Frequently asked questions It's cloudy, will my light still charge? Yes, but it will charge at a slower rate than on a bright, clear day. As your Luci charges via the red and violet frequencies of visible light, the charge times will vary based on the UV index or overcast skies. Generally speaking, the higher the UV index, the faster the charge. Should I charge my light if I don’t have immediate plans to use it? Yes! Our products can retain a full charge for up to 3 years.