wake up lithium battery

If your LiFePO4 has “gone to sleep”, the BMS has likely cut off due to low voltage or protection. Use a proper LiFePO4 charger with a wake/force-charge mode and let it raise the voltage gently. No such charger? A bench supply set to about 13.8–14.2 V with a low current limit (0.5–2 A) can nudge it awake; stop if it won’t take current. Avoid trickle/“desulfate” modes and do not jump it from a running car, unless you enjoy buying a new BMS.

Check for a reset button or app toggle, and only charge above 0°C. If pack voltage is under ~10 V (or any cell under ~2.5 V), stop and get it inspected. Once it wakes, finish with a full balance charge and fix the cause—parasitic draw, wrong charger, or sheer neglect. Yes, it’s a diva; read the manual and it’ll behave.