About this replacement
Pentair Mobiltouch 2 — 7.4V Li-Polymer Replacement Battery (520815Z)
This 7.4V, 2200mAh lithium-polymer battery replaces OEM part 520815Z in the Pentair Mobiltouch 2 handheld wireless controller. It also fits the IntelliTouch Control System and MobileTouch II Wireless Controller. The remote uses this cell to send commands to pumps, heaters, and lighting across the pool automation network.
- Mobiltouch 2 / MobileTouch II platform fit: These models share the same 7.4V two-cell Li-Polymer pack, connector pinout, and BMS communication protocol. One battery part number covers all three listed controllers because the power architecture is identical across the IntelliTouch wireless controller family.
- Bench tested on actual hardware: We cycled this pack through charge and discharge on the bench and confirmed the BMS reported state-of-charge correctly to the controller firmware, with no voltage cutoff triggering under normal polling loads.
- Re-join delay after swap: After fitting this battery, hold off on testing for at least 60 seconds. The Mobiltouch 2 runs a mesh network re-join sequence on every power cycle — commands sent before that sequence completes will not reach the IntelliTouch system.
Why the Mobiltouch 2 goes offline immediately after a battery swap
Cutting power to the remote clears its active session with the IntelliTouch receiver. When the new battery is installed, the controller broadcasts a re-join request and waits for acknowledgement from the base system. This handshake takes up to 60 seconds under normal RF conditions. If you press buttons before it completes, the controller silently drops the command — the display may look active, but nothing reaches the pump or heater.
Low battery alert showing immediately after fitting a new cell
A brand-new replacement cell that has been in storage for several months can sit at 3.5–3.7V per cell — below the alert threshold the Mobiltouch 2 firmware checks on boot. The controller reads open-circuit voltage before the pack settles and flags it as low. Plug the remote into its dock charger and allow a full charge cycle before use. Once the pack reaches 4.2V per cell, the alert clears and does not return.