Nintendo Switch HAC-003 Replacement Battery 3.7V 3600mAh

Nintendo Switch HAC-S-JP/EU-C0 — 3.7V Li-Polymer Replacement Battery (HAC-003)

This 3.7V, 3600mAh lithium-polymer cell replaces the original internal battery in the Nintendo Switch console (HAC-S-JP/EU-C0 and HAC-001). It fits directly into the main body of the console beneath the kickstand. Voltage and capacity match the OEM spec — HAC-003, HAC-A-BPHAT-C0, HAC-A-BPHAT-C1, and HAC-A-BPHAT-C2 are all covered.

• HAC-S-JP/EU-C0 and HAC-001 compatibility: Both Switch variants use the same battery bay dimensions, connector pinout, and BMS handshake protocol. The fuel gauge IC on the mainboard reads cell chemistry and voltage curve — this cell's Li-Polymer discharge profile matches what the IC expects, so the charge controller does not reject it.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a HAC-001 unit. The BMS accepted the cell without fault flags, the charge IC stepped through trickle, constant-current, and constant-voltage phases normally, and the fuel gauge read a stable state-of-charge across the full voltage range.
• First-cycle calibration on the Switch: After installation, run one complete portable play session until the console shuts itself off automatically — do not interrupt it by docking. The fuel gauge IC uses that first full discharge to set its empty-voltage reference point against the new cell's actual curve. Skipping this step causes the percentage to jump or drop unexpectedly in the first week.

Fuel gauge jumping after a Switch battery swap

The Nintendo Switch uses a coulomb-counting fuel gauge IC that tracks charge by integrating current in and out of the cell. When the original cell ages, the IC recalibrates its full and empty reference points to match the degraded capacity. Installing a fresh 3600mAh cell resets the actual capacity, but the IC's stored reference points still reflect the old cell. This mismatch causes the displayed percentage to jump — sometimes 20–30 points — mid-session. One full discharge cycle to automatic cutoff forces the IC to rewrite its empty-voltage reference, and two to three additional cycles bring the full-charge reference in line.

Switch not charging the replacement cell at the expected rate

The Switch charge controller applies a conservative current limit when it first sees a cell it has not profiled before — this is a protection behaviour, not a fault. On a new cell, it may hold to a lower constant-current phase longer than you expect before stepping up. This clears after the first full charge-discharge cycle, once the controller has logged the cell's internal resistance and voltage response. If the rate does not normalise after one full cycle, check that the USB-C port and cable are delivering at least 5V 1.5A — underpowered adapters keep the controller in low-rate mode regardless of cell state.