2025 Hyundai Ioniq 5: battery drain or dead battery

Filed Jul 15, 2026 · Engine, Fuel system · CA

The car entered a failed ICCU state (not confirmed until the car was looked at by Hyundai at the dealership) while I was driving down to Ano Nuevo regional park. Received a warning on the dash that said that electrical system has failed and to pull over. It restricted me from going over 10 mph on Highway 1 and I eventually pulled over the side of the road and got towed to the dealership. The car is home with me now but I do not feel safe driving this vehicle after all of the reports of ICCU failures. I am very concerned this will happen again and in a more dangerous situation. I was also stranded by this car in March 2026 with a dead battery.

Filed Jul 10, 2026 · Electrical · CO

Failure of ICCU and high voltage fuse. Known issue in this vehicle. 2022-24 have been recalled. 2025 needs to be recalled. Warning on dash when it occurred, then 12V battery died. Undrivable. Towed in and repaired under warranty by dealer. But apparently it can happen again because Hyundai doesn’t know how to permanently address the problem.

Filed Apr 30, 2026 · Electrical · CA

1. The repair work was done at San Leandro Hyundai service department. I do not have the parts that were worked on. 2. Fortunately, both incidents happened when the car was parked at home. The unpredictable nature of the issue though, raises safety concerns as it's unknown when the car is going to die. 3. I have repair orders from San Leandro Hyundai service department of the error codes and repair work conducted. 4. Unknown. I assume the dealership sent the faulty ICCU back to the manufacturer. 5. For the first incident, yes, there were brief notifications on the dashboard about the battery discharging. That was happening for a couple of months prior to the car dying the first time, Feb 9, 2026. For the second incident, no there were no warning messages before the car died the second time Apr 27, 2026. SUMMARY OF INCIDENTS Incident #1 — February 2026 — ICCU failure, vehicle towed to dealer — DTC P1A9096 fault code identified — 22 days out of service — ICCU assembly and high voltage fuse (H110) replaced — 12V battery tested healthy but not replaced, despite Service Advisor Alexa's explicit assurance that replacement was standard protocol for this repair type — Rental reimbursement of $209.96 still outstanding — Maintenance warning appeared approximately one month post-repair; dismissed by resetting service clock with no diagnosis Incident #2 — Current (April 2026) — 12V battery drained to 0%, vehicle completely unresponsive, towed to dealer — Hyundai app showed 47% battery and 'all systems normal' at point of complete failure — D00 fault code identified on 12V battery; sensors reactivated and battery recharged — Traction battery range reduced approximately 50% (~150 miles vs. expected ~344 miles); attributed to battery learning reset, root cause unknown — 4 panic notifications received from Hyundai app on April 30, 2026 while vehicle is in dealer's possession — cause unknown

Filed Apr 8, 2026 · Electrical · MD

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 the federal safety agency 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 the federal safety agency 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)

Filed Mar 19, 2026 · Electrical · CA

The Integrated Charging Control Unit (ICCU), part number 36400-1XAD5, failed on my 2025 Hyundai Ioniq 5 SEL RWD at 2138 miles. The ICCU is responsible for charging the 12V auxiliary battery from the high voltage traction battery. DTC P1A9096 was recorded on 03/02/2026. When the ICCU fails, the 12V battery drains because it has no charging source. The vehicle becomes undrivable as all vehicle systems depend on the 12V battery. The vehicle had to be towed on a flatbed truck to Hyundai dealer for diagnosis and repair. The failure was confirmed by the dealer using their diagnostic tools. This is the same ICCU failure mode covered by Hyundai Recalls 257 and 272 for 2022-2024 Ioniq 5 vehicles, however the 2025 Ioniq 5 is not currently included in those recalls despite using the same ICCU architecture. The failure at only 2138 miles on a 2025 model indicates the underlying defect was not resolved with the model year refresh. If this failure had occurred while driving at highway speed rather than while the vehicle was stationary, the progressive loss of motive power could have created a serious safety hazard. the federal safety agency should consider expanding the existing ICCU recall to include 2025 Ioniq 5 vehicles.

Filed Mar 11, 2026 · Electrical, Fuel system · PA

The vehicle exhibited charging failures on multiple occasions over the course of several days after being connected to a Level 2 home charging unit overnight. On repeated mornings, the high-voltage battery was found to have not charged. The vehicle also exhibited intermittent slow charging behavior during this same period. Approximately six months prior to the charging failures, the 12-volt auxiliary battery was found to be completely discharged. During this same period, the vehicle was started on one occasion to find that every warning and alarm indicator on the dashboard had triggered simultaneously. The vehicle was completely inoperable at that time. After several minutes, all warning indicators cleared and normal operation resumed without any intervention. The vehicle was brought to an authorized Hyundai dealership on March 6, 2026, where the technician diagnosed the root cause as a failed Integrated Charging Control Unit (ICCU). The ICCU is responsible for managing both high-voltage battery charging and maintaining the 12-volt auxiliary battery; a failure of this component can result in loss of charging capability, auxiliary battery drain, and potentially a complete and sudden loss of vehicle operability. As of the date of this report, the vehicle is awaiting parts with an estimated repair time of approximately one week. The repair is expected to be covered under the manufacturer's warranty. This failure occurred with fewer than 10,000 miles on a 2025 model year vehicle. Based on publicly available owner reports and online forums, ICCU failures appear to be a recurring issue across multiple Hyundai IONIQ model variants.

Filed Mar 19, 2025 · Electrical · CA

These cars still have problems keeping the 12v charged. Car was leased on Jan 19. 12v first died on Feb 15, took it to dealer where they trickle charged it. 12v died again on Feb 18, dealer replaced the 12v. The 12v died again on Mar 11 and is still at dealer service center. Case with Hyundai corporate was opened and the dealer is going back and forth with them. When car is left alone for 5 days, the 12v appears as needing a replacement, so there is something wrong with the system that keeps the 12v charged or there is some parasitic drain somewhere that is hard for the Hyundai engineers to diagnose.