Lexus RC Auxiliary Battery Alarm

It is indeed plausible that the auxiliary battery is the source of your concerns, given the age of your Lexus RC and the noted mileage. Batteries typically have a lifespan, and the symptoms you describe do align with a failing battery. Have you performed a voltage check on the auxiliary battery to ascertain its condition? This would offer a more definitive indication of its health.

Thanks for the quick response! I haven't done a voltage check myself yet. I was planning to get it checked out soon. What voltage should I be looking for to confirm a failing battery? Are there any specific tools or procedures recommended for checking it on the RC hybrid?

A healthy auxiliary battery should typically read around 12.6 volts or higher when fully charged and at rest. If the voltage is consistently below 12 volts, especially after the vehicle has been running, it is strongly indicative of a failing battery. Given the complexity of hybrid systems and the potential for electrical issues, I highly advise consulting a qualified technician for diagnosis and potential replacement of the auxiliary battery to mitigate any risks of unexpected behaviour.

That's very helpful information! I'll definitely take it to a trusted workshop for a proper diagnosis and battery check. I suspected the battery was the issue, but it's good to have confirmation. Thanks again for the advice!