# How to use more than 8 12V DC motor

The PDP only allow 8 12V DC output. Are there any means to power more 12V motor?

The PDP allows more inputs, just not with the 40A breaker slots.

edit: the ctre page says up to 16, 8 of the 40A and 8 smaller ones

This thing we have to power every part of our robot through with a 12 V battery only allows for 12V, is there anyway to get more than 12V.

Pretty sure no, as it would be illegal to bring an additional power source. If you mean power something that requires more than 12V, it depends on what it is. I believe that you could half power something that required greater than 12V, but it would quickly drain your battery and probably wouldn’t be worth it.

“Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.”

If you mean you want to power more things, then by all means fill every port on the PDP

, but you can’t get any more than that.

I agree. Is it legal to connect 2 motors to 1 talon or 2 talons to 1 output port on the PDP?

I think you should read R35 and R56 very carefully. (I was going to say R53, but R56 blocks what I was thinking of.)

one of the points in robot inspection is to make sure each motor controller only has one motor plugged into it, as well as making sure there is only 1 motor controller per motor. This is a rule to directly prevent what OP is suggesting, which would allow a motor to get over 12V

None of the OP’s posts in this thread seem to be suggesting that he was trying to get more voltage to the motors.

You seem to be saying that somehow by hooking up two motor controllers to one motor you think you can get more than 12 volts to the motor. Is that really what you meant?

Cite your source. I call R35 on your first claim, and the lack of a rule on your second. And… I cite physics on your third. Parallel paths do not increase voltage, series paths do (potentially).

The OP is trying to use >8 (qty) 12VDC motors, if I’m understanding his question properly. The obvious method is to use the other 8 ports on the PDP

for 16 available motors (8 of which are lower power). The second method is to use 1 motor controller on 2 motors (R35), which will only work on less-powerful motors. You can’t have 2 motor controllers on one PDP
connection (R56).

Ah yes, I misunderstood OP’s question and misremembered my inspector training. I have a bad habit of posting responses on Chief based on my memory and not checking them first.

Just to be clear. R35 specifically allows some (relatively low powered) motors to be powered by one motor controller:

AUTOmotive Window/Door/Windshield Wiper/Seat/Throttle Motors
AndyMark PG
Snow-Blower Motor

Motor Controller
Yes (up to 2 per controller)

Personally, I don’t see why FIRST

should limit the number and types of motors to be driven by a single motor controller (perhaps to protect the controllers) but it seems like a “YMMV, proceed at your own risk” disclaimer would be a better rule.

Be that as it may, there are some motors that you can drive two per motor controller.

Bonus question. I am not sure why you’d want to but COULD you connect them in series rather than in parallel? I can’t find a rule against it. So I guess it’s legal?

Dr. Joe J.

Is this question for students or engineers? Good way to make a lot of things “paperweight mode”

If you did, it seems you’d short the battery.

Cite your source. I call R35 on your first claim, and the lack of a rule on your second. And… I cite physics on your third. Parallel paths do not increase voltage, series paths do (potentially).
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Yes, R35 for the first point. For the second, Dr. Joe brings up a good point…

R56 would appear to make connecting them in series illegal, as you would have more than 1 motor controller on a single breaker. Why you would want to, I have no idea, but at least we have a rule to point to for it

R45, combined with R56, would make powering a single motor off two speed controllers (in parallel) illegal. It would be a single circuit being powered from multiple WAGO connectors. So the second point matt made (“only 1 motor controller per motor”) is correct. You CAN

have multiple motors per controller, for certain types of motors identified in table 8-2, but you CANNOT have multiple controllers per motor.

You don’t have to connect the motor controller power inputs to a single breaker in order to connect their outputs in series. So R56 does not apply.

The reason you don’t want to connect the motor controllers in series was humorously explained by efoote868 in a previous post, and illustrated with a sketch in my previous post.
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Am I correct in thinking that you are talking about connecting more than one motor to the output of one motor controller rather than connecting two motor controllers to one motor?

For your Bonus Question, it might make sense if the load on the motors is light (relative to the motor power) and you would always be running them at half-throttle or less.

I interpreted Dr. Joe as saying that you could connect two of those motors in series to one ESC (giving each one 6V if loaded evenly) instead of in parallel (giving each 12V). That would follow more with the “I am not sure why you’d want to” because you’d be quartering the power of motors with already dismal power.

That makes more sense, but it wasn’t where my head was. ::ouch::

Sorry, for the confusion folks.

I used the word “Them” the two motors. I was trying to ask if it was legal to wire two motors in series on the output of one speed controllers. FWIW, I am pretty sure the wiring rules prevent wiring two speed controllers in series.

Back to my question.

I have run motors in series on some goofy project I was working on, can’t recall the specifics.

I do recall that the behavior is not what a simple analysis would lead you to think at first blush.

They do NOT act like 2 motors reach run at 6V, I remember that.

If they are loaded identically, then yes, that is true but if you use them to power tje drive wheels of a vehicle for example, the motors act something like an “electric differential” where if you slow down one wheel the other goes faster (slowing down Motor A reduces the Back EMF from Motor A so Motor B effectively gets more of the voltage drop).

Anyway, I can’t think of a particular advantage of doing this on a FIRST robot but it is a curiosity that the rules don’t seem to make this illegal.

FWIW.

Dr. Joe J.

As I read the rules (in particular R35, second sentence, this year), only the smaller motors can be run two to a motor controller; the rules do not **specify **whether this would be in series or parallel, but I wouldn’t be too surprised to fail inspection with two window motors in series behind a motor controller.

I had also noted the asymmetric draw of motors in series when I did some experiments a few years back. I think my results were even wider - when both motors were running free, one motor wound up essentially stalled, with the other spinning at about 0.7-0.9 of ree speed. Now, the only way I would consider using motors in series would be if were using them to drive the same gearbox, such that they mechanically had to have the same speed. Even then, I would prefer to select “matched” motors from a relatively large pool.

If it doesn’t specify, then I don’t see how it would fail inspection. Then again, in all the robots I’ve ever inspected, I’ve never seen an attempt to have two motors on a single esc whether legal or illegal.