2025 Hyundai Ioniq 5

2025 Hyundai Ioniq 5 XRT, VIN [XXX] . Four 12V battery failures requiring jump-starts in under 800 miles of ownership. No fault codes stored at any failure event. Visit 1 (01/12/26, ~100 mi, RO HYCS79193): Factory OEM battery confirmed failed by GDS. Replaced under warranty. Visit 2 (01/30/26, ~300 mi): Second OEM battery confirmed failed by GDS. Replaced. Visit 3 (03/31/26, ~800 mi): Aftermarket AGM tested healthy but required jump-starts. GDS recorded 12V SOC dropping from 99% to 21% then recovering to 79% — consistent with intermittent LDC output interruption, not parasitic drain. Hyundai Techline contacted. No repair performed. Visit 4 (04/08/26, ~800 mi): AGM measured 5.5V, required jump-start. Maryland Lemon Law notice submitted to Hyundai Motor America. The Ioniq 5 has no alternator — the 12V system depends entirely on the ICCU’s DC-DC converter. Hyundai has acknowledged this ICCU defect under NHTSA Recalls 24V-204 and 24V-868, covering 2022–2024 Ioniq 5 models. The 2025 model uses the same E-GMP platform and ICCU architecture but is excluded from both recalls. My symptoms — repeated battery failure with no DTCs, confirmed SOC anomaly on GDS, failure across two battery chemistries — match the subclinical LDC failure mode documented in those recalls. A Hyundai North America case is open and engineering has been engaged. No repair has resolved the defect. I request NHTSA investigate whether the 2025 Ioniq 5 is affected by this defect and consider expanding Recall 24V-868 to the 2025 model year. Please add this complaint to Investigation PE23-011. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The 12V battery in my 2025 Hyundai Ioniq 5 failed under normal use, causing repeated loss of vehicle function. Voltage measured ~12.3V at rest, dropping to ~12.0V when opening the door, and collapsing to ~11V then ~9V under light load (headlights), resulting in system shutdown. After a failed start attempt, the vehicle experienced a brownout followed by a complete loss of 12V power for approximately 5 minutes while the battery was replaced. After installing a known-good replacement battery, the vehicle powered up and the instrument cluster displayed “The vehicle is On, Ready” without pressing the start button or providing any operator input. Due to safety concerns, I did not attempt to move the vehicle. Concern: After a complete loss of control power, the vehicle appears capable of entering or reporting a Ready state without explicit operator action. A vehicle should not present or enter a drive-ready state following a power interruption without a new, deliberate user command. This behavior is unpredictable and could present a safety risk if the system were to enable propulsion or mislead the operator about the vehicle’s state. At minimum, it indicates improper state recovery after a power failure.

On April 1, 2026, my 2025 Hyundai IONIQ 5 experienced a cascading electrical failure. The vehicle first displayed a warning about a problem with the on-board charger, followed shortly by an alarm and the 'Stop Vehicle and Check Power Supply' warning with a red 12V battery indicator, rendering the vehicle unsafe to drive. Had I been on the freeway this would have been extremely dangerous. My Bluelink diagnostics history confirms three fault codes from that date: P1A9096 (ICCU fault, Electric Vehicle / Air Flap system, still Open as of 4/3/2026), and P056216 (Voltage Regulation fault, Hybrid Control system, reported twice), consistent with a cascading ICCU failure causing 12V system collapse.

For the HYUNDAI Ioniq 5 XRT, the ICCU, fuse and perhaps hybrid battery malfunctioned. We were in a disabled car on a 4 lane highway with traffic: On February 10, 2026, as we drove out of our home we heard a loud pop. As we got out onto a large 4 lane road near our house, the notice “Check Electrical System” came on and the car’s power was drastically reduced. We made a U turn and drove (20 mph) back to our driveway. We were fortunate that this was mid-day and the road was relatively clear. Normally this is an extremely busy road with traffic moving at 40-50 mph and we would have had great difficulty even pulling out to the side -- as there is only marginal side space on this road. Hyundai has confirmed to us that the ICCU and a related fuse failed. They also think the hybrid battery is also involved and they are testing to confirm that. We had no warning at all -- except for the electrical warning that came on as the car's power was reduced. The car had charged normally and had had no warning signals/signs at all.

March 19, 2026, the car left my 18 y.o. daughter stranded at 10:00pm in a store parking lot. The car was fine when she went into the store. When she went back to the car, it was completely dead. No power at all. I had to pick her up to bring her home and left the car overnight. Called AAA the next morning. I have already previously reported about this car a few months back when it was in the shop for 3 months. Then, the ICCU and wiring harness were replaced a couple times.