Power expander issues with Lift

Good night guys, my team has had an issue with the power expander. Our Lift works fine when we connect it directly to the Cortex, but when we use the power expander the lift doesn’t go at the same speed. The last month we had a competition and it worked great, but until now we noticed that the issue with the speed of the sides was caused by the power expander. We also replaced it for a new one and it does the same.
What advices could you give me to troubleshoot this problem, and as always thanks for your attention.
Best regards.

I’m not sure if what I’m answering is the kind of problem you are describing, but I’ll give it a try…

Do you have the power expander powering one side of the lift and the Cortex powering the opposite side? If so, then perhaps differences in your batteries are causing asymmetry in your lift. I usually have my kids spread out the power distribution so it is always even on each side. For example, if 4 motors are driving a lift, then I have the power expander provide power to one motor on each side of the lift, and the Cortex provides power to one motor on each side, too. That way the motor power will be balanced even if the batteries are providing slightly different amounts of energy.

I hope that helps.

I’ve had a love/hate relationship this part. It’s nice but has a few drawbacks.

The battery cord is very stiff and easily broken. This ruins the $50 part. Suggest zip tying the power cord to a standoff at the hole right at the cord so it does not bend.

It seems the power draw on the expander does seem weaker, so I try and tell people to use lesser used motors on here. (Add it to the list of items to test.)

If you have four lift motors, spread them out two and two. Similarly, if you have four drive motors, please split among the expander and cortex. This way if you trip one of the two power areas, you can still move.

The other drawback is you have something else to plug in. I think team 80 was one of the reasons for the allow you to turn on your robot rule. But it has a hitch. If you move, you technically should not be able to reach in and plug in the power expander.

I wire the entire lift to the power expander and the rest to the cortex. Therefore even you forget to plug in the battery you can still pick up opponent’s cubes and block them…

There was one close catch for me once. After the ref asked everything was ready, our thumbs were up, ref counted down to two, I saw the power expander is plugged in but light not on… I called stop and jerked the connection and things worked. That was in semifinal and I still shiver thinking about that.