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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] Hi, 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 ..so 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..it (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] 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.
__._,_.___ Posted by: "Rich Barber" <c300@xxxxxxx> To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to https://groups.yahoo.com/neo/groups/all/manage/edit For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylang __,_._,___ |
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