Lesson 10
Jump Starting a Car
Understand the jump-start circuit, know when not to try, and see where the last clip goes, and why.
Borrowed current
A jump start borrows another battery’s current for a few seconds of cranking. Every rule that follows comes from two facts. That current is large enough to melt metal if it takes the wrong path. And a lead-acid battery can give off hydrogen, which a spark can ignite.
You can borrow from another car with jump leads, or from a portable jump pack. Each comes with its own instructions, and so does your car: the handbook’s jump-start page shows where to connect and anything your car needs that others don’t. Read both before you start.