1998 E320 Base Sedan, 175k
“Negative disconnect strap” is what exactly? And if those charging posts (or at least the positive for that matter) didn’t have connection the battery charger wouldn’t have charged the battery or even made a guess as to the percentage of battery life when charging through those posts, would it not?Measure voltage on the plus post (under the hood, driver side, under a lid marked with "+"), and the ground stud nearby. These are the charging posts for the battery. If no 12V there, you have a loose connection on one of the battery terminals, or the negative disconnect strap on the wall of the rear passenger seat under a lid.