EVs & Mobility 3 min read

Rivian Gen 2 R1T LFP BMS Calibration Issue: Why You Need to Charge to 100%

Rivian Gen 2 LFP owners are facing BMS calibration issues. Learn why charging to 100% is the fix and how to maintain accurate range estimates.

Rivian R1T LFP Battery BMS Calibration software update charging tips EV maintenance EV
Rivian Gen 2 R1T LFP BMS Calibration Issue: Why You Need to Charge to 100%

If you own a Gen 2 Rivian R1T with the Dual Standard LFP (Lithium Iron Phosphate) battery, you might have recently received a notification—or a shock—regarding your battery’s range. Following the 2025.38.30 software update, reports have surfaced of vehicles displaying inaccurate State of Charge (SOC) readings, leading to unexpected shutdowns even when the dash shows usable range.

This isn’t a battery failure; it’s a calibration issue. And the fix requires a change in habits for many EV owners: charging to 100%.

The Issue: “Ghost” Range and Unexpected Shutdowns

Owners of the Gen 2 Dual Standard pack have reported that after the 2025.38.30 update, their vehicles’ BMS (Battery Management System) seemed to lose track of the actual energy remaining in the pack.

  • Symptoms: The vehicle might display 20% or 30% charge remaining, only to suddenly drop to 0% or shut down completely.
  • Cause: The BMS is “drifting” in its estimation of the battery’s true capacity.

This happens because of the unique chemistry of LFP batteries.

Why LFP Batteries Are Different

Most EVs in the US use NMC (Nickel Manganese Cobalt) batteries. These batteries have a voltage curve that drops steadily as the battery discharges. It’s easy for the BMS to look at the voltage (e.g., 3.7V) and know exactly how much charge is left (e.g., 50%).

LFP batteries, however, have a very flat voltage curve. The voltage remains almost constant from 80% down to 20%. This makes it incredibly difficult for the BMS to estimate the State of Charge based on voltage alone. It has to rely on “coulomb counting”—measuring exactly how much energy goes in and out. Over time, small measurement errors add up, and the BMS “drifts,” losing track of the true 0% and 100% points.

The Fix: Charge to 100%

To fix this drift, the BMS needs a known reference point. For LFP batteries, that reference point is 100% charge.

Rivian’s updated guidance and the 2025.38.30 update emphasize this:

“Charge your vehicle to 100% at least once every two weeks or every 500 miles.”

When you charge to 100%, the voltage finally spikes, giving the BMS a clear “reset” signal. It knows exactly where the top is, and it can then accurately calculate the rest of the discharge curve.

What You Should Do

  1. Update Software: Ensure you are on version 2025.38.30 or later.
  2. Charge to 100% Immediately: If you haven’t done so recently, charge your truck to 100% as soon as possible.
  3. Repeat if Necessary: If you have experienced major jumps in SOC, you may need to charge to 100% multiple times (discharge a bit, then charge back to 100%) to help the BMS relearn the full capacity.
  4. Set a Routine: Don’t be afraid of 100%. Unlike NMC batteries, LFP batteries love being charged to 100% and do not suffer significant degradation from it. In fact, they degrade more if you don’t calibrate them regularly because the cells can become unbalanced.

Summary

This “issue” is actually a characteristic of the robust LFP chemistry. While the symptoms can be alarming, the solution is simple. Treat your Standard Pack R1T differently than an NMC vehicle: Top it off regularly.