I require your help regarding a problem I’m encountering.
I am trying to figure out a schematic (drawing) for wheelchair motor brakes using a Sabertooth 2X60. This drawing was posted here Sabertooth 2x60 and 4 wheel chair motors and it was also sent to me from a tech at Dimension Engineering. The drawing puzzles me as to the placement of the diodes do not make sense to me. I see the M1 and M2 connection connecting to the motor leads. Then diodes placed on each lead. After that you connect both leads together? Then wire a diode into both sides of the brake before continuing onto the battery negative? Is this seem right?
Thank you so much in advance for your help!
It makes perfect sense to me, follow the electrons. The reason for the diodes is that the Sabertooth goes positive/negative in the m1/m2 motor leads for forward and negative/positive for reverse. Without the diodes the brake would only release in one direction.
I’m still using the device regularly, runs well, 4-motors operated by the one little Sabertooth.
Thank you jongig for the reply. 4 Motors may be in the future for me as well. I am having a lot of fun building this and learning a lot. This is what I have so far for the braking system. I hope posting these helps others. So many nice folks on here.
I have a Sabertooth 2x60 on the way for a mower and have a few questions about the brakes:
I understand the two upper diodes in the above diagram, but not so much the bottom one across the brake inputs. Is that a flyback diode for the brake’s inductive load?
What type/rating of diodes would be appropriate to use for this circuit?
I appreciate the input. This is my first build and don’t want to fry anything, especially since I think I ordered the last 2x60 available anywhere for months to come with the shortages!
Three Years Later… Sorry for the long reply. Did you figure it out? I had to put my project on hold and just got back into it. I was just figuring this out myself when I placed this on hold. I used IN5401’s.
Hi Treetopflyer, I hope you got your answer from weatherjack.
I was wondering if you are considering making a PCB for accommodating the Sabertooth motor driver and other components. If you want to make a PCB, this one may turn out to be an important write-up for you. PCB Heat Management Processes and Systems - PCB Tracks
I have thought about this. It sure would make the build a lot quicker in the future. Thanks for the info.
After much consideration this is going to be my final layout for the brake circuit. The space inside my enclosure is getting limited real fast and the design layout was not thought out well enough. Anyone that wants to comment on errors or suggestions please do so. When the final pieces are set into place I might do a complete write up if enough interest is shown.
Realized diodes are backwards from the Sabertooth in last post drawing. I have everything wired and I am getting erratic to no response from the controller. The sabertooth switches are ↓↑↑↓↑↑. The S1 is connected to channel 2 and the S2 is connected to channel 3. This is set on the transmitter for channel 2 left stick and channel 3 for the right stick. I think the erratic behavior is from the brake circuit. I am at a loss? Anyone have any ideas? The wiring and case are temporary.
I figure someone is going to ask. This is a custom heat sink I made from a power supply on a tread mill. I have attached the relay to the front and a 24v fan from a copy machine I think to the bottom. The sabertooth is thermal taped to the top with the surfaces being the same size.
Hi. I’m a newbie so please be nice to me ifI say something stupid.
I’m building a RC mower.
I use a Sabertooth 2x60 and 4 wheelchairmotors with electromagnetic brakes.
I’ve seen the brake scematic many times.my question is:
How do I connect the second motor on the one side. Do I connect it parallel to the first motor and the brakes parallel to the first brakes ? Or does the second motor need its own circuit?
Nobody has an answer to my question about connecting 4 motors with brakes to a Sabertooth 2x60 ?
I’m still struggling…
Sounds like you want to operate four motors from a dual motor controller. As you already know, each channel can only receive one signal, so the two motors connected to the left channel will receive the same signal and the same for the right.
Q1) Are the four wheelchair motors identical?
Q2) What is the maximum current draw for each motor? If you have two connected, each needs to be less than 30A max (2x30 = 60A)
Q3) Do you need each side to operate at the exact same RPM? If so, you’ll find that despite being mass produced, small variations mean that one motor might spin slightly faster or slower than another.
As for the connections, you’d plug in one lead from the two left motors to M1+ terminal and the other lead from the two motors to M1- terminal. If one motor rotates the wrong direction, swap the wires.
Thanks for answering my question, C .
To answer your questions:
Yes, the 4 motors are identical
They draw 10.4 Amps each, si no problem for the 2x60 Sabertooth.
No problem if they are a little bit different in RPMs, on grass the wheels slip easy.
I understand how to connect the wheels in pairs, parallel on left and right.
The main question for me is: how do I connect the electromagnetic brakes?
I have seen the schematic that Dimension Engeneering provides. It was posted here by Weatherjack at the top of this thread.
How do I connect the 4 brakes? Do I connect them parallel to the one in the schematic (so 2 brakes left and 2 brakes right) or will I have to make 4 circuits in stead of 2 ?
I hope I make myself clear enough.
Thanks in advance for your answer,
Ah - understood. Don’t think that question has been raised here before. Have you tried Dimension Engineering directly?
Yes, I should have done that in the first place.
No worries. For more general question we’re happy to help here. For more specific cases which we have not encountered like this, it’s best we don’t speculate and instead see if the manufacturer can provide an accurate answer.