The 12V battery on my Ionic 5 SE AWD (US) keeps getting drained by a strong "vampire" current, until it dies. I purchased the car in March 2022, had no issues with the auxiliary battery until July.
A few times a week I would see the yellow light on the dashboard turn on, signaling a top-off of the 12V battery.I read about the dead battery issue reported by a number of users, so I bought a battery charger pack to jump start the battery in case I needed it.
Good thing I did, because in July I found the battery dead. Pretty much every day, unless I drove for more than 30 min, I had to open the driver door with the mechanical key, open the frunk,jump start the battery, hop in the driver's seat to turn on the main battery, disconnect the jump-start battery, close the frunk and get ready to drive.
After a week of torture I managed to book a service to inspect the problem.I had to leave the car for 3 days, as going through the diagnostics, charging and discharging the battery took some time.
In the end, the dealer was unable to identify the problem, but they installed a SW update (Control Shifter) and probably also the BMS update, both of which can only be done bythe dealer.
I kept my car updated on the infotainment side (May 2022 was the last update), but I doubt that this has anything to do with my current problem.
After I picked up the car, I noticed that the yellow light would go on much more often than before, probably 10 times a day, and almost every time I entered the car. At first I though that this was a good thing, as the large battery was taking care of tapping off the little one, to prevent me from being stranded. Fast forward 3 months, I noticed that the yellow light would no longer show up.
One week later I got a message from the Bluelink app saying that my battery was low. 58%. Yes, the main battery was at 58% (I never go below 30%) which I did not think it meant "low" battery charge.
But next morning my 12V battery was dead. I jump-started the battery, the main battery was still at 58%, so clearly the low-battery message was triggered by the dying 12V battery. But Bluelink seems to mix up the two.
This time the situation was even more extreme than in July. Even a fully charged 12 V battery (4 hours with a good charger) would die within the day, with the car locked, turned off, no use of Bluelink to check status etc.
I do have the BM2 voltage monitor installed, that many users suggested, but it does not help me because when the battery dies all the logged data disappears, so I haveno information about when the battery died.
I purchased a current meter, discovering that with the car turned off the vampire current from the 12V battery to the car ranges between 3 and 8 Amps, way more than the 50 mA used by the car circuitry when nothing is on. Strangely, after I disconnect the "-" cable from the car and reconnect, the current level changes, to 4 amps, 6 Amps, 5 Amps, 7 Amps after hearing various clicking of relays in the fuse box.
Having read about the misaligned charger port door that can cause high current when the flap touches the open/close button, I suspected that that could be the problem. But no, regardless of whether the flap is open or closed or kept slightly open to avoid touching the button, the leak remains substantial.
I tried all other tricks explained in this forum, refreshing the status on the Bluelink app, turning on the A/C to "unlock" something in the battery management system, staying away from opening the charge door via BlueLink app or voice command, that in some cases seem to leave something use a lot of current when the car is idle. But nothing works.
I brought tthe car to another dealership, closer to my home. They ran the car diagnostics, which reported that everything was working and the 12V battery was still in reasonable conditions, despite the numerous full-discharge cycles. As the problem kept happening every day, I brought the car a second time, for a full-day inspection. This time they confirmed that there is a problem, but they were unable to identify it.
Now I am scheduled for another service, lasting probably 2-3 days, to figure out what causes the problem by removing all fuses one by one. Whilst I am waiting for the service date, I tried myself extracting and re-inserting all the fuses in the main fuse box, close the the battery where the current meter is connected so that I can detect changes in current leaking. The only fuse (40A) that makes the current go down to 1-2A is labeled B+ (not sure what it is for).
Next step would be to do the same thing with the fuses next to the steering column, but then I cannot easily see the display of the current meter attached to the battery, in the trunk.
I am running out of patience and ideas on how to identify the problem. But it is probably not a simple issue, like a light stuck on, or a fan running for no reason, as every time I disconnect and reconnect the 12 V battery the current changes to a different stable level,accompanied by clicking of relays that indicate that different units are turning on or off. More likely to be a power management software problem.
The fact that the yellow light of the main battery management system never shows up again, whichever voltage the 12 V battery is at (13V, 12.5V, 12V, 11V, 4V...) makes me think that the battery management system itself may be faulty.
I am reporting this in case others encountered the same issue, and were unable to fix the problem using solutions presented in the past on this forum.
If the next service manages to find the cause, I will be happy to report, in case it may help others.
I love almost everything in my Iniq 5. but this battery problem is driving me nuts...
