If you're stuck with a dead battery, you can start the car by using jumper cables to connect the bad battery to a fully charged one, whether or not it’s fitted to another vehicle. Here’s a guide on how to jump start a car, assuming that the charged battery is fitted to another vehicle.
The cable connections for jump starting often allow only limited current flow, and the less expensive, smaller gauge cables are even more limited thant the better ones.
Depending on how dead the battery is, jumper connections may or may not start a vehicle immediately, and may require a few minutes of being hooked to a running car with a fully charged battery to charge it somewhat.
Be especially wary when jump starting modern cars with engine management systems – careless jump starting, particularly if the cables are allowed to spark, can cause damage to the car’s computer components.
It’s also a good idea to read your car’s manual carefully to see if there are any special recommendations to be observed when jump starting.
Some cars with remote mounted batteries, such as many BMWs, are fitted with special terminals under the hood to allow jump starting, and on these cars the jumper cables should only be connected to the special terminals provided. If in doubt, call AA or a local roadside assistance, as they will have the equipment to get your car running without any risk of damage.
Place your jumper cable connections in EXACTLY this order:
If the charging system and the battery of the car which had to be jumped is in good condition, 30 minutes of driving should being it back up to a full charge.
Remember, sometime in extreme cold conditions a perfectly functional car may need a boost to get started because batteries put out less energy the lower the temperature, while at the same time need more power to turn in the cold.