Alternator help

Hi. I've been having flat battery problems on my 365bb. After charging the battery overnight, voltage measured with a micrometer read 11.7v. After starting at idle, voltage was 13.7v. Revving to 3000rpm there was no change in voltage when measured at battery level. Ammeter in car does not fluctuate at all. The alternator belt is intact. Before I start pulling things apart, any thoughts on whether this points to an alternator or regulator problem?

Thanks

Greg

 

Um...........you mean multimeter Greg.

 

Charging the battery overnight,you should have over 12volts in that bad boy battery,before you start cranking the car. And at idle,the reading is 13.7v? That sound around the average,maybe just a little high at idle. And you get no voltage increase with rpm? That sounds like a regulator problem to me,but...................do the simple,"free" checks 1st. Id get that battery checked out 1st mate. Take the battery down to your local Autobarn/Repco,and have them load test the battery for you. They will do it for free and it takes around 10-15mins on the machine. It kinda seems to me that its not holding charge. You may have 2 problems,check the battery 1st,if thats ok,then get that alternator checked/load tested.

 

It sounds like you have a battery that needs to be replaced. If the voltage went up after start, that is the alt trying to charge it. Sounds like a few of the plates in the battery are failing.

 

Thanks Pap. I got it started again today. Voltage at idle 13.5. Turned all the lights on and voltage dropped to 10.5. Will trty to jack it up during the week and make sure wires etc haven't come loose.

 

Very good mate. Look into it and let us know

 

Oh man, Aussies in Ferraris...putting the Oz back into Tifozi.

Love it.


Oh, and buy a new battery, mate!

 

if the battery is ok you either have something drawing current or a faulty regulator or a diode gone in the alternator.check for current draw at the battery with an ammeter.then try and isolate the source could be anything from the radio to a glovebox light.if everything looks alright disconnect the battery feed wire to the alternator(with the battery terminal disconnected)tape the end as not to create a short.recheck for current draw.goodluck tony ps the belt isnt just slipping.have heard of the rubber in some crank pulleys allowing slip when the load comes on

 

check terminals are tight on the alternator and battery .sure the belt isnt slipping.normally the alternator will put out enough amps to keep everything running .regulator might have had a shock .didnt leave those lights on and then jumpstarted it .how many amps is your home charger 3/5/ 10 amps they are big batteries you might have to leave it on for a week if you only have a low amp charger.low voltage creates higher drawing amps.watch that starter if it struggling to turn over. hope it is just a battery goodluck Tony

 

13.5 volts is normal at idle. It should not go up when you rev the engine. 10 volts with the lights on is too low; I question if it's the alternator at all though. It may be the battery since it didn't charge up to 12v in the first place.

Ken

 

thanks Ken. I'm hoping you're right. I bought a new battery this morning and will fit it later on tonight. Let you all know what happens. Thanks for all replies. Greg

 

Did you get the battery checked Greg?? Did it fail the test?

 

mate, I got to Supercheap auto this morning before work. The guy there stuffed around and didn't know how to do the load test. I had patients waiting at work and thought f*k it just give me a new battery mate. Anyway checked all the alternator connections yesterday and looked OK. Seeing as though I could never get the battery fully charged and it seemed to be losing charge quite rapidly, I'm still figuring its the cause of my problems. Let you know

 

Lol...thats fair enough i guess. Supercheap punks

 

ok. Think i'm sorted now. New battery. Voltage readings as follows:

car off 12.2v
idle 13.5v
3500rpm 13.7v
all lights on/3500rpm 13.7v

 

Of course, the voltage regulator on a 365BB is under the dash, so if you DO have a problem, you may not need to touch the alternator at all....

But it sounds like you've nailed the battery anyway.

I have battery test equipment (load tester, deep cycle recovery charger, regualtor/rectifier tester etc etc).... I can't imagine why your local specialist wouldn't have it?

Who's your nearest Ferrari shop?

 

I use a small independent guy, but like to tinker myself. If I can't work it out then I go for the big guns!

 

OK, If you want a modern solid state voltage regulator anyway, let me know. I have a part number (at work) for an inexpensive Bosch one that swaps straight on.

Test your regulator by turning on all the lights and fans and operating the windows.... the ammeter should drop to a big MINUS (~35-40 Amps), then rev the engine gently to about 2000rpm, and it should show a positive again....

 

Well, the funny thing is, the ammeter barely moves from zero and only goes slightly negative when starting the car up. It has always done this. I also don't have a battery warning light on my car. I checked the alternator and it is a Bosch type (not marelli as fitted originally) so I assume the regulator is built into the alternator. I figured there may have been some creative wiring performed when the alternator was changed which might explain the lack of warning light etc. My manual however also does not indicate that a battery warning light was fitted.

Anway, where about behind the dash is the regulator supposed to be? Is it at the passenger footwell where all the relays are??

Thanks

 

365BB don't have any major warning lights.. no battery lamp, no low oil pressure lamp, nothing.

It's under the dash to the lower left of the steering column... 3 wires on it, yellow and grey from memory, maybe a black stripe too? A little tin box with one bolt holding it to the baulkhead.

Maybe you have an ammeter fault too...?

 

Sounds about right to me
Good work.

 

Thanks Phil.Checked and it aint got no separate regulator. Car idling, lights on ammeter slightly negative. Rev a little and does go slightly positive so I think it is ok. I read somewhere on another site that ammeters in 365bb tend to be heavily dampened and needle doesn't usually fluctuate wildly. Anyway, see how I go. Thanks again

 

Cool. Reasonable up grade, but I kinda like having separate regulator.

You could also use a current draw meter on your battery cable...

A good multi meter (fluke/snap on) can use one.

or you could even swap the wildly fluctuating ammeter from your 246 into the BB for comparison...

 

Greg - the ampere meter in my 512 BBI is quite damped. It does not fluctuate much at all. It does, however, discharge heavily on starting, charges appropriately for a few moments after starting, but then during normal driving fluctuates little. This may be a consequence of 1) shunt resistor across ampere meter, 2) dual alternators, 3) well-designed electrical bus and system (highly unlikely).

Jim S.

 

Haha, good one!!