Intro: You charged your battery to 100%. You went camping. You plugged in a phone charger, and poof—the screen dropped to 0% and the unit died. This is called “SOC Drift” (State of Charge Drift). It is extremely common in LFP (LiFePO4) batteries because their voltage curve is so flat that the computer gets confused about how much power is left. Here is the fix.
Proper calibration keeps your camping trips safe. See our CPAP Camping Guide for more critical reliability tips.
The “0% to 100%” Calibration Cycle
You must teach the computer where “Empty” and “Full” are. Do this once every 3 months.
Step 1: The Full Drain
- Plug in a steady load (like a lamp or fan).
- Run the battery until it hits 0% and turns off.
- Crucial: Turn it back on. If it still has power, run it until it dies again. You want it dead-dead.
- Note: Let it cool down for 1 hour.
Step 2: The Uninterrupted Charge
- Plug it into the wall (AC charging is more stable than solar).
- Charge it to 100%.
- Do not unplug it yet. Leave it plugged in for 2 extra hours after it hits 100%. This allows the cells to “balance” (top-balance).
Step 3: Verification
- Unplug and use it. The percentage should now drop linearly (99%, 98%, 97%) instead of jumping.
Why Does This Happen?
LFP batteries maintain the same voltage (approx 13.2V) from 80% down to 20%. The computer is basically guessing the percentage based on math. If you never drain it fully, the math gets “drifted” over time.
Summary Table: When to Calibrate?
Symptom Solution Battery jumps from 30% to 0% Calibrate ASAP Battery stays at 99% for hours Calibrate ASAP New Firmware Update Installed Recommended