We have a 2002 VW New Beetle. They made a very interesting design decision that involved sticking several wires and a fuse box on top of the battery.

Previously, ours was very corroded. I spent some elbow grease, Deoxit, and some good ol' Vise-grip persuasion to clean up the one wire. It appears that the alternator is happy to charge the battery now -- I'm measuring 13.5-14V across the terminals with a multimeter now.

However, after a drive of modest length (~10m, in-town), the wires are... well, what I would call quite warm:

thermal image of 2002 VW New Beetle fuse box on top of battery, with temperatures exceeding 150 degrees Fahrenheit

A non-contact thermometer reports about the same temperatures. I observed the same temps on a 15 minute highway speeds drive as well - it looks like ~180F is just the temperature that is my current normal for these wires. The left-most wire, if I understand correctly, comes directly from the alternator, and is protected by a 110A strap fuse (purplish, left. Unsure if that temp is accurate, as the metal is somewhat shiny.)

Are these temperatures reasonable for these wires? Or should I be concerned there's other electrical issues to worry about here?


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