Alternator & ChargingDIYCommunity Starter

2023 Rivian R1T — fast charging tapers earlier than it used to — second opinion before I spend money

V8ScoutCommunity StarterMay 10, 20262023 Rivian R1T Quad-MotorLas Vegas
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.
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8 replies

ShopBuilder989Community StarterCommunity StarterMay 10, 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. I'd do that before spending real money. 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. I'll poke at it this weekend.
UsedCarCommuter769Community StarterCommunity StarterMay 10, 2026permalink
That's a good start, but I wouldn't stop there. Try a second charger before blaming the 2023 Rivian R1T — site sharing and pack temp change the curve a lot. That's where I'd start. Any freeze-frame data saved? That's my plan before I call anyone.
MarketBuyer633Community StarterCommunity StarterMay 12, 2026permalink
Quick add on that: Leave the alerts on the 2023 Rivian R1T so service can see what you saw. That's where I'd start. That's the sequence I'd use. If this is nothing, great. I want that in data.
TrackDriver444Community StarterCommunity StarterMay 10, 2026permalink
Agree — and I'd add this: Leave the alerts on the 2023 Rivian R1T so service can see what you saw. I'd do that before spending real money. Do that first. If it repeats twice more I'll book time.
HighwayDIYerCommunity StarterCommunity StarterMay 11, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2023 Rivian R1T charge sessions. That's where I'd start. Have you gotten a second quote in writing? Only after sitting overnight so far.
HighwayDIYerCommunity StarterCommunity StarterMay 11, 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. I'd do that before spending real money. On “fast charging tapers earlier than it used,” that was the fork that mattered for me. This is from a 2023 Rivian R1T in Las Vegas. Did the worksheet show tax yet? Trying not to diagnose from the couch.
UsedCarCommuter769Community StarterCommunity StarterMay 11, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 2023 Rivian R1T — site sharing and pack temp change the curve a lot. Then you'll know the next fork. Was this after sitting overnight? Your commute and mine probably aren't the same, but the test still applies. I'm keeping receipts and dates in one folder.
DailyTraveler76Community StarterCommunity StarterMay 11, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2023 Rivian R1T charge sessions. I'd do that before spending real money. I'd want that in writing, not as a promise. That's my plan before I call anyone.
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