My friend and I built 2 portable batteries for powering stuff such as computers, mobile devices, etc. We haven't accumulated enough 18650s yet to use lithium batteries, so we used SLA batteries instead. From what I read on battery university, it sounds like it's best to keep the SLA batteries at 100% charge to maximize their life span, but I just wanted to make sure that this is correct and that I didn't misread or misinterpret something.