Yeacomm Z2200B Replacement Battery 3.7V 3350mAh Li-ion

Yeacomm P21 4G — 3.7V Li-ion Replacement Battery (Z2200B)

This 3.7V 3350mAh Li-ion battery replaces the OEM Z2200B cell in the Yeacomm P21 4G portable mobile hotspot. The P21 4G runs a combined 4G LTE modem and dual-band Wi-Fi radio simultaneously, which puts steady current demand on the battery throughout every session. Swap this in when the original cell no longer holds a charge or the device shuts down before expected.

• P21 4G platform fit: The Z2200B cell is specific to the P21 4G form factor — the connector pin-out and BMS data lines match the hotspot's charge controller directly. No adapters required.
• Bench tested on actual hardware: We ran this cell under a simulated multi-device load — modem active, Wi-Fi broadcasting — and monitored BMS cutoff thresholds. The protection circuit tripped correctly at the low-voltage floor without false shutdowns under sustained draw.
• Ventilation during extended sessions: Keep the P21 4G on a hard, open surface during long sessions. When connected devices are far from the hotspot, the cellular radio runs at full transmit power. That extra heat sits in the battery cavity and accelerates cell wear over time.

Why the P21 4G drops all connected clients mid-session

The P21 4G runs its LTE modem and Wi-Fi radio from the same battery rail. When several devices are active at once, peak current draw spikes sharply — especially during file transfers or video streaming. If the battery cell has degraded internal resistance, voltage on that rail dips enough to trigger the BMS under-voltage cutoff, and the unit restarts. A fresh cell with lower internal resistance holds the voltage rail stable through those peaks and prevents the cutoff from firing.

P21 4G won't power on after sitting unused

Li-ion cells self-discharge slowly during storage. If the P21 4G was left without charging for several weeks or months, the battery voltage may have dropped below the minimum boot threshold — typically around 3.0V per cell. The device's charge controller may refuse to start a charge cycle at that point, making the unit appear completely dead. Connect the hotspot to a wall charger — not a USB port — and leave it for 20–30 minutes before attempting to power on. If the original cell has dropped below recovery voltage, replacing it with this Z2200B cell will restore normal boot behaviour immediately.