Why do voltage regulators include temperature compensation

How is AC voltage inside the alternator changed to DC voltage at the output terminal? Ask your question! Help us make our solutions better Rate this solution on a scale of below We want to correct this solution. Tell us more Hide this section if you want to rate later. Questions Courses. How is AC voltage inside the alternator. Aug 09 PM. Himanshu t answered on August 11, Do you need an answer to a question different from the above? We want to correct this solution.

Tell us more. Was the final answer of the question wrong? Were the solution steps not detailed enough? Older batteries as in 60's, they are long gone. There is lots of info on battery charge voltage on the Internet, All cars except Bosch have that voltage for some reason. Check a non Bosch and you will see on a different car. As far as the voltage regulator goes it is a voltage regulator and that is what it does, regulate the voltage.

The temperature compensation is in the electronics I was talking about. That is to regulate the voltage at a constant amount not change the voltage with temperature. Adjust the circuit for changes in itself.

Why would the voltage need to be changed with temperature that the alt. Battery is the only thing that is affected with temperature and I would think it would require a higher voltage when warmer, I will check that is published. Ok, good theory. But if a VR is so well engineered to hold level voltage in varying temps, then why is it unable to hold level voltage when load is introduced?

So you are finding NO dip in voltage from cold to hot, even under a little load? Because you're simply drawing too much current. Do some voltage drops across your charging system and report in what and where your drops are. A voltage regulator in a rotating magnetic field alternator modulates the field current to maintain alternator voltage output.

Temperature compensation doesn't make much sense other than low load at cold start or a high load with high rpm with high voltage at cold start to ensure battery charge and hasten warm up. Who knows, I'm no Swedish engineer.

The voltage should be measured at the output post as that is the sense voltage for the regulator, nothing else matters as far as voltage regulation. The voltage regulator turns the current up and down inside the alt. A low voltage might be caused with everything at the alt. If it goes up with idle, the voltage, that would be a sign of too much current at idle. A slightly smaller pulley to increase the rpm at the alt. Eddy currents are current flows in the iron itself from a varying magnetic field, does not apply here.

My regulator mentioned seems to be quite flat with voltage output from cold to hot. Generalizations like that are not good. The Bosch alts that I have seen tested produce OK current down low, but they are still weak. Not all a alts are created equal.

Dave- If you are interested I might have a solution for you. It's not the cheapest method, an aftermarket external regulator.

I have a connection that might just be able to get you something that will work. If you aren't a broke TBer I can get you a real high-output alternator for your car. It's not cheap, but it's the best you can buy. That's all I need for my application. I can get up to a that should fit properly on your car.

It will mount slightly different, his granny has it on the driver top of the acc. PM me if you are interested. I scanned this discussion for any mention of the reason for temperature compensation in the charging system regulator. If it was there, I missed it. The reason the voltage is modified by temperature is the chemical process in the battery requires it. Read up on lead acid batteries. Dave knows his stuff, and has recommended the external regulator as a fix for the " problem," which is locating the regulator 4 inches from the exhaust manifold.

Bosch offered a solution using an external temperature sensor regulator internal, sensor external which is mounted where it ought to be, in front of the battery. It is the battery's temperature that determines what the proper charging voltage is, not a desire for brighter lights at night.

It sounds like there are several issues and goals: Issues: inconsistent voltage. Voltage decrease with extreme temp increase. This is a very significant variation when the reference voltage is used to drive an ECL gate, or the like, since the noise margin of typical ECL integrated circuits is in the range of only mV. Briefly, the circuit of the present invention includes a first terminal for receiving a first bias potential; a second terminal for receiving a second bias potential; an output terminal at which a reference potential is to be developed; a first resistor coupling the first terminal to the output terminal; a second resistor and a forward biased diode forming a first series circuit coupling the output terminal to the second terminal; a third resistor, a first transistor having a base, an emitter and a collector, and a fourth resistor forming a second series circuit coupling the output terminal to the second terminal; a fifth resistor coupling the base of the first transistor to the junction of the second resistor and the diode; and a second transistor having a base coupled to the collector of the first transistor, a collector coupled to the output terminal, and an emitter coupled to the second terminal.

A primary advantage of the present invention is that the circuit may be utilized to provide a reference voltage which is predictable even though manufacturing process variables cause the various component elements to have slightly varying electrical characteristics.

Other objects and advantages of the present invention will no doubt become apparent to those of ordinary skill in the art after having read the following detailed description of the preferred embodiments which are illustrated in the several figures of the drawing.

Although the various elements are shown in the form of discrete classical electrical components, it will be appreciated that these elements are only representative of the electrical characteristics exhibited by various integrated circuit components. The regulator circuit, sometimes referrzd to as a bias driver, is designated generally by the numeral 10, and is provided with three external contact points including a first terminal 12 to which a positive supply voltage V cc is applied, a second terminal 14 to which a negative supply voltage V ee is applied, and an output terminal 16 from which the reference voltage V REF may be taken.

It will be appreciated that the circuit is basically a voltage dividing circuit including a passive resistance R 1 connected between terminals 12 and 16, and in series with an active resistance means R a connected between terminals 16 and The active resistance portion of the circuit includes means forming what may generally be viewed as three series circuits 18, 20 and 22 connected in parallel across the circuit nodes 24 and The first circuit 18 includes a second resistive impedance element represented by the resistor R 2 and a uni-directional current conducting device such as the diode Q 1.

The second circuit 20 includes a third resistive impedance element R 3 , an NPN transistor Q 2 and a fourth resistive impedance element R 4. The collector 28 of transistor Q 2 is connected to circuit node 4 by resistor R 3 , while its emitter 30 is connected to circuit node 26 by resistor R 4. The base 32 of transistor Q 2 is coupled to the junction of resistor R 2 and the anode of diode Q 1 represented by the node 34 by a resistive impedance element R x having a particular value which will be discussed in detail below.

The third circuit 22 is formed by an NPN transistor Q 3 whose collector 34 is coupled to circuit node 24 and whose emitter 36 is coupled to circuit node The base 38 of transistor Q 3 is coupled to the collector 28 of transistor Q 2. The second variable that causes the reference voltage to vary is the base current.