I have a 1985 Mercedes 300d, with a battery with a cold-crank rating of 1000 amps. The battery is pretty much dead (and pretty much new). So far, I haven't been able to jump-start it with another car that has a 550-amp cold-crank rating on its battery, after letting the battery charge for about a half an hour.
If I let the jump car run long enough, will the Mercedes's battery eventually charge enough to start it, or do I have to find a charging source that puts out a higher amperage? If the former, about how long would I need to let the jump car run before trying to start the Mercedes?