Introduction: Make a 12V 280Ah LiFePO4 Battery for Golf Cart! Full Process of Battery Cell Assembly！

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

LiFePO4 batteries have lots of advantages and are becoming quite in demand in the market of trolling motors. When referring to the LiFePO4 batteries, you may compare them with the GEL batteries. For a long time, GEL batteries have played a role in our lives. Nowadays, we prefer LiFePO4 batteries.

As opposed to boats that use GEL batteries, electrical ships equipped with the 12.8Volt 280Ah lithium batteries are more economical, less polluting, and clearly better for the environment. The LiFePO4 battery has a longer life span and deep cycle times(even more than 5,000 times).

Are you a Lithium battery amateur and interested in li-ion battery pack assembly? Now we’d like to share the whole assembly process for beginners, which takes the 12.8V 280Ah LiFePO4 battery as an example.

*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 280Ah 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 4pieces)
  • Others: EVA cotton, screws, ribbon cable, plastic pipes, etc.

Tool Used:

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


Step 1: Install Signal Acquisition Wires in Sequence

The connecting piece has been connected to the battery cell by laser welding. Before installing the signal acquisition, we checked the consistency of the battery and fixed them with fiber tape.

Step 2: Cut the Signal Lines to an Appropriate Length

Tidy up the signal lines and tape them with fiber tape, then cut the signal lines to an appropriate length.

Step 3: Soldering Signal Lines With Lead-Free Solder

Generally, leaded solder is composed of tin and lead. The advantages of using leaded solder include: being easier to bring to working temperature, being shock resistant, and having fewer internal flaws in the structure after being cooled. However, lead material is harmful to the body as it’s readily absorbed. We’d better choose lead-free solder to protect our health and environment.

Step 4: Connect the Positive and Negative Power Line With Connecting Pieces

Step 5: Connect Power Line

Step 6: Connect the B- of BMS to the Negative of Battery Pack

A BMS is one of the most important elements in a LiFePO4 battery, like the brain of the battery pack. It calculates the State of Charge (the amount of energy remaining in the battery) by tracking how much energy goes in and out of the battery pack and by monitoring cell voltages, which can prevent the battery pack from overcharging, over-discharging, and balancing all the cells voltage equally.

There are two main sets of wires we need to install, the thick wires and the thin wires. The thick wires are your charging/discharging wires and the thin wires are your balance wires. Not every BMS is the same, but most are similar. Your BMS will likely have 3 thick wires or 3 pads to solder on your own heavy gauge wires. These are the B-, P-, and C- wires (or pads for adding wires). We usually start with the B- wire. We can connect the B- of BMS to the negative pole of the battery pack.

Step 7: Put the Battery Pack Into Shell, and Fill the EVA Cotton

EVA cotton can be shockproof, fireproof, and insulated.

Step 8: Secure BMS With Thermally Conductive Tape

The thermally conductive 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.

Step 9: Check the Signal Lines in Correct Order

Pay attention, the wrong sequence may cause BMS to burn out!

Step 10: Install Positive and Negative Power Lines to the Cap

Step 11: Plug Signal Acquisition Wires’ Port Into Interface

Step 12: Fill EVA Cotton

EVA cotton can be shockproof, fireproof, and insulated.

Step 13: Test Voltage of the Battery Pack

In these steps, we can use a multimeter to check the voltage of the whole battery pack. Attach the multimeter probes to the positive and negative battery terminals. Then we can check the voltage on the screen. The multimeter’s red probe must be connected to the positive terminal, while the black probe must be connected to the negative one.

A fully-charged battery must indicate a slightly higher voltage than the voltage listed on the battery. For instance, a 12 volts battery will indicate about 12.8 volts when it is fully charged.

Step 14: Charging Test

The battery capacity, or the amount of energy a battery can hold, can be measured with a battery analyzer. If you’re doing a capacity test, be sure to charge the battery until the battery reaches 100%. Then discharge the device until the battery is fully depleted. The charge and discharge rates of a battery are governed by C-rates. The capacity of a battery is commonly rated at 1C, meaning that a fully charged battery rated at 280Ah should provide 280A for one hour.

Step 15: Discharging Test

The discharging test of the battery is very helpful 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.