Adjustment of Variable Resistance in an automobile battery

[saadm]

TL;DR Summary

Adjustment of Variable Resistance in an automobile battery

How is the load (variable resistance) adjusted in an automobile battery? Mechanically (potentiometer, rheostat) or electronically

(digital potentiometer) or are both configurations possible.Can the load in a automobile battery be a three terminal divider (potentiometer) or is it almost always a rheostat?

Besides adjusting audio volume, what else is a potentiometer useful for specially in an automobile?

Please let me know if I should start a new thread for this. I included the questions here because of their relevance to the topics discussed in this thread.

Thanks,

 

[Steve4Physics]

How is the load (variable resistance) adjusted in an automobile battery?

Batteries don't have have a variable resistance in them. In normal operation, a battery simply provides a constant voltage (ignoring the effects of internal resistance).

The battery delivers current according to whatever the total load happens to be. E.g. if you turn the lights on, the battery delivers more current.

Maybe you are confusing this with a simple laboratory setup, where a battery and potentiometer or rheostat are used to perform experiments. That's not what happens in a automobile circuit.

Can the load in a automobile battery be a three terminal divider (potentiometer) or is it almost always a rheostat?

The 'load' just means whatever is connected to the battery, e.g. lights, starter motor, radio, wiper motor. It is never a rheostat,

Also, potentiometers and rheostats would be very wasteful because of the amount of heat they produce with large currents.

Besides adjusting audio volume, what else is a potentiometer useful for specially in an automobile?

Have you tried typing "automobile potentiometers" into a search engine? What did you find?

Edit - typo's corrected

 

[Baluncore]

An automobile battery does NOT have an adjustable variable resistance.
The battery voltage remains reasonably fixed, usually near 12 volts.
The load current drawn from the battery by electrical accessories is determined by the individual accessories.
The battery is charged by an alternator. The voltage and charging current are regulated by changing the alternator field current.

 

[Steve4Physics]

An automobile battery does NOT have an adjustable variable resistance.
The battery voltage remains reasonably fixed, usually near 12 volts.
The load current drawn from the battery by electrical accessories is determined by the individual accessories.
The battery is charged by an alternator. The voltage and charging current are regulated by changing the alternator field current.

Great minds think simultaneously!

 

[Baluncore]

Great minds think simultaneously!

Great minds think alike, fools never differ.

 

[saadm]

Great, thank you to Steve4Physics and Baluncore for the answers. One more question, the alternator and the battery are to be treated as two separate sources of emf or a single whole system of emf source?

 

[Baluncore]

While the engine is running, the alternator supplies all the accessories, and charges the battery.
When the engine is not running, the battery must supply the accessories.
The battery terminals are common to all circuits.

 

[Steve4Physics]

... the alternator and the battery are to be treated as two separate sources of emf or a single whole system of emf source?

That depends on what you are trying to do. For example:

If you are designing a car’s charging-circuit, you would need to treat the battery and alternator as 2 separate sources of emf.

But if you are designing the car’s audio system, you would effectively treat the battery and alternator as a single unit – a ‘black box’ which always supplies 12V; you don't care how the 12V got there!

Also,did you find uses for potentiometers by doing a search?

 

[shonuff]

TL;DR Summary: Adjustment of Variable Resistance in an automobile battery

How is the load (variable resistance) adjusted in an automobile battery? Mechanically (potentiometer, rheostat) or electronically

(digital potentiometer) or are both configurations possible.Can the load in a automobile battery be a three terminal divider (potentiometer) or is it almost always a rheostat?

Besides adjusting audio volume, what else is a potentiometer useful for specially in an automobile?

Please let me know if I should start a new thread for this. I included the questions here because of their relevance to the topics discussed in this thread.

Thanks,

If you are referring to the internal resistance. of a battery....
The internal resistance acts like a Thermistor....The resistance changes quickly with heat ..