LiFePO4 (Lithium) Battery Build (part 4)

After a few months of running my DIY lithium battery I thought I’d provide an update on it. We used the battery on our 5+ week trip out west, recharging it only via solar. In a few parks we had little to no sunlight during the day (Olympic National Park and North Cascades National Park were particularly deep within the tree canopy). Even still we never used more than 1/3 of the battery capacity during the trip. That was a huge improvement from prior trips where a few days in the shade and cold could result in us draining the lead acid battery down and then needing to break out jumper cables to recharge.

As cold weather is upon us I winterized the camper a couple weeks ago. This seemed like a good opportunity to do a true capacity test, so I pulled the battery off the camper and brought it home. I hooked it up my DC bench power supply and topped it off to 14.6V, then began a very slow capacity test by applying a steady 2A load.

It took almost a week but the test is now complete. The cells I purchased were listed on the Liitokala store on AliExpress as 280Ah. While they had very generic “Liitokala 280Ah” stickers on them when they arrived, they also had official CATL QR codes which said they were 271Ah cells (867 Wh). Upon completing the test, I measured a total of 262Ah of capacity. That’s plenty for my purpose, though it leads me to believe the cells were either used or extremely poor quality as the official capacity is typically determined by running at a relatively high discharge rate (20%, 50%, or even 100%) whereas at 2A I was running at a very low rate (<1%). If my goal was to use these in a high discharge environment like an electric car I suspect they would have about 240Ah of capacity. In our trailer though they work well enough, especially given the cost