Non-perfectly sealed car batteries will slowly leak flammable gas, and an active spark would light it on fire. So the proper procedure has you connecting the last time (which is most likely to produce sparks) far away from this potential fire source.
Cars are wired so that ‘ground’ connects to the negative terminal, and ‘ground’ is basically the metal chassis of the car. So connecting to the metal frame of the car *will* connect the batteries in a loop.
Latest Answers