maybe only for smaller engines

Bought this item to use to jump start my 2015 Kenworth on cold winter days using the new Jump start app just released for IOS. The cable is plenty long but I was unable to get enough power to get the old girl to crank over. My Iphone battery was only at around 75% though so it may have been my fault. also, My battery cables are colored red and black not red and white but I figured out the polarity easily by putting each end in my mouth and testing them prior to making the battery connection. FYI the red is negative!

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