Battery power connector issue

[dvanvoorst]

As CSA at the Lansing MI event this weekend, I ran into a surprising electrical issue. A team had their Anderson connector bolted to their frame, holding it solidly. They had discovered intermittent power loss was occurring when their battery wires were wiggled. Using a multimeter on the PDB, and wiggling the battery cables, they would see voltage go to zero. The Anderson connectors was completely connected, the cables were fully inserted and snapped into place, and the problem occurred with all of their batteries. After some discussion, they determined the problem to be that their ground line from the PDB to the Anderson connector was being pulled to the side, which was making the connector inside the Anderson connector to be slightly skewed. When the battery wires were wiggled, we believe that the internal connectors being skewed in opposite directions caused a complete loss of contact.
The team rewired it such that there was no side pull on the wires going into their mounted Anderson connector and the problem no longer occurred. I was surprised that a complete loss of contact could occur simply by the wires being pulled sideways. I wouldn't have been surprised to have a problem under heavy load, but this was showing voltage drop, occasionally to zero, with just a multimeter - no other significant load.
Hopefully this experience will help some other team troubleshooting robot reboot problems.