2001 V70 2.4T Brake Failure Service Urgent / Power Fluctuations / Engine Shuddering

[abscate]

So it's possible for the battery to have enough power to start the engine, but not enough power to safely power the vehicle's electronics?

bingo!

Here is my experience …

viewtopic.php?f=1&t=92161&hilit=bus+vol ... 9+v70T5m56

[prwood]

Here is my experience …

viewtopic.php?f=1&t=92161&hilit=bus+vol ... 9+v70T5m56

I hooked up a battery charger overnight and checked the voltage this morning. It was 14.1 volts at the moment I turned off the charger, but started dropping shortly thereafter down to about 13.5. Ambient temperature was 20F.

I did some more driving tests after this. This time I was able to go 30 minutes before there were any issues, so that's an improvement. However, the voltage was again steadily dropping as I drove. At 30 minutes, the voltage had continued to decrease to about 12.6, then the voltage started spiking up to around 16, and a minute after this I got the brake failure message. HOWEVER: I did *not* immediately get the engine clunking after turns. This did eventually happen close to the 40 minute mark, but it didn't seem as severe as the last time. One other thing to note, this time when I shut the car off, the engine cooling fan was still running at a high rate (ECT was at 191F which shouldn't have triggered it), so I started the car back up. The car started, and the engine cooling fan shut off, but I immediately got a 'OVER VOLTAGE STOP SAFELY' message which was a first for me. I shut it off and there it stays.

My hope was that fully charging it would improve things to the point where the symptoms wouldn't come back. The symptoms did come back after a full charge, but I don't know if that means the battery is bad, or if the alternator or regulator are bad.

I suppose I could get a new battery, just to rule out a battery issue? Pro: It's super easy to install, and I'd be able to tell pretty quickly if the same symptoms come back; Con: It's expensive ($100 or so): More expensive than a voltage regulator (~$50), less expensive than an alternator (~$250).

If it turns out not to be the battery, then the next candidates would be the voltage regulator

I believe I got the current battery in 2019 at Walmart, but also since 2019, the only things this car has been used for are daily short commutes (30 minutes of city driving per day total, less since March 2020 when I started WFH) and around town errands. Very little highway driving. I know this isn't great for batteries.

[TisMe]

You mention the concept of tying up a spot in your driveway with maintenance; this insinuates there are more cars in your possession. Would schedules allow you to temporarily hijack a battery from another car, simply for another diagnostic drive? I'm not sure a rent-a-battery service is provided by O'Reilly's.

It definitely seems like you're honing in on your antagonist. Good job eliminating the CEM from the equation!

I've had my cooling fan stay on in the past, but that was a localized failure, not voltage-related. I swapped the fan with a different one and the issue solved itself (mid-summer heat perhaps exacerbated the degradation). Your experience is more likely related to the variable voltages.

[prwood]

You mention the concept of tying up a spot in your driveway with maintenance; this insinuates there are more cars in your possession. Would schedules allow you to temporarily hijack a battery from another car, simply for another diagnostic drive? I'm not sure a rent-a-battery service is provided by O'Reilly's.

I hadn’t thought of this. We do have a Honda Odyssey which uses a 24F size battery and my in laws have a 2007 Volvo S40 which I believe uses an H7 size. The 2001 V70 uses an H6 size. Can I use either one of those batteries in my car even though they’re different sizes?

[TisMe]

AFAIK using a non-OEM battery size is fine, particularly if the CCA and voltage is equal to or even higher than spec. The only issue you should run into is if you used a battery longterm that can't handle the load your car demands, which could essentially stress and degrade the battery itself, not the car's internals.

H7 should be fine for an H6-spec to wield. 24F however, sounds like it may not provide the power for a variable-free diagnosis. I'd check the specs just for fun.

Perhaps someone with more intricate electronic knowledge will weigh in with better explanation.

[abscate]

You mention the concept of tying up a spot in your driveway with maintenance; this insinuates there are more cars in your possession. Would schedules allow you to temporarily hijack a battery from another car, simply for another diagnostic drive? I'm not sure a rent-a-battery service is provided by O'Reilly's.

