How to Build a Lithium-Ion Battery System for less than $400 per kWh

I have seen a lot of people on the internet repurposing old laptop batteries and batteries from electric vehicles. This is a great way to acquire low cost, high quality batteries, but it does require a lot of work to disassemble, test, and sort them. I think this will become a common method in the future because a battery that doesn’t work well for an electric vehicle might still be a good fit for a battery energy storage system (BESS), since the charge and discharge rates are so much lower in a BESS compared to an EV. Typically a BESS uses much lower power compared to an EV that needs to accelerate quickly.