About this replacement
Xiaomi Electric Scooter 4 Ultra — 46.8V Li-ion Replacement Battery (P2301-BD5A)
This is a 46.8V, 12750mAh (596.7Wh) Li-ion battery replacing OEM part P2301-BD5A. It fits the Xiaomi Electric Scooter 4 Ultra (P2301) and the Pro and Pro 2 Electric Scooter models. Same voltage rail, same connector, same BMS communication protocol as the factory pack.
- 4 Ultra, Pro, and Pro 2 compatibility: These models share the same 46.8V battery architecture, connector pinout, and BMS handshake sequence. Swapping between them does not require firmware changes or adapter cables.
- Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on the 4 Ultra platform. The BMS communicated correctly with the scooter controller — charge acceptance, cell balancing, and protection cutoffs all operated within spec.
- Cold-start charging protocol: After any period of storage in temperatures below 10°C, use the standard Xiaomi charger at a low state of charge rather than a fast charger. Cold Li-ion cells carry higher internal resistance, and pushing current into them before they warm up causes lithium plating on the anode that permanently cuts capacity.
BMS cutting out during hill start on the 4 Ultra
Hill starts pull peak current from the battery in under a second. On the 4 Ultra, this surge can hit 25–30A depending on rider weight and incline angle. If the battery is below roughly 30% state of charge, internal resistance rises enough that the voltage sag triggers the BMS over-current protection, cutting motor output instantly. The fix is straightforward: start the hill with the battery above 50% charge, and push off with your foot to reduce the initial current draw before the motor takes the full load.
Charger shows no activity after the scooter sat unused for months
Li-ion packs in storage self-discharge slowly. If cell voltage drops below approximately 2.5V per cell, the BMS enters a deep-discharge lockout state and the charger's LED shows nothing — no charge accepted, no response. To recover the pack, leave the charger connected for 20–30 minutes without interruption. Most BMS units on this platform will re-initialise once the trickle circuit pushes cells back above the acceptance threshold, typically around 2.8V per cell, at which point normal charging resumes.