Alternator / Battery Question - Toyota Nation Forum : Toyota Car and Truck Forums

jasonck08 · 07-15-2009, 02:54 PM

So... just yesturday my Brake light and battery charge light came on...

I just tested the voltage on the battery when the engine is running, and sure enough it is only reading about 12.03-12.13v (depending on if the AC is on or off). IIRC it should be reading something around 14v, for a strong alternator.

So my question is, could it possibly be the battery thats bad, and not the alternator? Or is it definitly the alternator?

If it is the alternator, how much can I expect to pay to have it replaced?

Thanks!

91 Camry · 07-15-2009, 05:27 PM

The samething happened to me. The alternator should be charging between 13 an 14 volts with the engine running. If your getting around 12, chances are the alrernator is bad. I picked mine up at NAPA for about $75 with a core return. Make sure you get the correct piece for your engine. I have a '91 3sfe. I was given a V6 alternator by mistake. Partly my fault, but I put the V6 unit on. The only problem is the belt adjustment bottomed out leaving a lot of slack in the belt. I returned the unit and got the correct piece.

Good luck!

jasonck08 · 07-15-2009, 05:33 PM

Quote:

Originally Posted by 91 Camry

The samething happened to me. The alternator should be charging between 13 an 14 volts with the engine running. If your getting around 12, chances are the alrernator is bad. I picked mine up at NAPA for about $75 with a core return. Make sure you get the correct piece for your engine. I have a '91 3sfe. I was given a V6 alternator by mistake. Partly my fault, but I put the V6 unit on. The only problem is the belt adjustment bottomed out leaving a lot of slack in the belt. I returned the unit and got the correct piece.

Good luck!

Was the intsall very difficult? How long did it take you? Since the alternator is most likely bad on my car, I'd like to upgrade from the stock 80A? alternator to one around 100A's. I plan to hook up several non stock parts that will draw some extra power. HHO gen, extra lights, subwoofer, so I'd like to get a better alternator.

91 Camry · 07-15-2009, 05:39 PM

Loosen the adjustment bolt behind the alternator. Then remove the two bolts holding the unit. The whole job should take about 20 to 30 minutes. If you are going to upgrade, check out the 170 amp Powermater unit. I plan on getting this alternator. Their only recommendation was to use a #6 charging wire instead of the stock harness wire.

Mike Gerber · 07-15-2009, 06:48 PM

If you are looking for more amps out of your alternator and a better rebuild then you get at most auto parts stores, check your local phone books for an auto electrical rebuilder in your area. IMHO these guys usually do a better job rebuilding your stock alternator then most of the rebuilts you find at most of the auto parts stores. It's usually about the same money. You can ask them about increasing the amps of your stock alternator.

Mike

Doctor J · 07-16-2009, 06:55 AM

Before changing your alt check the voltage drop between alternator's battery terminal and battery positive terminal with lights on /engine idling
Drop higher then 0.3 volts [real life figure] indicates bad connector in the charge wiring circuit.

jasonck08 · 07-16-2009, 08:19 PM

I've noticed some other things that seem a little strange, but may all be related to the alternator issue...

When I'm accelerating... the car seems a little jerkey at times... Like it will be accelerating good, then kinda jerk / bog down for like 1/4 second, then accelerate very good...

Could it have anything to do with the cars electrical system only getting 12v instead of the 14v they normally get? Perhaps this could be causing some of the sensors to be increasing and decreasing the gas output or something... Or maybe the fuel pump's acting strange because of the low voltage.

Also, when the car is idling the battery voltage is about 12.1v. When the engine is off, it measures about 12.4v. How low do you think the battery can go and still start the car... I don't want to get stuck somewhere...

Thanks!

Doctor J · 07-16-2009, 09:59 PM

How much the voltage at 2500 rpm???

jasonck08 · 07-16-2009, 10:44 PM

No RPM gage, but I can estimate... I'd need someone to help me test it. I'll go grab a friend and report back...

jasonck08 · 07-16-2009, 11:46 PM

Quote:

Originally Posted by Doctor J

How much the voltage at 2500 rpm???

~12.6v at probably about 2500RPM's. Now at idel though its lower than it was two days ago. Idle it tests out at 11.8v.

Also the difference between the lights being on and off at idle is less than .3v.

So.. based on these symptoms is it safe to say that the Alt is bad, and not the battery?

--------------------

Lastly, any comments on the slightly jerky throttle that started the same time the alt started going bad????

Doctor J · 07-17-2009, 08:23 AM

if you do not have voltage drop between the alternator B terminal and the battery AND/or between the negative post of the battery and the body/engine ground, the problem seems like diode failure in the alternator's rectifier.
On my customer's car

You Tube

the the rebuild alternator failed this way; the CHARGE light on the dash board was NOT illuminated.

jasonck08 · 07-18-2009, 01:43 PM

Quote:

Originally Posted by 91 Camry

Loosen the adjustment bolt behind the alternator. Then remove the two bolts holding the unit. The whole job should take about 20 to 30 minutes. If you are going to upgrade, check out the 170 amp Powermater unit. I plan on getting this alternator. Their only recommendation was to use a #6 charging wire instead of the stock harness wire.

These are the instructions in the owners guide:

http://www.camrystuff.com/manuals/Gen2/Charging.pdf

REMOVAL OF ALTERNATOR (3S–FE)
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL
OF BATTERY
2. DISCONNECT CONNECTOR AND WIRE FROM
ALTERNATOR
3. REMOVE DRIVE BELT
4. REMOVE ALTERNATOR
Remove the adjusting lock bolt, pivot bolt and alternator. (Is this the bolt behind the alternator that you are referring to? See the diagram on the link above.)

It doesn't really tell you how to remove the drive belt. It has a heck of a lot of tension on it... How do I remove it?

white90dx · 07-18-2009, 01:55 PM

Loosen the pivot bolt and the tensioner bolts to rotate the alternator down, then the belt comes right off.

-Charlie

jasonck08 · 07-18-2009, 02:53 PM

Thanks! Pulled the sucker out... Took about 20 minutes because I was doing it very carefully...

So whats a good brand alternator to get? I called up Kraigens and they have one for $109.99 that is remanufactured with a lifetime warranty. It's 70A. Brand is Autolite. They will only give me $10 for the old one...

NAPA had one (can't remember the brand) it was a new 70A one w/ 3 year warranty for $149.99 w/ I believe either a $30 or $35 core discount for the old alt.

Autozone has a Duralast thats Remanufacutred 70A w/ Lifetime warranty. Price is $109.99 after the trade in...

And brand suggestions??? I'm also going to try some other auto shops....

jasonck08 · 07-18-2009, 07:15 PM

Ended up purchasing the Duralast at Autozone for $109, the guy also suggested that I get a new belt and that it would be 20% off for the belt. So I paid $9 more and got a belt... Also signed up for a rewards card @ autozone...

Just installed the alt, and tested w/ a volt meter right after I had installed it and it read around 13.6v or so... The manual suggested when you install a new belt, to check the tightness after about 15 mins of the car running...

After driving the car around for about 15 mins... I once again checked the voltage going to the battery at idle and it only read around 12.6v... Not sure If I got a weak alt or whats going on...