About this replacement
Zebra ET40 / ZT45 — 3.87V Li-Polymer Replacement Battery (BT-000456)
This 3.87V, 7500mAh lithium-polymer battery replaces the OEM pack in the Zebra ET40 and ZT45 enterprise tablets. These are ruggedized Android tablets used in retail, logistics, and field operations. Capacity is 29.03Wh — matching the original specification from Zebra's BT-000456 series.
- ET40 and ZT45 compatibility: Both devices share the same 3.87V cell architecture, connector pinout, and BMS communication protocol — a single pack covers both models without modification.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on an ET40 unit. The BMS handshake completed correctly, charge IC accepted the cell without error flags, and the device registered full capacity.
- Fuel gauge recalibration after swap: After installing this battery, run one full discharge to automatic shutoff, then charge uninterrupted to 100%. This resets the fuel gauge IC calibration against the new cell and clears the inaccurate percentage readings that typically appear in the first few cycles after a swap.
Why the ET40 shuts down at 15–25% after a battery swap
The ET40's fuel gauge IC stores calibration data from the previous cell. When a new pack is installed, the IC maps voltage curves from the old battery onto the new one. Under combined display and WiFi load, the voltage drops faster than the IC predicts at low charge levels. The firmware reads this as a critical threshold and triggers an emergency shutdown. One full discharge-to-shutoff cycle followed by an uninterrupted charge to 100% re-anchors the calibration to the new cell's actual voltage curve.
Fast charging not available after battery replacement on ET40
The ET40 uses a proprietary charge negotiation handshake between the charge IC and the battery's BMS. On a fresh cell, this handshake requires at least one full accepted charge cycle before the device unlocks higher charge rates. If fast charging is unavailable immediately after swap, charge the device fully using the original Zebra cradle or USB-C adapter — not a third-party charger. After one complete cycle, the charge IC confirms BMS compatibility and enables the full charge rate on subsequent sessions.