Today I was sitting on the idle, suddenly the alternator, ABS and exclamation light lit intermittenly with beeping warning sound.
I can stop this by raising the rpm bit higher.
Very similar to the car sitting for a night and first start of the day with a blip of throttle to raise the voltage.
This happens only at idle from time to time but quite frequently, and it fine while car is driving.
I under that the alternator light will light if the voltage is below around 9V, but the voltage on my battery was around 13.1V at idle.
Voltage at battery at idle is around 13.2 and while driving it is about 13.6V.
Doesn't seem like a loosen connection since this won't happen while car is driving.
Any suggestion for the trouble shooting.
Thanks

 

13.6V while driving is a bit low unless you have everything on (lights, AC on max, radio up, etc).
These cars are very voltage sensitive; I might consider replacing the voltage regulator which should get you to 14V+ while driving.

 

Thanks,
The alternator was quite new was installed around 2 years ago.
It is a WOSP 240A alternator purchased from Classic Retrofit.
And it was converted to serpentine belt with the ratio is 1.65.
I had some test today. If I raised the rpm by just a little bit up to rpm.
Then there is no warning at all, as soon as the rpm drops to 1000 without any input then the warning will come back.
So I removed the alternator lamp and check, sitting at idle for about nearly 10-15 minutes. the warning never display.
And I can noticed the voltage slightly raised by .3 to .4 volt.
Will that be ok to run the car without any alternator lamp installed?
Could it be the issue for the particular lamp issue?

I noticed Clewett Engineering had some fix about the low voltage charging with serpentine belt.
By adding one more bulb to the circuit.
But I am not sure how to interpret the diagram correctly.
It is saying I added one side of the a bulb to the alternator blue wire and other side of bulb to the ground in the engine bay?
Not sure about why it is stating switched power.
Isn't the blue wire from alternator a 12v positive already?





Thanks

 

Ah, you're not running a stock alternator or charging system.
The bulb serves as an "exciter" telling the alternator that current is needed.
The diagram is showing you how to add additional resistance to that circuit.
One end connects to the blue wire, then it goes to a 4w incandescent bulb, then the other end connects to a switched power source (only on when ignition is on) in the engine bay.

 

Thanks
That switched power source will a 12v positive voltage from battery correct?

 

Switched means 12v positive voltage from ignition.
If you went straight from the battery it would be constant power not switched power.
You need a wire that is only hot (12v+) when the ignition is on.

 

Thanks,

Wha will happen if I remove the alternator bulb in the clock?
I tried remove it earlier today and the warning was gone and the voltage was raised about 0.3 v.

 

100% correct. I've installed 8 or 9 Clewett 993 serpentine belt setups and always add the additional incandescent bulb - just in case. I make a simple aluminum bracket that attaches to an existing stud in the fuse box on the driver's side of the engine compartment.
The bulb only illuminates for a few seconds at startup.






Andreas

 

Thank for your message.
Does bulb have to be a 4w exactly?
Or I can use other higher or lower size?
How will it affect the voltage?
Sine there is not much choice of 4w bulb style in the market.
I can only find BA9S 4w in my area.
Btw, is that ok if I remove the battery bulb inside the clock in my case?
I’ve seen people upgrade the bulbs in the dash to all led bulbs.
Will this affect the voltage as well?
Thanks again

 

4w or 5w is fine.


Andreas

 

Dear Andreas,

The journey continues.
Just discover something interesting earlier today.
I noticed voltage at the battery and from engine fuse box is about 0.5V difference, the once the one at the engine bay is higher than at the battery.
I wired an 3.4w bulb today as well like the diagram went out for a drive noticed the voltage is around 13.2 for the who drive, so I pulled over and shut down and try to restart, when i put the key into ACC the battery light won't light up.
So I pulled the wire bulb harness an revert back to normal, and still the same thing.
Pull the clock and swap another bulb for battery light in the clock, and battery is back to normal.
So I went out for a drive and the voltage is up to 14.0V at the battery and 14.5 V from the rear fuse box.
But at idle the battery voltage drop to 13.5V and voltage at rear fuse box it about 13.1V and intermittent battery light warning was triggered from time to time.
I also notice the voltage at the rear fuse box is fluctuating quite a lot and frequent, please refer to the video.
Could it be a bad VR?
I have a WOSP 240A alternator installed for the Electrical AC, and all the test was done with AC off.
Thanks again.

 

Two oppositions:
1. increase the idle RPM (idle valve adjustment)
2. change the crank to alternator pulley ratio
Also, soldering the alternator cable connection at the alternator can reduce a potential voltage drop. It's typically just crimped.

 

Thank Loren,

Did some drive today.
Found some strange behavior.
Started the car, meter showing voltage at car fuse box is about 14.2V and 13.7V at battery connection when car is idling at 1000 rpm.
When for a drive, the voltage at rear fuse reading is about 14.5V and 14.1V at battery.
After some 30 mins of driving, the voltage at rear fuse box is dipping into 13.2V when are is idling at traffic light and back to 14.0V above when car is driving again.
At the idling period I can see the battery post voltage is about 13.2-3V, the sitting voltage of my antigravity lithium battery.
And the intermittent battery light warning with the beeps comes back from time to time.
It seems that I will have the issue when the alternator or VR has warm up after the drive and acts normal when it it cold.

 

Have the clock circuit checked for dry joints. Notorious for causing charging issues on 964/993.

http://p-car.com/diy/clockrepair/

 

Thanks Jonny,

Here is my clock which I pulled last year.
Are those brown joint are so called dry joints?
In the charging system, is it fine to run without the light bulb in the clock dash or convert to LED bulb for the battery light location?
Thanks






last year.