My 2024 sedan wouldn't turn over after I did the dealer's over-the-air update last week. Battery reads 12.2V but the starter just clicks. Could the update have messed with the charging system or drained something I'm not aware of? The car sat for maybe 3 days during the update process.
The update itself almost certainly didn't drain the battery - that's not really how they work - but sitting for three days on a modern car can absolutely do it, especially if the car was powered up during the install process. 12.2V is borderline dead; a healthy battery should be closer to 12.6V at rest. Try a solid charge (not a quick trickle) for several hours, then attempt a start. If it cranks over fine after charging, you're probably just dealing with a normal discharge from sitting around. If it still clicks even after a full charge, then you've got a starter or internal battery problem that has nothing to do with the software.
A jump start or trickle charge will tell you real quick if it's just a dead battery or something deeper with the charging system. 12.2V is pretty low but not completely dead, so get it back up to 13-14V and see if the car cranks normally - if it does, the update didn't cause electrical damage. If the battery won't hold charge after that or keeps dropping, then yeah, something in the charging circuit got disrupted, but honestly three days of sitting with modern cars drawing power from various modules can drain even a healthy battery faster than people expect.
did the car have any lights or sounds running while it sat for those three days, or was it completely quiet the whole time?
the previous answer nailed the sitting period being the real culprit here, but i'd push back a bit on that voltage reading. 12.2V isn't just "low" - that's genuinely dead territory for a car battery. once you drop below 12.4V or so, you've lost most of your usable charge, and the starter clicking instead of cranking confirms it. so yeah, jump it or get a trickle charger on there, but the real question after you get it running is whether the battery stays charged or if it keeps dying.
here's the thing though: modern cars do have phantom drain from all the computers and modules sitting in standby mode. if you left it parked with the battery at, say, 75% and systems drawing power for three days straight, that's absolutely enough to kill it completely. the software update itself didn't cause this - but if your charging system was already struggling before the update, those three days would have exposed the problem. after you jump it, let it run for a good 20-30 minutes to see if the alternator is putting juice back in. if the battery drops again after a day or two of normal driving, then you've got a charging issue that needs dealer attention, not a software glitch.
Before you jump it, check if the alternator's actually charging when the engine runs - that's worth testing because a failed charging system will kill a battery fast even if the update didn't cause it. Get the battery back to life first with a jump, then drive it around for at least 20-30 minutes and recheck the voltage while the engine's running. If it's staying above 13.5V or so, your charging system's fine and this was just a sitting issue. If it drops back down or barely climbs, you've got a real problem that needs looking at.
Your battery voltage at 12.2V is genuinely borderline - it's enough to click the starter but not enough to actually turn the engine over, and sitting three days without the car running will absolutely murder a modern battery with all the parasitic drain from the infotainment system and other modules. I'd grab a trickle charger or get jumped, but here's the thing I learned the hard way: after you get it started, take it straight to the dealer and have them run a charging system test while it's running - if the alternator output drops below 13.5V or so, you've got a separate problem that'll keep happening even after you charge the battery.
That 12.2V isn't actually terrible for a car that sat unpowered for three days - modern vehicles draw parasitic current from the battery even when off, so it's honestly expected. The thing worth checking that hasn't come up yet is whether your car was in some kind of update mode or limp state during those three days, which could've kept systems partially active and drained things faster than normal. Jump it up and see if the alternator spins it back up to 13.5-14V once running, but also ask the dealer if the update process left anything running in the background - some OTA updates do have extended calibration periods that the owner manual might mention.
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