It definitely seems like you're honing in on your antagonist. Good job eliminating the CEM from the equation!

I've had my cooling fan stay on in the past, but that was a localized failure, not voltage-related. I swapped the fan with a different one and the issue solved itself (mid-summer heat perhaps exacerbated the degradation). Your experience is more likely related to the variable voltages.

Well done, TisMe


Be careful with those Odysseys, even a short trip can turn into an epic voyage, it helps to have a GPS device to get Homer

I completely brain farted the battery swap idea. Try to choose one under warranty in case the overvoltage hurts it, but a day test shouldn’t do that

[jonesg]

Check the big red cable on the regulator and the small signal wire next to it.
My signal wire was corroded and ran the battery down, it will not trigger the red dash warning light if it's bad or intermittent. I changed the connector and the alt started charging again.

[prwood]

Hi all, I'm back again with an update.

I tried swapping a battery from my father-in-law's Infiniti, which itself had recently had a battery swapped in which was obtained at a junkyard. This car had been running fine on this battery for a couple of weeks. We removed the battery from the Infinite, attached it to a charger on a recondition cycle, which after 24 hours changed to float charge. About a week after reaching float, I shut off charging. The battery showed a level of 14.3 immediately after charging stopped, which then dropped to 13.6 after a minute.

I installed it in the Volvo. It wasn't quite a perfect fit - the battery had a weird piece of metal sticking up alongside of the positive terminal, but I managed to wedge the clamp around it and tighten it down. The battery was a bit taller and narrower than the existing battery. But the car started up successfully and ran normally for nearly 30 minutes.

Here is the OBD voltage graph of my test run. The voltage after ignition was 13.0. It experienced a shallow but continuous decline throughout the remainder of the run.

IMG_4797.png (368.11 KiB) Viewed 617 times

At 30 minutes in, the voltage had reached 12.7. There was a brief voltage spike up to about 17, which caused the 'brake failure service urgent' message to appear but didn't cause any other symptoms, such as the clunking I had seen previously. 7 minutes later there were a couple of similar voltage spikes up to about 17.5, but no clunking symptoms. Then I remembered that in previous runs, I had the HVAC blowers on maximum, so I switched them on to max. This immediately caused voltage to drop by 0.3 volts to 12.4v. Once the car was in this state, it started experiencing larger voltage spikes up to 18-20 volts, as well as the return of the clunking that was seen in earlier.

Since I'm experiencing basically the same symptoms with a different battery, I tend to think it's not a battery issue, unless both batteries are problematic. The only other battery test I could do would be obtaining a brand new battery.

Since there were smaller voltage spikes prior to turning the blower on max, I tend to think it's not so much an issue with the blower motor, but rather that the alternator is not able to put out adequate voltage to power the car's systems, and that the blower motor adds just enough load to push it over the edge.

I believe my decision now is whether to attempt to replace just the voltage regulator, or the entire alternator. Any thoughts?

[jonesg]

It has to come out even for the regulator. You could try Holland salvage.

[prwood]

Here are the options I'm looking at:

Bosch alternator from FCP (remanufactured): $238 + $100 core: https://www.fcpeuro.com/products/volvo- ... 0805x-120a
Bosch voltage regulator from FCP: $41: https://www.fcpeuro.com/products/volvo- ... h-30667899
Duralast Gold alternator from Autozone (new): $314 + $40 core: https://www.autozone.com/batteries-star ... 766908_0_0
Duralast alternator from Autozone (remanufactured): $249.99 + $46 core: https://www.autozone.com/batteries-star ... 411011_0_0
Junkyard alternator: ~$50
Take alternator to professional rebuild shop: $??

I have replaced the alternator three times in this car:
- 6/11/2016 - replaced with $50 alternator from junkyard, failed almost within a week
- 6/16/2016 - replaced with remanufactured alternator from Advance auto parts
- 8/14/2017 - replaced with remanufactured alternator from Advance auto parts (under warranty from previous year's replacement)

The last one has been okay up until now - I have put over 50,000 miles on it since it was replaced in 8/2017.