Hyundai Ioniq 5 battery drain problems

Filed Oct 20, 2026 · Electrical · MA

The vehicle experiences catastrophic, recurring 12V auxiliary battery discharge and complete electrical system collapse due to a suspected repeating failure of the Integrated Charging Control Unit (ICCU). The vehicle was previously serviced for identical 12V power-loss failures and recall interventions in June 2025. Despite those prior repair attempts, the defect has recurred aggressively, resulting in four separate 12V battery collapse events in October 2026 (specifically on October 10, October 13, October 17, and a complete breakdown requiring a flatbed tow on October 19). This defect presents an extreme safety hazard: when the ICCU fails to step down high-voltage power to maintain the 12V system, the vehicle experiences sudden and unannounced loss of electrical power while parked or operating, risking a total loss of motive power, steering resistance, and exterior lighting in traffic. Diagnostic testing confirms internal 12V battery failure with normal resting parasitic draw, indicating the charging system root cause remains unaddressed despite prior manufacturer recall campaigns (such as Recall 272). The vehicle is currently at an authorized dealer awaiting diagnosis and repair.

Filed Aug 19, 2026 · Electrical · CA

After car has been parked, when trying to start car , car turns on briefly saying 12 v battery low come to safe stop. Then car dies. Car isn’t in motion since it’s been parked. First time it happened I needed a tow truck and the tow truck needed to jump my battery. Since then battery keeps dying when trying to start this has happened every time I start the car since July 11 2026

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 Jun 15, 2026 · Electrical, Engine · AZ

On June 13, 2026, my 2024 Hyundai Ioniq 5 experienced a sudden and dangerous propulsion failure while in active motion. The vehicle had approximately 9,447 miles on it and was at 58% battery charge at the time of the incident. The vehicle was leased in January 2025 and has been serviced exclusively at the Hyundai dealership. While driving with two occupants, the vehicle abruptly lost all ability to accelerate. The dashboard displayed a critical warning: “Stop vehicle and check power supply” along with a red battery icon. This failure occurred without warning and immediately placed us in danger of being struck by surrounding traffic, as the vehicle could no longer maintain speed or respond to throttle input. I was able to coast the vehicle off the roadway. Shortly after stopping, the vehicle issued an additional warning stating that auxiliary functions were draining the battery. Within moments, the vehicle shut itself down completely. This left both occupants stranded in extreme heat (over 100°F) with no air conditioning, no ventilation, and no ability to restart or power the vehicle while waiting for rescue. This created a serious risk of heat-related medical distress in addition to the initial roadway hazard. The vehicle’s complete loss of propulsion followed by a full electrical shutdown represents a severe safety defect. At no point should an electric vehicle with more than half a charge and fewer than 10,000 miles lose propulsion during active driving or shut down all systems while occupants are inside. This incident posed a significant risk of collision, injury, or heat-related harm. I am requesting that the federal safety agency investigate this failure mode, as it may indicate a broader defect affecting the propulsion or battery management systems of the Hyundai Ioniq 5. The vehicle is currently at the Hyundai dealership undergoing diagnostics and they confirmed they had difficulty jumping it to move it from where the tow truck had parked it on arrival.

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 29, 2026 · Electrical · GA

I tried to start car and it started but would not go into drive. A message saying "12v battery voltage low. Stop safely." Was on the screen. I turned the car off and back on and was able to drive home. Once home I tried to charge the car but it would not charge. However I left it plugged in and came back several hours later and the car had charged some. I started the car and the messages did not appear. The next day i went to drive the car and the car was totally dead. The auto key would not unlock the car. Thank goodness , I was not driving when the battery died. I took it to the dealer. This is the 2nd 12v battery I have had to replace in 4 years. The first replacement was covered under warranty. I asked them to try to identify the root cause of the 12v batteries dying so quickly and they claim it is only the 12v battery. I feel unsafe driving the car now knowing it could happen at any moment again, maybe while driving. I think the problem is related to the ICCU as my symptoms are very similar to other people with ICCU issues.

Filed Apr 15, 2026 · Electrical · TX

Known ICCU issue: the 12v battery died for no reason rendering the car undrivable.

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 Apr 2, 2026 · Electrical · CA

There were no dash warnings. The car slowed to 20MPH and then stopped just as we were about to pull onto a busy freeway. The dash stayed on and then went blank while I waited for the tow truck to take it back to the dealer. The tow truck driver was unable to move the car without jumping the dead battery to get the car to pull up the tow truck ramp. We were told it was an ICCU failure. The car was in the Hyundai dealer for replacement of the ICCU unit for approximately 10 days.