Black Diamond ReVolt 350 Replacement Battery 3.7V 1300mAh

Black Diamond ReVolt 350 / Sprinter 275 — 3.7V Li-Polymer Replacement Battery (620655B)

This 3.7V, 1300mAh lithium-polymer battery replaces the internal rechargeable cell in the Black Diamond ReVolt 350 and Sprinter 275 headlamps. Both headlamps use the same OEM cell (620655B / BD1800) and share an identical battery compartment footprint: 44.70 × 35.00 × 12.20mm. If your headlamp no longer holds a charge or won't power on after a full charge cycle, this cell is the direct replacement.

• ReVolt 350 and Sprinter 275 compatibility: Both models run the same single-cell Li-Polymer pack on the same voltage rail with the same connector pinout. The OEM part numbers 620655B and BD1800 refer to the same physical cell used across this headlamp platform.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the ReVolt 350 driver board. The BMS accepted the cell without triggering a protection cutoff, and the driver stepped through all output modes without fault flags.
• USB charging port behaviour after cell swap: The ReVolt 350 charges via micro-USB through the headlamp's onboard charging circuit. After replacing the cell, plug in immediately and allow a full charge before use — the driver's fuel gauge resets its reference point on the first full charge cycle from a new cell.

ReVolt 350 driver stepping down output before the indicator shows low

The ReVolt 350 uses a constant-current driver that monitors cell voltage in real time. When the cell voltage drops below the driver's brownout threshold — typically around 3.2V under load — the driver steps output down to protect the cell, even if the LED indicator hasn't triggered yet. This is not a fault; it's the driver responding to voltage sag under draw. A worn cell with high internal resistance will sag faster under load, causing the step-down to happen earlier in the discharge cycle. Replacing the cell restores the voltage floor and delays that step-down point.

Headlamp powers on briefly then shuts off immediately after cell replacement

This happens when the replacement cell ships at a storage charge — typically 3.6–3.7V — and the BMS interprets the initial load spike as an undervoltage event. The protection circuit cuts output within seconds to avoid drawing the cell below the minimum threshold. Connect the headlamp to a USB charger first and charge until the indicator shows full. Once the cell sits at or above 4.1V, the BMS releases the protection latch and the headlamp runs normally through all modes.