Introduction
I recently got my hands on a 3D printer and decided to put it to good use by designing and building my own PD battery bank. I wanted a battery bank that could charge my laptop, but I didn’t want to spend a fortune on it. Unfortunately, most of the battery banks available in the market that can charge laptops are priced above $100. A key feature I was looking for was the PD 3.0 spec that supported 20v@2A charging, since my laptop is a picky lenovo with a 65W minimum rating.
So, I decided to design and build my own battery bank. Plus this would be a good chance to test and tune my printer! I started by researching the different types of batteries that I could use. I wanted a battery that was small, lightweight, and had a high capacity. After some research, I decided to use some high capacity Li-ion batteries lying around for a 4S2P configuration.
Next, I designed the battery bank using Solidworks, dusting off my rusty skills that haven't been touched since university. I made sure that the design was compact and would fit in my backpack. With the help of my calipers, I made the port cover and enclosure to 0.1mm of tolerance, something that made the modelling, printing and testing a 1.5 week endeavor...
Once the design was complete, I printed the enclosure using my 3D printer. I used a PLA filament to print the enclosure, since thats what it came with, but considering it'll be in outdoor scourching environments, I plan to print the final pieces in PETG.
After printing the battery bank, I assembled it and connected the battery to the PD module I purchased, and behold! success! I tested it for a day to ensure charging, discharging and simultanious charging was as expected.
Finally, I wanted to address the final feature of the PD module, a small led pin for a flashlight. Now most commercial battery banks use a tiny 3.5mm led to act as the flashlight. But as a frequent camper, I wanted something that could light more than half a meter away.
One of my other queued projects is a 60W flashlight using CREE leds, known to be high illumination. So why not stick a few *proper* leds on the already high capacity battery bank?
and herein lies the mistake
Disaster
Waking up the next day, I did some final tests of the led driver circuit and hooked it up to the flashlight pin of the PD module. Immediately the leds lit up a blinding illumination... and in 10 seconds started smoking. I had calibrated and tested the voltage already and knew the led's shouldn't be burning. Shutting the power off, I tested the led driver.
It was fried.. likely having damaged the buck ic when I was soldering everything together. A sad expensive rookie mistake 😥
Worse, I immediately checked the PD module and it too, no longer worked. The display blinking a couple seconds before completely shutting down. I had overloaded the module.
for now I'll be placing this project on hold, waiting for the PD module to go on sale again and ordering.