Battery and efficiency

Why is Roamer's efficiency different from my vehicle's?

Rivian doesn't share how much energy a drive used. Roamer works it out from the battery percentage and the battery's usable capacity during the drive, and the distance on your odometer. That includes climate and anything plugged into the outlets, minus what regenerative braking put back.

The two numbers differ for a few reasons:

• Your vehicle has its own energy meter, and Rivian doesn't share it with apps. Roamer sees the battery percentage, which moves in 0.1% steps of about a tenth of a kWh. On a short drive, one step is a big share of the total.
• The battery re-estimates its charge. Its estimate of usable energy changes as it warms or cools, and a cold battery reports less.
• They cover different stretches. Your vehicle's trip figures don't start and stop where a Roamer drive does.

A long drive or a week of driving gives a fairer comparison. Efficiency is left blank for drives under half a mile, drives that used too little energy to measure, and drives that came out too high to be real. Imported drives keep the efficiency the other app recorded.

Does lower capacity mean battery degradation?

Not by itself. Roamer shows the usable energy your vehicle reports, and that dips in cold weather.

On the Battery page, the buffer line marks your pack's reserve. While capacity is above the line, wear comes out of that reserve and your range doesn't drop. If capacity stays below the line, your full-charge range drops.

Why is my battery size wrong?

Roamer works out your pack from what Rivian reports. If it got it wrong, open your vehicle's Settings and pick the right size under Battery → Size. The list has only the sizes your vehicle can have. This needs Roamer Plus. If your size isn't listed, email support@rivianroamer.com.

Rivian built some Gen 1 packs as a bigger pack and locked them in software to the size it sold. The battery cells Rivian reports show which ones, and Roamer names them by the size you bought, such as "Large (locked Max pack)". Keep the size you bought. Your vehicle charges, rates its range and keeps its buffer as that size. Its capacity reads a few kWh below an unlocked pack of the bigger size, and that gap isn't wear.

How is phantom drain measured?

Phantom drain, which some people call vampire drain, is the charge your battery loses while parked. With Roamer Plus, the Battery page follows your battery from when you park to your next drive or charge, and shows the loss as a percent per 24 hours parked. It leaves out energy used for climate, such as preconditioning, and the hours an R1's Camping energy setting keeps the R1 awake on Stay On. Each day's loss is charted in three parts: Gear Guard, awake and asleep.

The battery's estimate also shifts with temperature and as the battery recalibrates, so it can rise for a while after a hard drive. Checking Roamer doesn't add to the drain.

How is range rounded?

Every Rivian, R1 and R2, sends range in whole kilometers. Your current range in miles is rounded down to a whole mile, the way the Rivian app does it. Kilometers show as Rivian sent them. What Rivian sends for each model has the rest of the differences.

Why is pack temperature missing?

Gen 2 R1s, from the 2025 model year on, don't report a real pack temperature, so Roamer leaves it out for them rather than show a wrong number. Gen 1 R1s and R2s report it.