9 motors too much?

[nighterfighter]

It is highly unlikely you will be able to, because the internal resistance on the battery won't let you pull 120 amps, unless a freak of nature accident occurs.

Our 2009 robot had 10 motors, and we never blew the main breaker.

[Ian Curtis]

Originally Posted by Al Skierkiewicz

Andre,
Since the 120 amp breaker was introduced, I think I can count on one hand the number of tripped main breakers I have seen or were told about. Of those, I suspect most were due to defective breaker or some other catastrophic failure. The 120 amp breaker can withstand over 600 amps for several seconds before trip.

We tripped one once in 2006.

We had the four drive CIMs, and the big CIM, and the compressor and a pair of FPs running non-stop through 4 pretty darn close to back-to-back elimination matches. There was lots of pushing and shoving, plus our "ramp wiggle" to get into position involved "walking" the robot by cocking it and then running it into the drivers station over and over (which kept the CIMs fairly close to stall)

It actually took us a couple of minutes to find the problem, we didn't think it was possible to pop it under regular robot use!

OP, I've seen more than 9 motors on an FRC robot. I think you're okay.

[ajlapp]

10 motors here.

[zbanks]

If your worried, you could put some motors on 30A or 20A breakers. Depending on how you're using the motor, they won't come close to this under normal operation.

Keep in mid <R42>:

<R42> Each power-regulating device (speed controller or relay module) shall control one and only one electrical load (motor, actuator, light or compressor).

That's at least 9 jags/spikes/relays. Make sure you leave enough space!

[Chris is me]

We're probably running either 9 or 10 motors this year (6 drive, 1 arm joint, 1 deploy, 1-2 claw). The 120 amp breaker isn't a big concern for us because we will only be pushing over 240 amps when stalling the drive against a wall - and at that point the 40 amps will trip first.

If our drive and arm were simultaneously completely stalled, maybe. Or if we were in a massive pushing match, then tipped, self-righted, and pushed again or something ridiculous. But really, the battery's going to drain first.

[Hawiian Cadder]

6 motors on drive
1 for the lift
1-2 for wrist depending on how much space we actually have
1 for end manipulator
1 to deploy mini bot

even with 11 motors total, there is no way that all will be running at the same time, for instance cruising around the field with our CG so high from the mast means that there will never be more than 7 motors running at a time under any appreciable load. also keep in mind that the window motors and the tiny bane bots do not draw much current at all.

[Zachary Pilarsk]

we are using 5 motors
2 drive
1 arm
2 claw

and 2 on the mini bot

[Cyberphil]

We are using 8 motors: 4 drive, 4 lift, along with somewhere around 5 or 6 pneumatic cylinders.

[Brandon_L]

If everything works out as planned:
4 drive
2 arm (lifting)
1 minibot deploy
1 Pneumatic on claw
2 Pneumatic (extending arm)

Might swap the arm extending to a motor though

[Ken Streeter]

Originally Posted by NyCityKId

So for most teams its "panic now" time and it just really hit me that my team is using 9 motors in all for our robot (4 for drive and 5 for the arm). I was wondering if any other team was using 9 or more motors. Because right now I'm having nightmares of of the 120 amp APP CB tripping . I would feel a lot better if there are other teams using 9 or more motors.

Whether or not one trips the 120 amp breaker has far more to do with how the motors are being used, and particularly how many of them are being simultaneously operated near stall, rather than the total number of motors.

Nine motors is more than average, but not particularly unusual for a robot which is more complicated than typical.

Our team has traditionally used more than an average number of motors, but 9 seems like it will be fairly typical this year. We are currently planning for 10 motors this year. However, more motors doesn't necessarily mean a better robot -- we managed to use only 3 motors on a very successful robot in 2008.

Our past history:

• 2005 - 8 motors
• 2006 - 11 motors
• 2007 - 7 motors
• 2008 - 3 Motors (Speed Racer) or 5 motors (Fezzik)
• 2009 - 7 motors
• 2010 - 7 motors (all controlled via Jaguars with CAN)
• 2011 - 10 motors (all controlled via Jaguars with CAN)

My concern this year is actually with controlling 10 motors on a single CAN bus. We had success with 7 motors on CAN last year, but know of other teams that had trouble getting reliable CAN operation with so many devices. We're hoping that the new firmware changes since last year will make 10 CAN devices within the realm of possibility this year.

[Aren Siekmeier]

Originally Posted by Vikesrock

2175 will have at least 8 (6 drive, 2 manipulator) + at least 2 pneumatic cylinders.

Namely 4 CIMs and 4 RS 775s, which aren't low power/current draw motors. I don't foresee any problems with draw unless we're accelerating forward and sideways and lifting the elevator (and probably firing all solenoids back and forth repeatedly) - all at the same time.

Just make sure you don't do anything like this; keep all motors at or below half-stall torque most of the time and you should be fine.

[Arjun Namineni]

Our team last year used 11 motors. I don't think we ever had a problem with the main breaker. Then again, some of the motors were not really used as much.

[NyCityKId]

lol I like how this thread turned into a "what are u using motors for?" Anyway I defiantly feel better now knowing were not doing anything wrong as far as the amount of motors. We have enough jags and victors counting the ones from previous years, 2011 KOP and the ones we have coming in. And space isn't a big issue.

Originally Posted by compwiztobe

Just make sure you don't do anything like this; keep all motors at or below half-stall torque most of the time and you should be fine.

Haha I actually saw that and I thought it was pretty funny how everyone sort of ganged up on the team. But thank you for the reference. We are using 8" mecanum wheels, each directly coupled to a 2 stage GEM planetary gearbox. So I dont think we'll have any problems with the drive train specifically. as far as i know 9 motors is the most our team has ever used so it just seemed like a massive amount. But that's to CD a mental crisis has been averted. Guess its a good thing I'm not the electrical guy

[Garret]

We are either using 8 or 12 motors, depends on which robot we use. Maybe one or two pneumatic cylinders. We have lots of sensors as well this year.

[Hellfeier675]

We're using what seems to be a low amount of motors this year.

4 Cims - 2 for drive and 2 for our arm
2 Banebots - For the grabber

We do have 2 small 2" stroke pneumatic pistons for something special however