AZ Reman Alternator rarely pulls more than 14.0v

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Hello all,

I just recently had to swap my alternator due to mud failure (again), and the "new" (free replacement) one I put in seems to make a noisy bearing noise. On top of that, it seems to never want to output more than 13.7volts (14.0 is just about the highest I've ever seen it go). It will sometimes drop to 13.2 or 13.3. I am not sure if this is a lemon, or if my battery is old. The battery seems to hold a resting voltage just fine, and has about 535 CCA out of the original 725CCA.. maybe not the best measurement but the shop tested it this way and said I needed to replace it. I am skeptical of this.

My previous alternator was putting out 14.3 volts in normal conditions.

Just wondering if this alternator is a lemon or if the battery isn't accepting a higher voltage anymore. I have an OEM spare with low-ish miles on it and was thinking of swapping in my free time to see if maybe the noisy bearing sounds will go away. The truck just recently had all other pulleys replaced (new compressor, idler, fan bearing). Only other possibility is a noisy power steering pulley but the noise doesn't come from that side of the engine bay.
 
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I don't think an old battery can lower the system voltage. Mine has always been 14,3 volts regardless of the battery age.
 
Originally Posted By: Panos
I don't think an old battery can lower the system voltage. Mine has always been 14,3 volts regardless of the battery age.
so it would be safe to say I got a dud?
 
Originally Posted By: Panos
I don't think an old battery can lower the system voltage. Mine has always been 14,3 volts regardless of the battery age.


I would disagree. I have had bad batteries take out an alternator. Like the OP, his battery checks only about 2/3 capacity. Even if it shows proper voltage statically, I am willing to bet if he turns ignition to "on", but leaves engine off, turns on headlights, and blower, his voltage on the battery will be lower than 11 volts. Usually batteries like this overheat the stator and/or regulator portion on the alternator. The lower output is the result. Battery age is inconsequential to condition. You can have an old battery keep its capacity, or a newer one take a dump out of thin air. I'd replace the battery and go from there. It sounds like its about gone anyhow.
 
I think you got another dude. I suggest you get a known brand from RockAuto. Better is a local starter rebuilder if you can find one.

Your alternator has a full wave bridge for 3 phase AC. Converts it to DC. The good rebuilders replace the bridge. The third world rebuilders solder in new diodes to replace the broken ones.
 
I have started vehicles on a good battery, swapped one in that was dead (yes, while running) and immediately drove 6 hours.

I have NEVER, ever heard of a bad battery making an alternator work harder.

I think you have a bad alternator.
 
Load the system up before you do the voltage test, defroster on front and back, headlights, wipers, radio etc. See if its below 13.6 or so, if so its weak. Also check resting voltage on the battery, 12.3 is considered a decent number, but much below that it should be either recharged and tested or replaced.
 
Hey Linctex, maybe I'm a little lost on this but why would you put a dead battery in a car and then go and drive 6 hours with it. What's the reason ? Thanks.
 
Great information/link.

I've noticed in the lady's Camry that it would drop down in headlights, display, and fans when the old battery was in it and the car idled. If you went down the road everything lite right back up to normal. Got a new battery and that disappeared. Everything stayed the same whether at idle or going down the road.
 
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I'm getting conflicting answers... I will go ahead and swap in the other alternator and see what the output is. If it's better (and quieter to boot... because the bearings are better), I'll assume the alternator was bad.
 
Does an alternator have some sort of clutch like a driven fan does? I mean, the alternator has to know when to charge by resistance and when to freewheel.

So, if so, then maybe the alt is getting burned out by always being in charge mode since the battery and maybe the wiring are not up to par.
 
the AZ alternators i had were HORRIBLE. one died in less than a month. went through all the checks and after the 3rd or 4th "free replacement" i got my money back and went and bought one at advance auto which outlasted all of the AZ remans combined. that was on my accord.
 
Originally Posted By: Propflux01
Originally Posted By: Panos
I don't think an old battery can lower the system voltage. Mine has always been 14,3 volts regardless of the battery age.


I would disagree. I have had bad batteries take out an alternator. Like the OP, his battery checks only about 2/3 capacity. Even if it shows proper voltage statically, I am willing to bet if he turns ignition to "on", but leaves engine off, turns on headlights, and blower, his voltage on the battery will be lower than 11 volts. Usually batteries like this overheat the stator and/or regulator portion on the alternator. The lower output is the result. Battery age is inconsequential to condition. You can have an old battery keep its capacity, or a newer one take a dump out of thin air. I'd replace the battery and go from there. It sounds like its about gone anyhow.

