pack

    The units for electrical resistivity for any material are in ohm-cm (or milliohm-cm or ohm-m or ohm-inches, etc). If you look at my link, you will see that the epoxies manufacturer uses these units, and the resistances are even lower than my example. The reason the are ohm-cm is that when you...
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    Creating my own battery pack

    I know this is an old thread, but I was reading it and had to comment. Firstly, the proper units are 17mohm-cm (not mohm/cm). If there is a conductive epoxy with 17mohms-cm, then a 1cmx1cm patch wouldn't cause 7W of heat under 20 amps unless the epoxy was also 1cm thick. A real bond on...
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    19" Motorcycle Wheels vs 26" Bicycle Wheels (rim and tires)

    anybody know the effective spoke diameter for a pro-wheel 19x1.85 rim?
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    Avoiding fake batteries - how?

    Thanks. Those are Alibaba vendors right? You've had dealings with them before?
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    How do you recognize a real panasonic 18650pf battery

    You can also see the rank/grade stamped on the battery itself at the end of the battery next to the date code. I think someone (flathill?) has said in another thread that the grade has to do with factory sorting according to self discharge rate. A is best, F is worst...but don't know for sure...
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