[jerrybbluestein]

I purchased my XC40 Recharge in May & was going to my doctors @ 3;00. I went to get in the car & everything was dead! I figured how to get the key out of the fob, opened the door but nothing would
show on the dash or center screen.
I had charged the battery to 90% the day before & drove less than 3 miles!
I called Volvo Support to have my car towed to the local dealer The 1st wrecker did not show & the second wrecker showed about 4 hours later but said his wrecker was unable to pick up such a heavy car?
The 3rd wrecker showed up. From the timed I called Volvo Support, around 11am & it took until 7pm!!!!
I would hate waiting on on the side of the road for 8 hours!!!!

My dealer called me today & said that the 12 Volt battery ( 2nd car battery) had to be replaced &
( 3rd battery) needs recharging. I did not know the car has 3 batteries. Can anyone explain what they are used for? Dealer says that the car will be ready Friday after Thanksgiving,
Has anyone had this problem?

 

[Greg S]

I purchased my XC40 Recharge in May & was going to my doctors @ 3;00. I went to get in the car & everything was dead! I figured how to get the key out of the fob, opened the door but nothing would
show on the dash or center screen.
I had charged the battery to 90% the day before & drove less than 3 miles!
I called Volvo Support to have my car towed to the local dealer The 1st wrecker did not show & the second wrecker showed about 4 hours later but said his wrecker was unable to pick up such a heavy car?
The 3rd wrecker showed up. From the timed I called Volvo Support, around 11am & it took until 7pm!!!!
I would hate waiting on on the side of the road for 8 hours!!!!

My dealer called me today & said that the 12 Volt battery ( 2nd car battery) had to be replaced &
( 3rd battery) needs recharging. I did not know the car has 3 batteries. Can anyone explain what they are used for? Dealer says that the car will be ready Friday after Thanksgiving,
Has anyone had this problem?

Sorry to hear about your experience. That must have been tedious! All EVs to my knowledge still use a conventional 12V battery for the standard car systems (power windows, sound system, wipers, etc). So that’s what the dealer means when they say “2nd battery”. This is charged by a step-down inverter using the high voltage “EV” battery. It’s possible that a software or hardware glitch allowed your 12V battery to discharge, or it’s possible the 12V battery was faulty.

I believe the “3rd battery” the dealer is referring to may be a back-up battery for the TCAM, which is the telecommunications module that provides mobile, GPS and other antenna functions for things like the remote keyless entry system. I think typically the 12V battery would keep the TCAM back-up battery charged, but when your 12V battery died, it probably allowed the TCAM battery to discharge as well. Not sure how the dealer charges that TCAM battery. I believe it might be colocated with the TCAM, which is in the roof lining just below the “shark fin” antenna cover on the roof.

 

[JT Rock]

I believe it might be colocated with the TCAM

The TCAM backup battery (BUB) is near the left C pillar toward the bottom:

 

[Dan in Connecticut]

I purchased my XC40 Recharge in May & was going to my doctors @ 3;00. I went to get in the car & everything was dead! I figured how to get the key out of the fob, opened the door but nothing would
show on the dash or center screen.
I had charged the battery to 90% the day before & drove less than 3 miles!
I called Volvo Support to have my car towed to the local dealer The 1st wrecker did not show & the second wrecker showed about 4 hours later but said his wrecker was unable to pick up such a heavy car?
The 3rd wrecker showed up. From the timed I called Volvo Support, around 11am & it took until 7pm!!!!
I would hate waiting on on the side of the road for 8 hours!!!!

My dealer called me today & said that the 12 Volt battery ( 2nd car battery) had to be replaced &
( 3rd battery) needs recharging. I did not know the car has 3 batteries. Can anyone explain what they are used for? Dealer says that the car will be ready Friday after Thanksgiving,
Has anyone had this problem?

Same thing happened to me. Faulty 12V battery.

 

[XC90_Dinosaur]

Ugh... that is unfortunate. Perhaps it is not the battery but the charging algorithm. These type of batteries goes bad very hard and one of the ways is to overcharge them or charge with more Amperage than necessary. Another way to shorten their life is to discharge them too much. Do not forget the cold. Cold is one of the best ways to kill these batteries. Anyway the bottom line is that I am thinking that is another software issue.

 

[blitzswede]

Our late Model 3 experienced a similar 12-volt battery failure just 3 months after taking delivery of the new car. The little 12V battery dying effectively killed everything else too, such that the big high voltage battery could not be engaged and was unaffected; could not even open the doors (powered by 12v) and had to be pried open forcibly to get inside the car to try and engage Tow Mode. But then it turned out tow mode could not be activated either and so the Model 3 had to be physically winch-dragged out of the garage onto the tow truck, to the nearest Tesla service center about 250 km away. The trail of destruction continued towards the communications module's backup SD card, which the service center also replaced, together with the 12v battery. Tesla fixed everything under warranty and flat-bedded the car back to us within two days, so that was not so bad, all things considered. It turned out Tesla was going through a period of many such failures due to defective 12V batteries and not the software. A single bad cell in a 12V battery can take down the whole unit, just as it can happen in the big battery too, extending to the entire module containing the bad cell going down, but that is not so catastrophic in the overall scheme of things as the other nodules may still be working fine.

 

[Greg S]

The TCAM backup battery (BUB) is near the left C pillar toward the bottom:

View attachment 1840
View attachment 1839

Thanks for clarification on the location of the TCAM backup battery. Good to know! I should have recalled that from the PDF about the TCAM that was posted here earlier!