+1
This is particularly true on vehicles that have a battery excited alternator.
Also, on many newer vehicles the ECU (main computer) controls/regulates the alternator output. These vehicle don't have a traditional voltage regulator. Battery condition plays a part in what the ECU does to control the alternator output.
A bad battery can also take-out a starter and/or starter solenoid. Ask me how I know
smile.gif
 
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Originally Posted By: wag123
Originally Posted By: Propflux01
Originally Posted By: Panos
I don't think an old battery can lower the system voltage. Mine has always been 14,3 volts regardless of the battery age.


I would disagree. I have had bad batteries take out an alternator. Like the OP, his battery checks only about 2/3 capacity. Even if it shows proper voltage statically, I am willing to bet if he turns ignition to "on", but leaves engine off, turns on headlights, and blower, his voltage on the battery will be lower than 11 volts. Usually batteries like this overheat the stator and/or regulator portion on the alternator. The lower output is the result. Battery age is inconsequential to condition. You can have an old battery keep its capacity, or a newer one take a dump out of thin air. I'd replace the battery and go from there. It sounds like its about gone anyhow.

+1
This is particularly true on vehicles that have a battery excited alternator.
Also, on many newer vehicles the ECU (main computer) controls/regulates the alternator output. These vehicle don't have a traditional voltage regulator. Battery condition plays a part in what the ECU does to control the alternator output.
A bad battery can also take-out a starter and/or starter solenoid. Ask me how I know
smile.gif

I have a 2004 Tacoma, not sure if my alternator is that smart. That being said, my truck had sat for a day or two and I checked the voltage, right around 12.2. Seems a little low. Making me think it may be the battery, but not sure. It would be easier to swap the battery than swap the alt, that's for sure. Maybe I'll pick up a prorated new battery since it's still within the prorated warranty period and see what's up. I still think the bearings are bad in this autozone unit though.
 
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Originally Posted By: ThunderOne
Originally Posted By: wag123
Originally Posted By: Propflux01
Originally Posted By: Panos
I don't think an old battery can lower the system voltage. Mine has always been 14,3 volts regardless of the battery age.


I would disagree. I have had bad batteries take out an alternator. Like the OP, his battery checks only about 2/3 capacity. Even if it shows proper voltage statically, I am willing to bet if he turns ignition to "on", but leaves engine off, turns on headlights, and blower, his voltage on the battery will be lower than 11 volts. Usually batteries like this overheat the stator and/or regulator portion on the alternator. The lower output is the result. Battery age is inconsequential to condition. You can have an old battery keep its capacity, or a newer one take a dump out of thin air. I'd replace the battery and go from there. It sounds like its about gone anyhow.

+1
This is particularly true on vehicles that have a battery excited alternator.
Also, on many newer vehicles the ECU (main computer) controls/regulates the alternator output. These vehicle don't have a traditional voltage regulator. Battery condition plays a part in what the ECU does to control the alternator output.
A bad battery can also take-out a starter and/or starter solenoid. Ask me how I know
smile.gif

I have a 2004 Tacoma, not sure if my alternator is that smart. That being said, my truck had sat for a day or two and I checked the voltage, right around 12.2. Seems a little low. Making me think it may be the battery, but not sure. It would be easier to swap the battery than swap the alt, that's for sure. Maybe I'll pick up a prorated new battery since it's still within the prorated warranty period and see what's up. I still think the bearings are bad in this autozone unit though.

An alternator that is working real hard will make a noise that sounds like a bad bearing.
12.2v is too low, resting voltage should be at least 12.6v on a good battery. Replace it.
 
Like a clicking noise accompanied by dry grinding metal noises? I did notice that my Noco charger was never finishing charging this battery a couple weeks ago. I had let it sit overnight and it was still working, I had the fear that it was overcharging due to reading it at 13.3V so I unplugged it.

I have heard of the alternator whining as it works harder, but never dry bearing sounds.
 
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Well all of my paranoia was for nothing. Checked resting voltage with MM and it was 12.55. Swapped alternators and output was normal when checked with MM. All of my worry was due to my R3 radar detector reading the voltage incorrectly. Off by 0.3 volts. The noise I thought was the alt was actually my 3.4l Toyota valves ticking.
 
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