Category: Automobile

Direct Current and Your Car


Do you know the difference between AC voltage and DC voltage?

Most of you familiar with electricity do. car detailing melbourne But, for those of you who don’t, AC stands or alternating current, and DC stands for direct current. Most all automotive electrical systems operate on direct current, and this is good to know when you have an electrical problem with your car.

Let’s look at the starter on your motor. All starters have the same basic components: armature (the rotating part), stator (the stationary part) and brushes. The same goes for your window motor, door lock actuator, antenna motor, blower motor and fuel pump. They all work exactly the same way. Put 12 volts of power to the brushes and the armature will spin, or rotate. So what’s the difference between a starer and a fuel pump? Size and the amount of current it takes to move the armature, the amperage draw.

Just about every week, I receive a few emails about starter problems. They usually say that the battery is new and the alternator is working fine, but the starter turns over very slowly. What’s wrong?

Well, most of the time this is just because the brushes are worn out, although a defect in the armature or stator can cause this as well. A good starter will require (draw) between 120 and 150 amps. When the starter gets worn it can require as much as 400 amps. When this happens the starter will still operate, but it will be very sluggish.

These same symptoms that can effect a window motor and all the other 12 volt electric motors in your car as well. But, they may be harder to diagnosis. Your starter is the only motor in your car that doesn’t have a fuse, so it’s fairly easy to figure out where the problem is.

All the other motors in your car have either a fuse and/or a circuit breaker, and even a relay. Many times when a fuel pump or a blower motor goes bad, it can be blamed on a relay or even a resistor. However, most of the time it’s just that the motor itself is wearing out and drawing too many amps to operate properly. This can blow a fuse or pop a circuit breaker.

Another thing that can affect the proper operation of some electric motors in your car is a proper ground. If the voltage from the motor can’t get to ground, it can’t complete the circuit.

Many times the ground wire can become corroded or loose. It still completes the circuit, but it will require more amps to do so, and this will act just like a bad motor. This is the most neglected part of the electrical circuit. All power comes from the battery, and in order to complete the circuit, all power must return to the battery.

So, when you have a 12-volt motor in your car that isn’t working properly, make sure you check for proper voltage to the motor and from the motor. If all this checks good then you must have a bad motor, and if your good with motors and electrical items you may be able to repair it yourself.

Categories: Automobile