Yesterday my RLX suddenly started reporting that I had multiple ECU (emissions control unit) issues, and that my electric parking brake had simultaneously failed. As these two systems are completely unrelated, I was suspicious. Still, when I got home I popped off the left rear wheel to examine and test the brake. There were no bad wires and the brake worked perfectly. But by time I got the car off the jack and tried to park it, it wouldn't start.

I transplanted the battery from my Accord over (they're both 24F batteries) and all problems went away. Whew--it was only a bad battery, which is wayyy cheaper & easier to fix than either of the reported problems.

I'm just posting to 1) Let you all know what my RLX reported first as the battery started failing, and 2) ask what your experiences have been when your battery started going bad.

(Side note: The battery was only 26 months old. But Napa's warranty is a mere 24 months, so I couldn't get any credit from them for this seemingly premature failure. Guess whose batteries I won't be buying in the future?)

 

Mine died last year. Gave absolutely no warning signs. I came out one morning to go to work and she wouldn’t fire up. I panicked and assumed the worst (the hybrid battery). Turns out it was the other battery. I thought it was very odd to not show any kind of error messages.

 

My RLX SH OEM 12v battery failed in Dec/21 with a weak/bad cell at +18,500 miles. I had only 2 error messages in the navi screen:
- U0104-00 ACC may not work properly with braking system
- U1100-Gauge control module loss of communication

Acura replaced with another OEM battery and haven't had any issues since. Thinking about replacing the OEM battery this year as a preemptive strike since I'm at +4 years with the replacement 12v.