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Voltage jumping around

Jackpot50

Jackpot50

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When I start my car up the voltage jumps from 13.5-14, when you ref it up its fine.
Have replaced voltage regulator and no change. Not a problem during the day but at night the lights go bright and dim with the voltage when at idle.
Charges great and no other issues Any info .
Thanks
 
Jackpot50 said:
When I start my car up the voltage jumps from 13.5-14, when you ref it up its fine.
Have replaced voltage regulator and no change. Not a problem during the day but at night the lights go bright and dim with the voltage when at idle.
Charges great and no other issues Any info .
Thanks
Click to expand...

Situation normal.....exactly how the origional system operates.
BOB RENTON
 
Check any and all body grounds. Mine did the same thing till I added a ground from the firewall to motor. Now voltage is stable.
 
I wouldn't drive that beautiful car after dark, MWFan can attest to that by his Sunday post.
 
Jackpot50 said:
When I start my car up the voltage jumps from 13.5-14, when you ref it up its fine.
Have replaced voltage regulator and no change. Not a problem during the day but at night the lights go bright and dim with the voltage when at idle.
Charges great and no other issues Any info .
Thanks
Click to expand...

As already mentioned, It's normal with the stock Alternator.
 
Jackpot50 said:
When I start my car up the voltage jumps from 13.5-14, when you ref it up its fine.
Have replaced voltage regulator and no change. Not a problem during the day but at night the lights go bright and dim with the voltage when at idle.
Charges great and no other issues Any info .
Thanks
Click to expand...
You probably have a old points style regulator that can be changed with a electronic one. Make damn sure the case is grounded well to the firewall. In fact, run a separate ground from the regulator case to the firewall and or engine. A bad ground through thick paint or loose mounting screws will cause the alternator to overcharge, (like 17 volts) and it can cause damage.
 
All the above is great info I would be checking the connections in the bulkhead connector as well.
 
It may be normal but worn alternators will do this more than good ones. Just fixed this myself. Tach was jumpy, lights did as you described. Took the alternator apart, polished the copper rings and replaced the brushes. Nice and steady now. Common issue.
 
Nate S said:
It may be normal but worn alternators will do this more than good ones. Just fixed this myself. Tach was jumpy, lights did as you described. Took the alternator apart, polished the copper rings and replaced the brushes. Nice and steady now. Common issue.
Click to expand...

Yes.....good point. The copper rings, called slip rings and the carbon brushes, is how the rotating field gets its power. The rotor is what generstes the AC power in the stator windings. If the slip rings are dirty or the carbon brushes are worn, the alternator's output voltage and current will be erratic and varied.
BOB RENTON
 
Did you replace with the updated electronic regulator. Mine works great, no pulsing at all.

You don't have a higher than normal amp alternator?
 
RJRENTON said:
Yes.....good point. The copper rings, called slip rings and the carbon brushes, is how the rotating field gets its power. The rotor is what generstes the AC power in the stator windings. If the slip rings are dirty or the carbon brushes are worn, the alternator's output voltage and current will be erratic and varied.
BOB RENTON
Click to expand...
I will check that out, recovering from shoulder replacement right now, everything is hard. LOL
 
Jackpot50 said:
I will check that out, recovering from shoulder replacement right now, everything is hard. LOL
Click to expand...
More information please.
What alternator style and output are we talking about?
Which electronic regulator, like the stock '70 and up with the Triangle connector, or an electronic version of the points style regulator?
What crank and alternator pulleys? Stock, aftermarket, pulley diameters would help to figure crank to alternator speed ratio.
What is the idle RPM? With the pulley ratio, can calculate alternator RPM, and estimate the alternator output at that RPM for the type of alternator you have?
 
451Mopar said:
More information please.
What alternator style and output are we talking about?
Which electronic regulator, like the stock '70 and up with the Triangle connector, or an electronic version of the points style regulator?
What crank and alternator pulleys? Stock, aftermarket, pulley diameters would help to figure crank to alternator speed ratio.
What is the idle RPM? With the pulley ratio, can calculate alternator RPM, and estimate the alternator output at that RPM for the type of alternator you have?
Click to expand...
95 amp alternator, stock pulleys, triangle connector, and Idle 1000-900 RPM
 
Jackpot50 said:
Have a new electronic regulator and a high output alternator.
Click to expand...

One thing I noticed over the years is that manufacturers advertise their alternators at maximum output but we are talking outputs at idle. On most, you've got to dig to find out their idle output if it's mentioned at all.
 
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