While I've given and received boosts before I've always been following instructions by rote and never really understood what's happening.
The procedure I've been told is:
- Attach red clamp to the positive terminal on the dead battery.
- Attach the other red clamp to the positive terminal on the good battery.
- Attach black clamp to the negative terminal on the live battery.
- Attach the other black clamp to the engine or chassis on the car with the dead battery.
- Start good car.
- Hopefully start dead car.
I'm somewhat confused by step 4. since it's often described as clipping the last black clamp to "ground". But the tires should be insulating the car so it's not really grounded is it?
So what's actually happening when you start the dead car? Is it drawing power from the good battery to start the car? I don't understand how that happens since I don't see how there's a complete circuit between the two cars.