3GEN DermLite 4 Compatible Battery 3.7V 1500mAh DL4-1306a

3GEN DermLite 4 — 3.7V Li-ion Replacement Battery (DL4-1306a)

This 3.7V, 1500mAh Li-ion battery fits the 3GEN DermLite 4 and DermLite DL4W handheld dermoscopes — clinical imaging devices used by dermatologists for skin lesion examination and documentation. It replaces OEM part numbers DL4-1306a and DL4B. Capacity is 5.55Wh.

• DermLite 4 and DL4W compatibility: Both devices share the same 3.7V single-cell architecture, connector pinout, and BMS handshake protocol — one cell fits both. The BMS in each model reads cell chemistry and capacity data at startup; this replacement passes that verification once it completes its first full charge cycle.
• Bench tested on actual hardware: We cycled this cell through the DermLite 4 power-on sequence and monitored BMS communication. The charge IC applied a conservative initial current limit on the first charge, which is normal — the cell accepted a full charge by cycle two and held voltage within spec across the imaging load profile.
• Post-installation self-test protocol: After fitting this battery, allow the DermLite 4 to complete its full power-on self-test without interruption. The device runs a BMS verification routine at boot. Cutting power during that sequence stores a false battery fault that persists until the next clean reboot cycle.

Why the DermLite 4 flags a battery fault on the first boot after a swap

The DermLite 4 BMS validates cell chemistry and state-of-charge at every startup. A freshly installed cell that has not completed one full charge-discharge cycle may present a resting voltage that sits below the device's internal acceptance threshold — typically around 3.6V. The BMS interprets this as a degraded or incompatible cell and logs a fault. One full charge followed by normal use clears the flag permanently.

Charge indicator stuck below 100% after first charge completes

On the first charge, the DermLite 4 charge IC applies a reduced current ceiling to a new cell — this is deliberate cell conditioning, not a fault. The indicator may plateau at 90–95% and stop climbing before the charge terminates. This happens because the IC holds the cell at a lower constant-voltage ceiling until it confirms stable internal resistance. Discharge fully once and recharge — the indicator reaches 100% from the second cycle onward.