Voltage regulators - how do they work?

forgotmyname

I have noticed that younger / newer drivers often switch on their headlights before starting the car.

I have said to them one day your going to regret doing that, its going to be a cold frosty morning and you will put your lights on and by the time your ready to start the engine its going to go click or tirn over very slowly.

I know batteries are better these days, but the cold still hits them hard.

Richard53

forgotmyname wrote: »

I have noticed that younger / newer drivers often switch on their headlights before starting the car.

Cars today don't need the attention and understanding that they used to do 30-40 years ago. A lot of newer drivers think a car is like a washing machine, where it just works (or not). Very few have the concept of 'keeping an eye on things' like weekly checks, changing a lightbulb and so on. The headlights thing is just another example of someone not understanding what they are doing when starting a car, but just following a routine. Luckily, most modern cars will tolerate this - up to a point.

Gloomendoom

forgotmyname wrote: »

I have noticed that younger / newer drivers often switch on their headlights before starting the car

Some cars turn the headlights on when they are unlocked. Mine does.

Richard53

Gloomendoom wrote: »

Some cars turn the headlights on when they are unlocked. Mine does.

My wife's car does this. Why? Why?

AdrianC

Tarambor wrote: »

Maybe in the 1960s and 70s but they moved onto solid state over four decades ago when they moved from dynamos to alternators.

No, definitely not that simple. External, mechanical regulators were fitted with alternators by some manufacturers for many years - right up until at least the start of the 90s, 25 years after alternators replaced dynamos.

arcon5 wrote: »

Ectophile wrote:

When the engine's revving, the alternator can produce enough amps, and the electrics will be at about 13.8 to 14.4V. If the revs drops to idle, the alternator can't keep up, and you're running on battery. If you've only just started the car, that may be down to 12V.

Well that's not true at all. Otherwise the battery light would come on everything it falls to idle. The alternator will always produce sufficient voltage unless faulty.

Charge voltage does fall - but not as far as "no charge". Two seconds with a voltmeter will tell you that - low 13s, sure, 1v or so above fully-charged resting voltage, but no further.