I was somewhat conflicted when considering the battery. On the one hand, I found it convenient to buy a ready-made battery, but on the other hand, I was interested in the technology behind it because I also wanted to be able to repair the battery if I were to travel far from civilization.
So I decided to order eight 280 Amp, 3.2 Volt cells from China. These were shipped from Germany and arrived within a week. The Daly BMS with 150 Amps from China, however, took a bit longer. I also ordered an active balancer from Amazon.
The connecting bridges for the individual cells were included, allowing me to decide how I wanted to arrange them. It was clear that they should operate at 24 volts, or 25.6 volts as a lithium battery, for use in my truck. Since the cells need to be pressed against each other to prevent expansion and loss of power, I used two one-centimeter-thick wooden boards and screwed them together with threaded rods, as you can see in the picture.
The cells also need to be insulated from each other, because the outside of the cell is only covered with a thin layer of plastic, and the metal underneath is connected to the positive terminal. I took a simpler approach and laminated laminating sleeves (the kind normally used for laminating paper) without the paper inside, placed them between the individual cells, and used them as insulators. To protect the sides, I used aluminum composite panel (Dibond), with an insulating layer in between, of course.
Next, we'll connect the Battery Management System (BMS). Connect the marked negative terminal of the BMS to the negative terminal of the first cell. Then, assign the individual channels of the BMS to the corresponding cells. To verify correct connection, measure the voltage at the BMS connector in numerical order. Each measurement should show a voltage 3.2 volts higher than the previous one. If everything checks out, the cables are connected correctly, and you can plug the cable assembly into the BMS.
I decided to install an active balancer. While the Daly BMS does have a built-in balancer, it only balances the cells at a maximum of 0.5 amps. An active balancer can balance the cells at up to 5 amps and only costs around €40. It's connected in the same way as the BMS, so make sure you follow the correct connection sequence.
It's really not rocket science, but you can save a lot of money by building it yourself, and you have the advantage of understanding how the battery is constructed. For my 280 Ah, 25.6 volt lithium battery, I paid approximately €900 for cells, balancer, BMS, and small parts like wood, screws, and so on.
