methods
1 GW
First off a disclaimer - You guys know I am no "Captain Safety" so when I use the term "Extreme Hazard" I mean it.
Background: Nearly all throttles on the market are hall effect. Nearly all are plastic. The basic idea is that the plastic grip has a magnet attached(*) which is held close (via a spring) to a hall sensor which is fixed to the handlebar. When you twist the grip you compress the spring and pull the magnet away from the hall sensor. This causes the output voltage of the throttle to swing from something like 1.2V to somewhere like 3.8V. This swing in voltage tells the controller to increase the RPM of your motor.
(*technically there are actually two magnets that straddle the hall sensor and you would think this would create some sort of differential, fail safe signal but it DOES NOT)
Application This is fine for normal bikes. NO EXTREME HAZARD. On a regular bike you re pulling mostly forward and backward , perpendicular to the axis of rotation. This is why you can use slip-on grips etc.... Rarely are you pulling on your handlebars side to side.
On a Kart this is not the case:
Do you see how the handles are pointed nearly straight up?
In a Kart, if you are "getting crazy" you are leaning hard left and right and (especially inexperienced karters such as myself) will find that they are pulling "up" hard on the handlebars to maintain blance.
The Extreme Hazard Since the hall sensor throttle produces a greater voltage when the magnet is farther away, if you remove the magnet you will get FULL THROTTLE.
These hall sensor throttles are not meant to withstand a lot of pressure in the axial direction... in fact, many are assembled with a pressure fit - you "click" them on.
Logic follows that if you are riding a kart aggressively, pulling up on the handles to try to stay on 3 wheels there is a good chance you will yank the throttle right off resulting in UNCONTROLLED FULL THROTTLE
This is exactly what happened to me this morning on my maiden run.
Lucky for me it was a rainy day.
This is a 5305 X5 in a 20" wheel running off of 100V 5Ah
Peak thrust is near 200 lbs
We are talking about a motor that you *CAN NOT* stop with the brakes.
The only thing that saved me was the wet ground - the motor just lit up and starting smoking the tire
I did not have a kill switch. The trike pinned me against the curb (thank god) and the only way I could turn it off was to reach back and under my seat to hit this button:
Solution It is highly recommended that you use a potentiometer based throttle like the Magura pictured below. These are much tougher throttles and although I have not disassembled one, I suspect that they can withstand greater axial tension.
-methods
Background: Nearly all throttles on the market are hall effect. Nearly all are plastic. The basic idea is that the plastic grip has a magnet attached(*) which is held close (via a spring) to a hall sensor which is fixed to the handlebar. When you twist the grip you compress the spring and pull the magnet away from the hall sensor. This causes the output voltage of the throttle to swing from something like 1.2V to somewhere like 3.8V. This swing in voltage tells the controller to increase the RPM of your motor.
(*technically there are actually two magnets that straddle the hall sensor and you would think this would create some sort of differential, fail safe signal but it DOES NOT)
Application This is fine for normal bikes. NO EXTREME HAZARD. On a regular bike you re pulling mostly forward and backward , perpendicular to the axis of rotation. This is why you can use slip-on grips etc.... Rarely are you pulling on your handlebars side to side.
On a Kart this is not the case:
Do you see how the handles are pointed nearly straight up?
In a Kart, if you are "getting crazy" you are leaning hard left and right and (especially inexperienced karters such as myself) will find that they are pulling "up" hard on the handlebars to maintain blance.
The Extreme Hazard Since the hall sensor throttle produces a greater voltage when the magnet is farther away, if you remove the magnet you will get FULL THROTTLE.
These hall sensor throttles are not meant to withstand a lot of pressure in the axial direction... in fact, many are assembled with a pressure fit - you "click" them on.
Logic follows that if you are riding a kart aggressively, pulling up on the handles to try to stay on 3 wheels there is a good chance you will yank the throttle right off resulting in UNCONTROLLED FULL THROTTLE
This is exactly what happened to me this morning on my maiden run.
Lucky for me it was a rainy day.
This is a 5305 X5 in a 20" wheel running off of 100V 5Ah
Peak thrust is near 200 lbs
We are talking about a motor that you *CAN NOT* stop with the brakes.
The only thing that saved me was the wet ground - the motor just lit up and starting smoking the tire
I did not have a kill switch. The trike pinned me against the curb (thank god) and the only way I could turn it off was to reach back and under my seat to hit this button:
Solution It is highly recommended that you use a potentiometer based throttle like the Magura pictured below. These are much tougher throttles and although I have not disassembled one, I suspect that they can withstand greater axial tension.
-methods