The portability comes in the form of a fairly compact and energy-dense device on wheels, with the intention being to roll this over to wherever you want. The increased energy density relative to a typical UPS is indeed with a Lithium-ion battery, but one that uses LFP (Lithium Iron Phosphate) chemistry instead. LFP chemistry, for those interested, is relatively new to the battery market owing to challenges until recently in increasing the electrical conductivity, but offers advantages over most other options in not using nickel or cobalt, thus making it more eco-friendly, safer, and less costly, while retaining increased charge/discharge cycles at a usable efficiency. Indeed, the BLUETTI EP500 Pro claims 6000 cycles of use at retaining ~70-80% capacity at this point, which alone means you can run a small house for 15+ years should you find the means to charge it consistently too. The company is providing the means to hook it up to solar charging kits, as well as a fusion panel for 240 V operation from the 120 V units to run high-power machinery. Yes, it’s complete overkill for my needs and yours, and at $2799+ on Kickstarter for the SKUs it is priced out for many DIYers too, but it’s still interesting tech from a materials and engineering perspective that perhaps may interest some home owners here. Apparently others agreed with this already, seeing as how it met its goals within 24 hours and has a little under 2 months left to go to break some crowdfunding records. Hit the link in the source for more info if you are interested!
