Alternator issue - bad voltage regulator (1 Viewer)

[daphenom32]

Gents- I bought an 06 LX470 a few weeks ago. Took it to ACC here in Atlanta they said the vehicle was in good shape, but had a bad alternator. On my way up to New York the alternator went out - I bought a replacement from oreillys and put it on a few days ago. Not super mechanically inclined but followed directions of a few posts here in the forum and managed to get it done.

the issue: I took the cruiser to oreillys to get the alternator and battery tested to make sure everything is in working order. Battery read good, but the alternator read bc ad voltage meter. Voltage moved around between 13.44 - 13.48 with the a/c, lights radio on.Is the remand alternator I bought bad or potentially another issue? Taking the alternator off again for oreillys to test it, but wondering if I should just get the OEM alternator or if there is something more to it?

 

[flintknapper]

Typical for the voltage to vary depending on electrical load (demand) and the charge in the battery. 13.4 is on the low side, but not worrisome by itself, the high end might be 14.7 or so. On average mine will read 14.1 or thereabouts (scangauge reading).

 

[FxFormat]

Sounds normal to me, on morning starts my voltage reading would be 14.1, after a drive and the battery topped off, it'll read 13.5

 

[jerryb]

never higher than 14.2 on mine, all new s***. Regular africa hot day running 12.8-9 to 13.3-5v

 

[gungriffin]

Where are you getting a number that is that precise? I would ideally want to measure the alternator at startup and at about 1500-2300 RPMs. At startup, and while everything is still cool, you need to see numbers in the low 14s to properly recharge the battery. If you don't see those numbers for a few minutes then it might cause the battery to improperly charge and die prematurely. Especially in the heat, it was pretty normal for me to see numbers that are within the range that you are giving.

So while charging (at startup): 13.9-14.4
After the battery is charged: 13.1-13.7

 

[94SRUNNER]

I have a remaned Denso unit from NAPA I recently installed. At start up I typically see 13.5-13.9 and after the battery is charged up I see 13.1-13.4.

 

[gungriffin]

I have a remaned Denso unit from NAPA I recently installed. At start up I typically see 13.5-13.9 and after the battery is charged up I see 13.1-13.4.

What are you using to measure the voltage? Have you checked to see if you are getting any voltage dropoff to whatever you are reading off of? Maybe someone else can comment, but those numbers seem a little low to me. If you are voltages the battery is seenig and you are using a lead acid wet cell battery, you will likely see accelerated sulfation of the battery which will cause it to go bad somewhere between a little and lot quicker. If you are using an AGM battery, it is quite likely that it won't last long without aux charging with a trickle charger.

 

[94SRUNNER]

What are you using to measure the voltage? Have you checked to see if you are getting any voltage dropoff to whatever you are reading off of?

ScanGauge II is what is giving me the data. A few years ago I checked for voltage drop and it showed the data the ScanGauge is slightly lower than actual...~0.1-0.2V. Provided I checked correctly...

 

[gungriffin]

ScanGauge II is what is giving me the data. A few years ago I checked for voltage drop and it showed the data the ScanGauge is slightly lower than actual...~0.1-0.2V. Provided I checked correctly...

That is in line with the voltage drop I get from my Scan Guage as well. It is pretty much always ~0.1 low. Those numbers are low for ideal. I would also try running the lights for a 5-10 minutes with the motor off so that you know that the battery needs some charge. Restart the engine and if you are still seeing a peak of 13.9, I believe that charge voltage would cause some sulfation over time on a normal wet cell battery.

If you have a multi-meter, you can check the voltage at the battery. To check at the battery, ideally, leave the hood popped when you shut off the vehicle so that you don't need to get into the car before checking (unlocking the doors to pop the hood might activate computers that could cause draw on the battery skewing the reading), and let it sit for at least 6 hours after you shut off the engine (overnight is usually easiest). You want to see a voltage of about 12.65 for a wet cell battery or about 12.85 for an AGM battery at the battery with the engine off indicating 100% charge. Anything lower than those numbers indicates that the battery might not be able be charging to 100% with what the alternator is putting out. If you don't have a multi meter, they are $20 from Amazon and come in handy enough that I believe it is worth the investment. I just have the Astro AI.

If you still have your old Toyota stock alternator, they are quite easy to rebuild.

 

[daphenom32]

Where are you getting a number that is that precise? I would ideally want to measure the alternator at startup and at about 1500-2300 RPMs. At startup, and while everything is still cool, you need to see numbers in the low 14s to properly recharge the battery. If you don't see those numbers for a few minutes then it might cause the battery to improperly charge and die prematurely. Especially in the heat, it was pretty normal for me to see numbers that are within the range that you are giving.

So while charging (at startup): 13.9-14.4
After the battery is charged: 13.1-13.7

This is off the meter at oreillys after vehicle has been running for a while. Not concerned as much with the voltage as the reading “bad voltage regulator” which I assume will cause problems over time.

 

[jerryb]

aftermarket regulators, transpo, set points are 14.4v for the 98-02 and 14.2 for the +2003. I can't imagine the OEM reg being very far off.
I think I remember someone saying they were low. Not sure.
Going by the book for vvti you see 13.2-14.8v as normal from 580 to 2000 rpm taken at the alt stud. I don't like it, but that's what it says.
stock regulator measured the same for me. I have a few.
Add up s***ty grounds, a 20 year old +b 6 gauge wire and it is what it is.
If I saw 14.0-2 on any gauge measured anywhere other than the +B post I'd flip. lol.
BUT, mid thirteens is plenty to keep your LC running fine. There's just a very narrow line to the difference between good and bad battery wise. Drive it every 3 days or put it on a tender.


I wouldn't listen to anything oreilly has to say about your voltage regulator. Or anything really.