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I recently started having battery related issues, while poking around under the hood with my multimeter I noticed that the under hood positive post was getting hot, too hot to touch.
I suspected corrosion which I confirmed after peeling back the wire insulation. I tried to clean up the corrosion with baking soda and vinegar. It helped a little in that I could keep my finger on the under hood positive post without my finger blistering but it was still getting hot.
I wanted to figure a way to replace the under hood positive post instead of replacing the entire alternator cable (my A6 has 190K miles). After a trip to the auto parts store I picked up a couple of battery terminals connected by a bolt so that I can still jump start the car from under the hood.
My next step is to monitor the status of the battery since the old battery was slowly draining and getting a handful of battery related error codes. I replace my 5 year old battery ("geniune" Audi battery that was a non-AGM battery) with an Interstate AGM battery from Costco.
Below are some pictures, not factory looking but it works.
Thanks for the info sswari.
I found it interesting that the cable measured zero ohms across the corroded section. I would have thought that I would have measured some resistance to cause the overheating effect.
The resistance will likely increase with higher multi-amps current load and begin to thermally runaway which will also continue to increase the resistance.
The ohm meter will use milliamps to perform the resistance measurement on the cold connection so it may not show much loss in this state.
When I was dealing with electrical issues I think after I sorted out everything, parasitic drain went down almost to 0mA.
Not saying it was real 0mA measurement, but consumption was so small that my meter was not able to read it.
You need to wait about 2 min for all the modules to go to sleep.
Regarding the positive cable getting hot, it doesn't always have to be a bad connection (obviously not in your case).
I'm saying this because I was thinking the same while testing my cables (during summer time) and that cable pin was sooooo hot.
Later I realized that these V6 petrol engines are burning absolutely everything under the hood during summer time, so it's best to check for wire gauge overheating during the winter time, since the overheating was gone in my case.
When I was dealing with electrical issues I think after I sorted out everything, parasitic drain went down almost to 0mA.
Not saying it was real 0mA measurement, but consumption was so small that my meter was not able to read it.
You need to wait about 2 min for all the modules to go to sleep.
Regarding the positive cable getting hot, it doesn't always have to be a bad connection (obviously not in your case).
I'm saying this because I was thinking the same while testing my cables (during summer time) and that cable pin was sooooo hot.
Later I realized that these V6 petrol engines are burning absolutely everything under the hood during summer time, so it's best to check for wire gauge overheating during the winter time, since the overheating was gone in my case.
180mA is way to much, 50mA is bearable.
Correct, for some of the circuits I waited a minute or two for the module to go into sleep mode while measuring the current.
From my experience the positive post gets warm to the touch after an extended drive (due to engine heat, outside temps) but with the corroded cable the positive post gets hot. The corroded cable measured 0 ohms when I checked the resistance.
05-27-2024, 05:22 PM
Alternator Cable Getting Hot
