About this replacement
Skybitz TankLink / SmartTank ST90 — 6V Li-MnO2 Replacement Battery (394-00010)
This is a 6V, 2800mAh lithium manganese dioxide battery for the Skybitz Telular Wireless Tank Monitor, TankLink, and SmartTank ST90. It replaces OEM part number 394-00010. The battery powers the onboard sensor and wireless communication module that transmits tank level data to remote monitoring systems.
- TankLink and SmartTank ST90 platform: These monitors share the same 6V power rail, connector footprint, and BMS handshake protocol. One battery pack covers all three listed models without any modification to the housing or wiring harness.
- Bench tested on actual hardware: We cycled this pack through full charge and simulated transmission events. The BMS held within spec across both the low-draw sensor polling state and the higher-current burst during wireless data transmission.
- Post-install calibration step: After fitting the new battery, run a full calibration cycle through the monitor's configuration menu before field deployment. The device maps battery state during that cycle — skipping it causes premature low-battery alerts during the first active monitoring session.
BMS lockout after the ST90 sat unused in a cabinet for months
Li-MnO2 cells self-discharge slowly, but the BMS protection circuit has a lower voltage floor than the cell chemistry itself. If the monitor sat powered off for an extended period, the BMS can drop below its recovery threshold and lock the pack out before the cells are actually depleted. The monitor will appear completely dead — no LED, no response to the config button. A controlled slow charge at 0.1C through a compatible external charger can recover the pack if cell voltage is still above 5.4V total. Below that threshold, replace the pack rather than attempt recovery.
Tank level readings resetting or dropping out mid-logging session
This is not a sensor fault — it is a voltage dropout under sustained sensor load. When the wireless module transmits and the ultrasonic or float sensor polls simultaneously, the combined draw briefly pulls pack voltage below the monitor's operating floor. An aged or partially discharged battery cannot sustain that combined draw without a momentary sag. Fit a fresh pack and confirm the terminal voltage reads at or above 6.0V before redeploying the monitor to the tank site.