DIY Lithium Battery

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.

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Four 3.2V battery cells will compose a 12V unit (12.8V), each in combination with its own BMS (maximum discharge rate 120Ah) and fuse. As I put them together, I may include a heating pad connected to a temperature controller, to keep them warm during (for me severe) cold spells as they should not be charged below ~0°F. At these temperatures discharge rates tumble as well. Fortunately, I have no intentions to travel under these circumstances, so I may not install heating pads, unless necessary.

I will install 4-5 temperature controllers for these heating pads and for 12V computer fans at the battery bank, for fridge air movement and at my built-in computer.

When I received the battery cells, I immediately checked the cells individual voltage: 3.272V – 3.275V – 3.275V – 3.275V – 3.276V – 3.276V – 3.276V – 3.276V. Well within my requirements. The improve the status of each battery and level the voltages, I will now do a top balance by connecting the eight positives together and the eight negatives. The cells SOC is probably around 50%, which is a requirement for transportation, so they will stay connected to a small lab power supply for 2-3 days until fully charged. I anticipate future usage to be between 15-20% and 80-90% SOC for a longer battery life.

Reminder: The Chinese color scheme for indicating the terminal type of battery cells is apparently different from what is used in the West. My cells come with black and beige colored terminals, where black is POSITIVE and beige is NEGATIVE. In any case, ALWAYS check polarity before making connections!

The biggest issue has been to find a good working, yet affordable BMS (battery management system). The cells allow a discharge rate of 272A at 1C, but is limited by the BMS to only 120A. For a well-balanced system, with a 3000W inverter/charger, the two 12V batteries will have a max. discharge rate of 240A or 3072W, although I will likely never use more than about 2000W.

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With a cost of less than $1000 for a 550Ah battery bank, including all the components for the install, I would have an approximate cost of $0.15 per watt. A 100Ah Battleborn is approx. $0.70 per watt. That is a big savings, but… There is always a but. There goes much work into development of the BMS and the entire system as a whole. Then there is the risk of a DIY installation; it’s easy to make a mistake or miscalculation. That is a risk I’m willing to take in return for a cheap Lithium battery bank. But, will it be a good choice for you?

In the upcoming weeks, I will be posting multiple videos on how I put everything together, in great detail, as usual.

TOOLS & MATERIALS*

Lab Power Supply
Lithium Battery Cells ➜ See Resources below.
Klein MM400 Multimeter
Loctite Threadlocker
Bus bars ➜ See Resources below.
Serrated Flange Nuts
Set Screws
Woodworking Clamps
Wrench and Socket Set
Isopropyl Alcohol
Sandpaper
Metal File
Vacuum

*Some of the links above are affiliate links, meaning at no additional cost to you, I will earn a small commission if you click through and make a purchase.

RESOURCES

Lithium Battery Cells

I bought my cells through Alibaba.com from Shenzhen Xuba Electronic Trading Co., Ltd. Their email contact is Pina Long.

Lithium Battery & Solar Info

Will Prowse – YouTube
DIY Solar Forum

Other Resources

My Experience of Buying from China
How to Buy Batteries from China

Disclaimer: I’m not an expert at this and I’ll probably make some mistakes that I have to correct. Always consult an expert if you ever think of doing this yourself.

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