battery dead?

Battery possibly has a bad cell and needs to be replaced. While driving, the alternator/voltage regulator is providing power, so everything is OK, but the battery is not charging. Once you shut off the engine, no power. You might double check for corrosion on the cables and also to make sure both have good connections, but a bad battery is a very simple and likely cause.

Taz
Terry Phillips

 

I would suggest you start the car and put an voltage meter across the battery terminals (use the posts in the right rear engine compartment......idling the voltage should exceed 14 volts and should increase to around 14.6 volts as you rev the motor.....this will confirm your alternater is working.
If all is ok you are almost sure your battery is toast.....but for good measure take your battery to your local auto centre and have them load test it.....this will confirm it is shot and replace it.

 

Time for the Optima red top...

 

Hi there,

Hear this... a few days ago, while driving my 94 348 GTS, the tensioner bearing just stucked and the alternator belt just vanished as well as the A/C belt and the tensioner support and it's fixing screw... obviously the battery light flashed permanently at the dash board.
From that moment I knew that maybe I could drive for 15 to 20 mns... I manage to do it and reached a near by exhausts shop of a frind of mine...
There, was when we saw all the picture!
So during five days I manage to buy the dayco 5k 760 alternator belt as well as the other belt a new bearing a new aluminium soldering job for the support...
All the job done and everything went almost ok... The light on the dashboard still on.
Ok, so maybe some component of the alternator suffered some damage... Alternator to the repair shop... new regulator.
During the stopped period the battery switch was OFF.

Just drived back home...

Next day...
The battery was dead! Well, I thought maybe that 15 mns drive just made that happen... Since it is a 20 days new battery I tried to plug it to a charger for 24 hours, indeed the battery recovered at full.
Just drove the car for one day.

Next morning...
Battery dead again!! What now?

Then I noticed, that the front right driving light was off, burned fuse. New fuse on, still no light!! The lamp is fine!!!!! Replaced by a new one, just for the peace of mind, still no light...

What could have happened on that tragic day?? When the belt broke, could the alternator charged above the 14,6v? Did it "assassinated" the almost new battery?
I don't have the dashboard light anymore the car runs perfectly when the battery is charged...

A bit confused.

Obviously tomorrow I'll do all the checkings and belt tension value. But would like to hear from you...

Regards,

Mont

 

Do not jumpstart your 355!

Take a look at this thread

http://www.ferrarichat.com/forum/showthread.php?t=250838

 

First step. Fully charge battery and have it load tested. I would also check the specific gravity of each cell. If it passes next step is to check voltage at battery with key off. Start car and recheck voltage. Shoud be just over 2 volts running versus not running. Should not be over 14.7 volts. If this is OK your altenator needs to be load tested. The maximum output should not be less than 90% of the altenator's rated output. If it is not putting out enough amps have the diodes checked in the altenator. Lots of 355's have bad diodes in the altenator and no one ever knows. If you have a bad diode your altenator can also drain your battery when the car is not running.

After you know your battery and the altenator are working correctly check for excessive milliamp draw at the battery with the key off. Hard to remember the max for every car but should be less than 35 to 40 ma's. Could be below 20 ma's which is normal for many cars. If you have more than a 50 ma draw you are going to have to find out what is causing it.

 

Stupid question That I don't know the answer to. If your battery switch is shut off is it possible to jump start the car if the jump is made "after" the kill switch? Stated another way, does the battery kill switch upset the entire electrical circuit or just the battery portion of it?

 

NOOOO!!!!!! Do not do that!! This could possibly damage many of the electrical components in your car. To jump any car, the batter must be in the circuit. But don't jump the Ferrari anyway even with the battery in the circuit.

 

Thanks for all the ideas and thoughts...

The Alternator was charging 15v+!! So the first job, changing just the regulator wasn't well performed...
Today a new regulator as well as a new rectifier were instaled. The system was tested stoped and charging at throtle touch is 14,6v.
Let's wait for the road test...
But some questions, could the battery suffered any damage beeing "charged" by the alternator at a higher voltage than it should? Do I have to charge it again "manualy"?
Or, is it charged plus than it should?

Regards,

Mont

 

It is possible that the battery was damaged by being overcharged by the alternator. You just need to have the battery load tested.

 

If the rectifier had to be replaced your battery was recieving some AC voltage. DC batteries really don't like that and will shorten their life. Again a proper load test and checking each cells specific gravity will tell the truth.

 

I agree completely....I was just wondering if it was possible