I continue with the assembly of the two LiFePo4 Lithium batteries by adding all the components, that connect and control the different parts of this setup.
The assembly so far, indicates a slightly taller battery than expected; that forces me to enlarge the storage area access first.
Now that I know that the battery boxes do their job as expected, I will add four threaded rods to hold pressure on the sides of the battery cells, which will avoid undesired bulging of the cells when charging. A washer and nylon lock nut at each end will lock everything in place.
This is one of a series of articles, describing my journey of assembling and installing Lithium battery cells, as part of my van conversion. I will likely make mistakes and may not even reach my goal of a cheap, yet large Lithium battery bank. This is the continuation of Part Two of my journey.
I used a small 12V Lab power supply to top balance the battery cells. I connected all the positives with bus bars and separately, all the negative ones. My LiFePo cells accept a max. of 3.65V and that’s how I set the power supply. Then set the amperage to maximum (<1C) and I let them charge until the charging amps showed <0.1A. Actually I disconnected the power supply a bit early, when the cell terminal voltages rose above 3.65V
Two simple battery boxes will hold four cells each, making a 12V configuration, each with their own 120A charge/discharge BMS. Together they can handle 240A max (240A * 12.8V = 3072W max. output). Charging will probably be limited to 60-80A.
This is one of a series of articles, describing my journey of assembling and installing Lithium battery cells, as part of my van conversion. I will likely make mistakes and may not even reach my goal of a cheap, yet large Lithium battery bank. This is Part Two of my journey.
A short update
I finished top balancing my eight Lithium battery cells (3.2V @ 272Ah). Had them charging at 3.65V (max. allowed for these cells), most of the time at around 10A. The top balancing should finish when the amps on the power supply drop below 0.100A, but I disconnected the power at about 0.385A. At that time, checking the cell’s terminals with a high-quality multimeter, I saw a cell voltage of 3.653V, clearly getting above the allowed 3.65V.
Today, after a two month long wait, I received my Lithium battery cells form China. I’ve done period purchases through Alibaba and AliEpress now for the last 2 years, mostly below $20.00 each and haven’t had any issues so far. That gave me the confidence to try a $750.00 buy on Alibaba for eight 3.2V – 272Ah Lishen Lithium battery cells. I spent another $200.00 or so on other components, to make it all work. That included a good Multimeter, a small power station to top balance the batteries, heavy wiring, bus bars, switches, BMS’s and lots of lugs, bolts and nuts.