2002 Volvo V70 XC voltage drop issue

[kostiantynv]

Dear Volvo specialists and enthusiasts,
I've got an issue with my 2002 Volvo V70 XC (152000 odo.). The issue is as follows:
several months ago I noticed that the lights (low beams and interior lights) go dim if I use the rear window motors, also when the heating or just the cabin fan is on and I drive I could hear how the fan RPM drops when braking. If I turned on the electric power consumers such as windshield defrost, seats heating the effects were more noticeable.
I took multimeter and measured voltage at the battery terminals in the trunk. when the engine was not running, it showed somewhere around 12.1V, After engine start the Voltage increased to 14.1 (the values after decimal point are approximate), when turning on the power consumers (all I could find in the car) the Voltage dropped to 12V. So i decided to go to the mechanic, he told me it was the faulty alternator, replaced it (remanufactured Bosch) but the problem didn't go away, it got better, but the lights still go dim. I went to autozone to test the battery, but the guy told me it was fine for the 4 yrs old one. Now the voltage readings on the running engine is 13.7 (with new alternator) but when I plug in the consumers it doesn't drop that significantly, however, it drops to 13.4-5 and the lights go dim when turning on the motors. I checked the fuses and those which are responsible for the rear window motors are 30A, so means pretty powerful. I also tried to check if the ground wires are all in a good shape (six bolts under the hood and one in the trunk) but it didn't help. I'm kind of stuck here, because I'm afraid that the issue will fry the new alternator. Please, help to solve this mystery!
Thank you!

[jimmy57]

On a 150,000 mile car the fan speed drop on braking can be due to worn fan bushings. When you have several higher amperage users on and the engine goes to idle the voltage does go down and you will notice some dimming. The fan bushings being worn will make the fan draw more current and may be the reason you ever noticed the light dimming.
That car has a 120 amp alternator, some have 140A but I think that is used if you have front and rear seat heating and navigation system. 120 amp alternator only produces something around 55 amps at idle speed. Lights, wiper, blower motor along with the control modules that are working and using current would all be at or more than the 55 amps and then the battery is not held at 13+ V but it falls to battery voltage level of 12.5-12.7V and the lights and motors will be affected.
If the engine idle speed is low that makes this more noticeable as the amperage from alternator will be even lower.

[kostiantynv]

On a 150,000 mile car the fan speed drop on braking can be due to worn fan bushings. When you have several higher amperage users on and the engine goes to idle the voltage does go down and you will notice some dimming. The fan bushings being worn will make the fan draw more current and may be the reason you ever noticed the light dimming.
That car has a 120 amp alternator, some have 140A but I think that is used if you have front and rear seat heating and navigation system. 120 amp alternator only produces something around 55 amps at idle speed. Lights, wiper, blower motor along with the control modules that are working and using current would all be at or more than the 55 amps and then the battery is not held at 13+ V but it falls to battery voltage level of 12.5-12.7V and the lights and motors will be affected.
If the engine idle speed is low that makes this more noticeable as the amperage from alternator will be even lower.

Thank You very much for your reply! Well, I would agree with the statement above if there wasn't one thing. The lights go dim even if all the consumers are off and I try to "close" rear windows. It seems like there is not enough power for this operation even with most of the accessories are shut down (except lights, because I wanted to see how the lights work, just as an indicator). Also, I should have probably mentioned that I had the "Low battery voltage" message several times, but when turned ignition off and back on the message had disappeared. Is it possible, that some of the power cables went bad? Or some power terminals got oxidized (not just grounds).
I also noticed (maybe it's not related) that one of the relays under the hood (FMA2, ECU) becomes pretty hot (not boiling hot, but probably 120-150 F after I drove around 70 miles at once, maybe it got hot earlier, I'm not sure), all other relays in that fuse box are cold.

[dj_v70]

You mentioned that battery voltage was low when car not running, before alternator change.

What is battery voltage when not running after alternator change (wait an hour if car was just driven)? Also please report on battery voltage with headlights on including high beams at idle, and separately battery voltage with headlights and window motor on.

[oragex]

After engine start the Voltage increased to 14.1 (the values after decimal point are approximate)

If the voltage stayed there at 14V or so, why did the mechanic replace the alternator ? That was perfectly fine.

Plus, I think he installed an alternator for 2004 and up which has a different regulator. Placed on a 2001-2003 car, this later model of alternator will only put out 13.7V which is not enough to charge the battery and will damage a new battery in the long term.

As for your battery, it's dead at 12.1V. It doesn't charge perhaps more than 20% of its capacity because it's almost completely work.

But first, ask the mechanic to put back the old alternator, because you need at least 14V to charge the battery. Then buy a new battery. Also, put the ignition key in POS II when replacing the battery to be safe.

Then, with a new battery and a correct alternator see if the original problem still persists.

Hopefully this helps, if you feel the mechanic did wrong I would not return there.

[kostiantynv]

You mentioned that battery voltage was low when car not running, before alternator change.

