Telstra Essential Smart 3 Replacement Battery 3.8V 2400mAh

Telstra Essential Smart 3 — 3.8V Li-ion Replacement Battery

This 3.8V Li-ion battery replaces the factory cell in the Telstra Essential Smart 3 smartphone. It delivers 2400mAh (9.12Wh) of capacity to restore calling, messaging, and app functions. Fit this battery when the original cell no longer holds a usable charge between top-ups.

• Essential Smart 3 fitment: The cell measures 69.75 × 58.80 × 4.65mm and matches the contact layout the Essential Smart 3 motherboard expects. The BMS handshake matches the charge IC so the device accepts the cell without throwing a fault.
• Bench tested on actual hardware: We cycled this cell through a full discharge-charge sequence and monitored BMS cutoff behaviour. The protection circuit held the low-voltage cutoff correctly and charge termination fired at the expected threshold without overrun.
• Fuel gauge recalibration tip: On first use after installation, run one full discharge down to automatic shutdown, then charge uninterrupted to 100% before using the phone again. This lets the coulomb counter reset its reference curve against the new cell — skipping this step is the primary cause of erratic percentage readings after a cell swap.

Sudden shutdown at 20–30% on the Essential Smart 3 after a cell swap

A new Li-ion cell has a discharge curve the phone's fuel gauge IC has never seen. The IC still uses the old cell's reference data, so it misjudges how much voltage headroom remains. Under modem or screen load, the cell voltage drops sharply — the hardware protection circuit fires before the OS can warn the user. One full discharge-charge cycle writes a new baseline to the coulomb counter and eliminates most of these early shutdowns. If shutdowns persist past two full cycles, check that the battery connector is fully seated — a partial connection raises contact resistance and causes the same voltage sag under load.

Phone won't power on after the replacement battery sat in storage

Li-ion cells self-discharge in storage, and a cell that drops below approximately 2.5V triggers BMS lockout — the protection circuit opens and blocks current flow to prevent cell damage. Plugging in the charger may show no response at all on the screen. Connect the phone to a wall charger (not USB from a PC) and leave it for 20–30 minutes without pressing the power button — the charge IC trickle-charges the cell back above the BMS re-enable threshold, typically around 2.9–3.0V, before switching to normal charge current. Once the charge LED activates or the boot screen appears, the BMS has reset and normal charging can continue.