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    "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS...

    I was just going to place my order, but the TP Packs website is selling old printers, software, and movies from the mid 1990's?
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    Will noise generated by switching effect shunt mV signal?

    There are quite a number of places to buy shunts on the cheap. http://ebike.ca/store/store_accessories.php has a 300A shunt, 0.25mOhm. So that would be 75mV at 300A. I would recommend this one for your ride. That's a 300A continuous rating. I use a 500A, 50Mv ( .1mOhm) Shunt on my 350A...
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    BLDC Efficiency at different voltages

    I believe I've made a noobish mistake. All of these graphs are sampled at 100% throttle, maximum acceleration. However, decreasing the throttle compresses the efficiency curve, effectively raising the motor's efficiency at lower speeds.
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    BLDC Efficiency at different voltages

    Thanks Amberwolf for the link to the simulator. True, they're not the same hub motors, but the physics should be the same. I would have guessed that graph #1 would have been the more accurate one: But according to the simulator, it appears that graph #2 is closer to reality: Can anyone...
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    BLDC Efficiency at different voltages

    I'm planning on building a BLDC hub-motor driven scooter. The motor is 7kW, 72V, and 11.5Kv. I plan to overvolt it to 96V. It should theoretically increase my top speed from 47.2MPH to 62.9MPH. My question: Is motor efficiency a function of (current RPM / maximum RPM)? I'm trying to figure...
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    "Zephyr" - Finally, the "v4" Fechter/Goodrum/Hecker BMS...

    This looks really good. I'm looking forward to using this BMS in my 24S, 40Ah scooter.
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    Minimum Lifepo4 for a 750w motor?

    Ping batteries are rated for 2C continuous, 4C max. 2C from a 10Ah, 36V pack is 720 Watts. That's certainly pushing the boundaries. Headway cells, however, are rated for 5C continuous, 10C max. That would be 1,800 watts continuous from the same size pack. If you buy Headway 10Ah screw...
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    Help troubleshooting Zapino - No power to wheel

    Hi all. I'm trying to troubleshoot a friend's 2007 Zapino scooter. He recently purchased it from a previous owner. They claim it was dropped on the right side while the power was off, and now power won't go to the wheel. The error LED in the instrument panels flashes 1 and 2 repeatedly. - -- -...
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    Capacitance balancing BMS connection

    Have you had any progress on your PayPal claim, Spacey? There hasn't been any action on my dispute at all, although PayPal says, "We'll contact you with any developments or if we require additional information from you by Jan 31, 2011." We're a few weeks past that deadline now...
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    Removing Decals...

    I successfully removed the decals. I tried the oil, but it didn't seem to penetrate. I ended up using a hairdryer on low to gently heat the decals. The first one I heated the entire thing, and it came off in a gooey mess that left sticky residue behind. The remaining three decals I heated...
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    Removing Decals...

    Is that without using heat?
  12. G

    Removing Decals...

    I've done a lot of work on my X-Treme XM-3500li electric maxi-scooter. I added cells, replaced the dashboard with a digital version, and changed out the controller and motor. It's essentially a brand new bike. At this point I would like to start doing conversions for other people, and I don't...
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    Batteries vs Cold ☃

    From personal experience, cold cells definitely affect energy output. Normally my 24 x 40Ah Thundersky pack can get my motorcycle up above 60MPH, but last week it was 39 Fahrenheit and I couldn't push it faster than 47MPH. I was concerned it might be the new controller I put in last month, but...
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    New EV Range Calculator

    Haha of course we could go back to the processes of farming and food production as well, but the farther back we go the more unknown variables... I'm just trying to determine the validity of the bicycle calculator, and why there is a discrepancy between it and my calculator. I guess you could...
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    New EV Range Calculator

    I can't see the code behind their calculator, or have a complete understanding of the equations they're using. However, it seems to me that the key to the problem is that you're measuring losses in the conversion of electricity to work, where in a human powered bike those losses are ignored...
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    New EV Range Calculator

    I believe that the inefficiency lies in the electromechanical resistance within the motor and transmission. In the bicycle calculator I put in 200lbs combined weight, MTB tires, and 75% system efficiency. It gave me 13.5 MPH at 160 watts. Is the 160 watts the amount of energy being consumed...
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    New EV Range Calculator

    SamTexas, That bike calculator that you link to seems like it's intended as an exercise guide. It does not take into account battery chemistry for one. Second, the power field is the total power output to the pedals so it has no concept of motor or controller losses. I could add more...
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    New EV Range Calculator

    I've had requests for the calculator that I use to estimate the usable range of an EV. It takes into account aerodynamics and battery chemistries. EV Range Calculator The example above is for a lead-acid based bicycle, but it will work for lithium-based large cars and trucks as well. You...
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    Capacitance balancing BMS connection

    I ignored the picture that is upside-down because there is no reference point to the rest of the board. Naturally, I used the schematic drawing which shows that the negative-most connection goes on the side of the board with the B- lug connection. I wired it properly. Does your own wiring...
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    What's your quickest e-bike 0-50kmh time?

    Not a bicycle, but a maxi scooter. It was originally an XM-3500Li, but now it's more of a 6000+... Time (No pedals):~3.5 seconds Motor: Kelly Controller 4500W 13" brushless hub motor, high speed version (~17.5 Kv). I'm abusing it. Controller: Kelly Controller KEB-72801X 350A, 50% Battery...
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    Capacitance balancing BMS connection

    Spacey, Has EV Assemble replied to your PayPal dispute? I haven't heard anything from them and it's been nearly a week. Remember that you have to escalate the dispute after a reasonable amount of time, or PayPal will assume it has been resolved and close your dispute! I think it's a two or...
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    CycleAnalyst: Tuning Watt-Hours?

    The pack's nominial voltage should be around 36V, but under load it will sag. Still, 60 Wh divided by 2.3A is about 26V. I can't imagine why voltage would sag 25% under a reasonable load. If you cycle through the displays on the cycle analyst, what values is it giving for min and max voltage?
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    Capacitance balancing BMS connection

    I've filed a paypal dispute:
  24. G

    Capacitance balancing BMS connection

    Michael hasn't replied since I sent him the picture of my setup that I labeled. During the times he hasn't contacted you, he was contacting me. He has no excuse. He'll probably claim to be on "Chinese Holiday" or something. I'm forced to file a PayPal dispute as well then... EVAssemble is...
  25. G

    Capacitance balancing BMS connection

    I provided evidence to Michael that the BMS and resulting fire was not my fault and asked for a refund of the cost of the BMS ($37) to my PayPal account. He is arguing with me that I wired it wrong and that what I'm saying needs to be "verified by his engineers". I think he's stalling for...
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