Thursday, July 11, 2013

Well, we've cleaned up the Porsche a bit.

Erick and I have run through the battery management system (Valence) and we aren't having any luck. For some reason, it is speaking (electronically, CAM) to us and our computers (we've used 3 so far) haven't been able to translate the chatter into anything intelligible.

Roberto and I are waiting on this information to determine the State of Charge (SOC) so that we know where the batteries are, if there are problems, and if they are charged at any point. We don't know how balanced the pack is, and if we might do damage by doing anything to them.

I also looked at the EV specific fuse box, which runs some of the electronic systems and should also run the center touchscreen which we have been having problems with. All (4) the 15A automotive fuses were questionable, and I don't know why. The modes of failure were interesting too. I wish I had a photo of them. The first had melted plastic, but the filament was still intact.The second had a hole in the plastic melted around the filament, but the filament was still intact. The third was no longer conducting and was so brittle that the process of grabbing it and pulling on the plastic caused it to fall to pieces. The fourth's filament was broken. I'm still puzzled by what we found there.

abrajam giving the Porsche a little love!
As a quick note, if they failed, they should have failed from the filament only, like the picture below. The left has a broken filament, and the right is intact. The discoloration on the left may also hint at some sort of thermal stress, which makes sense due to the fact that the filament breaks via a current induced heat stress.

A melted fuse itself might indicate that something is drawing not quite the rated capacity of the fuse, but close to it, causing the filament to heat up and melt the plastic before breaking the filament. Food for thought.

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