TransLite VLED-BAT Replacement Battery 3.7V 1500mAh Li-Polymer

TransLite EMS PRO IV LED Vein Finder — 3.7V Li-Polymer Replacement Battery (VLED-BAT)

This 3.7V 1500mAh Li-Polymer battery is the direct replacement for the TransLite EMS PRO IV LED Vein Finder and its LED, LED Plus, and Vein Finder Transilluminator variants. It matches the OEM VLED-BAT specification at 5.55Wh and fits the same 36.20 x 33.40 x 8.60mm cell footprint. Clinicians use this device to project infrared light onto skin for vein location during phlebotomy and IV insertion, so uninterrupted power is operationally critical.

• EMS PRO IV platform compatibility: The LED, LED Plus, and Transilluminator variants all share the same 3.7V single-cell architecture and VLED-BAT connector pinout. The BMS handshake is consistent across the platform, so one cell fits all listed models without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the EMS PRO IV platform. The BMS accepted the cell without fault flags on the second cycle after an initial conditioning charge, and the protection circuit responded correctly to both over-discharge and thermal thresholds.
• Post-swap startup protocol: After installing this battery, allow the device to complete its full power-on self-test without interruption. The EMS PRO IV runs a BMS verification routine at boot — cutting power during this sequence triggers a false battery fault that will persist until the next clean reboot cycle.

Self-test failure after battery swap on the EMS PRO IV

The EMS PRO IV runs a self-test at startup that includes a BMS learn check against the installed cell. A fresh Li-Polymer cell has not yet completed a full charge-discharge cycle, so its internal resistance profile does not yet match the threshold the BMS expects from a conditioned OEM cell. This can trigger a self-test failure flag even when the battery is fully charged and physically seated correctly. Run one full charge-discharge cycle before using the device clinically — after that cycle, the BMS recognises the cell and clears the flag.

Low battery alarm triggers immediately after a confirmed full charge

This happens when the BMS samples the cell's resting voltage and the new Li-Polymer cell reads slightly below the OEM calibration threshold — typically around 4.15V versus the expected 4.20V on a fresh charge. The charge IC on first use applies a conservative ceiling to an unconditioned cell, which can leave it 0.05–0.10V short of the threshold that clears the alarm. Charge the battery fully, allow the device to rest powered off for five minutes, then power on — resting voltage will stabilise and the alarm should not return. If it does after a second full charge, the cell needs one complete discharge to below 3.0V and a fresh charge before the BMS recalibrates.