Critical 12v Charging failure

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riskymoth
Posts: 79
Joined: Fri Dec 08, 2023 2:17 pm

Post by riskymoth »

Yes, will get it back to the dealership asap - they are currently awaiting stock of the 12V battery(!) - whether it's actually that at fault though is hard to know.

Various dire messages referred to eCall failure, and there's a red SOS message on the dashboard along with a dictate to return the car for service. The rescue guy said he'd replace the TCAM battery with a freshly charged one, but didn't. He did say it should eventually recharge after a longer trip, but that they can fail when allowed to run down completely.

poleposition
Posts: 129
Joined: Tue Jan 04, 2022 11:45 am

Post by poleposition »

I spent a lot of time investigating my TCAM battery as I kept getting intermittent eCall failure. I thought it was the TCAM battery, but turns out it was ok. The dealer can measure the battery status, and charge it up in the workshop. My battery measured 3.9V, SOH 93%, SOC 80% using an OBD scanner and a free app on my phone. They have a test procedure for the battery, and should be able to tell if it is faulty and needs replaced.

Agree it is not obvious what is happening with your 12V battery, but if they can't find anything else they should change it to at least eliminate it.
XC40 MY23 B4P Plus AWD 7 Speed Auto AAOS
berryberry
Posts: 25
Joined: Mon Dec 30, 2024 7:04 pm

Post by berryberry »

Very possibly not related but if you see our post on New XC40 Sudden power loss - safety issue, we had a complete loss of power in one fell swoop and ultimately this was found to be a faulty MVCM mid voltage converter module, critical in transferring power from 48v to 12v battery and vice-versa, and it took some enhanced diagnostics at Volvo UK Technical before this was finally found.

Might just might be worth asking the question.
riskymoth
Posts: 79
Joined: Fri Dec 08, 2023 2:17 pm

Post by riskymoth »

Thank you - given that my car also experienced something fairly similar (once, whilst very new, it "stalled" when entering a car park) this might be a potential issue - I'll ask the service centre to consider this.
riskymoth
Posts: 79
Joined: Fri Dec 08, 2023 2:17 pm

Post by riskymoth »

The TCAM battery did indeed recharge after driving about 64 miles yesterday - all warning lights now extinguished and the service notice has vanished. Still awaiting news of a replacement 12V battery from the dealer - I wonder if there's a reason they're in short supply...
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