Alternator or battery needs replaced? or both?

luckyirish7 · Post by **luckyirish7** » 09 Apr 2011, 13:11

I am having an electical problem on my 850 R. I have found the drain on my battery was at first very high. It was the glove box light. i took that out and thought that I had fixed the problem. The car drain is now a normal .03-.04 when it is just sitting there not running. Now that I have fixed that problem the battery still loses energy after a couple days or a couple times driving.

I had the battery charged from Advanced Auto. The crank and the the voltage were good and the battery showed good. Then i go home, install my battery and drive to the part store... 2miles tops... with AC running and radio. I get to store and the battery tests bad at 10.63v and said "bad cell-replace." The alternator test results show no problems 13.72v no load and 13.190 at load. The load test is almost at the min. and the no load test is less than half way between min. and max. I would like to see if someone has an idea on which one I need to replace. The guy that works at Advanced said he thought it was the alternator and I had probably been running on straight battery on the drive over.

If alternator is the problem is it worth getting one from the junk yard?
If its the battery what does everyone think about getting a battery from the junk yard (only $20). Thanks for the help

Post by **Pauloil** » 09 Apr 2011, 14:10

cables, cables, cables first thing to do is check your cables under load. search voltage drop on this site and read how to check them

Post by **Pauloil** » 09 Apr 2011, 14:20

here's discussion with link to what i'm talking about

https://www.matthewsvolvosite.com/forums ... =1&t=38080

VolvoTurbo850 · Post by **VolvoTurbo850** » 10 Apr 2011, 03:58

How old is the battery?

As far as the alternator. Are you installing it or having a mechanic do it? The alternators on this car take about 1 hour to remove so consider that when you purchase a used one. I find them pretty dependable but as anything that gets older it will wear out.

Post by **JRL** » 10 Apr 2011, 09:08

CHECK THE TWO CABLES (positive and B+ cables)
My guess is if they're original...they are SHOT

luckyirish7 · Post by **luckyirish7** » 10 Apr 2011, 11:45

The battery is 3 years old and 1 month. The cables look to be original... so I guess I should replace those? Where is the recommendation to get new battery cables for this car?

VolvoTurbo850 · Post by **VolvoTurbo850** » 10 Apr 2011, 11:56

Okay so it sounds like your battery isn't working based on your ride to the parts store. How long did the shop check your battery for? Did they just voltage or did they do a more involved 5 minute plus test? I find the expertise at these shops varies. It would be worthwhile for you to check it out again to ensure your not going to have to change more expensive parts.

Check that first then check your cables. 850's are pretty good when it comes to cables unlike v70's who use a 4 wire cable to the secondary box.

If your battery is the culprit then you will have sorted things out. Batteries prove less dependable after 2.5 years.

Post by **JRL** » 10 Apr 2011, 11:57

They are but they still go bad
We're taling about 15 year old cables

zhenya · Post by **zhenya** » 10 Apr 2011, 20:04

Replacing any of these parts in the hope that they might fix the problem is not a situation you want to get in to. You need to methodically check each part of the charging system in order to find your problem, otherwise you are more likely than not, going to end up spending a lot of time and money chasing a problem you don't really understand.

First, check your battery. Get a hydrometer from an auto parts store (less than $10), charge the battery fully via a charger (ie. overnight). Then check each cell with the hydrometer. It is the most accurate way to tell if the battery is good. Next, check the alternator - what is the voltage at the battery at idle, and under load? What is the voltage under the same conditions at the alternator posts? Next, follow each cable from the battery until you understand where it goes, and check the voltage drop across each cable, one by one.

My suspicion is that you do in fact have a bad battery. If you were draining the battery somewhat regularly when the glove box light was on, it most likely damaged the battery to the point that it cannot hold a charge. This can happen in a matter of months, even with a brand new battery. The hydrometer will answer this question definitively. I would definitely not be buying used batteries or alternators unless you really knew how to test them. A 3 year old battery should typically have about 50% replacement warranty still left - so check that out if the battery is in fact bad.

luckyirish7 · Post by **luckyirish7** » 11 Apr 2011, 07:46

Thanks for the information. I will get the hydrometer and test the battery as you have stated. I am thinking it is the battery as well. It has a 72 month pro-rated warranty so I should be able to get a discount on a new one. I wont be able to get to it until next week probably, because this is my long work week. I will update the situation when I am able to finally get to it.