12V 200Ah Lifepo4 Battery Assembly For Off-Grid Solar Energy Storage

Do you know what is a solar battery? A solar battery is a device that is charged with energy from Solar panels. Batteries can store the electricity generated in the daytime. Solar batteries are great for those who want to be completely self-sufficient with their energy or suffer from power outages sometimes.

There are several types of the storage batteries, such as LiFePO4 batteries, GEL batteries(lead-acid), and Sodium-ion batteries. Nowadays, LiFePO4 batteries are popular in our daily life. It is non-toxic and lighter than a lead-acid battery. It shows great performance with deep cycle times and a longer lifespan.

Are you interested in the process of prismatic battery pack assembly? In the following post, we will share the assembly process of the 12V 200Ah battery pack.

*Note: It is recommended that you learn some basic knowledge about LiFePO4 batteries before assembling the battery pack. Keep safe when you are assembling the battery pack.

Materials Used:

  • 3.2V 200Ah LiFePO4 battery cells (4 pieces)

There are currently three common shapes of LiFePO4 batteries: cylindrical, prismatic, and pouch. Different shapes of batteries will have a certain impact on performance. At present, the most suitable battery DIY enthusiasts are the prismatic LiFePO4 batteries, which are very suitable for both performance and operational difficulty. 

We recommend you purchase the Grade A battery with a high quality and reliable warranty.

  • BMS (Battery Manage System, 1 piece)
  • Connectors (About 4 pieces)
  • Others: EVA cotton, screws, ribbon cable, plastic pipes, etc.
lifepo4 cells 100ah

Tool Used

  • Spot Welder
  • Spot Welding Pen
  • Soldering Iron
  • Wire Cutter
  • Wire Stripper
  • Multimeter

Assembly Methods: 4 Series And 1 Parallel

  • Series(S): The way of connecting the positive and negative electrodes of two different cells is called a series connection. As a result, the voltage of the battery pack will increase while the capacity remains the same.
  • Parallel(P): where the positive and positive electrodes of two different cells are connected in parallel. The result is that the capacity of the battery pack increases while the voltage remains the same.

Assembly Process

1. Tied 4 Battery Cells Together With Fiber Film to Prevent Loosening

Before we connect this group of battery cells, we should use the multimeter to check their voltage of them to ensure consistency. It is better if you have a testing device to check the internal resistance. Without testing the consistency, the battery pack may cause an accident.

Then we place them in order and fix them with fiber film. (Made of hot melt adhesive and forms a stronger tape that is resistant to tears and has better temperature tolerance than regular  tape.)

2. Connect the Four Battery in Series With Connecting Pieces

Connect the cells using the connectors in series while connecting the indicator cables to the CPM and the cells. Don’t tighten connectors and nuts too tightly.

When connecting the voltage collection lines (equalization lines), do not connect the external protection board to avoid accidental burning of the protection board.

3. Install A Signal Acquisition Line

Connect the white end of the signal acquisition line to the positive(black end) of the battery then the cables will collect the signal of the positive electrode of the battery.

4. Put The Battery Pack into The Shell

There is shockproof cotton in the shell(this cotton will be filled with the shell for fixing at the end), and the battery is placed close to one side leaving room for heat dissipation for BMS.

We can not put the battery pack into bare condition. It is a great choice to put it into a plastic shell. The plastic shell has a good insulation performance, cells can be directly assembled into a DC high-voltage battery pack. The insulation strength is not affected by the air humidity, and the anti-lightning performance is good without grounding.

5. Connect The Other End of The Acquisition Line to BMS

Connect the blue wire to the negative pole(white) of the battery and fix it with screws. Connect the red wire to the negative pole(black) of the battery and fix it with screws.

6. Fix BMS on The Shell With Soft Adhesive Tape

The soft adhesive tape for battery packs keeps the BMS in place and protects them from the shock of extreme temperature changes.

Besides, these tapes provide electrical insulation, which prevents short circuits and provides a barrier to BMS.

7. Connect The P- of BMS to The Negative of The Shell. Connect the P+ of BMS to The Positive Of The Shell.

8. Fix The Signal Acquisition Line With Screws

Connect the cells using the connectors in series while connecting the indicator cables to the CPM and the cells. Don’t tighten connectors and nuts too tightly.

When connecting the voltage collection lines (equalization lines), do not connect the external protection board to avoid accidental burning of the protection board.

9. Connect The Signal Acquisition Line to BMS

10. Connect The BMS Monitor to The Power Supply

Connect the negative pole first and then the positive pole, and the monitor will light up.

11. Fix The BMS Monitor to The Shell

12. Arrange and Fix The Cables With Plastic Strips

13. Fix The Signal Wire With Screws With Silica Gel

To prevent the line from breaking in the process of transportation shaking.

(p.s. BMS has a signal protection function, if one line breaks the battery, it will stop working, so we should check it carefully. )

14. Put on the Shell

Congratulations! Your battery is successfully assembled. You can prepare the battery tests in the next steps.

15. Charge Test

The battery capacity, or the amount of energy a battery can hold, can be measured with a battery analyzer. Connect the black line to the negative pole, and the red line to the positive one.

The data will be displayed on the BMS display screen, such as the total voltage, current, power, SOC, etc.

After the charging test, we can make a discharging test for our battery pack. The discharging test of the battery is beneficial to the battery cycle life and discharge performance evaluation.

16. Aging Test

Lithium batteries need a high-temperature aging room for high-temperature aging. Parameters will be shown in the aging test machine. There are several advantages of aging tests, such as making the electrolyte soakage better, and the active substances in the anode and cathode materials can accelerate some side effects, which is conducive to the stability of lithium battery pack performance.


After passing the tests successfully, you will get your new battery pack and start your solar energy storage trip! 12V 200Ah LiFePO4 batteries are suitable for small-scale off-grid solar energy storage, such as using a laptop, an electrical fan, or a hair drier. It is also a professional partner for your RV trip.

Thanks for reading the full tutorial on assembling the 12.8V 200Ah LiFePO4 battery! It is not hard for us to build a LiFePO4 battery. Which voltage and capacity of the LiFePO4 battery do you need?


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