MyPhone HAMMER 3.7V 1700mAh Compatible Battery

MyPhone HAMMER — 3.7V Li-ion Replacement Battery (HAMMER)

This is a 3.7V, 1700mAh Li-ion replacement battery for the MyPhone HAMMER smartphone. It fits directly into the HAMMER handset and restores full power to calling, messaging, and app functions. Replace a degraded or failed original cell without swapping the entire phone.

• MyPhone HAMMER fit: The HAMMER battery slot uses a fixed connector pinout tied to this voltage rail. This cell matches that connector layout, cell dimensions (52.45 × 36.00 × 10.40mm), and the BMS handshake the phone expects on power-up.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS engaged correctly at both low-voltage cutoff and charge termination, with no false capacity readings on first power-on.
• Fuel gauge recalibration on first use: After installing this cell, disable fast charging and run one full discharge-to-charge cycle before normal use. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before high-current charging begins on an uncalibrated reference.

Sudden shutdown at 20–30% on the MyPhone HAMMER after a cell swap

This is a voltage cliff, not a capacity fault. The HAMMER's modem and screen draw a combined current spike that the new cell can't sustain if its internal resistance hasn't settled after installation. When cell voltage dips below the BMS cutoff threshold under that load — even briefly — the phone shuts down despite showing remaining percentage. The fuel gauge IC is still reading the old cell's curve, so the percentage displayed doesn't match the actual voltage. One full discharge-charge cycle resets that reference and moves the reported cutoff to the correct voltage floor.

MyPhone HAMMER not powering on after the replacement battery sat in storage

Li-ion cells self-discharge in storage. If this battery sat below 2.5V per cell before installation, the BMS enters lockout mode and blocks current flow to protect the cell from damage. The phone will show no response — no boot screen, no charge indicator. Connect the phone to a wall charger and leave it undisturbed for 15–30 minutes; the charge IC on the phone will trickle current into the cell until voltage rises above the BMS recovery threshold, typically around 2.9V, at which point normal charging resumes.