Arjo Maxi-Sky 440 Replacement Battery 12V 2300mAh SLA

Arjo Maxi-Sky 440 / Maxi-Sky 400 — 12V Sealed Lead Acid Replacement Battery

This is a 12V, 2300mAh (27.6Wh) sealed lead acid battery for the Arjo Maxi-Sky 440 and Maxi-Sky 400 patient lift systems. These motorised overhead lifts use this battery to power the lifting mechanism that raises and lowers patients during transfer. When the original cell degrades, the lift loses lift power or fails to complete its startup sequence.

• Maxi-Sky 440 and 400 compatibility: Both models share the same 12V battery rail and connector format. The BMS in each lift expects the same sealed lead acid chemistry for voltage curve recognition — substituting a lithium cell will cause a persistent battery fault regardless of charge state.
• Bench tested on actual hardware: We ran this cell through the Maxi-Sky lift cycle under load. The BMS accepted the cell without fault codes, and the charge controller stepped through its standard absorption and float stages correctly.
• Post-installation self-test protocol: After fitting this battery, allow the lift to complete its full power-on self-test without interrupting the sequence. The Maxi-Sky BMS runs a verification check at startup — cutting power mid-sequence registers a false battery fault that persists until the next clean reboot.

Why the Maxi-Sky 440 shows a battery fault on a freshly installed cell

The Maxi-Sky lift controller checks the battery voltage curve during startup against thresholds set for a conditioned cell. A brand-new sealed lead acid battery sitting at resting voltage after shipping may read below that threshold before its first full charge cycle. The BMS flags this as a fault rather than treating it as a new cell. Run one complete charge-discharge cycle before placing the unit into clinical service — this allows the BMS to map the actual capacity curve of the new cell.

Lift powers on but cuts out mid-raise on the first few uses

Sealed lead acid cells deliver lower peak current in the first several cycles as the plate chemistry activates fully. The Maxi-Sky motor draw during a raise cycle is the highest load the battery sees, and the BMS trips on voltage sag if the cell hasn't stabilised yet. This is not a faulty battery — it resolves after approximately 10 full charge-discharge cycles. Confirm charger output is sitting at or above 13.5V during the absorption phase before ruling out a charger issue.