2021-2025 Jeep 4xe High Voltage Battery SOC Drop TSB S2608000038

Symptoms of High Voltage Battery SOC Drop

Owners of 2021-2025 Jeep Wrangler 4xe (JL) and 2022-2025 Jeep Grand Cherokee 4xe (WL) vehicles may observe that their high voltage (HV) battery's State of Charge (SOC) is lower than expected after the vehicle has been parked overnight. This symptom, officially termed "High Voltage Battery Has Lower SOC After Overnight Sleep Cycle" in manufacturer communication S2608000038, typically occurs when the HV charger is not connected. A reduced SOC can impact the available electric range for the next drive cycle.

Understanding the Silent Charging Strategy and Normal Operation

The high voltage system in your Jeep 4xe utilizes a "Silent Charging strategy." This design prevents the 12V battery from depleting by allowing the HV system to provide supplemental power to the 12V system, even when the ignition is off. Additionally, automatic Battery or Cabin Conditioning can decrease the HV system's SOC below 100%, and this is considered normal operation.

Diagnosis and Potential Causes

Manufacturer communication S2608000038 outlines several potential reasons for a high voltage battery SOC drop and provides diagnostic steps for technicians.

Normal SOC Drop (<10%)

If the HV battery SOC drops by less than 10% after an 8-hour sleep cycle, this is often considered normal. This minor drop can be attributed to the silent charging strategy, as well as battery or cabin conditioning activities. If a customer requires or expects 100% SOC for maximum electric range after a sleep cycle, the vehicle must remain connected to the HV charger overnight. This recommendation is outlined in the 4xe Hybrid Supplemental Owner's Manual.

Significant SOC Drop (>10%)

A drop greater than 10% may indicate an underlying issue requiring further investigation.

• Aging 12V Battery: A common cause for an HV SOC drop exceeding 10% is an aging 12V battery. Technicians are advised to perform a 12V battery test using an approved Mopar Battery Tester. If the test fails, the 12V battery should be replaced. After replacement, the HV battery should be charged to 100%, and an 8-hour sleep cycle performed. It is expected that the HV battery will then lose less than 10% SOC.
• Ignition Off Draw (IOD): A significant overnight drop in HV SOC, such as 40-50%, is likely due to a standard Ignition Off Draw (IOD) issue draining the 12V battery. When the 12V battery is drained, the HV system is forced to continuously provide supplemental 12V power, which can substantially decrease the HV SOC. Any standard IOD must be diagnosed and repaired before proceeding with other HV battery diagnostics.
• Software Issue: If the 12V battery tests good or has been replaced, and the HV battery continues to lose significant SOC after an 8-hour sleep cycle, it may be due to a known software issue with the silent charging strategy. This is particularly relevant for the 2023 Jeep Grand Cherokee high voltage battery SOC concerns.

What Owners Should Know

• Cabin Conditioning Schedules: To minimize the possibility of Battery Conditioning affecting SOC, customers should disable any pre-set Cabin Conditioning schedules. Keeping the vehicle indoors or in an environment with stable ambient temperatures can also help reduce the need for Battery Conditioning.
• Future Software Update: Stellantis is developing an updated software to improve the efficiency of the silent charging strategy. This software is expected to be released near the end of 2026. This update aims to address certain instances of the 2023 Jeep Grand Cherokee high voltage battery SOC issue.
• Overnight Charging: If you consistently require maximum electric range after a sleep cycle, connecting your Jeep 4xe to the HV charger overnight is recommended. This practice is detailed in the 4xe Hybrid Supplemental Owner's Manual.
• Normal Operation: A minor drop in the high voltage battery SOC, typically less than 10%, after an overnight sleep cycle is often normal and not indicative of a fault.

Repair Procedure Summary for Technicians

Manufacturer communication S2608000038 outlines the following diagnostic and repair steps for technicians:

1. Disable Cabin Conditioning: Advise the customer to disable any pre-set Cabin Conditioning schedules and, if possible, park the vehicle in stable ambient temperatures to reduce the need for Battery Conditioning.
2. Check for IOD: Perform standard Ignition Off Draw (IOD) testing. If a 12V battery drain is detected, it must be diagnosed and repaired before proceeding with other HV battery diagnostics.
3. Charge HV Battery and Test Sleep Cycle: If no traditional IOD is present, fully charge the HV battery to 100% and then perform an 8-hour sleep cycle.
4. Evaluate SOC Drop:
   • <10% Drop: If the HV SOC drops by less than 10%, return the vehicle to the customer. Explain that this is normal operation due to the silent charging strategy and conditioning. Advise overnight charging for full SOC if desired.
   • >10% Drop: If the HV SOC drops by more than 10%, test the 12V battery with an approved Mopar Battery Tester. If the 12V battery fails, replace it, then recharge the HV battery to 100% and re-test the 8-hour sleep cycle.
5. Software Update Consideration: If the 12V battery is good or replaced, and the HV battery still loses significant SOC, it indicates a potential software issue with the silent charging strategy. Inform the customer about the upcoming software update (expected late 2026).

Owner Action

If you own a 2021-2025 Jeep Wrangler 4xe or Grand Cherokee 4xe and observe a significant drop in your high voltage battery's State of Charge after an overnight sleep cycle, especially if it's more than 10%, it is advisable to contact your authorized Jeep dealership. Reference manufacturer communication S2608000038 when discussing the issue. While a minor drop may be normal, a larger drop could indicate an aging 12V battery or a software-related concern that may be addressed by a future update. For consistent maximum electric range, consider connecting your vehicle to the HV charger overnight.

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Source: NHTSA ID 11038557