I have a volvo s80 and the battery just died. I had a shop diagnose the problem and they said the alternator was bad and want 750$ to replace the alternator.

I'm fairly mechanically inclined so I am having it towed back to the house to do the work myself if needed. (several video's shows it's not too labor intensive).

Doing further research I've read about slow cranking on the s80. Incidentally my Volvo has had this problem for 6-7 months making me think that the alternator has been going out. Reading up on the slow crank I've read about the alarm system causing a high drain on the battery and / or the starter not spinning freely and causing high drain from the battery.

When the car gets brought back home I'll get out there with my voltmeter and check the battery while it's running to see if indeed the alternator is over-voltage or under - voltage at the battery terminals.

If the voltages are not in-spec does anyone have recommendations for an alternator? I called the volvo dealership and the 130 amp alternator costs 650$ which is WAAAY outside my price range for this job. I don't have the car so I might need the 120amp or the 140amp so that price might change depending on what my car needs.

If the alternator is not the problem I'll start looking at starters. Has anyone else had this issue with the slow crank? Takes a couple seconds for the car to start while cranking and the crank is quite slow... sounding like the battery is about to die.

 

I went out of town and when I got back I got out to start testing the car. The battery was dead. 2.1 V when connected to the car 4.3 V when out of the car. I had the battery charged at Autozone and they said it needed another 20minutes of testing. The voltage on the battery was 12.11 V. I put it in the car and ran the car for 10 minutes. Voltage on the battery was fluctuated between 13.2 and 13.6 volts for a couple minutes... after 10minutes the voltage held steady at 13.6 volts with the car running. Also with all the accessories on lights/radio/windshield wipers etc. the voltage held around 13.6 volts.

I put an amp meter in line with the battery and I'm getting a 4.2 amp draw with the car off and all accessories off. Wish I had a clamp meter to test if the alternator was drawing current ( IE: one of the diodes was bad or something. )

Any suggestions?

 

i tested The Alternator with the Car on and the voltage was grounds 13.6 V. then tested the current going through the battery with the car off and There Was a 4.3 A current draw. I replaced the Alternator and tested the diodes in the old alternator and there was a 4.3 V voltage drop so I think the of Alternator is good. I put in the new alternator since I had already ordered it and I still have 5.6 Amp Current draw from somewhere. My next move is to poll the Alarm. Will the car run without The Alarm hooked up?

 

Ok for anyone doing a search later I'll update this.

So: to go over all the symptoms of the alternator and what I did.

1. Battery dies for the second time in 2 weeks.
2. Alternator is diagnosed as bad by a shop with no explanation as to why.
3. Car taken home and I test the alternator using a voltmeter. The battery shows 13.6 volts while car is on. When accessories are turned on the battery voltage stays at 13.6 volts.
4. With a current meter I show 5 amps of current draw while car is off. ... I suspect one of the alternator diodes has been burnt out at this point.
5. Take alternator out and check diodes. Get a 4v drop across diode and 0 volt drop the other way... alternator looks good. I had already bought a new alternator and put it in when I took old one out. -- waste of 250$?? ... maybe ( bought a boshe alternator)
***NEW alternator now***
6. Test the current going to battery with car off -- 5 amps. Further testing shows that these 5 amps are from the interior lights of the car the alarm and the trunk lights. Close the latch on the trunk--trunk lights go out. Wait 30 seconds after door is closed -- interior lights dim. Alarm is pulling like .4 amps -- pulled the fuse. After this battery is pulling .4amps. No drain. Have battery fully charged by shop and check battery voltage when car is on. 13.6 volts. Stays fairly steady when accessories are on.

Don't know if I fixed the problem. I really couldn't tell if the old alternator was actually bad. Car still has a slow start. I've read about starters having problems and pulling a lot of current.

BTW: the remove/replace is fairly simple. For the S80 turbo it's like the video's you see on youtube but you have an extra tube up front you need to remove that goes to the turbos. The removal of the alternator took about 20 minutes. Shop's I think like to charge 1.5 hours for this. My shop wanted 300$ labor for this.

 

usually when car is in sleep it gets 0.01-0.02 A readings.
So 0.4 A is high.

 

Plus 13.6 Volts from alternator is good when outside temperature is more than 10 grad C.
When less it should be more than 14.