Introduction: DIY a 48V 200Ah Powerwall Battery for a 10kWh Home Solar Energy System

By QH Technology
About: We want to lighten the world💡💡--LiFePO4 batteries for energy storage(#solarenergy, RVs, Golf Carts, Forklifts, etc.)

The Powerwall battery 48V 200Ah is the most commonly used specification in our daily lives. It is an integrated battery system that stores your solar energy for backup protection, so when the grid goes down your power stays on. Your system detects outages and automatically recharges with sunlight to keep your appliances running for days. With two or three powerwall batteries, we can get enough electricity from solar power for our daily consumption.


Are you interested in the assembly process of the 48V 200Ah lithium battery? Which materials should we use to build? Please check the following detailed process!


*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.

Supplies

Material Used:

  • 3.2V 200Ah LiFePO4 battery cells (16 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 16 pieces)
  • Others: EVA cotton, screws, ribbon cables, plastic pipes, etc.

Tool Used:

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

Assembly Methods: 16 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.


Step 1: Fill EVA Cotton to the Shell

EVA cotton can protect our LiFePO4 battery cells, which are shockproof, fireproof, and insulated. Cut two EVA cotton into suitable sizes and tape them on the battery shell.

Step 2: Install Ports Board

Next, we can install the port board on the side. After installing the port board, we can put the battery cells inside.

Step 3: The Connecting Piece Has Been Connected to the Battery Cells by Laser Welding

  • First, we should check the voltage of each battery to ensure consistency.
  • Next, we divide the battery cells into two groups and place them in order.(Each battery pack is 24V)
  • Then, we should install the signal acquisition wires in sequence.

Step 4: Connect Power Wires

Step 5: Two Battery Packs Are Connected in Series

If we want a 48V powerwall battery, we can connect two 24V battery packs into series to increase the voltage. Connect the negative terminal of one battery to the postive terminal of another.

Step 6: Lay Down the Battery Packs

If we want a 48V powerwall battery, we can connect two 24V battery packs into series to increase the voltage. Connect the negative terminal of one battery to the postive terminal of another.

Step 7: Put the Epoxy Board Between the Batteries

Put the epoxy resin board insulation board between the battery packs. The epoxy board is suitable for the protection and bonding of the LiFePO4 battery.

Step 8: Fill EVA Cotton to the Batteries

(EVA cotton can be shockproof, fireproof, and insulated)

Step 9: Put on the Shell

Step 10: Secure Shell With Screws

Step 11: Install BMS

A BMS is a really important safety feature to add to a lithium battery. Not only will it make your battery safer by protecting your cells from over and under-discharging, but it will also make the entire charging process much simpler.

Step 12: Connect Power Wires to the Shell

Step 13: Install BMS Again

Step 14: Check the Signal Lines in the Correct Order

(Attention: The wrong sequence may cause BMS to burn out)

Step 15: Fix the Temperature Measuring Probe Near the Battery Pack

Step 16: Plug Signal Acquisition Wires’ Port Into the Interface

Step 17: Insert Ribbon Cable

Step 18: Tidy Up the Wires With Tie Straps

Step 19: Rearrange the Wires With Plastic Pipes

Step 20: Secure Plastic Pipe With a Tie

Step 21: Install the Monitor to the Cap

Battery monitor, indicating the state of charge percentage and more data. We can install it to the cap.

Step 22: Connect the Monitor to the BMS

This is the final step of the assembly process. After connecting the monitor to the BMS, the battery is ready for working.

Step 23: Charging Test

Through the test, we can check that the charging value is normal and that the battery is abnormal during the charging process. We need to pay attention to the battery charging time and charging current.

Step 24: Discharging Test

The discharge test of the battery is beneficial to the battery cycle life and discharge performance evaluation. We can use a professional device(Such as a Programmable DC Electronic Load) to check whether the battery works well or not during the discharging process, which can protect our battery and devices for further daily use.


When testing, there are three factors we need to pay attention to the port voltage of the battery, the resistance of the wire between the battery and the electronic load, and the temperature of the battery.

Step 25: Communication Test

To test if it can communicate well with the inverters. In the whole household solar energy storage system, the inverter can change the direct current into an alternating current. The battery should be compatible with the inverters, then we can make full use of the inverters, such as reading information from the inverter’s screen.