Battery Died, Portable Jump Starter Didn't Work
So my car recently had an "Auxiliary Battery Malfunction" warning pop up, and the next day, the car was entirely dead. Turns out the auxiliary battery had failed and the car used the main battery to cool down the turbos after I had turned the car off that night. Mercedes replaced the aux battery under warranty, but I was stranded for a good hour that morning waiting for a jump. I tried to use my portable jump starter (rated for 4.0 liter engines), but it did not work.
Does any one have any recommendations for portable jump starters that work with this car? I would like to avoid this issue in the future because I might not always have a second car to get a jump start from.