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.

[SmokeTest]

I've seen this happen several times. The larger/stiffer the wire, the more likely to be an issue.
We also have had many instances of a crimp tool deforming the connector so that it pushes down too much on the spring clip in the connector housing. When the other mating connector also has a bent crimp or torqued wire, it is likely you'll have intermittent electrical contact.

-MikeY

[Al Skierkiewicz]

This is a possibility when the connector has been around for a while or has been abused. The metal spring under the contact becomes deformed and does not provide the contact force needed to keep the contacts in position. It seems to be more of a problem with the stamped contacts. Please check the red plastic inside where the contact comes through from the back of the connector. If you see obvious depressions left by the contact, then I suggest a replacement.

[Bill_B]

I think it is a useful skill to be able to extract the connector from the housing. You can inspect the contact surface and test the spring. If you're dissecting the battery connections, remember to do the removal ONE AT A TIME. Put the removed on back into the housing before removing the other one. Batteries can weld, and it won't do your connectors any good to be part of the fireworks involved.