Search results

Date Relevance Most replies

  1. X

    12v gas generator output to 24v Ebike battery work?

    They make 12V -> 24V DC DC step up converters. You will have some efficiency losses (the one posted below is 80% efficient). But it will do what you want it to. Example: http://www.digikey.com/product-detail/en/VHK75W-Q24-S24/102-2268-ND/2162745 That definitely isn't the only one made there...
  2. X

    How to generate hall signals from a sensorless hubmotor?

    Usually your controller has to be set up for running sensor-less. A add on board to get the position information for the controller will end up being almost as complicated as the motor controller itself. This is because you need to know which two phases are getting driven with current and which...
  3. X

    Hi power electric ducted fans

    You can definitely make an electric powered ducted fans. However I am not sure hiding them in the fuselage would help your aerodynamics all that much. I think the issue of having the make the entire fusalage larger might not make up for the drag decreases from not having the fans exterior on the...
  4. X

    What does 9 kWh of LiPo look like?

    Have you guys thought about using a small RC turbo-shaft engine to power the youfly? There are quite a few around, some can output 10KW or more. Like the ProX shown here, http://www.jakadofsky.com/htm_en/daten.htm It weighs ~8lbs, and you can run it for about 20 min off of 1 gallon of jet A...
  5. X

    Why mass means less for ebikes' efficiencies

    Yea I am only referencing the bike part of the mass, the human part of the mass has many more factors involved in the equation. :wink: As with anything increasing something in orders of magnitude tends to have a significant effect. I am more referencing the trend in semi-competitive bicycling...
  6. X

    Hi power electric ducted fans

    Well the only problem is you would need EDF's that are significantly larger to get the same amount performance out of that jet. Its all about the exhaust velocity, and the mass flow rate. Jet engines have a high exhaust velocity, with a moderate mass flow rate. EDF's tend to have a low(ish)...
  7. X

    Can someone design this for me?

    20 A seems like a lot to send through a 3.5mm header, those are usually rated for ~7A or less. This seems like a hot water heater pump or something? If this is a prototype, I would recommend using off the shelf components, and just Jerry rig it together for your initial proof of concept. Even...
  8. X

    Why mass means less for ebikes' efficiencies

    I've heard that adding 5 pounds to a bicycle is similar to taping a pencil upright to the handlebars as far as efficiency loss. If you are aiming for maximum speed in some respects its helps to add mass. This is because you will have more kinetic energy with the increase mass, so it will take...
  9. X

    Quality Thumb Throttles

    I am still an advocate for using a standard cable throttle from a motorcycle, ATV, or snowmobile. Than running the cable down to near your controller, and connecting the cable to a pot box. Gives the most satisfying throttle to use, no battery voltage is near your hand, and they are...
  10. X

    Fabrication - (video) circular saw - cutting 1" steel plate

    That is most definitely the downside! On the upside, it will teach you to use safety glasses REAL quick. :wink:
  11. X

    DC to DC Converters

    Here are some options for the OP: http://www.mouser.com/ProductDetail/Mean-Well/SD-150D-12/?qs=sGAEpiMZZMtwaiKVUtQsNRU%2fEBWfzYNE4JWrTd3p8HA%3d http://www.mouser.com/ProductDetail/Mean-Well/SD-100D-12/?qs=sGAEpiMZZMtwaiKVUtQsNRU%2fEBWfzYNEdi1Mo6yaa1Q%3d...
  12. X

    Fabrication - (video) circular saw - cutting 1" steel plate

    I used a slugger saw for cutting sheet metal and such in a metal shop quite extensively for a few years. http://www.trick-tools.com/Fein_Slugger_7_inch_TCT_Circular_Saw_MCSL07_2181#.UmiYyuKsozA It was great for sheet metal and stuff up to a quarter inch, but I probably wouldn't spend my time...
  13. X

    Why can't you run 2 brushless motors off 1 controller?

