NEO Motors power draw issue

We are attempting to lift our elevator systems with the NEO motors. Approximately 50 pounds. We completed our first competition using CIM’s and decided to switch them in an attempt to save weight for climbing. However, they brown out when we attempt to lift our power system. If we have a 12.9 V battery, it takes very little time to kill our battery. We are running 3 separate NEO’s for our elevator system. We also have 4 on our drive train. Is there a parameter that needs to be checked? Any tips would be appreciated. If it comes down to it, we will return to our CIM motors and Talon SRX’s. Thanks!

Are you using any current limiting on the spark maxes at the moment? If not, I believe it should be set.

What is the final reduction from the NEO motors to your elevator drive?

Lifting 50 lbs on an elevator? What are you lifting, exactly? My team’s elevator last year could go bottom to top in ~1 sec using a single CIM, 3 NEO’s seems like overkill, unless you’re using it for climbing… in which case it still seems like overkill.

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I second @SoProTheyGoWoah and suggest turning down the Smart Current Limit to 40A to start with to see if that is enough to operate your lift. It is set to 80A default.

Have you calculated your per-motor expected operating current for your 50lb lift?

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I think the current limiting would solve our issue. And sorry. Our whole elevator system weighs probably 50 pounds. We are not lifting the whole thing. With CIMs we can go full extension in 2.5 seconds. We have a separate motor per stage and 3 stages. I will tweak with the current limiting.

Are you sure that you are driving all 3 motors in the same direction?

You can also try counter balancing the elevator if you havent already using constant force springs. It would add weight but would almost eliminate the need for so many motors.

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I strongly agree with this. Definitely consider adding constant force springs.

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Adding onto what everyone else has said, constant force springs are your friend. Adding those to our elevator (2 NEOs) changed it from an automatic breaker-popper to one that is suitably fast even at 50% power.

Please be careful when installing them. We always have 2 people to install them. One to hold the springs and one to bolt them to the elevator stage. We raise our elevator all the way up (manually), then attach it with both people involved wearing gloves. By raising it all the way up we minimize the distance that they can wind up uncontrollably if accidentally released. We disengage the springs before we bag the robot for safety during transport, and then re-engage them first thing when we unbag it. It might be overkill but I am terrified of those things.

Could you explain how to turn down the Smart Current Limit?

You can set it in the SPARK MAX Client (be sure it is up to date) on the Advanced tab. Be sure to click Save Configuration in the Client.

You can also configure it in your code by using the setSmartCurrentLimit​(int limit) method, or equivalent in the other languages.

We have 3 motors because each stage is a ball bearing acme rod. One power each acme rod to spin it. I’ll try to attach a video later tonight.

You can check your motor currents and battery voltage in the Driver Station Log.

Here is the video of our elevator system for those who wish to see why we have 3 seperate NEOs. Each individual motor powers it’s own stage of the elevator system. (This was with the CIM/Talon setup pre-competitions)