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There is a thread on here with voltage monitoring of the 12 volt. If I remember right it did charge during main battery charging.

Hopefully the creator of that knowledge sees this or a linker see this abs links the thread.
 

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2021 XC40 Recharge
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I wonder if there's anything you can do on the Volvo app that will somehow trigger charging of the 12V.
Yes, if you start cabin climate, the 12v battery will also start to charge. But then it wastes a lot of energy into heating (or cooling) if you're not going to use it.

can you tell if the 12V battery gets charged while plugged in during traction battery CHARGING… and/or just plugged in (charge complete but still plugged in I guess)? For that matter, does it get a charge from the traction battery when parked (unplugged) and dips below a certain voltage?
Yes, the I notice that whenever the HV battery is charging then the 12v battery will also be charging. When the HV charging is complete, then the 12v charging stops immediately.
It also will charge whenever the 12v battery goes below 12v (even when EVSE is unplugged). (I wish it was a higher threshold because AGM batteries like to be at higher voltages to last longer)
(This behavior is with a properly working TCAM unit)

Also it would be very interesting to see if the draw changes when they key is near. A few dealers have said that having the key nearby keeps the car “awake”
They'll say anything to get you off their back. I've tested this and the keys don't cause extra draw unless you actuate the buttons on them. Actually, that is the reason why I got myself the small sport key which has no buttons. In the past, I had inadvertently hit the buttons while in my pocket many times.
 

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'21 XC40 Recharge P8 Sage Green
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I've tested this and the keys don't cause extra draw unless you actuate the buttons on them. Actually, that is the reason why I got myself the small sport key which has no buttons. In the past, I had inadvertently hit the buttons while in my pocket many times.
The RKE (Remote Keyless Entry) receiver is always "listening" so it's always taking at least a tiny bit of power. As mentioned above, pressing a key fob button nearby will definitely put the car into some kind of "wake state" which presumably uses a bit more power. But in our P8s I don't think we have any "proximity-only" features that can trigger power usage - like some former cars I've had where convenience lights came on whenever you got near.

Normally you'd think anything the RKE receiver does should be negligible power usage. But then again - RKE is part of our infamous TCAM module - so anything is possible!
 

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Just had a call with the dealer's service department. I missed the beginning of the conversation (my wife took the call, and I joined on speaker), but the dealer apparently now says that the main battery was NOT fully discharged, and that the issues were entirely due to a discharged 12v battery. As far as I know, they did not discover any fault in the 12v charging system.

The dealer then went into "blame-the-driver" mode. She told us that Volvos must be driven 15-30 miles per day to maintain the 12v battery's charge. If we can't commit to driving 15-30 miles 365 days a year, we should purchase a trickle charger, and once a week we should pop all of the plastic panels under the frunk to expose the 12v battery and trickle charge the 12v overnight. She told us that this was an issue with ICE Volvos as well- they drain the 12v battery because of "all the technology" and thus must be driven 15-30 miles a day.

I asked her if this recommendation was documented in a service bulletin from Volvo, or if this was just her opinion. She told me that this recommendation is "in the owner's manual." Of course, it is not.

The owner's manual does say this about the 12v:

Under normal conditions, the 12V battery is charged at the same time as the car is charged, as well as via current transmission from the high voltage battery when the car is not connected for charging.

Seems to suggest that if the main battery has been charged a high level, the 12v should also have been charged while the main battery was charging, no? Not clear exactly what the second part means ("...as well as via current transmission..."), but it certainly doesn't state that the car needs to be driven to charge the 12v. Does anyone know the conditions under which the 12v charges? Definitely during charging... but also while driving? While parked and not charging?

It would be insane if a normally-functioning 12v car battery could discharge completely in 36 hours, even if it were not trickle-charging from the main battery while parked.

The owner's manual also has recommendations for long-term storage, which they consider to be periods of longer than a month... which suggests that 36 hours should be fine!

At the very least, we seem to have some problem with the 12v charging system, though I don't think there's any way of knowing whether this was a hardware or a software problem... and thus hard to know if it's fixed!
Not much chance of me leaving the car at the airport for a fortnight then! Come home to a flat battery, this is stupid and Volvo head office should be told of this stupid remark from the dealer! I don't think I'm the only one that has to leave a car at the airport for a few days.
(My car had to be towed 270 miles because the traction battery would not charge - I was told nobody else has had these issues, think volvo should read this forum). Had it nearly a year and getting rid of it in June, bought a Volvo for its good name and had a XC60 T8 prior to this. Now bought an MG half the price so half the moaning when things go wrong.
 

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First time posting on the thread, can add some data points. XC40 P8.
In November parked for two weeks, returned to brake pads rusted to drums, dealer replaced but still a hassle. Now hitting the emergency braking system (the PARK mode button) on a regular basis to remove rust.

