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Alternator & ChargingQuestionCommunity Starter

Need advice: Fast charging slows down earlier than it used to

RoadEnthusiastCommunity StarterJul 22, 20262023 Rivian R1T Quad-MotorPhiladelphia
2023 Rivian R1T Quad-Motor, about 96,000 miles. On road trips the car used to hold a higher charge rate longer. Now it starts tapering sooner even when the pack is warm. Could this be charger-side variation, battery temperature, software, or an actual battery-health issue? Appreciate any ideas on what to check first.
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3 replies

BoxerRoadie58Community StarterCommunity StarterJul 23, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 2023 Rivian R1T, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. That's where I'd start. On “fast charging slows down earlier than it,” that was the fork that mattered for me. Do that first. Climate here is different, so treat that as a local data point. Not interested in a five-hour wait for a shrug.
TrackWeekend48Community StarterCommunity StarterJul 25, 2026permalink
Same neighborhood, different next step: Leave the alerts on the 2023 Rivian R1T so service can see what you saw. That's where I'd start. Not gospel, but it saved me a headache. I'd rather be boring and correct. I'll poke at it this weekend.
RoadEnthusiastCommunity StarterCommunity StarterJul 23, 2026permalink
Tried a second charger / second scan and the story on the 2023 Rivian R1T didn't change. Not interested in a five-hour wait for a shrug.
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