How To Jump Start A Vehicle Battery
Follow along for instructions and tips to reviving a dead battery the right way– an essential skill any time of year, especially during the winter.
Tools you'll need:
- Jumper Cables
- Hand & Eye Protection
- A Functioning Car Battery to provide the boost
Safety comes first
Every vehicle is different. When it comes to maintenance and repairs, always follow the vehicle's owner's manual.
Safety should be your number one priority. Don't smoke, drink alcoholic beverages, or wear a necktie while working on the car. Watch out for hot objects, sharp instruments, hazardous materials and other potential safety hazards in and around your workspace.
Don't work with a Philips when the job calls for a flat. Substituting tools can compromise your safety or your vehicle's performance.
Finally, when the fun turns to frustration, or if the job requires specialized knowledge beyond your capabilities, please do not attempt it yourself. Talk to a professional mechanic or installer. The last thing we want is someone getting hurt.
Before you begin
The three major reasons for getting a dead battery are:
- Leaving your lights on
- Not maintaining your battery properly with the correct water levels (for older maintenance batteries)
- Breakdown of the diode bridge or voltage regulator in your alternator
Of course, some people get a bad starter, but the odds of that are low compared to the other causes.
Line both cars up so the batteries are as close as can be. Make sure the cars are in park and that both cars are turned off and not touching each other before you connect the cables.
Make sure all headlights, blinkers, car radios and A/C's are off, and cell phones are unplugged. Unplug all accessories from cigarette lighters and other power sockets from both cars.
Jump-starting a battery can crank 300+ volts through your system and the transients can destroy equipment. These voltage spikes are caused by inrush current into the inductances in your electrical system
Familiarize yourself with the Positive (+) and Negative (-) terminals of both car batteries so you know exactly which one is which. All batteries are clearly marked so if you can't find it, it's probably under 1/8" of caked-on corrosion around the terminals. Wipe off any battery acid that may have leaked.
IMPORTANT: If the battery is cracked and liquid is leaking out, DO NOT go any further! Bite the bullet and go buy another battery and swap it out. If you try to jump start a battery with a crack in it, it will explode.
Try to clean off any corrosion around the dead battery terminals. If you have tools, loosen the wires from the terminals, clean them off, and then re-tighten the wires to the shiny posts. Corroded posts prevent the power from getting through the cables and into your battery to revive it. If you have a file handy, try to file the metal battery posts until they are nice and shiny. In a pinch use pliers to clamp down and scrape off corrosion too as the metal is somewhat soft.
Usually the Positive(+) battery cable is red or orange, and usually the Negative (-) or ground cable is black, but always check to be sure.
Steps for connecting the car battery jumper cables
- The cables must be connected in the exact order listed below. If possible, wear personal protective equipment such as eyewear and gloves, as batteries can be dangerous.
Connect one end of the Positive(+) cable to the Positive(+) post of the dead battery.
Connect the other end of the Positive(+) cable to the Positive(+) post of the good battery.
Connect one end of the Negative(-) cable to the Negative(-) post of the good battery.
Connect the other end of the Negative(-) cable to a good solid SHINY, NON PAINTED metal part of the engine on the dead car. Usually a giant shiny nut on the engine block will do. A painted, dirty, or oily nut will not work. You usually want to avoid placing the Negative(-) cable directly on the dead battery to minimize the chance for explosions. You should only use the ground post on the dead battery as a last resort. On this step you'll get a normal spark as you connect the ground and complete the circuit.