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.
I continue where I left off in the previous article Van Ceiling Panel Part II. As a reminder, I use an automotive tweed protected against daily wear and UV, very similar in color and texture as the front seats of the van.
Before I can install the ceiling panel, I still have to finish and attach this black foam block above the sliding door, as well as a small cabinet that houses two switches and the gas heater control knob and a top cabinet.
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.
Today, after a two month long wait, I received my Lithium battery cells form China. I’ve done period purchases through Alibaba and AliExpress 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.
With the Van Build coming to an end, several important projects need some attention. Today I’ll start working on the battery bank of my solar system. Originally, and that was at the beginning of the van build, I installed two 6V Golf cart batteries. This netted me only ~100Ah at 12V nominal. Sufficient for only the most basic usage. At the time also more than sufficient, with only a minimal number of trips planned.
The main reason however, was that only 3-4 years ago, Lithium battery technology was hardly existent and very expensive. As I look back now, much has changed. We know now, that charging a Lithium battery at below freezing temperatures, is a big No-No, cell balancing must be part of the setup and many more issues are better understood. The development of low priced BMS’s (Battery Management Systems) has also made the DIY setup a possibility.
Just received a dozen puck lights; these 12V LED light fixtures are the main lighting source inside the van.
The main advantage of these LED lights is their energy consumption; with about three watts per light, you can leave them on without worrying about a dead battery. While made in China, they seem to be of a fairly good quality and produce a lot of light. Continue reading 12V Led Light Fixtures→
A very short update about the flexible solar panels from Link Solar. Many of these flexible panels on the market today, are of a low quality, but with the arrival of ETFE laminates and high quality Backcontact solar cells, I took a gamble on these improved panels. Now, about six months after the original installation, this first update shows that the panels still look brand-new and no wear or tear is visible. Another uncertainty was the VHB tape, used to attach these panels directly to the metal roof of the vehicle. After driving around and exposure to the harsh sun here in Florida, I can say that these first six months have had no visible impact on the panels and the VHB tape looks to be the best way forward to attach these flexible panels to the roof.
This is a short review of two brand-new flexible solar panels. The Day4 Tech panel looks very similar to the current flexible panels, but uses two fine wire meshes to connect the individual solar cells together, one mesh on each side. They replace the bulky silver contacts, seen on regular panels. While bending these panels, may still break some of these contacts, the panel’s power output is usually not affected, as many more contacts remain. Continue reading Solar Blanket And Day4 Tech Solar Panel Review→