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Unread 01-21-2018, 01:51 PM
tnguyen tnguyen is offline
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How many motors of the same kind can we use?

Hi there,

I was wondering if there is any limitation regarding how many mototrs of the same kind a FRC team can use during competitions

Thank you,
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Unread 01-21-2018, 02:02 PM
MuskieProgramme MuskieProgramme is offline
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Re: How many motors of the same kind can we use?

How many PDP slots do you have?
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Unread 01-21-2018, 02:38 PM
liavt liavt is offline
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Re: How many motors of the same kind can we use?

There is not a limit this year. You can use as many motors as you want as long as you have PDP slots for them.
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Unread 01-21-2018, 03:17 PM
CEF CEF is offline
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Re: How many motors of the same kind can we use?

Quote:
Originally Posted by tnguyen View Post
Hi there,

I was wondering if there is any limitation regarding how many mototrs of the same kind a FRC team can use during competitions

Thank you,
In previous years, there was a limit of 6 CIMs. That limit doesn't exist.

There are practical limitations. Motors draw current, and there's a master circuit breaker and breakers on the PDP. (But, those aren't instantaneous.) You will have a "brown out" condition on the roborio if your motors start drawing too much current.

So, yeah, in theory, you could max out your PDP with 16 CIMs on your robot. But, if you try to have all (or even most) of them running at the same time, you're going to have a problem.
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Unread 01-21-2018, 03:40 PM
Mr.R^2 Mr.R^2 is offline
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Is it legal to put motors on the 30 amp circuits of the pdp?

If so, is it advisable to put a 775 pro or red line on them for light duty applications?

It looks like the 775 pro pulls 28.5 amps at max. That does not sound like a lot of headroom.
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Unread 01-21-2018, 03:45 PM
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Re: How many motors of the same kind can we use?

Quote:
Originally Posted by Mr.R^2 View Post
Is it legal to put motors on the 30 amp circuits of the pdp?

If so, is it advisable to put a 775 pro or red line on them for light duty applications?

It looks like the 775 pro pulls 28.5 amps at max. That does not sound like a lot of headroom.
You can definitely put 775pros/redlines on 30A breakers. I know at least one team was thinking of using a 30A slot for a 10-775 drive (though they eventually decided against it.) If you decide to do so, consider undervolting them to limit current draw.
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Unread 01-21-2018, 09:55 PM
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Re: How many motors of the same kind can we use?

Quote:
Originally Posted by Lazro View Post
You can definitely put 775pros/redlines on 30A breakers. I know at least one team was thinking of using a 30A slot for a 10-775 drive (though they eventually decided against it.) If you decide to do so, consider undervolting them to limit current draw.
Or even better, fully volting them but using SRX-based current limiting. This will keep your current draw down (at a cost in acceleration, of course), but allow you a full top speed.
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Unread 01-21-2018, 10:08 PM
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Re: How many motors of the same kind can we use?

Thankfully there's no limit this year.

We'll have 14 or 15 775pros on our robot.
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Unread 01-21-2018, 10:13 PM
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Re: How many motors of the same kind can we use?

If I'm not mistaken, 42 CIMs (full-sized), minus however many are needed to fit the required control system components in the weight limit. As the biggest motor we can use is the CIM by weight, that should give you a pretty good idea of just how many of the other motors can be used...


Of course, I never said they'd all be functional, did I?
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Unread 01-21-2018, 11:15 PM
tnguyen tnguyen is offline
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Re: How many motors of the same kind can we use?

Thank you for the responses!
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Unread 01-22-2018, 02:44 PM
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Re: How many motors of the same kind can we use?

I, for one, am excited to see teams use CIMs as ballast this year.
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Unread 01-27-2018, 05:50 AM
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Re: How many motors of the same kind can we use?

i think the motor is not a problem for this season, but you have to look how many connections you can do the pwm connectors with the roboRio, and decide by it
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Unread 01-27-2018, 08:10 AM
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Re: How many motors of the same kind can we use?

Quote:
Originally Posted by KevinG View Post
I, for one, am excited to see teams use CIMs as ballast this year.
I had the same thought
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Unread 01-29-2018, 03:02 PM
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Re: How many motors of the same kind can we use?

Wait so we can have like 10 CIMs this year? Is this correct? Can anyone give me a source of some kind on the number of CIMs we can have? I'm a second year mentor and kind of a noob.
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Unread 01-29-2018, 03:04 PM
MuskieProgramme MuskieProgramme is offline
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Re: How many motors of the same kind can we use?

The manual no longer defines a limit to the number of CIMs you can have. Source: 2018 Manual.
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