    Well the initial power conditioning circuitry that feeds the output channels (voltage regulation, smoothing etc.) could be the same, you could also use the same microcontroller so long as it has enough i/o pins and ADC's onboard for the double the inputs and outputs. There would just be 6 phase...
  14. X

    Why can't you run 2 brushless motors off 1 controller?

    I think you mean brushless, for brushless controllers, as long as the power output is sufficient, the only real difference is that the controller for the two motors would have 6 phase outputs, and 2 sensor inputs (or 0 still if you want sensorless) If you were running brushed motors you would...
  15. X

    Why can't you run 2 brushless motors off 1 controller?

    Brushless motors rely on accurate rotation signals coming from the motor. Since the motors are not physically connected they will fall in and out of phase with each other as they rotate, since each wheel naturally travels a slightly different distance every time you go over bumps, turn, or drag...
  16. X

    "Forming" Custom Size Battery Cases

    Where the plastic becomes malleable but before the bubbles start to form. :lol: I wouldn't recommend my method where anything relies on its structural integrity, since overheating the polycarbonate compromises its structural integrity since the plastic boils and creates air cavities in the...
  17. X

    "Forming" Custom Size Battery Cases

    Why not go with polycarbonate? I've made some pretty complex shapes for battery boxes just using two heat guns, some straight pieces of metal to act as straight edges, and a couple vice grips. Plus you get the added benefits of its lack of brittleness, unlike acrylic or PVC. It is also what...
  18. X

    1000kWhr lipo pack !

    That actually likely isn't much of a over-sizing at all. A ship that large likely would normally have a pair of 1200HP+ diesel engines. So it would require a set of ~1000 KW electric motors to replace them. So that boat likely cant travel much more than 30min to an hour or so. Boats unlike cars...
  19. X

    Zero-Draw, Solid State Contactor w/Precharge (Arduino)

    I think a TI Launchpad would be a better fit for your application vs. an arduino. Unless you plan on using the arduino to control other functions You seem to be only using 2 DIO pins and want as low of power draw as possible. It has plenty of IO pins for that task, and only draws 220 uA at...
  20. X

    Hybrid Jet Engine

    Well this is certainly an interesting idea. The biggest problem you would have with ducted fans, is first the exhaust velocity of an EDF is pretty low, and second they are built to produce a large volume of airflow at a pretty low static pressure. I think what would likely happen is when you...
  21. X

    Lipo fire- no one hurt- my fault

    I designed and built a 176V 45 Ah Pack using the cheap 20C turnigy hobbyking lipo. The mass of batteries weighed approximately 125lbs. We had numerous problems as it was a prototype snowmobile built in a relatively short timeframe. While I did have several vivid nightmares about what 125lbs of...
  22. X

    Nissan Leaf EV

    Yea a blackout would be rather problematic. Though they are pretty infrequent now. Our city actually has the worlds largest battery. It acts like a UPS for the entire city. It is capable of powering the whole city for around 60 minutes. It used to be a huge problem, since some of the power for...
  23. X

    SR1 EV1 Electric Baja Race Buggy

    I think they use these LiFePO4s http://www.evwest.com/catalog/product_info.php?cPath=4&products_id=50&osCsid=k3h8hocrhesrb6de7ppvlm59g3 They use them in all of the other EV's they have on YouTube. Definitely not a 2000Ah pack, that pack size in those batteries would weigh 10,000 lbs. I think...
  24. X

    Nissan Leaf EV

    The thing about Fairbanks is there is plugins everywhere. The local box stores have plugins in their parking lots so they people can plug in their block heaters while they are in the store shopping. So in a way we are already set-up for EV's up here :D. If you ran a EV up here you would just put...
  25. X

    Nissan Leaf EV

    IT ISN'T THAT COLD HERE... :wink: Took these this morning. Yea I think most of the EV's up here that I know of use resistive heaters. As well as some heaters in the pack to plug into the wall when not in use. There are some that use Heat pumps in their house up here, but often times they...
Back
Top