Power Problems

I have recently encountered problems with power in my robot. I noticed that when i turned on my flywheel, my program would detect that the battery level decreased dramatically (ex: if the battery was 8.0, it would become something around 7.2) but turning on the flywheel wasn’t my only problem. if i were to also turn on the Intake, its power would be very minimal as if the outtake would take all its power. My intake used to have a gear ratio and i took it out to see if that would fix it (maybe it was taking a lot of power) but it didn’t do much. I was wondering if a power expander would fix this problem. I have a friend that had a similar problem but the power expander didn’t help him much. is there another way? Is power expander my only way to go?
Thanks in advanced

The voltage drop on the flywheel definatley is expected and many teams are compensating for this with pid/tbh or corrections based on voltage and if you had a speed gear ratio (intake) that would nake sense especially if you had one motor for your intake. Power expander could be a good idea for the flywheel then you would have a seperate battery for that but there is always going to be a voltage drop when the flywheel is powered up (pid is a good way to correct for this). I might be wrong, but i think you have nothing to worry about but see what some other people say first.

Good luck!

Our team 8505X has had the same problem this year and the power expander definitely does solve the problem because the flywheel drains power from the power expander and not from the cortex battery therefore other motors attached to the cortex will not be affected by the power drain. Attach the flywheel motors to the power expander for this to work.

The decreased voltage in the battery is to be expected when anything draws current. I can’t explain why, since I’m not an electrical engineer, but I’ve noticed that any current drawn from the battery results in a decrease in voltage. I’m surprised that the flywheel causes a .8V drop, but then, our 4 motor flywheel on startup causes our LCD screen to turn off briefly, so I shouldn’t be. We account for this, and our batteries’ rapid power loss, with a P/TBH/D (maybe soon to be PID-TBH) controller that works really well for us, but a TBH loop should work fine if your programmer doesn’t feel like making it that complex.

The voltage drop is due to the every battery having an internal resistance. The more current you draw from the battery the more voltage drop there is over that resistance. For older (measured by recharge cycles) batteries it tends to increase due to uneven electrode buildup, etc…

So the problem is, likely, that launcher is drawing too much current. Power expander will help by providing more power from the second battery, but the better solution would be to find where that power is going. If it is consumed by the friction (and eventually turns into heat) try to find where it goes and reduce the friction. You will be able to increase your fire rate, accuracy, and avoid having to replace batteries very often.