OK so I didn't do a very good job of posting that last night, as it wasn't clear that it was a kind of quizzing post & not a seek for help post.
The reason for the in depth look at this was because the car came in with a reported breakdown due to a flat battery at motorway speed, where the RAC came out & put some jump leads on, to start the car & during the journey home it repeatedly cut out & had to have another brief charge to get her going again.
Since then it had travelled over a hundred miles back to Coalville, so that I could take a look at it. All basic tests that I performed, showed that the charge system & battery were good. There were "under & over" voltage DTC's in many modules though.
I thought it would be interesting to monitor voltage vs current over several minutes, in the hope that something would stand out. I have seen voltages drop quite low before at idle with all consumers turned on, but this case made me question (or maybe over analyse) everything that I was seeing.
I noticed that the battery light would come on after prolonged periods of idle with high electrical loads. I even considered the possibility that the battery might have been on its last legs & not have enough reserve capacity for the task. I duly fitted a loan battery for the purpose of elimination, which made no difference.
Anyway here is the full capture, taken from the car when I managed to witness it misbehave.
I have used both amps clamps (60 & 600 amp) because I wanted to see a more accurate representation of current than the 600 amps clamp will deliver. I used the 600 amp clamp because clearly the expected current flow exceeds the limits of the 60 amp clamp.
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