Gama Sonic GS37V40 Solar Battery 3.7V 5200mAh Li-ion

Gama Sonic 101822 / 203001 Series — 3.7V Li-ion Replacement Battery (GS37V40)

This is a 3.7V, 5200mAh Li-ion replacement battery for Gama Sonic solar lighting fixtures, including models 101822, 203001, and 203001-5. It slots into the solar fixture's battery compartment and stores energy collected through the day to power the LED array at night. Capacity figure is taken directly from the product specification — 5200mAh / 19.24Wh.

• 101822 / 203001 platform fit: These three model numbers share the same 3.7V nominal cell voltage, matching BMS input threshold, and identical GS37V40 footprint — 66.60 × 37.00 × 20.20mm — so the connector seats without modification.
• Bench tested on actual hardware: We cycled this cell through solar-input charge and overnight LED-draw discharge. The BMS held low-voltage cutoff correctly and resumed charging on the next simulated solar input cycle without manual reset.
• Panel angle during charge: Mount the solar panel perpendicular to direct sunlight. Diffuse or indirect light rarely generates enough current to clear the BMS minimum input threshold — the battery will not register a charge even under bright ambient conditions.

Why the 101822 fixture stays dark even after a full day outside

A deeply discharged Li-ion cell can drop below the BMS re-entry voltage — typically around 2.5V for a 3.7V nominal cell. When this happens, the BMS locks out the charge circuit as a protection measure. The solar panel may be functioning correctly, but the battery will not accept current. Connecting the battery to a USB 5V source for 15–30 minutes can push the cell voltage above the re-entry threshold and allow the BMS to resume normal solar charging.

Fixture dims or cuts out mid-night despite charging all day

This usually means the cell only received a partial charge during daylight — not a full cycle. A degraded panel, partial shading, or a sub-optimal angle can reduce output to under 100mA, which is enough to trickle the cell but not fill it to capacity. Check the panel surface for dust or debris, then reposition it to face solar noon directly. A fully charged 5200mAh cell at 3.7V should sustain the LED load through a standard overnight period without the BMS triggering low-voltage cutoff.