Nintendo Mario Kart Live HAC-038 Compatible Battery 3.7V 1750mAh

Nintendo Mario Kart Live Home Circuit — 3.7V Li-ion Replacement Battery (HAC-038)

This 3.7V 1750mAh Li-ion cell replaces the original battery in the Nintendo Mario Kart Live Home Circuit physical kart controller. The kart is the camera-equipped car unit that drives around your real floor while the game runs on a Nintendo Switch. Without a working cell, the kart won't move and the AR session can't start.

• Mario Kart Live Home Circuit kart compatibility: Both the Luigi and Mario kart units use the same HAC-038 cell with identical voltage rails and connector orientation. The BMS in each kart communicates charge state back to the Switch dock over USB-C, so the replacement cell must match the 3.7V nominal spec exactly — which this one does.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the kart's own BMS. The protection circuit triggered correctly at low-voltage cutoff, and the charge IC accepted the cell without flagging a fault on the Switch's charging screen.
• First-session calibration after swap: After fitting this cell, run one complete play session to automatic kart shutdown before recharging. The kart's fuel gauge IC sets its empty reference point against the first full discharge cycle — skipping this step causes the battery indicator on Switch to read inaccurately for several sessions.

Kart battery indicator jumping around after cell replacement

The fuel gauge IC inside the kart learns discharge behaviour by tracking voltage drop over time. A new cell has a slightly different discharge curve than the worn cell it replaced, so the IC's stored model no longer matches reality. The result is a percentage reading that jumps — often from 60% straight to 10% with no warning. Three to five full discharge-and-charge cycles let the IC recalibrate its curve to the new cell. After that, the indicator tracks correctly and low-battery warnings arrive at the right point.

Kart stops responding mid-race before battery indicator hits empty

The kart runs its camera, motors, and wireless radio simultaneously during a race. That combined draw creates short current spikes that push the cell voltage below the BMS cutoff threshold — even when the displayed percentage looks healthy. An aged or partially degraded cell hits this sag point earlier because its internal resistance has risen. A fresh cell at 3.7V nominal handles those spikes without tripping the BMS, so mid-race dropouts stop. If dropouts persist after fitting this cell, check that the connector is fully seated — a loose contact raises effective resistance and mimics a weak cell.