Of course, in modern cars, there are battery charge indicators (in the same panel as the speedometer, fuel gauge and temperature gauge). Using these indicators, you can be able to know when your battery is developing problems, like when it is losing charge too quick, even without opening your car's bonnet. Naturally, these indicators only work for as long as the battery is at least 'basically functioning;' for it is the very same battery that powers them.
Bulbs, though, are probably No. 1 on the replacement list because they're used so much and because there are so many of them. Most cars, for example, have at least three bulbs and usually more on each side for brakes, taillights, backup lights, turn signals and side marker lights. In front, there are headlights, maybe separate high beams, frequently daytime running lights and fog lights, turn signals, "parking" lights and side markers. Chances are that over time at least a couple of those will burn out or stop working because of corrosion or excessive jostling from rough roads.
Quirky Problems Require Expert Repairs. There were 266,539 new vehicles sold in Victoria in 2008. There are over 3,921,574 cars on the road in Victoria. If you could talk to the various car owners who have experienced engine problems, odds are you would find the quirky problems are related to electrical issues. Fortunately the right diagnostic equipment can make it much easier to pinpoint the problem quickly.
Alternator: now this was a breakthrough!! Before the alternator was the dynamo-machine. A DC generator who wasn't that bad, but had a lot of glitches, the regulator system was complicated, it was large and in some cars highly unreliable. Then came the alternator. It was brilliantly constructed, highly dependable, half the size of the dynamo and very easy to repair. The output that it gave was much more stable and consistent thus allowing more appliances to be put in the car.