Why does your unit sometimes "hangs" at 99% during AC charging.

The battery percentage shoots up incredibly fast, but when it hits 99%, it suddenly seems to "hang" there for an unusually long time before finally clicking over to 100%. You'll even see the incoming AC wattage drop significantly on the app during this phase.

Don't worry, this isn't a display glitch, this is the internal BMS performing "top-balancing" on the LiFePO4 cells. It intentionally throttles the charging speed at the very end to carefully equalize the voltage across all individual internal cells.

If you ever see it stuck at 99%, don't unplug it thinking it's "close enough." Let it finish that final 1% to keep your battery health perfectly balanced over the long term.