Idle motor limit?

Does anyone know how much power can be safely put into the vex 393’s without damaging them? because my robot likes to go down on its own easily and i want to put as much power as I can into the motors without destroying, as i have destroyed 1 already because of overheating.

You should not be able to damage a motor, the internal PTC protection should cut power before that happens. This post has the theoretical torque-speed curves.

https://vexforum.com/showpost.php?p=310291&postcount=2

In sack attack, I put 4 motors under a power level of 25 and it lasted through all of qualifications and eliminations. Despite this, the motors were quite hot after matches, so the limit is probably around there

@Jpearman Yah i thought so as well but when i was testing motors after a competition , that one motor was dead. I took apart the motor and the only way the motor would work was when we physically touched it at the same time we put power through it My teacher explained the phenomenon but I forgot now lol :smiley:

If you want to go a bunch further you can test with one of these current sensors yourself to see what’s going on. It’s not competition legal, but nothing says you can’t test with other electronics. I think you will pay more in shipping than the sensor costs. You’ll need a soldering iron and sacrifice a 2 wire extension too.

This sensor will give you a good idea if your motor is getting a lot of current at its hold point. If it’s too much you could be overheating the motors.

You may want a spare motor or two as you experiment and find that sweet spot of how much juice to give it for how long.

Even though you can probably go up to around 30+, I would try to avoid going over 15, just to reduce the risk of the PTCs heating up. You should be able to hold your lift up with a trim of 10-15, but if you need more than that you might want to consider using elastics to help raise the lift, as this will also help with the movement of the lift as well.

nice i will consider getting this as i am in electrical engineering as well

It’s what I used to make these measurements.
Estimating motor current - Part 3