Toughbox vs KOP Toughbox Mini

[Ether]

Originally Posted by nathan_hui

Increasing the gear ratio (making the drive slower) would make it harder for someone else to push you around, but you run the risk of popping breakers.

Don't you have that backwards?

[nathan_hui]

Do I? Increasing the gear ratio means the motors turn more to get a single rotation of the output shaft, which slows down the drive, which allows more torque, which wins pushing matches while drawing more current. But I'm an EE, so what do I know?

[Jon Stratis]

Originally Posted by nathan_hui

Do I? Increasing the gear ratio means the motors turn more to get a single rotation of the output shaft, which slows down the drive, which allows more torque, which wins pushing matches while drawing more current. But I'm an EE, so what do I know?

It allows more torque at a higher motor speed... But your forgetting that the other robot is sitting there stalled. Stall = much, much higher current draw.

And seeing Ethers past contributions, like his recent tests on the speed controllers at Whirlpool's motor lab, I'm going to go with him on this one.

[pfreivald]

We used four 9:1 BB p80s on our Octocanum drive last year, then geared down a further 5:1 (net -- between the smaller traction wheels and a Gates belt with appropriately sized sprockets) when we got into pushing matches.

We got into lots and lots and lots and lots of pushing matches last year, and never once popped a breaker with a 45:1 reduction on four CIMs. Indeed, even with using pneumatics for the first time last year, and some extremely aggressive driving, we had better battery life than any other year thus far.

[Donut]

Originally Posted by nathan_hui

Do I? Increasing the gear ratio means the motors turn more to get a single rotation of the output shaft, which slows down the drive, which allows more torque, which wins pushing matches while drawing more current. But I'm an EE, so what do I know?

I think what Ether was pointing out is the part at the end about current. Increasing your gear ratio does increase motor revolutions relative to the output shaft, and increases torque. But this lowers overall current draw for the equivalent torque output, which would reduce breaker trips.

[nathan_hui]

I see. I guess you'd only see the current problem in a pushing match, or when you start flooring the accelerator. But for the purposes of the OP, extra motors (to the limit of the Toughboxes) shouldn't make a difference.

[Ether]

Originally Posted by nathan_hui

extra motors (to the limit of the Toughboxes) shouldn't make a difference.

Extra motors on a drivetrain make a difference when it comes to not popping breakers:

http://www.chiefdelphi.com/forums/sh...48&postcount=8