[Lochlin]

I have these two Shihlin DC 24v motors and I have absolutely no idea what I need to get them running with a battery. A team at my school is trying to make this run and turn it into a gokart/quad to tow stuff around the school.
Any information?

 

[floydr]

a brushed 24v Ebike motor controller should work . and batteries, do you have the joystick with wiring from the wheelchair/hoveraround for steering, speed control?
Later floyd

 

[Lochlin]

Nope all I have are the motors

 

[remy_martian]

Get some booster cables, connect to a car battery, and tap the leads of the motor briefly to see if it spins. If so, go to a salvage yard and ask for a glow plug solenoid from a diesel Ford truck.

You'll use this to switch the motor on and off. If you want reverse, you'll need four of those. I think the trucks have a couple of solenoids...another is used for the starter motor. You can also make a crude two speed with two car batteries in series and two solenoids...

This will give you full on and full off. If you want to adjust speed, you'll need a speed controller for a Brushed DC motor, as was stated already. You can find these in wheelchairs, even old golf carts.

 

[floydr]

Brush Motor DC 12V 24V 36V 48V 5500W High Power 100A Reversible Motor Controller | eBay would work. Electronic reverse or @remy_martian says wheelchairs,Golf carts.
later floyd
Probably a little overkill

 

[Lochlin]

So far I've found a 24v battery, throttle controller, break lever, and a starter switch that all connect to a speed controller. But I can't seem to find a speed controller that works with two motors. Would I just wire the motors to the same speed controller or is that a horrible idea and there's actually a controller with two motor connectors that I just can't find?

 

[brian_]

... But I can't seem to find a speed controller that works with two motors. Would I just wire the motors to the same speed controller or is that a horrible idea and there's actually a controller with two motor connectors that I just can't find?

These motors would likely normally be used for a vehicle which steers by varying the speeds of the two driven wheels, so it would have two separate controllers, set up to run in a coordinated way. Separate motors like this in a 24 V system that doesn't use them for steering are certainly possible but would be rare, so controllers set up to be used that way will be uncommon.

 

[Lochlin]

These motors would likely normally be used for a vehicle which steers by varying the speeds of the two driven wheels, so it would have two separate controllers, set up to run in a coordinated way. Separate motors like this in a 24 V system that doesn't use them for steering are certainly possible but would be rare, so controllers set up to be used that way will be uncommon.

There's electric bikes and scooters that use two motors but I don't know how they work. Do they use two speed controllers? Or another type with a special adaptor or wiring for dual motors?

 

[brian_]

There's electric bikes and scooters that use two motors but I don't know how they work. Do they use two speed controllers? Or another type with a special adaptor or wiring for dual motors?

Two motors on a bike are rare, and a mobility device (sometimes called a "scooter") which uses two motors is usually a power chair that steers with them... but yes, there are some devices that use two motors the way you want to. They're just uncommon. If you can find one and can get close enough look to see the controllers (there are likely two), that would be a good start on finding possibilities.

In the full-sized EV world, the motors are AC, and each needs its own controller, regardless of the number of motors or which axles they're on. In that case, a central control unit communicates with all of the motor controllers digitally, and coordinates the controllers.
Edit: in case it was not obvious, these motors are not AC.

 

[Lochlin]

If you can find one and can get close enough look to see the controllers (there are likely two), that would be a good start on finding possibilities.

Does that mean there's another "controller" that connects the two speed controllers? If so what would it be called?

Edit: Or could I wire two speed controllers to one throttle control and one battery

 

[remy_martian]

These are high school kids with ambition, not bags o money adults, Mr Theory 🤦‍♂️

Just connect the wires of the motors together, Black to red of the other motor and red to black of the other motor (because they need to turn in opposite directions). That way you can use one controller to run both motors. Same voltage, double the current of one if you want full power.

 

[Lochlin]

These are high school kids with ambition, not bags o money adults, Mr Theory 🤦‍♂️

Just connect the wires of the motors together, Black to red of the other motor and red to black of the other motor (because they need to turn in opposite directions). That way you can use one controller to run both motors. Same voltage, double the current of one if you want full power.

So if I needed a 400 watt controller for one motor would I need an 800 watt to run both of them or??

 

[remy_martian]

Correct....for full power output. Use anything less and you get less power to the pavement.

746 watts in a horsepower...

Or you can just flip them on and off with solenoids (big relays). Start with 12V, one solenoid to switch on and off, no speed controller. That's how the Barbie Jeep and other kiddie cars work...on/off only. Play with that, add speed control later.

 

[floydr]

3.4A x 24v=81.6w Seems kinda low 163.2w for the pair? but geared low enough it works. I Must be missing something.
Later floyd

 

[remy_martian]

TBH, I didn't read the nameplate right and saw it as 34A. Darned eye infection

 

[floydr]

You may be right with the 34A. But first getting the motors to run like you said before. Is more important than how many Amps it takes. Could be it is my eyes seeing something really not there.

TBH, I didn't read the nameplate right and saw it as 34A. Darned eye infection

Later floyd

 

[Lochlin]

Yes the most important thing is to get them running, my school has all the machines though to CNC our own gears so once we get them running we were gonna do that. We found out the top speed was only like 8mph and that is too slow for my liking

 

[brian_]

Does that mean there's another "controller" that connects the two speed controllers? If so what would it be called?

Edit: Or could I wire two speed controllers to one throttle control and one battery

In production EVs, one of the several controllers coordinates the motor controllers - the name will vary depending on the vehicle manufacturer. Some controllers for small equipment (such as those from Curtis Instruments) are set up in a master-slave arrangement, where the accelerator input goes to one of them, and it tells the other controller what to do. In both designs, communication between controllers is over a network communications link.

You can indeed just wire the motors in parallel to one controller, since these are DC motors. Like anything in parallel, the two motors would get the same voltage, and you have no control over which one gets more current and power - that's determined by the motor characteristics and how fast the wheels turn.

 

[remy_martian]

Yes the most important thing is to get them running, my school has all the machines though to CNC our own gears so once we get them running we were gonna do that. We found out the top speed was only like 8mph and that is too slow for my liking

Now you're engaging in something called "creeping elegance", the pitfall of everyone new to defining systems, where your initial application is lost sight of for something more elegant or for greater capability:

"A team at my school is trying to make this run and turn it into a gokart/quad to tow stuff around the school."

It's like the old Rodney Dangerfield joke where a girl calls him to come over cuz there's nobody home; so he goes over to her place and...there's nobody home.

Wut is he rattling on about, you say? Your spec says "around the school", just like "nobody's home" -- it's subject to interpretation, which is not good. Is that in the hallways or are you doing laps around the building? You really want to go more than running speed inside a place with blind corners and people popping randomly out of doorways?...think about that.

Also, speed is not free. Speed times towing force is a constant for the motors you picked. Go faster and you aren't towing $hit with it. Go slow enough and you can pull out tree stumps.

Work with what you have. You can get more speed going from the 12V starting point to the 24V. You can use pulleys or belts to speed up or slow down, paying attention to the equation I gave you. You can't afford different motors, motor controllers are expensive, and you're not trying to set the world speed record for a wheelchair on the Bonneville Salt Flats.

Take it a step at a time. Make everything work a section at a time. Make the whole thing functional to your original spec. Then, as time and money permit, go back and hack it to be more elegant -- but you need to think about some idiot running it full speed and running into someone.

Those speed limits in school zones for cars? There are charts that predict probability of death from impact at a given speed. At 60mph, heads, arms and legs come off if you get hit because energy goes up with the square of speed. Go from 8mph to 11.2MPH and the impact energy doubles.