Two weeks ago left on another trip with car left in garage on a 120v (slow) charger, all we have, returned to a completely dead vehicle. This morning removed the plastic panel from around the frunk-mounted battery, which was not fun and now parts of two 'pop-fasteners' are lost somewhere down in the machinery. This was an annoying chore in a warm well lighted garage and would have been really unpleasant in the rain at night on the street. Connected an old but good quality battery charger, it would overload the charger after a few seconds of charging which tripped a cut-out in the charger that would turn back on after cooling for 10 seconds or so. Gradually the time between cut-outs became longer until it held.
The info screen when it first appeared indicated 0% main battery charge state, then reported 92% charge.
Car now running long enough to pull out of the garage and hopefully indefinitely. Reviewed and printed hard copy of How to enable Towing Mode for later reference and stored in glove box.
Not really sure where to go from here.
 

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How many of the dead as door nail cars were charging vs just sitting there?


Have left my car a couple of times for up to two weeks with no Ill effects but I was not charging it.

Curious.
 

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MY22 XC40 Recharge Twin Plus
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Has the service centre looked into the inverter being faulty?

The 12 V battery controls all the electronics in the car and according to the XC40 manual it also gets charged by the high voltage battery.

I wonder if the inverter isn't triggering the 12 V charge or even worse, the inverter is constantly charging the 12 V and causing it to fail prematurely.
 

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2021 XC40 Recharge
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I haven't had my 12v battery die yet, but I really think Volvo has a bug with how they maintain the charge of it. Remember, I have attached a voltage logger to my 12v battery. The 12v battery has been intermittently draining downward right after HV charging has completed AND while the EVSE cable is still plugged in. As soon as I unplug the cable, the draining stops.

I have attached a screenshot showing several days worth of data. The 4 areas circled in RED are an example of the voltage dropping after HV charging has completed. The ripple period is close to every 12 minutes where the car does something causing a power spike (dip in voltage). Eventually, when it dips below 12v, it automatically engages the LV charging circuit soon afterwards.

Font Parallel Pattern Electronic device Technology


Sceenshot showing that the car does automatically engage the LV charging circuit:
Slope Rectangle Font Parallel Pattern


This behavior doesn't seem to be healthy for the longevity of the LV battery. AGM batteries are supposed to be kept fully charged in order for them to last a long time.
I see 2 main issues:
  • Volvo should raise the lower bound threshold where it will automatically engage LV charging. <12v is too low. Maybe 12.5v would be better. (I know that it depends on the temperature as to what the optimal voltage should be. My results were at around 35°F in a garage.)
  • There appears to be a bug where the car keeps turning something on every ~12 minutes when the EVSE cable is plugged in. I would like to know if it is just my car that is doing this or if it is happening to everyone. I have tried 2 EVSE's (Grizzl-E & the one that came with the car - same issue)
 

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I haven't had my 12v battery die yet, but I really think Volvo has a bug with how they maintain the charge of it. Remember, I have attached a voltage logger to my 12v battery. The 12v battery has been intermittently draining downward right after HV charging has completed AND while the EVSE cable is still plugged in. As soon as I unplug the cable, the draining stops.

I have attached a screenshot showing several days worth of data. The 4 areas circled in RED are an example of the voltage dropping after HV charging has completed. The ripple period is close to every 12 minutes where the car does something causing a power spike (dip in voltage). Eventually, when it dips below 12v, it automatically engages the LV charging circuit soon afterwards.

View attachment 2688

Sceenshot showing that the car does automatically engage the LV charging circuit:
View attachment 2690

This behavior doesn't seem to be healthy for the longevity of the LV battery. AGM batteries are supposed to be kept fully charged in order for them to last a long time.
I see 2 main issues:
  • Volvo should raise the lower bound threshold where it will automatically engage LV charging. <12v is too low. Maybe 12.5v would be better. (I know that it depends on the temperature as to what the optimal voltage should be. My results were at around 35°F in a garage.)
  • There appears to be a bug where the car keeps turning something on every ~12 minutes when the EVSE cable is plugged in. I would like to know if it is just my car that is doing this or if it is happening to everyone. I have tried 2 EVSE's (Grizzl-E & the one that came with the car - same issue)
I normally leave my car plugged in all the time at 90%, the other night I was in garage having a smoke when I noticed the charging cable light begin to blink signifying it was charging even though I hadn't used it for past 2 days. I suspected it was probably charging the 12v battery since green lite in charging port was steady green but this was the first time I ever noticed this and I could hear clicking going on once in awhile. I normally notice the white light always on thru a garage window facing my office. After about an hour and it was still charging I used a voltmeter to check battery and it was at 14.66 volts, about 30 mins later the charging had stopped.
I'm happy now that I leave it constantly plugged in since I quite often don't use car for 2-3 days.
 

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If I have to take those panels off again to get at the battery I will install a cable long enough to extend to the frunk with 30amp Anderson PowerPole connectors, and then can charge it without panel removal, and I have a voltage logger that I can plug into it when not emergency charging. But to have to do all of this is so stupid.
 

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Has anyone had a dead car that was not plugged in?
Yes.
I had a complete discharge of the main battery and the comment that the 12 volt had failed. They originally blamed a low voltage flow from a dashcam that was not on.....I unplugged it and the problem recurred.

The complete power loss occurred twice when not plugged in and once while being charged.

