RE: [Chrysler300] Generation and regulation of volts
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RE: [Chrysler300] Generation and regulation of volts

As a mechanical guy, I yield to those with better training and experience and heartily recommend against removing the battery as a system check.  The potential for damage far outweighs the simplicity of the test and any information gained therefrom. 


Rich Barber

Brentwood, CA.


From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of 'John Grady' jkg@xxxxxxxxxxxxxxxxx [Chrysler300]
Sent: Wednesday, March 30, 2016 10:22 AM
To: 'Ronald Busenhart' <RB1937Ford@xxxxxxx>; 'Rich Barber' <c300@xxxxxxx>
Cc: 'Larry Jett' <LarryWJett@xxxxxxxxx>; chrysler300@xxxxxxxxxxxxxxx; 'Jamie Hyde' <Jamie.Hyde@xxxxxxxxxxxxx>
Subject: RE: [Chrysler300] Generation and regulation of volts





As we got into before, you cannot disconnect the battery, as this phenomenon is called “load dump” in EE , on cars—a well known issue..look it up. ; Motorola makes a big surge diode clamp (Zener) fitted to many cars to hold volts at like 15 max or so, due to this V surge taking out the car electronics. . In a new car , all the computer stuff can be wiped out by doing this. (BMW has 90 small computers) The reason is that the field coil ( controlled magnet in the alternator) has a time constant about 10-20 milliseconds,  so even if the VR sends a “reduce” signal to control it , it takes that long for magnetic field to change, During that time the volts go through the roof, as nothing is connected anymore to soak up the 5 amps or 30 it was putting out before lifting the cable 30 or more volts ! Spike.  Your meter will show 13 or 14 , as it is not fast enough to see this  ; and it does usually get it under control , but it takes time. In our cars,  any electronic ignition are toast, as are the VR and the radio if on . Why “mysterious failures” of this stuff like Pertronix happens. Loose battery cables. Also the battery dampens the servo response of (VR) can be  therefore made fast, to avoid a somewhat normal volt upswing when you suddenly shut off your 2 35A AC fans , leaving the alternator full on momentarily , just like a portable gas generator VR does . So it may overshoot pull back overshoot pull back (called oscillation) without the battery . This is even worse, can blow all your light bulbs too.


If someone got away with it, buy a few lottery tickets…


The alternator can self excite if already running, or even if off ,as the rotor is slightly magnetized anyway..some  cars, GM and Ford , use the idiot light current drain for this too,, a bad idiot light,  it will not start charging ; note one wire alternators will still start up. Called residual magnetism in rotor . like happens to your screwdriver tip….


John Grady


From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Ronald Busenhart RB1937Ford@xxxxxxx [Chrysler300]
Sent: Wednesday, March 30, 2016 1:28 AM
To: Rich Barber
Cc: Larry Jett; chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Generation and regulation of volts


You must have a battery in the car and connected with the cables to excite the alternate or it will not put out any current.
Sent from my iPad

On Mar 28, 2016, at 10:38 PM, 'Rich Barber' c300@xxxxxxx [Chrysler300] <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote:




The alternator regulator should maintain alternator output Voltage at about 13.5 +/- ½ Volts whether the battery is there or not.  Most electrical power requirements are served by the alternator, even at low speeds.  The ALTERNATOR gauge on the dash should hover near the mid-point unless power windows, power seats or top motor are in use.  If the battery were there and needing charging, the gauge would indicate some current in the “C” direction as some alternator current is directed to the battery through the ammeter.


If you are checking the system with the battery disconnected, I suggest monitoring the system Voltage.  Actually, this Voltage should also be checked before disconnecting the battery with the engine idling.  The Voltage should be stable in either case.


Most auto parts stores will perform this check with a little more sophisticated instrument for free with no obligation.


Rich Barber

Brentwood, CA


From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of Larry Jett LarryWJett@xxxxxxxxx [Chrysler300]
Sent: Monday, March 28, 2016 3:22 PM
To: chrysler300@xxxxxxxxxxxxxxx
Subject: [Chrysler300] Generation and regulation of volts



If the alternator and regulator in a 1966 300 are working as they should, could you not give it a quick and dirty test by having the engine running at a fast idle, undoing the positive cable from the battery positive post and observing..........engine quits, something is wrong.  Engine keeps running.........alternator and regulator are working.  Is this the way it can be tested?  Ruin any diodes or other do-dads?


Larry Jett        I want my children to have all the things I never could afford.............then I am moving in with them.








Posted by: "Rich Barber" <c300@xxxxxxx>

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