Jump-starting preliminary steps
Carrying a set of jumper cables
can help you help a fellow
motorist—or the other way
around. Jump-starting a vehicle is usually
pretty simple, but it's serious business and
you have to do it right to do it safely. Every
year people are seriously injured while
attempting to help another driver with a
“jump.” Clip this article and put it in your
glove box. Then, before you even connect
the cables, go through these steps:
- Make sure both batteries are the same
voltage (most batteries are 12 volts) and
the same polarity (both have a negative
ground). You can check this information
in your owner's manual in your
- Pull your cars close enough to each
other to connect the cables, but never
let the vehicles touch. This could cause
- Shut off the ignition switch, lights and
accessories in both cars. Be sure the vehicles
are in park or neutral and that the
parking brake is set. Wear safety glasses.
- Don't smoke. Sparks near a battery can
cause an explosion.
- If the weak battery is frozen, don't try to
jump it! It could explode. You can tell if
it's frozen by looking through the
inspection cap to see if the water is
frozen. One or more sides of the battery
case will bulge if it's frozen.
- Make sure you can identify the positive
and negative terminals of both batteries.
Also be sure you'll have enough
room to clamp to the cable terminals.
The positive terminal is most likely
connected to the car's starting/charging
system with a red cable that has a plus
sign. The negative is connected to the
engine of the vehicle and usually
has a minus sign.
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How to hook up the cables and start the car
- Clamp the positive (red or yellow)
cable to the positive terminal of the weak
battery. Make sure the other end doesn't
touch any part of the car's engine or body
or you could get a dangerous spark.
- Clamp the other end of the positive
cable to the positive terminal of the good
- Clamp the negative cable (black) to the
negative terminal of the good battery.
- Clamp the other end of the negative
cable to a clean metal part of the engine
(like a bolt head or bracket)
in the car with the weak
battery. Keep the clamp
away from the battery, any
moving parts and the fuel
attach the negative cable to
the negative terminal of the
weak battery! This common mistake could
ignite hydrogen gas directly over the battery.
Battery explosions can cause serious
injury. Even if you've gotten away with it
before, use a metallic engine part instead.
Now start the car with the good battery,
let it charge the weak battery for 5 minutes,
then try to start the car with the
weak battery. If it doesn't start, shut off
both ignitions, make sure the cable clamps
are making good contact and then try it
again. When the car with the weak battery
starts, wait (about 15 seconds or so) to
make sure it doesn't stall.
Disconnect the cables in the reverse
order: First remove the negative cable
from the car you jumped, then the negative
cable from the car with the good battery.
Then remove the positive cable from
the car with the good battery (don't touch
a grounded part of either car with the
clamp of the positive cable). Finally,
remove the positive cable from the car with
the weak battery. Remember, both engines
will be running (with any
luck!), so work carefully
as you remove cables to
avoid belts, fans and
other moving parts.
Tip: If you live in a very
cold climate, buy the
you can find (the lower
the number, the
thicker the cable).