Bigblue VL15000P-Pro Mini 25.9V Replacement Battery 3500mAh

Bigblue VL15000P-Pro Mini — 25.9V Li-ion Replacement Battery (BATCELL18650X7)

This is a 25.9V, 3500mAh Li-ion replacement battery for the Bigblue VL15000P-Pro Mini and VL15000P-Pro Tricolor Mini dive flashlights, as well as the CB30000P-II and VL33000P-II models. It matches the OEM part number BATCELL18650X7 and slots directly into the battery compartment of these underwater torches. Voltage and cell count match the original seven-cell 18650 configuration.

• Multi-model compatibility across the VL and CB series: The VL15000P-Pro Mini, VL15000P-Pro Tricolor Mini, CB30000P-II, and VL33000P-II all run the same 7S 18650 cell configuration at 25.9V nominal. They share the same battery housing geometry, connector, and BMS communication protocol — which is why one part number covers all four platforms.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on the VL15000P-Pro Mini driver circuit. The BMS handled high-current turbo draw without tripping, and cell voltage balance across all seven cells stayed within 30mV at full charge.
• Multi-cell replacement rule for dive lights: Always replace the entire seven-cell pack as a unit — never mix this new pack with old cells from a partially functional original. In a high-draw torch at turbo output, a weaker cell will bottom out first, forcing the BMS into a hard cutoff that kills the light at full power.

Why the VL15000P-Pro Mini steps down output before the battery indicator hits low

The driver circuit in this torch monitors pack voltage continuously, not just cell count. When the 25.9V nominal pack drops toward 21V under load, the driver activates brownout protection and steps the output down to a lower lumen mode — even if the indicator still shows charge remaining. This is intentional: it protects the cells from collapsing under sustained high-current draw. If your light steps down mid-dive, switch to a standard or low mode to keep the driver stable and finish the dive. A pack sitting above 24V at rest but stepping down quickly under turbo draw is a sign of capacity fade — time to replace.

One cell draining faster than the rest in a multi-cell dive torch

If you have mixed an older cell or partial pack with newer cells, the weakest cell carries a disproportionate burden under the high current turbo mode draws. That cell hits the BMS low-voltage cutoff first, dragging the entire pack offline even when the other six cells still have charge. The fix is not a reset — it is replacing the full pack with matched cells from the same production batch. After installing this replacement, charge to full (the pack charger should terminate at 29.4V) before the first dive.