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 14th Apr 2008, 02:46 #21 Altron LIKE A BAUCE!!!!     Join Date: Dec 2002 Location: an island on the Hudson Posts: 3,183 Make sure you get a battery that's capable of many full charge/discharge cycles... I know that car batteries are not made to be fully discharged and recharged, and doing so damages them. Another issue to think about is security and durability... are you going to chain this thing to a bike rack all the time? If you are, definitely fabricate a metal cover with lots of Torx or some other irregular screw head, to prevent someone from stealing the motor and associated parts. Even if it's going to be mostly inside, you should get some sort of plastic case over the electronics to prevent things from shorting out if you get caught in a surprise rain. __________________ If this post is not up to your standards, please lower your standards. e^i(pi)+1=0
 15th Apr 2008, 06:39 #22 MercuryRising Minimodder   Join Date: Mar 2008 Posts: 22 Hmm okay. I will try to find a deep discharge motorcycle battery. (that's what i would be looking for, right?) Terrible drawing, i know. But that's the main idea, is there a better/easier way of controlling the speed? There are three taps on the motor, a low medium and high. At high speed it gets 1075 rpm @ (i think) 2 hp. So, how does this factor into gearing? I know that it would allow me to use a gigantic gear ratio, but how would i figure out the optimal? Okay, going by the how stuff works high gear of 4:1, i am getting 306 miles per hour????????? motor spins at 1075 rpm * 4 (gear) = 4300 rpm * 60 = 258000 rph * 2*3.14*1 (assuming a 24 inch wheel, it'll be a 26 but for the ease of calculation) = 1620240 / 5280 =306 mph????? Where did i go wrong in this calculation?????? And also, how much battery life do you think I would be looking at with a 20Ah 12v battery? (i'm guessing not very good at all...) I would need a 2000w power inverter since the motor uses 1600w. If this plan doesn't work out, I think an alternative plan would be to find a motorcycle body and then use a car batty.
 15th Apr 2008, 21:06 #23 Altron LIKE A BAUCE!!!!     Join Date: Dec 2002 Location: an island on the Hudson Posts: 3,183 You would be swapping the gears (so you have the little one on the motor and the big one on the wheel) The motor won't have nearly enough torque to move the bike if you gear it 0.25 overdrive. Gear it for speeds you expect to travel at. If my math is right, a 2000 watt load will drain a 20Ah 12v battery in 7 minutes and 12 seconds. __________________ If this post is not up to your standards, please lower your standards. e^i(pi)+1=0
 16th Apr 2008, 02:52 #24 MercuryRising Minimodder   Join Date: Mar 2008 Posts: 22 Will the 2000w inverter always suck 2000w? Seems like that would be a ridiculous waste of energy. And it seems as though I will need to find another battery, or devise a way to get better battery life. Motor mounted to a friction wheel?? A deep cycle car battery seems like it would be in order, but they are ridiculously heavy. There's gotta be another way?
 21st Apr 2008, 12:51 #25 MercuryRising Minimodder   Join Date: Mar 2008 Posts: 22 Okay I scratched that idea, switched to a DC motor. It is a 12v 32a (it also says 1/3 hp on it, but that can't be right?)DC motor. The motor controller is 14v and 60a, so I should be covered there. The motor controller comes with a header hookup for on/off, throttle, and it comes with a charging port which is very nice. The motor comes with a large gearing on it already, I will post some pictures later. Should I still not be satisfied, I can switch motors, there's a 16a 36v motor at the store as well, and an \$8 controller that does 36v 30a. But that motor says it's 350w, it doesn't make any sense! Pics later.
 21st Apr 2008, 20:37 #26 Altron LIKE A BAUCE!!!!     Join Date: Dec 2002 Location: an island on the Hudson Posts: 3,183 Well, 1hp = 746 watt, and since the motor isn't 100% efficient, 1/3 hp (~250w) sounds reasonable for a motor drawing ~380w, that's like 65% efficient __________________ If this post is not up to your standards, please lower your standards. e^i(pi)+1=0
 21st Apr 2008, 21:19 #27 Ramble Ginger Nut     Join Date: Dec 2005 Location: Helsinki, Finland Posts: 5,402 There's nothing wrong with your calculation apart from you've used stupid numbers. You want a wheel that rotates at 4300rpm?? Generators in power stations don't spin that quickly. You're going to want to reduce the speed of rotation quite a lot indeed. __________________ Kirk, Spock, McCoy, and Ensign Ricky are beaming down to the planet. Guess who's not coming back.
 22nd Apr 2008, 02:48 #28 MercuryRising Minimodder   Join Date: Mar 2008 Posts: 22 Here's the pictures I promised. WTF is that thing on the back of the motor? That's the output shaft Motor controller. It's got battery connections, charger connections (really nice), throttle, on/off, and battery. This is the 1/3 hp motor.
 22nd Apr 2008, 07:49 #29 xen0morph Bargain wine connoisseur     Join Date: Jun 2002 Location: UK Posts: 2,925 The problem with electric cycles is the battery. You will not get enough power from a motorcycle battery - it will be flat in a matter of minutes (not only that, but there is no such thing as a 'deep discharge' motorcycle or car battery - what you need is a gel battery.) Even gel batteries can't really store enough power to make this feasible for everyday use. I'm thinking about building a hybrid cycle using a steam engine to power a generator connected to a battery. That way the battery provides a 'float' so the engine has time to speed up and the bike can still accelerate in the meantime.
 22nd Apr 2008, 16:25 #30 Ramble Ginger Nut     Join Date: Dec 2005 Location: Helsinki, Finland Posts: 5,402 Why a steam engine? Much too inefficient for a small vehicle and probably wont provide too much power. I'd go with a gas turbine and a DC generator, small weight with lots of power. At least that's my plan in the summer (to build a jet). __________________ Kirk, Spock, McCoy, and Ensign Ricky are beaming down to the planet. Guess who's not coming back.
22nd Apr 2008, 20:19   #31
xen0morph
Bargain wine connoisseur

Join Date: Jun 2002
Location: UK
Posts: 2,925
Quote:
 Originally Posted by Ramble Why a steam engine? Much too inefficient for a small vehicle and probably wont provide too much power. I'd go with a gas turbine and a DC generator, small weight with lots of power. At least that's my plan in the summer (to build a jet).
I've heard that a well-designed steam turbine with a good boiler would be much more efficient than a gas turbine. And it can run on any fuel that combusts, I plan to build a waste veg oil burner.

 22nd Apr 2008, 20:43 #32 Ramble Ginger Nut     Join Date: Dec 2005 Location: Helsinki, Finland Posts: 5,402 I imagine it might well be, however you've got to take into account the space for a condenser if you want to conserve your water and that the whole turbine is pressurised, adding in another layer of complexity. Plus a gas turbine will also run on virtually anything, diesel, propane, whatever. Plus you can get whatever speed improvement from thrust (not too much I'd imagine). Both options are awesome though, steam turbine or jet. __________________ Kirk, Spock, McCoy, and Ensign Ricky are beaming down to the planet. Guess who's not coming back.

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