About this replacement
MYO Gesture Control Armband — 3.7V Li-Polymer Replacement Battery (571830)
This is a 3.7V 220mAh Li-Polymer replacement battery for the MYO Gesture Control Armband. It fits the original armband hardware and restores power to the onboard motion sensors and wireless transmitter. Voltage and physical dimensions match the OEM cell exactly: 31.50 × 17.00 × 5.50mm.
- MYO Gesture Control Armband fitment: The armband uses a compact Li-Polymer cell to power eight EMG sensors, a 9-axis IMU, and a Bluetooth radio simultaneously. Voltage and connector orientation must match the OEM spec — this cell meets both requirements.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the BMS-managed circuit. The protection IC responded correctly to charge cutoff at 4.2V and engaged undervoltage lockout at 3.0V with no anomalies.
- Connector re-seating on the MYO mainboard: The MYO armband uses a small ZH-series JST connector. Press it firmly until it clicks — a partial connection will show the LED cycling but the device will not pair or respond to gestures.
Why the MYO armband drops Bluetooth mid-session after a battery swap
The MYO's wireless radio draws a surge of current during Bluetooth reconnection attempts. If the replacement cell has a high internal resistance — common in counterfeit or improperly stored Li-Polymer cells — voltage sags below the radio's operating floor during that surge. The BMS then cuts output to protect the cell, and the armband appears to disconnect randomly. A cell with correct internal resistance holds voltage stable through those peaks.
Armband LEDs flash but gesture recognition stops working after replacement
This symptom points to the IMU and EMG sensors losing consistent power rather than the radio failing. The sensors require a stable 3.7V rail — if the new cell's connector is not fully seated, resistance at the contact raises effective voltage drop under sensor load. Remove the battery, inspect the connector pins for debris, re-seat firmly, and confirm the armband holds pairing through a full gesture sequence. If the issue persists, check resting cell voltage with a multimeter — it should read above 3.7V before first use.