You should be able to replace the alternator belt meanwhile by heading to an auto parts store and purchasing a replacement. You can then try to install it yourself or try contacting a mechanic to do so for you if you are not confident enough yourself. If not then you may have to try charging your car using a car battery charger which works much like a jump start – supplying your car with energy from an external source – except for it can be left to run for a long period of time meaning it can completely charge the battery rather than just doing so partially. If you leave this overnight then your car battery should be completely charged by the next day.

You should also try connecting a multimeter or a voltage meter to test the alternator while the engine is idled. You should find that the readout is somewhere between 13.6 and 14.3 volts. If not then your alternator is likely to be the problem.

Another quick test is to try revving the engine while getting someone to watch the car headlights. If the car headlights get brighter as the engine is revved then this is usually a sign that the alternator is charging the battery still and that the problem is with the battery rather than the alternator.

If you are unsure then you should probably check with a mechanic. However if you would rather avoid the expense of a mechanic you can use these checks, and if you remain in doubt then try changing the battery first as this is significantly cheaper than trying to replace the alternator.

If you are looking for an alternator for your vehicle you should look on our auto parts store online. Use can also use an auto parts store to shop for the other tools you may need here such as the car battery charger or multimeter. You should also look to buy protective eye wear if you are working under the bonnet of your car.

In theory the purpose of the short drive after boosting your car should be to charge the battery via the alternator. If you cannot start the engine at all then the chances are that the battery is the problem or something unrelated and more severe. If from this point on your car drives fine and doesn't lose its charge again then this may have been a 'one off' problem and it may be that you simply accidentally left the lights on in your car, or maybe left the radio on too long. Cold weather can also sometimes be enough to 'freeze' the fuel cells in the battery and prevent them from working if you have an old car, while leaving the car for a long period of time without using it can also cause it to gradually lose charge.

However if the battery loses its charge again then this means either the battery has lost the charge faster than the alternator can charge it back up, or the alternator has failed to charge it as you've driven and it is hard to differentiate these two cases.

To do so, one quick method is to look through your car's service history and see how recently the battery was replaced – if it only just happened then this might suggest you have a damaged alternator or another problem. To inspect closer, open the bonnet and look at your battery and alternator. The battery will have a small lightning symbol on it and may have a plastic cover over it, while the alternator may be located behind the engine on a bracket. Consult your car manual if you are not certain where your car parts are located.

Now direct your attention to the connections between the alternator and the battery (with the engine off of course). You should also check the alternator belt for damage. Either of these can be the cause of your problem and may allow you to fix the problem yourself. In the former case this might suggest that the problem is not solely the battery or the alternator, but rather the conduit between the two.

If your battery is faulty then this will mean that it is charged by the alternator, but that it does not actually hold on to that charge.

The first step to diagnosing this problem then is to try jump starting your battery. This is necessary to charge it again at least briefly and this will help you to diagnose the problem. To do this you will need the engine from another car and two jump leads. Simply connect the positive terminal on your battery to the positive terminal on another car, and then connect the negative on theirs and ground it on your car by clamping it anywhere on your engine that is made from metal. Now ask the owner of the other car to start their engine and keep it running for around ten minutes. After this time you should then be able to start your own engine. Keep both sides running and then after a few minutes disconnect both without turning off your engine. Now when you disconnect the batteries make sure to go for a short drive.

Your alternator is the part of the car that charges the battery in your car. It does this by taking the energy that you create from actually driving and using this to recharge the battery which powers things like the engine and the lights as well as the ignition which starts the car.

This then means that without an alternator you would find your car ran out of battery power and was then thus unable to operate at all – you wouldn't be able to turn on the lights or listen to the radio, let alone actually start the car. As such then, this exactly what you would find if your alternator stopped working and you would no longer be able to do any of those things. However the main difficulty with alternator problems – and knowing whether or not to replace it – is that these symptoms can be caused by a faulty alternator or a faulty battery.