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2024 BMW i4 — eV has plenty of main battery but shows a 12V warning

RoadCamperCommunity StarterJun 1, 20262024 BMW i4 eDrive40Baltimore
2024 BMW i4 eDrive40, about 42,000 miles. Traction battery is charged, but a low-voltage warning appeared after the car sat overnight. I know the small battery can still immobilize an EV. What information would you capture before service? Interested in real owner experience more than guesses.
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2024 BMW i4 eDrive40

$619/mo

New York, NY

41 replies

TowTunerCommunity StarterCommunity StarterJun 2, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. That's where I'd start. On “ev has plenty of main battery but,” that was the fork that mattered for me. Verbal 'we'll take care of it' is not a plan. Only after sitting overnight so far.
BoostGal550Community StarterCommunity StarterJun 2, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. That's where I'd start. I'd want a dollar figure or a measured spec, not 'should be fine.' This is me being the wet blanket on purpose.
UsedCarTuner681Community StarterCommunity StarterJun 2, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. I'd do that before spending real money. Did the worksheet show tax yet? This is me being the wet blanket on purpose.
CityFan766Community StarterCommunity StarterJun 2, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. Then you'll know the next fork. A shop burned me once by skipping that step. Next check is the cheap one I can do in a driveway.
CityFan766Community StarterCommunity StarterJun 2, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. I'd do that before spending real money. Had a similar mess a couple years ago and that's what finally sorted it. Heat soak after errands is the other window.
HybridDriver928Community StarterCommunity StarterJun 2, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. Then you'll know the next fork. Write the result down so the next test isn't a repeat of the last one. Your commute and mine probably aren't the same, but the test still applies. This is me being the wet blanket on purpose.
NewCarMechanicish876Community StarterCommunity StarterJun 2, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. I'd do that before spending real money. A shop burned me once by skipping that step. Heat soak after errands is the other window.
RoadCamperCommunity StarterCommunity StarterJun 2, 2026permalink
Checked the easy stuff on the 2024 BMW i4 and found one clue worth chasing before I book a shop. I refuse to clear codes until someone else sees them.
MarketBuyer897Community StarterCommunity StarterJun 2, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. That's where I'd start. On “ev has plenty of main battery but,” that was the fork that mattered for me. Post the numbers (or the code) and people can get more specific. I'd rather look cautious in this thread than stuck later.
CityFan766Community StarterCommunity StarterJun 2, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. That's where I'd start. This is from a 2024 BMW i4 in Baltimore with 42,000 miles. Learned this the expensive way on a previous car. Trying not to diagnose from the couch.
TowTunerCommunity StarterCommunity StarterJun 2, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. Then you'll know the next fork. This is from a 2024 BMW i4 in Baltimore with 42,000 miles. I'd want that in writing, not as a promise. Make the next action something you can finish this week. Only after sitting overnight so far.
GarageWeekend132Community StarterCommunity StarterJun 3, 2026permalink
That's a good start, but I wouldn't stop there. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. I'd do that before spending real money. Not gospel, but it saved me a headache. I keep a notes app thread for this now.
RoadShopper778Community StarterCommunity StarterJun 2, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. I'd do that before spending real money. This is from a 2024 BMW i4 in Baltimore with 42,000 miles. Do that first. I'd rather look cautious in this thread than stuck later.
RoadShopper778Community StarterCommunity StarterJun 2, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. That's where I'd start. On “ev has plenty of main battery but,” that was the fork that mattered for me. Stop there until you know. This is me being the wet blanket on purpose.
WeekendGuy384Community StarterCommunity StarterJun 2, 2026permalink
Quick add on that: Leave the alerts on the 2024 BMW i4 so service can see what you saw. That's where I'd start. This is from a 2024 BMW i4 in Baltimore with 42,000 miles. That's the sequence I'd use. I'd rather be boring and correct. Doing the boring step first on purpose.
RoadShopper778Community StarterCommunity StarterJun 3, 2026permalink
Agree — and I'd add this: Leave the alerts on the 2024 BMW i4 so service can see what you saw. That's where I'd start. This is from a 2024 BMW i4 in Baltimore with 42,000 miles. That's the whole play. I'd sleep better after that step, even if it finds nothing. If the story changes I'll post the new data.
RoadShopper778Community StarterCommunity StarterJun 2, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. That's where I'd start. That's the whole play. Might be overthinking it, but I'd rather overthink than overspend.
TowDadCommunity StarterCommunity StarterJun 2, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. I'd do that before spending real money. On “ev has plenty of main battery but,” that was the fork that mattered for me. If they can't show the line item, I assume it's hiding. Heat soak after errands is the other window.
TruckLearner280Community StarterCommunity StarterJun 2, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. That's where I'd start. Verbal 'we'll take care of it' is not a plan. Next check is the cheap one I can do in a driveway.
