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  1. C

    laptop battery challenge

    Seems like a lot of the folks on this forum know how to accomplish some pretty awesome stuff with electronics, so I wanted to offer a challenge. I know a number of Haitians who use laptop computers off-the-grid in Haiti. Small solar panels are not particularly expensive, but the cost barrier...
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    9-speed cassette freehub

    In order to use your existing shifter, you'd need a 9 speed freewheel. Search google for 9 speed freewheel. Note that your crystalyte wheel with a 9 speed freewheel may be too wide to fit in your frame. With a steel frame, you can just bend to fit if you want; non steel frames (any metal or...
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    Need advice on mixing chemistries

    Just one of those 48V20Ah packs is some serious range. Two packs and you'll be able to go a long, long way.
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    Do 5303's make noise?

    At anything near 100% of the no-load speed, pulse width modulation is normally not what limits the current to the motor, it's just I=V/R (current equals voltage divided by resistance) because the effective voltage is small (back EMF voltage being nearly as high as battery [forward] voltage)...
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    will a car wiper run a dc ebike motor

    I suspect car wiper motors are something like 50 watts at the most. The motor and controller are both designed for that kind of low power use. If you want something that even matches a low power ebike, neither the DC controller nor the motor will be suitable, I suspect.
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    System (U, Motor, Controller) Efficiency

    This is for the commute I used to do. The motor's controller broke and I switched jobs, and these days I commute without a motor. 1. Efficiency (Watt-hours/mile): 6 - 7 watt hours per mile 2. Speed (mph | kph): 16mph (65 minutes each way, 17 miles each way) 3. Gradient (%): lots of hills, 10%...
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    use 48v 20ah on rc controller

    If it breaks we will know why. It apparently has capacitors (and other components, maybe) that are designed for 50 volts (actual volts) max. The ping battery is rated at "48V" but its actual voltage during use starts at about 56 volts and only drops to 48 volts when the battery is nearly 100%...
  8. C

    Reconfigure Ping LiFePo4 battery?

    Each cell may be folded over on itself several times. A 48V12Ah pack that's made of 3V4Ah cells must be set up as 16-series x 3-parallel for a total of 48 cells. (note, most packs do not have the same number of cells as their voltage.. just a coincidence)
  9. C

    Reconfigure Ping LiFePo4 battery?

    to the best of my knowlege, your pack consists of cells that are 4Ah, nominal voltage 3V. (actual operating voltage closer to 3.1V to 3.4V) If that's true, you could set it up as 72V 8Ah provided you had an appropriate BMS or some other way to avoid over-discharging individual cells. The...
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    7, 8, 9, 10 speed inefficiency

    On an e-bike that you pedal, yeah, 5 speeds should be enough. E-bikes can keep much more consistent speeds with up-hills, compared to regular bikes. So there's generally no need for ultra-low gears.
  11. C

    Odd lengths of wire between batteries.

    If it seems like the long wire is eating more energy than you want it to, all you need is a wire that is fatter than necessary... Like fechter says, the wire will drop the voltage some, (under load only) but not the current. If the total voltage of the pack is dropped too much across the wire...
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    BMS's That are Available NOW

    What component is used to switch the capacitors?
  13. C

    experts weigh in: 72v at 10A or 36v at 20A, performance?

    Besides high amperage and high voltage, another factor that could influence whether or not your gears will strip is rider+vehicle weight. If you put a lot of power into the motor and there isn't much resistance then why would the gears get damaged... but if there is a lot of weight to keep the...
  14. C

    Manufacturers/Dealers to Gravitate Towards

    Peak power of 1,400 watts is a lot! Yes, crystalyte 4xx motors can do well over 1400 watts but, assuming you are not looking for an e-motorcycle, 1400 watts should do.
  15. C

    Motor Bicycling Max Speed

    The 20mph is part of what can get you within the definition of "bicycle" and out of the definition of "motor vehicle". If you're riding a "motor bicycle" (moped) you may need a vehicle registration and liability insurance. Once you have a registered mo-ped, it's probably not legal on bike paths...
  16. C

    Extreme efficiency?

    The way to make aero efficiency go much higher is to get yourself a full coverage fairing similar to the varna diablo. (There are a number of copies of that fairing, and one or two Varna molds where a person can make his/her own fairing.) http://images.google.com/images?q=varna%20diablo...
  17. C

    Thread for new battery breakthrough PR releases

    it looks likely that they're nonrechargeable, and they may never become rechargeable. half the "power" may actually refer to half the energy density... ...relative to alkaline nonrechargeable cells maybe?
  18. C

    Connecting two BLDC motors in series?

    This is correct. What Papa is missing is the fact that there's very little reason why the motors would want to maintain the same RPM at different speeds. Going around a very tight u-turn at very low speed, the inside wheel will receive slightly more torque than the outside wheel. But the outside...
  19. C

    2 Brushed motors in series will....

    Papa, you've got it right. Two in series will get all the amps and half the voltage. So you should expect twice the torque. The only way to know for sure if it'll work well is to try it, though. If you want to, you could also try halving the voltage of your battery (for example if it's four...
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    The REAL difference between 30mph and 50mph !

    The bicycle speed/power calculator http://www.kreuzotter.de/english/espeed.htm says that: 1000 watts gets you about 37 miles per hour on a road bike and 43 miles per hour on a high end timetrial bike. (upright bicycles). According to the calculator 1000 watts gets you about 73 miles per hour...
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    How to reverse brushless motor, even if it wont.

    Whether or not the motor has sensors, it MAY be possible to run it off of a sensorless controller, and then switching two of the phase wires will be enough to put it into reverse.
  22. C

    48V, 93 MPH

    The extra weight is an advantage, maybe, in the sense that you do anything you can do to keep the thing going in a straight line with all of its wheels on the ground....
  23. C

    Cyclone Current Draw?

    run longer wires, (to the front of the tandem) and go light on the throttle. I didn't realize there was no currentlimit in the cyclone controller. I used a 1c-rated 24v10ah battery with my cyclone and never tripped the 20-amps bms current limit. But this is using the motor as assist only, on...
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    fwd ice(honda)+ellectric driving rear wheels

    I saw a honda CRV (i think that's what it was) trying to reverse in snow, and the rear wheels were spinning while the front wheels just sat there. That was the first I ever realized that they might use a freewheel on an SUV or car made by a major auto-maker.
  25. C

    19 new 100 mile range electric cars announced

    It would, but I think it's about as likely to exist in our lifetimes as warp drives and star-trek transporters.
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