LFP Blade Battery Calibration Guide: Why & How to Run the <10% to 100% AC Balance Charge Every 3 Months
-
One of the biggest misconceptions from people coming over from NMC (Nickel Manganese Cobalt) EVs is thinking "I should only ever charge my BYD between 20% and 80%".
Do NOT do that on a BYD LFP (Lithium Iron Phosphate) Blade Battery! Here is the engineering reason why, and the exact calibration procedure recommended for all BYD EVs and DM-i PHEVs.
Why LFP Needs 100% Top-Balancing
An LFP cell has an extremely flat voltage curve between 15% and 95% SOC — sitting almost unchanged around
3.28V – 3.33V. Because of that flat curve, the Battery Management System (BMS) relies on coulomb counting (measuring amps in/out) to estimate your dashboard percentage.- Over weeks of partial 30% → 70% top-ups, small coulomb-counting drift accumulates (up to 8–12% error!).
- It is only when the cells reach the steep upper "knee" of the LFP voltage curve at
3.60V – 3.65Vper cell (99%–100% SOC) that the BMS can reset its 100% reference point and activate the passive bleed resistors to balance all cells evenly.
The Official 2-Part LFP Calibration Procedure
- Weekly Routine: Charge your BYD to 100% on AC at least once a week (and leave it plugged in for 30–45 minutes after hitting 100% until the wallbox reports
0.0 kWso cell balancing finishes). - Every 3 Months (Deep Calibration): Drive the car down to 7%–9% SOC, let it sit parked for 30 minutes so cell voltages settle, and then do a continuous 7kW / 11kW AC charge all the way to 100% until the charger automatically stops.
-
-
Spot on explanation! I used to only charge my Seal Dynamic to 80% for the first two months in Canberra because a mate with a Model 3 LR told me to. One cold morning my car dropped from 18% to 4% in 10 km because the BMS had drifted! Did the 8% → 100% AC calibration charge overnight and the gauge has been rock-solid down to 5% ever since.
-
Watching the cell voltages in CarScanner Pro during the final 98% → 100% phase is fascinating. At 98%, my Atto 3 sits around
3.42Vper cell; in the last 15 minutes of AC charging, the highest cell hits3.62V, the BMS drops charge current to1.8 kW, pulls the lagging cells up within0.005V, and then clicks the contactor off. -
Does this also apply to the 18.3 kWh / 29.58 kWh Blade Battery in the Sealion 6, Seal U DM-i, and Shark 6 PHEVs?
-
Yes! Since PHEV owners often run between 25% and 70% in HEV mode on long trips, plugging your Sealion 6 or Shark 6 into a home AC socket/wallbox to hit 100% SOC at least once a week keeps the DMO/DM-i BMS perfectly calibrated.
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login