Modifying top speed

[Scoot 787]

I came across this during my search for speed increase:
"Attach the negative of the battery to the negative of the motor. Keep all of the other wires in the scooter connected. Your reward should be extra power so that you can easily go faster."
How does this procedure works?
Also I am thinking of increasing the voltage of my scooter from 48v to 60v. The last time I did it, the scooter ran much faster, the controller only last for about 10km before burning out, but the brushed motor was cool to touch. I finally replaced it after waiting 6 months for the controller to be back in stock. Is there a way to increase the voltage to 60 without changing my controller? I won't want to burn off another controller :wink:

 

[amberwolf]

See your other thread for what you need to do for the voltage increase; it's got all the details there (except for whatever questions werent' answered when you didn't come back after the last replies).


Regarding the wiring change, if the motor positive goes to battery positive normally, and motor negative goes to controller, then the brushed motor is powered by the controller, and there is a tiny bit of loss inside the controller in the FETs. But you have control over the motor speed/power, and can turn it on and off, too.

If you connect negative of motor to negative of battery instead, you no longer have any control over the motor, as it will always run full speed whenever battery is connected. Also, using the power switch to turn this on and off under load (so you can still stop and start the motor) will usually damage the switch, eventually (often quickly) welding the contacts together so it's always on and will never shut off. Additionally, since there is now nothing to limit current to the motor, it has no protection against overheating and can burn out under load.

If the motor positive and negative both go to the controller, then doing this mod *might* let you still control the motor speed, depending on controller design, but the controller can no longer monitor current drawn by the motor and so cant' limit it to protect the motor (or controller) from burning out.

So you might get more power for a little while before you have to replace the motor (and possibly controller).

If the wiring wasnt' thick enough for the higher current, then that can also be damaged (melting insulation, allowing things to short together, which can start a fire).

 

[Scoot 787]

"Attach the negative of the battery to the negative of the motor. Keep all of the other wires in the scooter connected. Your reward should be extra power so that you can easily go faster."
https://itstillruns.com/make-electric-scooter-faster-2292171.html

I am thinking it means the battery positive and negative still goes to the controller while an additional split from the battery negative goes to the negative of the motor (all other connection remains). With that connection, will I still be getting control on the motor and is it going to give me more speed?
Won't be doing much mods to the controller (replacing capacitor, FET, etc) since I neither have the schematic nor knowledge to know what I am doing. I definitely know that the motor can take 60v easy since it was running cool the last time I try it. I am more looking for an easy hack to increase my voltage without frying my controller.

 

[amberwolf]

I am thinking it means the battery positive and negative still goes to the controller while an additional split from the battery negative goes to the negative of the motor (all other connection remains). With that connection, will I still be getting control on the motor and is it going to give me more speed?

If you do that, you're shorting across whatever the controller's negative connection does, so those functions are lost. Usually that is the current monitoring and at least half of the PWM (speed/etc control). Sometimes it is *all* of the control (for cases where motor positive isnt' PWM'd but just goes to battery positive).

Would it give you more speed? Don't know. You'd have to test that out in your particular situation, because having no current limiting and no speed control (always on at max speed and current) may still not give you more speed, if the reason your speed is limited isn't caused by those.

If your speed is limited by the voltage available, vs the motor's winding / gearing, vs the size of the wheel, vs the terrain and wind resistance, then it's not going to change the speed.

Go to http://ebikes.ca/simulator , read the entire page, and then play with differnet systems to see what things affect your speed. I don't think there's any brushed systems there, but it doesn't matter, the stuff you see is the same either way.

Won't be doing much mods to the controller (replacing capacitor, FET, etc) since I neither have the schematic nor knowledge to know what I am doing. I definitely know that the motor can take 60v easy since it was running cool the last time I try it. I am more looking for an easy hack to increase my voltage without frying my controller.

There isn't one, if you already found that model controller fries under that voltage.

You would have to buy a controller intended for the higher voltage.

 

[Scoot 787]

Thanks for the help Teddy!
I will try to source for a bigger controller.