Jump a Dead Car Battery




30 years experience as a mech ,my first concerns are safety .
ask questions ,your local mech will show details of what need to be checked .
boost boxes are a good way to start a dead car ,i included them as well as jumper start

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Step 1: Safety First

eye protection only pirates look good with eye patches
hand protection use latex gloves like medics do
electrical protection short piece of broom handle
Acid protection >Baking soda (I store it in a m&m mini tube remove M&M first )

Step 2: ID What Is Under the Hood

Where is my battery?
Under the hood might have a dust cover on it (owners manual )
important parts of the Battery?
Almost all battery's (even maintenance free) have a cover to check/add distilled water
a “DRY “ battery can explode
the Post (what cables attach to) one marked with “ + “ one “ - “
the + or positive one is hot/red
Cables (most) one is red one is black
Black cable other end from the battery is it bolted to the motor?
Take the time to look for the belt on the motor
is the belt on the pulley? Is it lose?
The modern flat belts last many miles but when they break everything stops

Step 3: The Running Car

Jumper cables are always too short
check where both batterys are so cables reach
short broom stick to keep tangled cables from arcing
identify the Positive post “ + ” clip the red Jumper cable to it
it does need a good connection
black Jumper cable clamp goes to “ - “

Step 4: The Dead Car

now its gets a little different
the black Jumper cable clamp goes to where the cable is attached to the motor
most important to ground the motor to the jumper cable
it has to do with not arcing the dead battery (yes it can explode)
then the red Jumper cable gets clamped to the “ + “ Positive post

Step 5: What Is a Boost Box?

this is a battery in a nice case with a wall plug to keep it redy
they work best when the dead car is not completely dead .
they are nice and cost less than a wrecker will charge to jump you.nicer ones even have air compressor to inflate a low tyre.

Step 6: The Right Way

thanks to ted for use of his truck (1971 Toyoda) and his little boost box
all photos are mine ask me first most likely will let them be used

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    14 Discussions


    3 years ago

    One thing to keep in mind, if your battery is low or dead and you need to start your car it's the starter motor that you need to connect to not the battery!

    Once the car is running, and you remove the negative cable clamp from the engine ground then the positive cable clamp from the batteries positive post.

    You're charging system then will take over. If the battery or alternator is damaged the battery will not keep a charge.

    (I repeating what other have said) If the battery has a dead cell ,connecting a good battery directly to the dead battery will overheat the dead battery in seconds. The electrolyte solution inside your battery is a mix of sulphuric acid (35 per cent) and water (65 per cent). Getting sulphuric acid in your eyes and on your skin will send you to the hospital with serious burns.

    Alway use eye protection when working with a car battery!

    Note: an electronic booster box will detect a dead cell and will shut down, a car battery will not!


    10 years ago on Step 4

    This is a little bit incorrect: If you would do it in this order, you could put the black '-' cable directly to the '-' terminal of the battery as well.
    The point of putting the black cable on a metal (grounded) part of the car (like the motor itself) instead of the '-' terminal is to avoid the battery from exploding or leaking acid:
    First you connect the red '+' cable to the '+' terminal of the dead battery and THEN you connect the black '-' cable to a grounded metal part of the car. That way if there was a lightning (the arcing), sparks won't be near the battery itself. This way it's safer!!

    1 reply

    11 years ago on Introduction

    this is good for someone that needs to learn to jump start a car


    11 years ago on Introduction

    Glad to see your connecting to the frame and not to the battery of the car needing the jump. A lot of people try to jump through the dead battery despite the possibility for trouble.

    5 replies

    Reply 11 years ago on Introduction

    Have never jumped using the clamp on the frame and it has always worked for me, dad, cousins, uncles. And the frame just get grounded to the battery. So way the frame?


    Reply 11 years ago on Introduction

    jumping can throw 300-600 amps at 12VDC .hooking up to the battery the recoil from turning the key from start to run is way to much power for any normal auto battery dont belive me?hook up an oscilloscope to the circuit and watch the spike. might get lucky 1000 times.might blow your arm off.7200 watts is nothing to take for granted


    Reply 11 years ago on Introduction

    How does someone have a 600amp alternator in their car? Even a big ford diesel can't be much more than 300 amps.


    Reply 11 years ago on Introduction

    not the alternator its the transfer in the jumper cables .
    the repair shops have load meters hook one up and then jump start the car 300 to 600 amps will flow from good car to dead car ( i have melted cheap jumper cables trying to start my diesel wrecker ) the problem is that when you stop trying to crank the car for a millisecond you get a recoil back from the huge amp draw were putting to the starter if battery is directl connection the recoil can bounce into the battery that might be full of hydrogen gas if the battery doesent have the cells covered in water/acid the cells can arc from the massive amp input ,this is why need to top off the battery before jump starting .a good friend lost the left side of his face this way.
    GM/delco makes a 180 amp alt for boats it works on any car/truck/boat called "one wire "one wire


    Reply 11 years ago on Introduction

    You connect the negative clamp to the frame of the car being jumped as a last step so if it sparks it has less potential to ignite any possible gas buildup from the old battery.


    11 years ago on Introduction

    This is a good instructable, however I'd reccomend that you label your pictures to include different tips. While It is a good idea to clamp the negative to the frame, that's also that much closer to the hundreds of electronics you're also trying to power whilst the car turns over. Unless the clamps are crap and can't secure a tight grip on the battery terminal, it shouldn't spark ever.


    11 years ago on Introduction

    People are way to dumb these days if theres actually a need for this instructable... it well done and all that but i don't see a point since i known how to jump start a car since i was 10 yrs old...


    11 years ago on Introduction

    These are some good instructions on how to jump a battery and congrats on finishing your first instructable. The pictures are pretty good too. Just remember... capitalize and use punctuation!

    1 reply

    Reply 11 years ago on Introduction

    yes this is my first try,i composed it with open office cool bullet points too cutting and pasting it i have no idea where they went thank you for comments