Notes on creating a DIY solar-charged portable DC power station

This project started when I recovered a big lithium battery from a broken/abandoned eScooter and solar panels from broken temporary street lights from the streets around me. The objective was to create a portable DC power station for charging laptops, USB devices, and portable refrigerator offgrid or as a backup during a grid blackout. 

I purchased $105.94 in materials to make this happen, and invested lots of my time in learning, testing, and building the enclosure. Theoretically, I could reuse those materials in future projects if I decide to dismantle this. Without counting labor, the price comes down to about $0.11 per Wh (watt hour), which is a lot better than $1.10 per Wh in commercial options. 

Portable power station components, using scrap plywood and clear acrylic for the housing:

1. Scrap YiChi Li Battery 18650 48V 20Ah JTCNW26 YC202108261128: recovered from broken and abandoned Dagway eScooter, with XT60 connections, 960Wh capacity
2. 30amp Charge Controller, PWM Solar Controller 30A Solar Power 48V Lithium: set to “3.7-7” per guidance received from the manufacturer
3. DC Voltage Regulator Buck Converter DC 48V Step Down to 24V 10A 240W: to step down from 48V to 24V
4. 6 Way Fuse Block Blade Fuse Box with Negative Bus
5. 12 Volt Cigarette Lighter Socket: for running a 12V fridge or other function
6. 83W Laptop Car Charger Socket 12V USB Outlet, USB-C, 18W QC3.0 Outlet: for charging laptop with USB-C

Testing the panels wiring in series:

Troubleshooting the box with Mike of Actinica, a friendly neighbor. The issue was poorly stripped wires that caused a short, and the solar charger smartly shut itself down. He helped with some heatshrink and diagnosis.

Lowtech Magazine now has an article that also talks about how to build little systems like this.