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    K2 LiFePO4 batteries

    I have been seeing these batteries on line - K2 Energy LFP batteries, 25.6V, 9.6AH. They seem to be coming out of some sort of medical equipment, like wheelchairs or something. They are going for very cheap - $50-60 online used. That means $250 per kwhr, which is better than anything outside...
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    Molex high current 3 layer boards

    Just talked to Molex about a process they have for making 3 layer boards. The center layer is stamped copper, so can be as thick as you want. (Could be .1" copper if you wanted that thick a materials.) The top and bottom layer are more conventional plated copper. This seems like it would be...
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    Need advice about cheap solar panels.

    About $3/watt.
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    Room temperature superconductors

    One of the holy grails in science is the room temperature superconductor. It's important because a superconductor transmits both heat and electrical power with zero loss, which would make motors, transmission lines, heat pipes etc far more efficient and practical. For a long time metals had to...
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    Question on switched reluctance generators

    A question for all you electric-machines people: So I think I get how an SR motor works. In motoring operation, phases are driven so that current is driven through a phase winding before the salient pole of the rotating core aligns with that phase winding. The energy in the coil is given by...
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    Merry Christmas everyone

    Have a good Christmas and a productive new year! May it be filled with better batteries, smaller hub motors and more efficient controllers.
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    EV efficiency - new record

    My Leaf got about 3.6 miles per kwhr; my Prius Prime gets about 4.2 miles. But purpose built cars are now hitting over 29 miles per kwhr. And this isn't a trike with a formed canopy and a bunch of solar; this is a four door, four seat vehicle that comes close to being practical (top speed of...
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    Climate warming = more solar/storage

    I just got a note from a solar installer in Northern California. He is seeing a big increase (just this morning) in the number of orders for battery backed solar power systems. As the climate warms, several things happen: 1) People turn on their air conditioners. Power demand goes up. More...
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    Note on battery placement

    Just a quick note on battery placement - I just switched my battery placement from rack bag to low on the seat tube (or whatever you call that tube right in front of the seat tube on the Montague frame.) And man, what a difference. The bike went from squirrely to rock solid, with no shimmy...
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    Odd motor failure

    This morning I pulled my bike out to go to work and got no response to the throttle; it juddered once and stopped with an error code. (Bike: HSR3540 motor 26” rim, PhaseRunner, Cycle Analyst V3, Lunacycle 54V battery) I power cycled it and hoisted the rear wheel up. I gave it some throttle...
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    Direct drive hub for 16" rim ~800 watt

    Anyone know of a direct drive hub that is good for ~800 watts and will fit in a 16" rim? I found the Crystalyte SAW20 which is supposedly good for about 500-600 watts max. (This is going on a trailer.)
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    Using Crystalyte H35 series with 16 inch wheel

    I have a trailer I'd like to convert to a pusher. It uses a 16 inch wheel (it's the Bob Ibex) and ideally I'd like to use a Crystalyte H35 motor. It physically fits - inner diameter of wheel is 292mm and outer diameter of motor is 248mm - but it seems pretty clear that conventional spokes...
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    Drop bar throttle?

    Anyone have any suggestions/recommendations on a throttle that works on drop bars? I have a tandem that I'd like to add power to, but it's a road tandem first and foremost and is _really_ comfortable with the drop bars on it.
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    EMS E+ Flex Kit Cabling Notes

    I just went through this so I thought I'd post this to potentially save other people the trouble. The EMS E+ flex kit comes with three cable sets - the brake/throttle cable, the data cable and the power cable. The brake/throttle cable goes from the throttle to the display. There are two...
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    LT6082 BMS IC

    Linear Tech recently announced an IC intended for li-ion BMSes, the LT6082. It looks like a nice integration of a lot of functions. Includes: monitoring of up to 12 series cells .25% total voltage error max onboard temp monitoring communication with an external processor via an SPI interface...
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    Questions on li-ion balancing

    (I asked this before in the wrong forum!) A few questions/observations on li-ion balancing: Thus far I have seen a few methods of cell balancing. 1. Actual charging of low cells. An isolated charger is connected to the low cell and the cell is charged until it is closer in charge level to the...
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    Li-ion balancing questions

    A few questions/observations on li-ion balancing: Thus far I have seen a few methods of cell balancing. 1. Actual charging of low cells. An isolated charger is connected to the low cell and the cell is charged until it is closer in charge level to the rest of the cells. I have only seen this...
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    Setup for long distance riding

    I've been thinking about a cross-country trip for a while now, and Justin's trip was further inspiration. I'd be doing the US southern tier. I've been contemplating a few possibilities for the bike itself: 1) My current commuter ebike (a Tidalforce M750X) with an additional battery (2.1kwhr)...
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    Source for Metri-Pack 480 connectors?

    Anyone have a good source for Metri-Pack 480 connectors? I just got a Tidalforce wheel back from the factory and they replaced my Anderson connector with the Metri-Pack. It looks like a nice connector (waterproof and more rugged than the Anderson) so I figured I'd try it.
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    Golden Motor freewheel problem

    So I hooked up a Golden Motor 1000W 48V this weekend to try it out. Under power it seemed to work OK. Then I pedaled a few revolutions. Then I stopped. The chain kept going, trying to drive the cranks. When I forced the cranks to stop, the chain spilled over the top of the rear cluster onto...
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    Lithium Mobile Power 2007

    I was not able to attend the Lithium Mobile Power conference of 2007, but I did get a copy of the proceedings for $99 from knowledgefoundation.com. It has some interesting papers, including: SAFT's very high power li-ion technology Abuse tolerance studies on li-ion cells Safety mechanisms for...
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    Trailer power

    Sorry if this has been asked before - I have been considering converting an Ibex trailer to a powered trailer by adding an X5305 Crystalyte hub motor. (Alternatively a 400-series motor if I can't talk my mech-E friend into designing an adapter plate for the small rim.) That way the bike...
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