My solar lights original battery capacity was 150 mAh. They worked, but didn’t power the light for very long. So I switched to 900 mAh batteries. They worked, but faded quickly. I reasoned that the small solar panel couldn’t fully charge a larger capacity battery. So, I tried these 300 mAh batteries. Success! In a side-by-side test over several days, the lights with these batteries worked longer and brighter than the lights with the 900 mAh batteries.I have ordered another pack, and will be installing them in all my lights. One caveat would be that this may not apply to all lights. It depends on the size/output of the solar panel. Be guided by the capacity of the original battery that came with the light.