2025 Hyundai Ioniq 5

My 2025 Hyundai Ioniq 5 has experienced repeated catastrophic 12-volt battery failures following an ICCU (Integrated Charging Control Unit) failure in November 2025. The ICCU failure caused the vehicle to lose power in traffic and required towing. The ICCU was replaced but the 12-volt battery was not replaced. Since that repair, the vehicle has experienced repeated electrical failures. The 12-volt battery dropped to approximately 3.5 volts on one occasion and approximately 1.72 volts on another. These voltages were measured and documented on video using multiple multimeters before any jump start or charging. At these voltage levels the vehicle cannot unlock doors, power systems, or operate normally. The vehicle required towing by AAA. The dealership has repeatedly recharged the battery before testing and then claimed the battery “tests good,” refusing to replace it under warranty. Numerous owners online report similar failures where ICCU problems lead to repeated 12-volt battery collapse and vehicle immobilization. Because loss of 12-volt power can disable critical vehicle systems and leave the vehicle stranded or stopped in traffic, I believe this represents a potential safety defect. I don't have the repair reports from the dealer scanned in but I can if you want them. ICCU is known failure and recall but for some reason our car doesn't appear on any recall list. 12V battery that drops below 6V is deemed unsafe and bad and 3 times (including this time) it's been below 6v but they don't believe it's a bad battery.

While traveling at highway speeds, the vehicle suffered a catastrophic and sudden loss of motive power. This resulted in a dangerous situation with no immediate ability to maintain speed in traffic. The manufacturer (Hyundai) identified a failure in the Integrated Charging Control Unit (ICCU). Despite a formal 'Notice to Cure,' the manufacturer refused to replace the 12V battery which was stressed during the failure, potentially leading to a repeat high-speed power loss event. This is a known issue with the E-GMP platform (Ioniq 5) that poses a significant unreasonable risk to public safety.

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.

While leaving Grandson’s Basketball game parking lot, we heard an audible “pop” and began traveling while the dash lit up with warning lights. We were only a few miles from home so I continued on at a maximum of 25mph, which was the max available. We contacted Hyundai and arranged for a tow the next day. The dealer, Heritage Hyundai, received the vehicle and it’s been there for over a week. The car’s code system indicated a ICCU fault. The dealer told me no recalls were made on our vehicle.

The contact owns a 2025 Hyundai Ioniq 5. The contact received notification of NHTSA Campaign Number: 25V797000 (Seat Belts); however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The dealer was contacted, and it was confirmed that the part was not available. The manufacturer was made aware of the issue, and a case was opened. The contact had not experienced a failure.

While driving, car displayed a check electrical vehicle system warning light. The 12 volt battery completely died and could not maintain charge resulting in slower and then complete loss of propulsion. Towed to dealer and the following Monday determined it was an ICCU failure. Part is back ordered but verbally told on 2/24/2026 that part would be delivered in two weeks. We'll see!!! If this issue occurred while driving on an interstate at full speed with traffic it seems this might result in an accident since the max speed dropped to 25 MPH and then 12MPH after warning before being able to safely pull over.