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2023 Rivian R1T — fast charging tapers earlier than it used to — Connecticut owner

RustBeltGarageCommunity StarterJul 4, 20262023 Rivian R1T Quad-MotorConnecticut
2023 Rivian R1T Quad-Motor, about 5,500 miles. On comparable road trips the charge rate now starts tapering sooner. I am trying to separate charger sharing, battery temperature, software changes and actual battery health. I am in Connecticut. What would you check next?
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12 replies

TrackPilot512Community StarterCommunity StarterJul 4, 2026permalink
Log the conditions before you spend. Move a coil or plug on the 2023 Rivian R1T if it's cylinder-specific and see whether the code follows. Don't erase codes until someone who can help has seen them. On “fast charging tapers earlier than it used,” that was the fork that mattered for me. Any freeze-frame data saved? I'd rather pay for diagnosis than a second guess-repair.
TowEnthusiast182Community StarterCommunity StarterJul 4, 2026permalink
Start with the test that can prove you wrong. Move a coil or plug on the 2023 Rivian R1T if it's cylinder-specific and see whether the code follows. If the cheap test changes it, stop and reassess. That's the whole play. Happens in gear, not in park, for what that's worth.
RoadTraveler327Community StarterCommunity StarterJul 4, 2026permalink
If it were in my driveway, write temp, speed, and in-gear vs coast when the 2023 Rivian R1T does it — then decide on parts. Don't erase codes until someone who can help has seen them. A shop burned me once by skipping that step. If the story changes I'll post the new data.
V8Nerd850Community StarterCommunity StarterJul 5, 2026permalink
Ask what changed right before it started. Two 2023 Rivian R1Ts can feel identical and have different causes, so measure before you copy someone else's repair. That's the branch I'd chase this week. Not gospel, but it saved me a headache. Trying not to diagnose from the couch.
QuietGeek9Community StarterCommunity StarterJul 5, 2026permalink
Intermittent stuff lies if you only catch it once. Capture voltage while the 2023 Rivian R1T is actually failing — after it restarts you've lost the clue. If the cheap test changes it, stop and reassess. On “fast charging tapers earlier than it used,” that was the fork that mattered for me. Verbal 'we'll take care of it' is not a plan. Climate here is different, so treat that as a local data point. Next check is the cheap one I can do in a driveway.
DealTuner471Community StarterCommunity StarterJul 6, 2026permalink
Agree — and I'd add this: Move a coil or plug on the 2023 Rivian R1T if it's cylinder-specific and see whether the code follows. Save the big job until that test fails. On “fast charging tapers earlier than it used,” that was the fork that mattered for me. This is from a 2023 Rivian R1T in Connecticut with 5,500 miles. Run the total, not the monthly, before you commit. Climate here is different, so treat that as a local data point. Video is ugly but it shows the hesitation.
TowTunerCommunity StarterCommunity StarterJul 5, 2026permalink
I wouldn't throw parts yet. Two 2023 Rivian R1Ts can feel identical and have different causes, so measure before you copy someone else's repair. If the cheap test changes it, stop and reassess. Verbal 'we'll take care of it' is not a plan. I've seen both outcomes, which is why I'd test instead of assume. If it repeats twice more I'll book time.
FlatSixMechanicish898Community StarterCommunity StarterJul 5, 2026permalink
I'd want a measurement, not a hunch. Loaded-suspension checks on the 2023 Rivian R1T catch play that a wheels-hanging inspection misses. Don't erase codes until someone who can help has seen them. Verbal 'we'll take care of it' is not a plan. Not interested in a five-hour wait for a shrug.
TrackPilot512Community StarterCommunity StarterJul 5, 2026permalink
I'd want a measurement, not a hunch. Swap the cheap/easy piece first on the 2023 Rivian R1T and see if the fault moves. If the cheap test changes it, stop and reassess. Any freeze-frame data saved? Not trying to scare you — just skip the expensive first guess. Not driving it hard until I know more.
RoadTraveler327Community StarterCommunity StarterJul 5, 2026permalink
This is usually cheaper to test than to guess. If a shop can't duplicate it on the 2023 Rivian R1T, bring a video plus freeze-frame data, not just a story. Don't erase codes until someone who can help has seen them. Learned this the expensive way on a previous car. That's coming from doing this as an owner, not a shop. If the story changes I'll post the new data.
DealTuner471Community StarterCommunity StarterJul 5, 2026permalink
This is usually cheaper to test than to guess. Write temp, speed, and in-gear vs coast when the 2023 Rivian R1T does it — then decide on parts. Don't erase codes until someone who can help has seen them. This is from a 2023 Rivian R1T in Connecticut with 5,500 miles. Run the total, not the monthly, before you commit. Heat soak after errands is the other window.
TrackPilot512Community StarterCommunity StarterJul 6, 2026permalink
I wouldn't throw parts yet. Get a real battery/charging test on the 2023 Rivian R1T, not just resting voltage, before blaming a module. You'll know quickly if you're on the wrong tree. When does it actually happen? Cold start is when I can actually reproduce it.
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