About this replacement
Yeacomm P21 4G — 3.7V Li-ion Replacement Battery (Z2200B)
This is a 3.7V 2600mAh (9.62Wh) lithium-ion battery for the Yeacomm P21 4G mobile hotspot. It replaces part number Z2200B and fits the P21 4G directly. If your hotspot is shutting down early or no longer holding a charge, this is the battery to replace.
- P21 4G compatibility: The P21 4G runs a combined 4G modem and Wi-Fi radio off a single cell. The Z2200B matches the voltage rail and connector pinout that the device's BMS expects — no adapter or modification needed.
- Bench tested on actual hardware: We ran this cell under simultaneous modem and Wi-Fi load at maximum connected clients. The BMS held a stable discharge curve without triggering an early low-voltage cutoff.
- Ventilation during extended sessions: Keep the P21 4G in an open, unobstructed spot during long hotspot sessions. When connected devices are far from the hotspot, the cellular radio pushes to maximum transmit power — that heat transfers directly into the battery cell and accelerates capacity wear over time.
Mobile hotspot disconnecting users mid-session on a new battery
The P21 4G drives both a 4G modem and a Wi-Fi radio from a single 3.7V cell. At maximum client connections, the combined current draw can cause a sharp voltage sag on a degraded or under-spec cell. The BMS interprets that sag as a low-battery event and triggers a protective cutoff — even if the percentage indicator still shows charge remaining. A cell matched to Z2200B's rated capacity handles the combined load without the sag hitting the cutoff threshold.
P21 4G won't power on after sitting unused for weeks
Li-ion cells self-discharge slowly in storage. If the P21 4G sat unused long enough, the battery may have dropped below the minimum boot voltage — typically around 3.0V for this cell chemistry. At that level, the device's protection circuit blocks power-on to prevent damage, so the hotspot appears completely dead. Plug into the original charger and leave it for 20–30 minutes before attempting to power on; the circuit needs to see enough voltage to re-enable the output before the device will respond.