Help with electronic bicycle throttle

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  #1  
Old 02-02-12, 07:34 AM
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Help with electronic bicycle throttle

hi i am working on a project where i have converted a push bike into an electric powered bike. i wanted to know if there is any way to wire up a electrical throttle to a motor and a battery without a blackbox? because i see that a throttle has 3 wires and i dont know what wire goes to what thanks.

here is a picture of the kind of throttle im talking about
 
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  #2  
Old 02-02-12, 11:26 AM
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It all depends on what you've got but looking at the size of the wires on that twist throttle they are not intended to carry the current of a motor, meaning you'd need some type of speed controller (black box).
 
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Old 02-02-12, 11:35 AM
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what i have is an old set-up of a stand up scooter but when i got the scooter it didn't have the wiring set-up and i found out there isn't a controller black box thing in there. so i decided to add the batteries and 24volt motor to my bicycle and the batteries but i didn't know how to wire up the throttle so for now i have just got a button that i press and it spins the motor at full speed. so its quite dangerous.
is there now way of making something that will adjust the speed of the motor spinning. it doesn't have to be this throttle but some sort of device maybe? I have no experience in this type of work but i wanted to try and learn it.
thanks
 
  #4  
Old 02-02-12, 01:50 PM
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Thats just how the razor scooters work. The throttle is only a on/off and offers no variable speed control.

You can just wire the throttle to replace the button.

Whats more important IMO is brakes!!!!!

Mike NJ
 
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Old 02-02-12, 02:19 PM
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Depending on the type of DC motor I'm wondering if a universal motor speed control would work. Experts help me out.
 
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Old 02-02-12, 04:10 PM
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If it's a simple, brushed DC motor a old fashioned DC speed controller will work. It's also a simple matter to create multiple, fixed speeds by putting resistors in one of the leads going to the motor. Different resistor values will offer different speeds. If large enough resistors can't be easily found lengths of heater wire from an old electric heater can be used.
 
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Old 02-02-12, 04:57 PM
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Plenty of rheostats at Ebay. Here is an example: 100W 250 Ohm Ceramic Disk Variable Industrial Resistor Rheostat | eBay I don't know what watts or max resistance you need but using Dane's suggestion you could make a temporary variable resistor out of a length of heater nichrome wire stretched between two porcelain insulators mounted on a board. One side of the motor to one end of the nichrome wire and one battery lead to an alligator clamp. Try various postilions no load and then under load starting at the highest resistance point no load the motor will turn at. Measure your resistance values with an ohm meter and you have your specs.

Yes, there is a "math" way to figure it but it doesn't take into account minimum voltage needed under load to have sufficient torque to move the bike.
 
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Old 02-04-12, 05:33 AM
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Is there a label on the motor that tells you how much current it draws? Is there a fuse or circuit breaker and if so, what is the rating?

You have to know how many amps the device pulls before you can add resistors or you'll have nice plumes of smoke trailing behind you.
 
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