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Diagnosing a charging problem V70-XC70 2000

Hi All:

My 2000 V70 base is not charging properly. It is still quite cold here in Ontario (-15C). Yesterday I ran an errand. When I left the store the car barely started, which was a surprise, since I installed a new battery earlier this winter and measured 13.7V across the battery terminals with the car running then.

When I got home and shut the car off, it would only click when I tried to restart it. I put a charger on it so I could diagnose it once it would start again.

I noted the positive battery cable was warm, which I know is indicative of high resistance. After some reading, I suspected the B+ cable. This morning the battery was fully charged, so I started the car and started taking measurements.

With the headlights on, blower on, rear defrost and a seat heater on, I measured 12.5V across the battery terminals-- this is low-- I expected 13.7-14.2V, probably on the low side because of the cold.

I measured a voltage drop of 0.05V on B+ between battery + and the fuse box, suggesting this was not the problem-- from what I read, 10X this voltage drop would indicate a problem. The ends did not look corroded.

I measured 13V between the big red wire connection at the back of the alternator and ground (a bit less when the accessories were all on).

Based on these measurements and the observation of a warm positive battery cable, I am suspicious of that cable. I am a little worried about the alternator output as well.

If anyone has any additional test suggestions before I start buying parts, I`d appreciate them.

Thanks!








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    Diagnosing a charging problem V70-XC70 2000

    On the south side of the border, I usually tell folks to visit an autoparts store as they will check the alternator output and battery voltage for free.

    I suspect the alternator brushes are getting bad and need replacement. Unfortunately, I think you need to get a new voltage regulator as I have yet to see any brushes sold separately. The alternator should be putting out 14.5V, or close to that.

    The red wire at the battery getting hot is not a good thing. If your volt meter has needle probes, stick the red wire about an inch down through the insulation and take another reading. The end of the wire at the battery is exposed to the elements and can get pretty bad. Replacement of the large wire is quite expensive. Then again, warm is normal but almost burning hot is not.

    --
    My back feels better when I sit in a Volvo seat








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      Diagnosing a charging problem V70-XC70 2000

      Thanks Klaus-- it certainly seems like I have two problems-- the warm battery cable with a voltage drop of 0.5V and low alternator output (I am assuming the post where the big red cable attaches is the best place to measure). This car has 240K km on it (~150K mi), so it is due for brushes.

      Do you know if the voltage regulator can be replaced without removing the alternator? The prices for the VR are outrageous-- $136 at FCPgroton. With the battery cable this job will cost $200 USD in parts...








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        Diagnosing a charging problem V70-XC70 2000

        The voltage regulator can be changed out without alternator removal, but the access is tight. The upper coolant hose is in the way, of course, but most of the stuff can be moved to get some visibility.

        On the 850, there are 2 wires for the AC compressor that are hard to see. The large bolt holding the red wire is fairly easy. The regulator is behind the black plastic cover, held on with phillips screws (?). The regulator is also held down with phillips screws.

        Call a few electrical/alternator shops in your area and ask if they could replace the brushes. That would be the cheapest way to go. And, no, I do not know the size of the brushes. Perhaps they could determine that by the make/model of the alternator.

        Over on Matthews volvo site, someone 'fixed' the large red wire at the battery end.


        --
        My back feels better when I sit in a Volvo seat








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          Diagnosing a charging problem V70-XC70 2000

          That's good that the alternator doesn't have to come out!

          I think I want to go with replacing the whole assembly (the brushes look a little more involved than on my '69 Karmann Ghia, where they are held in place by a machine screw). I need to look around a bit more for pricing-- it looks like the Volvo part number is most likely 30667899 (I'm at work and don't have the model number for alternator). If I could find the Bosch number (F-00M-xxx-xxx), it will likely be much cheaper (the best price so far is $91.43 at RMeuropean.com).

          I saw the post on Matthew's Volvo site on the cable repair-- lots of flux and a blowtorch to solder the area with high resistance. I did note that iPD sells replacement terminals. I'm tempted to just pay for an aftermarket cable because they are not that expensive.








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            Diagnosing a charging problem V70-XC70 2000

            You just might have to do the exercise twice: Remove the black plastic on the rear of the alternator so that you can get the number from the voltage meter, replace it all so you can still drive the car, and then order the correct part. Don't lose the washer on the large bolt for the red wire.

            The last time I pulled one from an 850, it was in a junk yard. The hoses and radiator were already out of the engine bay, so it just looked at me...
            --
            My back feels better when I sit in a Volvo seat








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              Resolution: Diagnosing a charging problem V70-XC70 2000

              Just thought I would follow up on this. After some digging around, I determined that the Bosch F-OOM-145-230 voltage regulator would work with my Bosch 0124515019 120 Amp alternator. In fact, that was what was the part number on the voltage regulator in my alternator when I pulled it. At ~$40 in aftermarket (Transpo IB230), this is far cheaper than the one that FCPgroton.com has listed at $136. The original VR had very worn brushes.

              It was possible, but not fun, to remove the Phillips screw on the alternator back cover behind the intake manifold using a small ratchet. After that the job is easy. One minor setback-- I dropped this screw on reassembly and couldn't find it (probably will when the ice finally melts!).

              The spec on the set point for this regulator is 14.1V. I'm seeing 13.9V at the battery terminals, which is good. I still need to order a proper positive cable-- I tried the flux and solder on the original cable, but it wasn't successful, so I have a temporary cable in place now.







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