I have developed a semi-autostack function for my robot. Basically what happens is I bring my lift to the right height, and then I press a button. As a result of pressing the button, the chainbar goes to the right place, the scissor lift goes down a little, the rollers drop the cone, the scissor lift goes back up a little, and the chainbar goes back down. During this stacking time, I can drive to the next cone. What typically happens is I’ll be stacking starting at about 2 cones, and near the last cone (the twelfth) the robot becomes “disconnected,” out of nowhere. (By this I mean the joystick VEXnet light flashes red and the cortex VEXnet light flashes red.)
After this, I will turn the robot and joystick off and back on again. When they connect, the power expander motors work, but the rest of the robot doesn’t move at all for a while. (As in, the motors don’t tire out and slowly acquire more torque over time. They just don’t move.)
Apparently the current limit of the cortex is like 5 amps (or 4???), and when I checked, my robot was pulling 6 amps from driving and running the chainbar. Also, my 4 lift motors are on the power expander, while my drive, secondary lift, mogo lift, and roller motors are on the main battery.
Is there any way to stop this from happening? Would it be beneficial to change which motors are on the power expander? How do teams like Fuzzy Wuzzy run nearly all (nearly all as in eleven) of their motors at once? Will it be necessary for me to do only certain functions at the same time to not burn out???
Can you tell us what your motor distribution is as in what is plugged into what ports in the cortex and power expanders? What I’m guessing is your drawing to much out of one of the breakers in the cortex and that’s causing your stuff to fail.
This problem can probably be solved by always having a fully charged “backup battery” in the robot at all times. Obviously the best fix would be to try and reduce the amount of amps being pulled, but putting in a backup battery could work.
6A is nothing on a healthy VEX battery. Our batteries have 100-120mR of internal resistance, so even under 6A load won’t sag more than 1V, safely staying way over 5V for the logic power. Are you sure it is the load and not a code issue? Certainly try with the backup battery.
I will replace my backup battery and charge my main battery. As for my motor distribution, I have my mogo lift on port 1, my two scissor lift (power expander) wires on ports 2 and 3. One of my chainbar motors is on port 4, while two of my drive motors are Y-cabled on port 5. The other two power expander scissor lift motors are on 6 and 7, the other Y-cable fro the drive is on 8, the other chainbar motor is on 9, and my roller intake is on port 10.
Would I benefit from moving certain motors to the power expander, and if so, what would be the best way?
I imagine adding the chainbar to the power expander would be worth it since the chainbar and scissor lift don’t draw much at all.