Alternator, Battery Problem ?

Messages
802
Location
Under the Hood
2002, Ford Ranger, 3L Engine With a Voltage Meter Gauge plugged into Cigarette Lighter, I am noticing an Alternator output fluctuating between 12.2V and 14.4V while driving. The Battery Light on dashboard came on and Dash Gauge showed near the 'L' Battery: Replaced 3-1-19 / Walmart EverStart 590 CCA Alternator: Original Because the Voltage is fluctuating every 30 seconds, my testing options are limited. I have inspected: 1) Drive Belt 2) Tensioner Pulley 3) Alternator Wiring 4) Battery Connections 5) Use my Computerized Battery Tester and it shows ALL Good I'm guessing it's the Alternator, but wanted to get some other opinions. Any help will be appreciated. Alternators (if I need to buy) RockAuto …. Reman Motorcraft $147.00 NAPA …… Reman $140.00
 
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Messages
2,597
Location
High Tax Illinois
Best way to me is take off alt and bring it to NAPA, AZ, etc or Electrical shop and have it load tested. Does this alt have the voltage reg built in?
 
Messages
1,825
Location
missouri
The regulator on that alternator is probably held on the back with 4 screws. The brush life is around 150K miles. The commutator is usually still usable. The rectifier is pretty solid usually, has plenty of heat sink for cooling. There is aground to test function on the regulator, turn on lights and ac first, it full fields a 95 amp alternator, you want some load. The brushes are with the regulator, sometimes you can get brushes separate. The brush holder goes on with 2 screws. In many cases you can take off the regulator without removing the alternator and renew the brushes. It is a good design of alternator and this would probably fix it. Rod
 
Messages
2,317
Location
pa
it can be load tested on the car. Napa professional series are FULLY rebuilt + worth the $$$
 
Messages
802
Location
Under the Hood
With my limited ability to diagnose (professionally), I may have to assume it's the Alternator. I don't like jumping to conclusions, but considering the age, I am going to replace the Alternator. Only vehicle I own and can't be without. I will report back tomorrow.
 
Messages
8,815
Location
MA
Just take it to an auto parts store and have the car load tested, they would tell you if the alternator or battery was bad. I would get it locally. Check Autozone and Advance auto as they also have coupon codes that lower the price. Usually alternators have lifetime warranties so you'd want to buy it locally because if you get it from rockauto, even though they also have a lifetime warranty you have to pay shipping back to them to use the warranty.
 
Go with the NAPA, basing off my brother's 21 years as a mechanic. As stated above, NAPA Professional are essentially brand new alternators with a seasoned housing, whereas AZ & AA ones are generally subpar quality compared to others. I don't care about a lifetime warranty if the thing is failing every year or two....lifetime means the remainder of that car's time with me in my book and is worth the small premium for the NAPA part.
 
Messages
24,561
Location
Upstate NY
A lot of battery testers can also test the alternator. Assuming the engine RPM is constant and no one is turning on and off the headlights the voltage should not fluctuate. For the battery voltage I would only trust a quality DVM connected across the battery terminals. But the alternator is now 17 yr old. It likely has worn brushes or similar. Time for a new one. Even if its not the alternator its likely the alternator would have not lasted until you got rid of the car, so good to change it now. When you bring the old alternator back for core charge, ask them to test it.
 
Messages
802
Location
Under the Hood
OP here, Just went to NAPA and bought their Bosch Alternator (remanufactured). Contains the Pulley so one less thing I have to deal with. Not in stock and had to wait 3 hours for their Delivery Truck. Employee felt sorry and gave me 10% off. I have my Smart Charger on Battery now and will replace Alt. in morning. On the way to NAPA, the Voltage Meter read 12.1V thru 14.4V At 14.4V, I believe the Alt. was performing normally At 12.1V, looks like the Alt. was not putting out at all and V. Meter was showing Battery V.
 
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Messages
2,202
Location
Lyndhurst NJ
Since you have the digital readout, its much easier to do a quick load test at idle. Turn AC on high, rear defrost, high beams, radio, interior lights etc, every accessory, and see where it falls. 13.5 or below is game over.
 
Messages
58
Location
Great Lakes State, USA
The alternator is bad. The number one reason for faltering voltage levels is the regulator. The next problem area is bearings. Never have I had the brushes go bad before the others in an alternator. Wise decision to replace. Personally I would also exchange your battery out on warranty. If the regulator goes bad, it will mess up the battery also which can cause both to go bad again in the near future. On another note, never had short life issues with AAP or AZ alternators like some have claimed. The car usually is sold or junked before the replacement goes out.
 
Messages
6,748
Location
Lake Havasu City, Arizona
Originally Posted by oldhp
Best way to me is take off alt and bring it to NAPA, AZ, etc or Electrical shop and have it load tested. Does this alt have the voltage reg built in?
No need to take it off. Just drive it over there. They'll do it right on the car. They did mine and it was bad. (1991 Ford running off the battery). I installed a new one with a new serpentine belt, drove it back over and he tested it again. I was good to go. Both tests took all of 2 minutes each. Autozone, O'Reilly, Pep Boy's, Advance all offer this service.
 
Messages
803
Location
AR
just replace the whole alternator. Something else will go wrong after the voltage regulator anyway. Just fix the whole problem at once.
 
Messages
802
Location
Under the Hood
OP here, Put on the Bosch Alternator (reman.) bought at NAPA / 15 minute job. Took for a Test Drive and Voltage Meter (plugged in cig. lighter) shows 14.4 Volts. No decrease in Voltage when turning on all accessories. All is well. Thanks for the reply's confirming my suspicion.
 
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