The number of lights you need is entirely dependent on how big your campsite is and how bright you want it to be. For brightness, consider whether you want a single string light that crosses a campsite for some added ambiance, or if you want to crisscross string lights across your campsite to provide illumination. · Some brands offer long strings with dozens of lights (like the Brightech Ambiance Pro Solar String Lights). However, you may actually be better off opting for smaller sections of lights you can string together. Just remember, the more you string together, the faster the battery dra

The length of time your lights can stay on will depend on how bright you have them set and how powerful the battery is. Sometimes the power source is built into the lights, but others can be plugged into an external power bank. The bigger the bank, the longer the lights will last. · Still, with most high-efficiency LED lights used in these products, you can expect your lights (like the ENO Twilights) to last for at least several hours. If you use a lower-power setting, some string lights can even last for days at a time, and features like built-in solar panels on the BioLite Luci Solar String 

Yes, these lights will work with any USB-C power source.