Three wire extension for two wire motors

[MartinMaVEXForever]

Hi, VEX forum. I have a question about 2 wire motors and three wire extensions…

So previously in a thread discussing whether VEX should sell motors with integrated motor controller 29, I remember that jpearman said that:

Motors will not work at long distances from the cortex unless the motor controller section is redesigned. Large voltage drops due to wire resistance and high current occur when the motor starts, this tends to cause any logic (ie. the MC29) to reset if it is placed at more than say 5 feet from the cortex. This is currently circumvented by keeping the MC29 close to the cortex and running 2 wire extensions to the motors.

So this year robots are mostly very tall, which makes the power supply to motors on top of the lift an issue. If keeping motor controller close to cortex can reduce power loss, considering that we do not have 2 wire extensions and neither do we plan to buy them, is it legal to use only two wires of the three wire extension cables? That means, only plug in two pins of a three wire extension into the motor controller, leave out the third pin and only use two wires. It is basically using a three wire extension as a 2 wire extension.

I have not seen any rules against this, but neither have I seen any teams doing this. So I’ll just post it here and let the community discuss. Thanks!

[4149G]

Hi, VEX forum. I have a question about 2 wire motors and three wire extensions…

So previously in a thread discussing whether VEX should sell motors with integrated motor controller 29, I remember that jpearman said that:

So this year robots are mostly very tall, which makes the power supply to motors on top of the lift an issue. If keeping motor controller close to cortex can reduce power loss, considering that we do not have 2 wire extensions and neither do we plan to buy them, is it legal to use only two wires of the three wire extension cables? That means, only plug in two pins of a three wire extension into the motor controller, leave out the third pin and only use two wires. It is basically using a three wire extension as a 2 wire extension.

I have not seen any rules against this, but neither have I seen any teams doing this. So I’ll just post it here and let the community discuss. Thanks!

It should be legal. I have seen teams do this. That extra third wire posses no danger as it will not have any connection on either side.

[Kevin_Boenisch]

Sure, in fact I’ve even considered bundling 2 2-wire extensions into 4-wire extensions, but unfortunately they only exist in lengths up to 12", which makes it impractical.

[Sten_7701]

In this thread, it says that as long as you don’t use longer than 12" extensions, it is legal as of last year.

[MartinMaVEXForever]

Thanks. I hope this will help with our 60’’ double reverse six bar!