Is it OK to drive w/alternator light on?

The alternator light tells you that your alternator or one of its sub-systems (voltage regulator) is not working. If you feel lucky, you can drive with the light on... for a while. Once your battery is drained you will be stuck. The worst damage you can do is to ruin your battery.

On a regular car (non F-car), replacing an alternator is about $250 plus or minus a few bucks. About $100 if you DIY.

Scott

 

YES, it can.

Discharging down to 11.5V is a 90+%discharge. A lot depends on your battery's tolerence for discharge, In general, lead-acid car batteries don't like discharges below 40%-50%, repeated deep discharges can significantly cut the battery's life. Deep cycle/RV batteries are built to handle many more discharges to 50%-80%, but still don't tolerate 90+% discharges very well. Lots of info on the web, just google: lead-acid discharge cycles

If you can pull your alternator out & take it to a BOSCH rebuilder, they can check it out & rebuild it if necessary. It shouldn't be more than $200 - $300 to rebuild the alternator unless somethings severely worn.

Pulling the alternator on a 308 is a bit of a PITA, but not technically difficult. Be sure to disconnect the battery before your start.

Search should turn up several alternator removal write-ups. Be sure to search the body of texts in the old ferrarichat.

 

Driving on a dying alty you will eventually have to replace both the battery and possibly the starter solenoid. Once your alternator starts to go, it drains the battery, at first little by little. This increases the stress on the starter motor from cold. The battery begins to take over the role of the alternator until it's dead. And gradually the starter motor has been compromised as the cold cranking amps of the battery are weakened.

And once the alty goes, and the battery finally drains down, it just dies and the car stops. It cannot be driven. Not even a jump start will allow the car to run because nothing exists anymore to create spark.

 

You can go to an Autozone and they will perform an in-car test of your alternator/charging system for free . If it is in fact bad, any auto electric shop will rebuild it for you for ~$150 or so. I had the same issue on my BB512i a few years back and had both alternators rebuilt for $300.

 

Absolutely right. If you discharge down to 11.5 volts, eventually (and much sooner than with normal operation) you will begin to notice that the battery is not holding its charge. This is due to lead sulfate crystals forming on the negative plates and impeding the electrochemical processes. You've probably gotten away with it so far because you're putting the charger on it immediately. Still, I'd say that you're on borrowed time.

What's counterintuitive is the fact that just a 1.1 volt difference (from 12.6 to 11.5) from nominal OCV (open circuit voltage) can represent such a high degree of discharge. But it does. As Verell has stated, at 11.5 volts OCV, the battery has been discharged 90+%.

In summary, have the car checked out by a professional. If it's just the alternator, it shouldn't even be that expensive. No way would it be "several thousand dollars". My guess is $500-600 tops.

 

Dear Ferraristi,

Hey TestaRob....why didn't you post in the TR section? We would have been all over this in seconds.

All that has been said is correct. The ALT light comes on when the ALT is no longer charging. A bad alt usually kills a good battery and a bad battery kills a good alt. You're probably at the point where you need to change both.

Not to worry, this is not an expensive or difficult ( getting your hands in there is...) to do. To rebuild your alt is about $250 and a new Optima Red top is $180. Does your battery still have a warranty? If so, get it swapped out. But don't use it until you do the alt.

The thread below is the cross reference thread where I listed where to send you alt in Orlando. They do all of Central Florida's alts so they are good. They've done the starter and alt on both my Ferrari and Lamborghini. Ask for Ray.


http://www.ferrarichat.com/forum/showthread.php?t=125008


BTW, I would be a little cautious driving on a low charge. Low voltage and low power can kill electronics....even simple (but expensive) computers on a TR.

Do a search on "changing an alt in a TR". I did a full thread on it and you can do it.


Shamile

Freeze....Miami Vice !

 

One more quick idea,
For about $7. you can buy a plug-in-the-cig. lighter tool from most auto part stores. It will tell if you are getting the lower, mid, and upper ends from your regulator (Alternator). You may not be getting the bump up when needed at the higher RPM's. This cheap little device will tell you if and where your problem is.

Good luck and stop driving the dam thing, it won't be that much time or $$$ to fix it....

Poor boy

 

It might not be the alternator. It could be a worn or loose alternator belt. Heres what happens the battery calls for more charge after starting the motor, the alternator tries to put the additional current out but the worn belt slips and does not allow the alternator to spin up enough. Now you are using the battery charge and the charge light comes on. Use a genuine Ferrari belt not a cheap aftermarket piece opf junk. Using a genuine belt means you won't be tightening the belt continuiously.

If it is a Bosch alternator they have an external regulator/brush holder assembly screwed onto the back of the alternator under the aluminum heat shield. In most cases 2 things keep an alternator from charging, one a brush or brushes won't make contact with the slip rings either thru worn brushes or contamination causing the brushes to hang up, or a failed regulator. This regulator is the retangular or round black plastic box mounted on the rear housing of the alternator and holds the 2 brushes. Very easy to remove and check out. Most any parts store can test the regulator and sell you a replacement for around $60.00. I just went through this with my 308 regulator was $48.00 and a rebuilt alternator with regulator complete and a 2 year unlimited warranty was only $59.00 thru Schucks/Kragen auto parts. It took 2 days to get it to my shop. The 308 alternator is the same as a Lancia it even has the same Bosch i/d number and is rated at 60 amps. I would reccomend getting the complete replacement unit and taking advantage of their warrenty.

Howard
tr0768

 

Dear Ferraristi,

Very good points. But to get to the regulator on the back of the Alt, you have to remove it anyways. On the TR, the alternator has a backing cover with a fresh air tube. You can't get the backing plate off. Perhaps if you remove the upper part of the intake. But, why go through all that trouble to fix one potential part. Just remove the whole alt and have it rebuilt with a ( I totally agree) new Ferrari belt.

Testarob, you can do this yourself. Put a towel on top of the intake and just undo all the bolts. If you can't a typical mechanic can do it. I wouldn't send it to someone not familiar with Italian cars though....they really need a different mindset. Again, this is NOT costly. If you have any questions, post or PM me, I'm here to help!

Oh...if you have the alt rebuilt, it comes with a warranty ( made good on an issue )


Shamile

Freeze...Miami Vice !