This is my client's car. They've had it for about 10 or 12 years, since then they've acquired two Teslas and this cherry looking ride sits for long periods.

The other day he couldn't start it, no surprise, it had sat for about two months. Oddly enough the main battery reads 12.5v. He had called AAA, they said there were three batteries in the car, I don't know about that, but he ordered an auxiliary battery for this model on the web, we found instructions that it's behind a little panel to the left of the instrument cluster, facing out towards the door.

We took that off and the battery's not there. Web searches and his owners manual (it refers to it as the "consumer battery") indicate it's in the trunk somewhere. One hit I found says it's on the right side, just behind the butt of a guy sitting in the right rear seat.

Not sure if this is the best forum for this question or not. I'm sort of a diesel head so I don't get over here much.

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Te futueo et caballum tuum

1986 300SDL, 362K
1984 300D, 138K