Howards Astronomical Adventures

: Tales From The Night Sky

Two Years of Lithium Power

Two years ago I took the picture above showing I had gotten the parts together for my super battery (as I call it). The four blue cells are temporarily clamped together for a test charge / discharge cycle. Total capacity was right about 270Ah (at 10 amps per hour rate), a serious amount of power. It would be several months before I had a fully finished battery I could carry around.

Like many of my projects it took me longer than planned to finish. I often change the design or revise part selection as things come together. For example the early battery above used a low cost Daly Battery Management System (BMS). That model turned out to be seriously inadequate in several areas (low voltage disconnect for one). I changed to a 120A JBD model that had much better options and higher current capability. Pictured below is a partially assembled battery with the JBD BMS.

The cells I used are Lishen brand Lithium Iron Phosphate (LiFePo) I ordered in December 2020. Shipped by boat it took over a month to get them from China. Things have changed in the past two years, there are several companies with US based warehouses so you can get these or similar cells much faster now. Interestingly the price today is about the same as when I bought mine. Some brands of similar high capacity LiFePo cells now have different options to attach the bus bars. Welded studs on the terminals have become somewhat popular. I can see this is a good idea if they are welded properly. The M6 size tapped holes in the Lishen cells, common when I purchased, are easily stripped out if over torqued.

This brings up another area that has changed since I built my battery: prebuilt LiFePo batteries are much more common and available. Power stations is what many are now called and high capacity ones like mine are not cheap. Today I would not recommend someone build their own LiFePo battery unless they have experience in electronics, DC, various tools for construction, and good diy skills. I know I have some shortcomings and design tradeoffs with my diy approach. i can work around those issues and will upgrade a few parts later. For anyone else, if you just need a reliable portable power source its best to buy a prebuilt model from Renology, Jackery or other quality brands.

After two years my battery build has meet my expectations and I am happy with the investment. The potential longevity and capacity more than offsets the cost. I use this battery regularly to power my astronomy equipment whether at home or on the road. It has worked well in 100 degree temperatures and at -10F. Weighing in at 65lbs its portable and can run all everything for many days.