My alternator is around 3-4 months old with a brand new battery that has higher than the recommended specs. My voltages are a little lower then i would like them to be.So i am wondering if my alternator is a dud because just redid all my cables such as power amd ground with not much improvement.

My alternator is a Ultima from orielly rated at 117amps max output with a lifetime warranty, at idle its inputing 48amps according to the test i got done at Orielly's, So my question is that output number low ?

 

The voltage output should not be lower than specs. I read somewhere that 25 percent of replacement parts are defective anyway.

 

48 amps at idle is more than fine. You specify alternator voltage, but talk about alternator current (output in amps). Whats your concern?

Just above idle, the voltage should read 13.5 and 15.
At not more than 2000rpm, you should be reading over 90% of the 117 amps.
Both reading are at the alternator NOT at the battery. The only way to read the current (117 amps) is with a Carbon Pile.

And then to confude you, the voltage reg is in the PCM, so all bets are off.

Ron

 

I am at around 13.6-13.7 at idle checked again today after adding the new engine ground, also my output at idle after the latest test is 45amps

 

1) Check your grounds. It's amazing how often I've tracked automotive electrical problems back to shonky grounds. Particularly check the chassis attachment points - corroded screws or ring lugs can cause trouble, and the factory usually grounds through paint (!) - cleaning the contact patch down to bare metal and applying a corrosion inhibitor - and replacing the screw PRN - will usually take care of those. Also clean the engine ground points, particularly if they're below the valve cover rail (they usually are.)

2) As mentioned, a certain percentage of "chain store" replacement parts are defective in the box. Bear in mind that they buy them by the CONEX box - usually from shops on the Pacific Rim. QC is minimal, which is why the "better" stores try to teach their countermen to test every part before it gets paid for by the customer (and even that is spotty. The usual parts house bench checks for voltage output at 1-2A, and I've got flashlights that draw more current than that!

The best warranty is the one you don't need. The "lifetime" warranty offered by the chain stores is a gamble - while it does reduce their profits on the reman parts, they're betting you have a good part that lasts while you are betting that the part won't last. A lifetime warranty is nice, but I don't want to have to use it - I just like knowing it's there.

With that in mind, you're better off finding a local shop that does rewinds - not only are you dealing directly with the guys that do the work that way, but their test benches (which usually look like they belong in Frankenstein's lab...) will actually wring out your alternator properly. The shop I use (San Jose Generator - I made a couple of pages for them on my site) has a bench that can pull 250A out of an alternator and test it, as well as an inbuilt O-scope to check for diode ripple, rectifier failure, and other causes that aren't tested on the "voltage-only" bench.

If you decide you want to get something from Rod, you'll deal with him directly - his contact information is on my site, and he keeps Banker's Hours in California (his only flaw. His parts are top-notch, I've been dealing with him for about fifteen years now...)

 

what is the PRN.

 

Sorry - it's a medical notation. I don't recall the original Latin (and I honestly don't feel like looking it up - you may if you like,) but it comes out to "as necessary."

Kinda like if you get a scrip for painkillers - the label will say something like "take on tablet by mouth as needed for pain," but it's written on the blank as "T PRN pain" - which translates the same. "Take one or two tablets as require for pain" is written as "T/TT PRN Pain." (The "by mouth" is generally assumed - else it would be written as "PO" for "per oral." Other abbreviations include "IV" - intravenous - "IM" - intramuscular - "SQ" - inject in any fleshy part - "PR" - per rectal, for suppositories, and the like.)

My shorthand is derived from a number of disciplines - my notebooks (for my own consumption) have symbols from logic, mathematics, chemistry, physics, and medicine - as well as notations in Greek and Latin - as well as some other languages.

This often slips through into writing out longhand posts - so if I throw something out there that doesn't make sense, do feel free to ask!

 

Have you checked your voltage above idle? Do a test and see what voltage you get at 1500, 2000, 2500, etc.

 

Like 5-90, I too use a small shop for rebuilding both starters and alternators. Sometimes you have to look for them a bit, but the guys that do this work are generally know what they are doing. And the charges are usually very inexpensive.

I have gotten a few bad alternators and starters right out of the box, but I've never had a bad rebuild.

 

Unfortunately im in Southern california there is nothing but scammers out here and even if they do good work i will have to pay a pretty penny.........

 

Well that is the only way i have recieved information of the alternator output, in amps. My concerns and what i am assuming is that with more alternator amperage i will get a increase in running voltage.


What is the best way to clean engine grounds, steal wool and decreaser ?

 

[QUOTE=bigboy813;1042845]Well that is the only way i have recieved information of the alternator output, in amps. My concerns and what i am assuming is that with more alternator amperage i will get a increase in running voltage.

QUOTE]

You should get a slight increase in voltage above idle, but it will be minimal. The voltage regulator should take care of that, but it would be wise to put a meter right across the battery terminals and see what is going into the battery, voltage wise, at various rpm.

I had some concerns about my voltages as I could see a drop on the analog gauge in the dash as I turned on the AC, blower, lights, etc. I've since installed an additional digital volt meter so I can see voltage more accurately.

 

As far as replacement parts go.... IMHO

Aftermarket new > Rebuilding > Parts counter re-manufactured.

 

X2 Brother!

 

Find my testing writeup - it's going to be indirect for testing current output, but it's still doable (you simply increase load/demand while monitoring voltage. Fluctuation of up to 0.5VDC is nominal, more than that can be cause for concern.

The running voltage should me min 0.5VDC above resting battery voltage, unless you manage to put so much load on the alternator that it can't keep up.

If you don't mind waiting a couple of days for your part, you can click the link in my sig. Scroll down, click the "San Jose Generator" link, and call Rod. Everything he does gets tested before it leaves the shop, and I talked him into doing mail-order a couple years or so ago.