Bus bar heating up

[ojoj]

I have made 90 degree Cu-ETP copper busbar 4mm*25mm with M10 hole on each end, for the positive cable to exit the battery box more cleanly.

Before this bus bar i have 70mm2 cable, which goes to battery disconnect switch with M10 bolt, then comes this bus bar, and after the bus bar comes 70mm2 cable again (m10 tinned copper lug).

When running heavier loads for 20-40minutes, this busbar warms up, not so much you couldn't hold it, but still. All the other connections on the battery and elsewhere are cold.

What would be solution to stop it warming up? Some sanding with 800 grit, then putting some antioxidant paste over and tightening the bolt hard?

 

[RCinFLA]

4mm thick x 25mm wide should be fine. Heating is likely from poor terminal connections. Cu-ETP is okay but not the greatest due to oxygen content and rough surface. The surface roughness may be the connection issue.

You should not use bare copper against aluminum battery terminal. Over time the aluminum terminal surface will develop pits from interaction with copper. At least put NoOxy grease to reduce the intermetallic reaction.

 

[ojoj]

I have copper busbar to tinned copper lug conenction.

 

[S Davis]

I would look at the lug to wire connections and see if they are generating the heat.

 

[ojoj]

Its crimped, like all the rest 70mm2 lug to wire. I could tighten it some more perhaps.