UsedCarTuner681Community StarterCommunity StarterJun 2, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. Then you'll know the next fork. Did the worksheet show tax yet? Not driving it hard until I know more.
TowTunerCommunity StarterCommunity StarterJun 2, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. Then you'll know the next fork. If they can't show the line item, I assume it's hiding. Happens in gear, not in park, for what that's worth.
RoadCamperCommunity StarterCommunity StarterJun 2, 2026permalink
Tried a second charger / second scan and the story on the 2024 BMW i4 didn't change. If that fails I'll eat the diagnostic fee.
CityMom597Community StarterCommunity StarterJun 2, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. Then you'll know the next fork. If they can't show the line item, I assume it's hiding. This is me being the wet blanket on purpose.
BoostGal550Community StarterCommunity StarterJun 2, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. I'd do that before spending real money. I'd want a dollar figure or a measured spec, not 'should be fine.' I'll poke at it this weekend.
GarageWeekend132Community StarterCommunity StarterJun 2, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. I'd do that before spending real money. Not gospel, but it saved me a headache. That's my plan before I call anyone.
BoostGal550Community StarterCommunity StarterJun 4, 2026permalink
I hear you, though I'd still want a second check. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. I'd do that before spending real money. On “ev has plenty of main battery but,” that was the fork that mattered for me. This is from a 2024 BMW i4 in Baltimore with 42,000 miles. If it doesn't change the out-the-door or the repair estimate, it's noise. Not driving it hard until I know more.
CityMom597Community StarterCommunity StarterJun 2, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. Then you'll know the next fork. On “ev has plenty of main battery but,” that was the fork that mattered for me. Verbal 'we'll take care of it' is not a plan. Next check is the cheap one I can do in a driveway.
TowTunerCommunity StarterCommunity StarterJun 2, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. Then you'll know the next fork. I'd want that in writing, not as a promise. No warning lights, which is why I'm documenting it.
NoMarkupFanCommunity StarterCommunity StarterJun 3, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. Then you'll know the next fork. If they can't show the line item, I assume it's hiding. A day of patience here is cheaper than a wrong part. I'll update if anything new shows up.
RustBeltLearnerCommunity StarterCommunity StarterJun 3, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. I'd do that before spending real money. If you share a photo of the worksheet, easier to sanity-check. Heat soak after errands is the other window.
MarketBuyer897Community StarterCommunity StarterJun 3, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. That's where I'd start. If you share a photo of the worksheet, easier to sanity-check. I'd rather look cautious in this thread than stuck later.
CityFan766Community StarterCommunity StarterJun 3, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. That's where I'd start. On “ev has plenty of main battery but,” that was the fork that mattered for me. Learned this the expensive way on a previous car. Climate here is different, so treat that as a local data point. Doing the boring step first on purpose.
CanyonMiles650Community StarterCommunity StarterJun 3, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. Then you'll know the next fork. Run the total, not the monthly, before you commit. I'll poke at it this weekend.
RoadCamperCommunity StarterCommunity StarterJun 3, 2026permalink
It did ev has plenty of main battery but twice this week, both times after sitting. No change in mileage feel. This is me being the wet blanket on purpose.
RoadCamperCommunity StarterCommunity StarterJun 3, 2026permalink
Checked the easy stuff on the 2024 BMW i4 and found one clue worth chasing before I book a shop. Not interested in a five-hour wait for a shrug.
RoadShopper778Community StarterCommunity StarterJun 3, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2024 BMW i4, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. Then you'll know the next fork. On “ev has plenty of main battery but,” that was the fork that mattered for me. Stop there until you know. Wrote this up on my lunch break.
RoadShopper778Community StarterCommunity StarterJun 3, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. Then you'll know the next fork. Do that first. I've seen both outcomes, which is why I'd test instead of assume. That's my plan before I call anyone.
UsedCarTuner681Community StarterCommunity StarterJun 3, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2024 BMW i4 charge sessions. I'd do that before spending real money. Any freeze-frame data saved? Happens in gear, not in park, for what that's worth.
RoadCamperCommunity StarterCommunity StarterJun 3, 2026permalink
It did ev has plenty of main battery but twice this week, both times after sitting. No change in mileage feel. Heat soak after errands is the other window.
TowTunerCommunity StarterCommunity StarterJun 3, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2024 BMW i4 — site sharing and pack temp change the curve a lot. That's where I'd start. If they can't show the line item, I assume it's hiding. Checking again after work.
TruckLearner280Community StarterCommunity StarterJun 3, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2024 BMW i4 so service can see what you saw. Then you'll know the next fork. If they can't show the line item, I assume it's hiding. Not trying to scare you — just skip the expensive first guess. I'm in no rush to be a hero on it.
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