To start your car, you need to jumpstart it with another car's battery. if the engine starts, but doesn't stay running under its own power for more than fifteen seconds, you probably have a dead battery. simply connect the jumper cables in the following order: red-red (positive cable), black-black (negative cable), red-black (positive cable), and black-red (negative cable). to complete the circuit, touch one end of each wire to an unpainted but metal surface on your respective vehicles. when connecting positive to positive or negative to negative–short out–you should see sparks fly and/or hear a faint “pop.” watch this video for more information on how to jumpstart your car
what are the signs of a dead battery in a car?
it's always a wise idea to plug your car in as soon as you get home so it has power for the next day. sometimes, though, the battery is just too old and will need to be replaced. and, of course, it never hurts to carry jumper cables and a first aid kit just in case you need them. never let that dead battery put an end to your day!
how do i know if it's the battery or the alternator?
the 12 volt battery provides the power to the electrical system, which sends power to components like bulbs, starter motor and other loads. problems with these parts will show up on your battery first. alternators keep the battery charged by infusing it with extra energy when needed, but it also starts your car like a traditional engine would (charging the battery as it runs). if you don't want to take your vehicle over for an alternator test at a garage just yet, you could start by testing out all of these previous mentioned problems- if they're not working then chances are that either your wires or voltage regulator need replacing.
can you test a car battery if it's dead?
no. a battery can be either fully charged or completely drained of charge, but not in between the two. in other words, you cannot test a car battery with a voltmeter because there is no range on a volt meter that spans a full 30 volts to indicate a dead cell.
note: the 12v system uses six cells for voltage and each automotive battery is itself around 48 volts – so they are wired in series/parallel to produce the 12 volts desired by the vehicle's electrical system software. if one of those six cells goes bad then it'll usually just read as lower voltage according to your voltmeter–not dead outright!
to check if your car battery has been fully drained see below image from pixab