I am of the belief that the 12 volt failure is secondary to the TCAM which does interface with the electrical system.

I have left my keys in the car for over 24 hours, leave it unlocked, and have not had any issues since the new TCAM, firmware and I sealed the shark fin.

I follow all of these threads postulating about the 12 volt failure and causes.

I'm still not convinced this is all secondary to the TCAM having intermittent issues. All of the TCAM resets that "cure the problem" and the need to find the TCAM battery threads, are all, (in my opinion), aimed at TCAM reboots due to a failure of the circuitry. This is no different than a hard reboot on a computer when an internal board is having intermittent failure. The reboot seems to get things working again...albeit short term. But, as everyone knows, this is a temporary solution.

For the moment, my car has performed without a hitch, after three complete power failures including complete loss of all power to the 12 volt and a main battery that showed zero charge. The antenna, firmware update and TCAM have, seemed to resolve the issues for my vehicle.
 

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I had the same issue last week with my XC 40 Recharge Twin. The main battery was fully charged at 90% but the 12V system died while the car was parked for a week in the garage. The car was completely unresponsive. I had to unlock it with the manual key. The roadside assistance mechanic jump-started the 12V battery and the car came back to life within a minute or so of charging. The car now seems to be running normally though it shows a 'service required' message on start-up. Restarting the car from dead like this seems to have fixed the charging problem. It has also fixed the cruise control 'unavailable' fault that had developed a few weeks ago. I have booked a service for the car next week so that the dealer can run diagnostics on it. I'm guessing that it needs a software patch. I'll post any useful updates after the diagnostics have been checked.
 

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I was thinking about fitting an Anderson plug too, but really, we should not need to. There should be no need to access the 12V system. Why isn't the status of the 12V system reported through the main interface panel?
Those silly little push-in clips on the access panels are ridiculous. What were they thinking? I managed to get almost half of them out without breaking them or losing the pin down the hole.
 

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I do not want to jinx myself, but we routinely let either P8 sit for a few days not connected to the charging cable. Typically we charge it when car dips down ~40-45% and run it up to 90%. Typically we use the car the day after it was charged then again run it down a few days before charging. We also do not lock either rear while in the garage as I feel like the deep sleep creates more issues connecting to LTE when it wakes back up.
 
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First time posting on the thread, can add some data points. XC40 P8.
In November parked for two weeks, returned to brake pads rusted to drums, dealer replaced but still a hassle. Now hitting the emergency braking system (the PARK mode button) on a regular basis to remove rust.

Two weeks ago left on another trip with car left in garage on a 120v (slow) charger, all we have, returned to a completely dead vehicle. This morning removed the plastic panel from around the frunk-mounted battery, which was not fun and now parts of two 'pop-fasteners' are lost somewhere down in the machinery. This was an annoying chore in a warm well lighted garage and would have been really unpleasant in the rain at night on the street. Connected an old but good quality battery charger, it would overload the charger after a few seconds of charging which tripped a cut-out in the charger that would turn back on after cooling for 10 seconds or so. Gradually the time between cut-outs became longer until it held.
The info screen when it first appeared indicated 0% main battery charge state, then reported 92% charge.
Car now running long enough to pull out of the garage and hopefully indefinitely. Reviewed and printed hard copy of How to enable Towing Mode for later reference and stored in glove box.
Not really sure where to go from here.
Curious. Do you keep your car keys while parked in your garage anywhere nearby (less than about 20+ ft) due to the fact the car will be looking for the key fob and vice versa. Wears out key fob batteries. Did you sign onto your APP and check the car while you were away multiple times. It also wears the main battery along with 12v.? Also curious whey if you were plugged into at least a 15amp outlet your car had any issues.
 

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Curious. Do you keep your car keys while parked in your garage anywhere nearby (less than about 20+ ft) due to the fact the car will be looking for the key fob and vice versa. Wears out key fob batteries. Did you sign onto your APP and check the car while you were away multiple times. It also wears the main battery along with 12v.? Also curious whey if you were plugged into at least a 15amp outlet your car had any issues.
Two and perhaps three of the key fobs were very close by. Can you explain more about the fob batteries?

We do not have the car connected to an app ever, have not set that up yet. We are considering setting up the app and waking up the car every few days as a means of reminding it to charge the 12v. What do you think?

The car was plugged into a 15amp 120v outlet and had a charge of 91% after 15 minutes on a charger, although when it first woke up it reported a 0% charge.
 

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I had the same issue last week with my XC 40 Recharge Twin. The main battery was fully charged at 90% but the 12V system died while the car was parked for a week in the garage. The car was completely unresponsive. I had to unlock it with the manual key. The roadside assistance mechanic jump-started the 12V battery and the car came back to life within a minute or so of charging. The car now seems to be running normally though it shows a 'service required' message on start-up. Restarting the car from dead like this seems to have fixed the charging problem. It has also fixed the cruise control 'unavailable' fault that had developed a few weeks ago. I have booked a service for the car next week so that the dealer can run diagnostics on it. I'm guessing that it needs a software patch. I'll post any useful updates after the diagnostics have been checked.
Is that a 2021 or 2022?
 
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