Answered: Power expander use with a second battery

This question came up at a scrimmage today, which we weren’t completely sure how to rule on:

If a team wants to use a second battery on their robot as a counterweight (or for anything else), they have to be “utilising” a power expander.

Does this mean using a power expander for its intended purpose, using a power expander for something functional, simply having a power expander on the robot, or something else? It seems odd that a team who wants to use a second battery for reasons unrelated to power should have to pass one of their motor wires through a power expander just to satisfy a technicality in the rules.

Yes, this is correct, if a team wishes to use a second battery they must be using a power expander. Batteries are meant to power robots, not to be used as ballast. If you really insist on using a battery as ballast, you must plug into a power expander and plug the power expander into the robot. You are not required to use the power expander for its intended purpose, but it must be present.

Thank you, we will rule this way at future events if the situation comes up again.

You’re welcome.