[fox46]

After building and running robots with 6 motor drive for the past few years, I had never experienced an issue with blown main breakers. This year the team had no issues through 3 regional competitions and champs seeding matches until they found themselves in eliminations on Curie. At this level of competition we had the main breaker kick out near the end of four of our elimination matches. Luckly it did not impact the outcomes of the match as they were very close to the end but it just goes to show the stress on the equipment at that level of competition.

Now you've gotta understand our machine is running 6 CIMs (2 speed 18fps/6.5fps) on drive, 2 RS775s on the reloader, an RS550 on intake and the compressor, so it is a very hungry little thing- drivetrain excluded. We would never dream of running a battery that hadn't come right off the charger fully charged. Even a battery that was fully charged and settled overnight was noticeably sluggish in our machine. It was typical for the battery to be warm after our matches as well as all the 6AWG wiring. I wouldn't use this experience to say that 6 CIM draws too much power. There were other inefficiencies which could have been improved to mitigate the breaker trips. First off, you've got to get the power from the battery to the PD board. Solder all your 6AWG terminals (torch, flux, solder, heatshrink)! The mentor in charge of wiring our machine refused to follow my advice and insisted crimped connections were sufficient. During elims on Currie, each of the terminals was a hotspot capable of burning you at the end of the match- any heat generation is a loss of power so here is improvement #1. Secondly, all the 6AWG wiring was warm- In the future it would be prudent to use 4AWG including higher capacity Anderson connectors (not sure if this is legal as per rules though since there is wording specifying a part number for these to be used). Thirdly, the main breaker was cooking hot. We did try swapping it out for a brand new unit but this did not affect the performance. Instead we borrowed some computer duster from the Robonauts #118 (Thank you so much!) and were able to delay the trips by cooling the breaker between matches. I am not sure if the heat buildup was being generated within the breaker or if the poor connections with the terminals were sinking heat into it through the lugs.

Basically, you just have to be very conscious that a 6CIM robot is going to be hungry. You need to design your gearboxes at the mercy of the main breaker and battery. If you are using 6 CIM single speed, make sure the machine breaks traction before stalling the motors. If you are using 2 speed, then make sure you actually use it! Next time around I would insist on some sort of current sensing device combined with the feedback from an encoder on the driveline which would automatically kick the gearboxes to low gear if there existed a current increase past a certain limit for a certain motor speed for a set amount of time. I can't count how many times I had to yell at our driver "LOW GEAR!" when he found himself in a shoving match. Outside of this, make sure your electrical system is robust as the additional strain is hard on these components. Oversize the wiring if you can afford the weight so that you eliminate your losses due to heat.