Q: What is a key to heavy duty jump starting success?
A: First, like every other application, make sure you have right jump starter for the job. Multiple batteries in the vehicle to be started usually means you need multiple batteries in your jump starter to have the power to start it.
Also, always make sure to make your positive battery connection to the battery closest to the starter when jumping multiple battery systems. This will ensure that the power available from the jump starter is transferred to the starting system, not depleted by the battery bank, which can be quite taxing.