Nintendo Switch Joy-Con Replacement Battery HAC-006 3.7V 520mAh

Nintendo Switch Controller — 3.7V Li-ion Replacement Battery (HAC-006)

This 3.7V 520mAh Li-ion cell replaces the original battery in Nintendo Switch Joy-Con controllers. It fits the HAC-015, HAC-016, HAC-A-JCR-C0, and related Joy-Con variants. OEM part numbers HAC-006 and HAC-BPJPA-C0 both cross-reference to this cell.

• Joy-Con HAC-015 and HAC-016 compatibility: Both left and right Joy-Con units share the same battery bay dimensions, voltage rail, and connector orientation. One cell spec covers both controllers — no separate left or right variant exists at the battery level.
• Bench tested on actual hardware: We cycled this cell through the Switch's charge IC and confirmed the BMS accepted the charge handshake without fault flags. Capacity reporting stabilised after the first full discharge cycle on the console.
• First-cycle calibration on Joy-Con: After installing, run one complete wireless play session to automatic cutoff before recharging. The Joy-Con fuel gauge IC sets its empty reference point against the first full discharge curve — skipping this step causes the battery indicator to jump or report inaccurately for weeks.

Joy-Con fuel gauge jumping after a cell swap

The Switch reads battery state through a fuel gauge IC inside the Joy-Con, not a simple voltage divider. When a new cell goes in, the IC still holds the discharge curve data from the old degraded cell. This mismatch causes the indicator to skip segments or report full charge when voltage is already dropping. One complete discharge-to-cutoff cycle overwrites the reference and realigns the gauge to the new cell's actual curve.

Controller disconnecting before the battery indicator hits empty

Joy-Cons draw combined load from the wireless radio, HD rumble motor, and IR camera simultaneously. Under that combined draw, cell voltage can sag below the BMS cutoff threshold before the fuel gauge registers low. This is a real-load voltage sag issue, not a pairing fault. If disconnects happen consistently during rumble-heavy games, check that the replacement cell is seated flat with no pressure on the connector — a partial connection raises internal resistance and worsens sag.