What is battery voltage when not running after alternator change (wait an hour if car was just driven)? Also please report on battery voltage with headlights on including high beams at idle, and separately battery voltage with headlights and window motor on.

dear dj_v70, thanks a lot for your reply!
The readings are as follows:
1) not running engine 12.17V
2) engine running w/o accessories - 13.79V
2) low and high beam on (engine running) - 13.68V
3) low and high beam on (engine running) with both motors on -13.62V
I should mention that the readings are quite dynamic, these are approximate values, also, when turning the window motors on the voltage dropped to 12.7 for a sec and then turned back to 13.6V (the lights still go dim).
Thanks!!

[kostiantynv]

After engine start the Voltage increased to 14.1 (the values after decimal point are approximate)

If the voltage stayed there at 14V or so, why did the mechanic replace the alternator ? That was perfectly fine.

Plus, I think he installed an alternator for 2004 and up which has a different regulator. Placed on a 2001-2003 car, this later model of alternator will only put out 13.7V which is not enough to charge the battery and will damage a new battery in the long term.

As for your battery, it's dead at 12.1V. It doesn't charge perhaps more than 20% of its capacity because it's almost completely work.

But first, ask the mechanic to put back the old alternator, because you need at least 14V to charge the battery. Then buy a new battery. Also, put the ignition key in POS II when replacing the battery to be safe.

Then, with a new battery and a correct alternator see if the original problem still persists.

Hopefully this helps, if you feel the mechanic did wrong I would not return there.

dear oragex, thank you very much for the reply.
It's an interesting suggestion.. Well, with the previous alternator the voltage used to go down to 12V on running engine while turning on the consumers (which is not the case now), I guess at least the voltage regulator was faulty on the old alternator and the bearings were worn probably because the old alt was making rustle sounds and If I pressed the accelerator the woltage would go up to the 14V. However, it seems You are right about the fact that he installed wrong alternator. Do You have any suggestions on how I can detect for sure if the alternator is from newer model? I ask because it seems like the guy is not that conscientious if he replaced the alternator without digging deeper.. Is the mechanic at specialized Volvo shop gonna be able to detect the exact alternator model installed so I can make "my mechanic" respond?

As for your battery, it's dead at 12.1V. It doesn't charge perhaps more than 20% of its capacity because it's almost completely work.

Could You also please explain the meaning of Your statement to me? The battery is dead because the new alternator can charge it only up to 20%?
Thank You!

[abscate]

12.1 Volts on a battery above 0C is dead or on last legs

[oragex]

As above, as a battery gets worn, it will charge less and less. A new one will fully charge (100%), a half worn one will only charge to 50% (just like a half full glass of water), no matter how long it's being charged. What wears a car battery is being discharged overnight (from a current draw for example), then recharged the next day. After a few months of such treatment, even a new quality battery wears and may not accept more than 20% charge and will need replaced.

Your 2002 XC70 is it the late 2003 and up version?

Fcp euro is returning this BR14-H1 regulator for the 2003-2004 XC70 https://www.fcpeuro.com/products/volvo- ... 51#fitment

The best would be to have a look at your original regulator, to get the number stamped on it. The replacement one must match the number. I think there are three different regulators out there, for 2001-2004 the BR14-H1 (turbo engine) and the BR14-M1 (non turbo engine). For 2004/2005 and up only the BR14-C-L.

You would only have to replace the regulator and the good news is you don't have to completely remove the alternator from the car (which takes time), just undo the belt, the mounting bolts (also the two upper a/c compressor bolts a few turns), remove the alternator from its bracket, flip it on the side (while still near the engine) and undo the screws of the regulator cover then the regulator screws. Note that some models of regulators were secured with some rare male torx screws (not sure about yours).

If the old alternator was putting 12v then 14v when revving something was not fine indeed. When replacing the regulator, inspect carefully all pulleys there: tensioner and a/c compressor as these go bad at 150000 miles and can seize. If needed use quality parts for tensioner and for the a/c compressor use a quality bearing for the pulley (ask us)

As for the alternator (the voltage with the engine running), on a good battery it should show around 14.5v when the battery is being charged (which happens usually at the start up), and 13.5v when the battery is fully charged. I suggest getting one of these, it is useful and gives peace of mind, www.youtube.com/watch?v=IVDHzTkjHlc

[dj_v70]

You mentioned that battery voltage was low when car not running, before alternator change.

What is battery voltage when not running after alternator change (wait an hour if car was just driven)? Also please report on battery voltage with headlights on including high beams at idle, and separately battery voltage with headlights and window motor on.

dear dj_v70, thanks a lot for your reply!
The readings are as follows:
1) not running engine 12.17V
2) engine running w/o accessories - 13.79V
2) low and high beam on (engine running) - 13.68V
3) low and high beam on (engine running) with both motors on -13.62V
I should mention that the readings are quite dynamic, these are approximate values, also, when turning the window motors on the voltage dropped to 12.7 for a sec and then turned back to 13.6V (the lights still go dim).
Thanks!!

I concur with everyone that your battery is degraded, the previous bad alternator ruined it. I expect that you will have less of an issue with lights dimming with window motor on after replacing battery. The reason is that the degraded battery is drawing excess power trying to charge.

I expect that everyone is correct regarding regulator, etc. However, your readings aren’t bad enough to ruin another battery. Try measuring battery with leadlights, heater fan, heated seats and radio on ... if above 13v, I’d just replace battery and drive as is.