Battery discharge

dtb522 · Post by **dtb522** » 18 Apr 2011, 12:30

Hi to everyone. I'm new to the forum and and have the following problem with my 2002 V70, 2.4T. Car will start ok for awhile and then out of the blue the battery will be dead and I have to jump it. Have had the battery and alternator checked too many times to count and always passes. I have troubleshot this to death. The other night I got it to duplicate, with an ammeter on the negative battery lead. Reading was -2.5 amps with everything asleep. Pulled every fuse in the car, all at once, so no fuses were left in the vehical and still pulling -2.5 amps. Pulled all relays in eng and rear comparments no change. Pulled the two relays I could get to in passenger compartment, no change. Besides bad diodes in the alternator, what could be pulling -2.5 amps with all the fuses removed? Usually when I do the parasitic draw testing I find draws of around 30-40 milliamps. I was just lucky to find that 2 amp draw the other night. The thing will go from starting fine all day to being dead after being parked for 3 hours or so. What next? This all started after getting engine mounts replaced. Shop double checked work and found no issues.

Post by **JDS60R** » 18 Apr 2011, 12:35

Keep checking. Disconnect the alternator and unplug the ignition switch. Some of the cars have issues with the alarm.
Wiring diagrams are above in the repair database. You only have a few circuits left.

elchopperfreak · Post by **elchopperfreak** » 18 Apr 2011, 12:54

I had a similar problem on my 1999 S70
After parked one or two days the battery would not have enough charge to start the car. It was taken to the Volvo dealer several times (under warranty) and they could not find what it was.
I cant pinpoint the exact problem since I changed a couple things at the same time,but could be reasons to.
Found a faulty micro switch on the rear left door, which would leave a faulty light on, although the light was toast ( courtesy,interior light)
Also changed the locking system box, since the original was faulty, intermitent and had a mind of its own.
Dont know if theres any relation but also changed the main switch system ( at the drivers door)
I cant say exactly what was the draw since it was a problem since the car was still under warranty and I changed/ fixed the above mentioned a couple years ago.
I also removed all the window switches and cleaned them up at the plug and inside ( good how to in the 850 s70 section)

Hope this helps in some extent.

dtb522 · Post by **dtb522** » 18 Apr 2011, 16:00

Thanks JDS60R and Elchopperfreak for the info. When I got home today I put the clamp on ammeter on the lead going from the jump start junction in the engine compartment and found the 2.5 amp draw was duplicated again. That junction is as follows: one heavy red wire coming from the alternator via the starter, connecting to the other wire which goes back to the battery. When I disconnected that junction, isolating the alternator and starter, the amp draw goes down to normal as far as I can tell. I had just had the alternator load tested again and the diodes rechecked so I'm thinking somehow the starter is intermitantly drawing on the battery with the car off and the keys out of the ignition. Have to figure out how or what on the starter can be causing a draw. Still at it!

elchopperfreak · Post by **elchopperfreak** » 21 Apr 2011, 20:25

Also remembered, again I do not know if its relevant or not, that I changed the headlight switch also and left it on the non daylight lights.
Was thinking about it aince I changed the position yeasterday, to have the headlights on all the time and when I start the car the dash lights seem pale until you rev the car a bit..

dtb522 · Post by **dtb522** » 30 Apr 2011, 09:55

For now I think I found the problem. Caught the 2.5 amp draw with all the fuses out and relays pulled. Pulled the lead to the alternator and the draw went away. Ohmed from b lead stud to frame and had 1000k, should have been open. As alternator cooled current draw dropped and resistance to ground on b lead went up to open. Replaced alternator and so far so good. All third party tests on alternator showed it being good. Don't know what was happing inside of it. Thanks for all the posts.