Gama Sonic GS-5 IFR18650 LiFePO4 Replacement Battery 3.2V 1800mAh

Gama Sonic GS-5 / GS-6 Series — 3.2V LiFePO4 Replacement Battery (IFR18650)

This is a 3.2V 1800mAh LiFePO4 IFR18650 cell for Gama Sonic solar lights, including the GS-5, GS-6, GS-52, GS-53, and 26 additional models in the same family. It replaces the original cell when the light stops illuminating after dark or holds charge for a noticeably shorter period than it once did. Capacity is 1800mAh (5.76Wh).

• GS-5 / GS-6 family fit: These models share a common solar charge circuit and cell housing sized for the 18650 form factor. The BMS handshake operates at 3.2V nominal — the LiFePO4 chemistry matches that voltage rail exactly, where a standard Li-ion cell at 3.7V would overvolt the charge controller.
• Bench tested on actual hardware: We cycled this cell through a solar charge controller sim at 4.0V charge cutoff and 2.5V discharge cutoff. The BMS protection triggered correctly at both thresholds and recovered without requiring a manual reset.
• Panel orientation matters more than sunlight duration: The solar charge controller on these lights has a minimum input current threshold. A panel tilted away from direct sun — even on a bright day — can produce ambient light current that stays below that threshold. The battery will not charge at all unless the panel receives direct overhead sun for the majority of the day.

Why the GS-5 stops lighting up after sunset even with a full day of sun

LiFePO4 cells degrade gradually through repeated shallow discharge and recharge cycles. Once internal resistance climbs past a threshold, the cell accepts a surface charge — the controller reads it as full — but actual usable capacity has dropped significantly. The light turns on at dusk, then cuts out within an hour or two as the true cell voltage collapses under the LED load. Replacing the cell is the fix; no amount of solar exposure will recover a degraded LiFePO4 cell.

Battery reads charged during the day but the light is dim or off by midnight

This happens when the solar panel only partially charged the cell — not a faulty battery, but insufficient input energy. A partly shaded panel, low winter sun angle, or overcast sky can cut panel output to under 100mA, well below the charge controller's minimum. The controller still registers a charging state, but the cell never reaches full charge voltage of 3.6–3.65V. Check the cell voltage with a multimeter after a full sunny day — if it reads below 3.5V, the panel angle or shading is the problem, not the cell.