Introduction: 24V 150Ah Lithium Ion Battery Pack Assembly for RV Travelling

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

Lithium-ion battery pack works well in an RV. You can enjoy your RV traveling without worrying about the power outage. We do not use LiFePO4 battery as a starter battery to get the RV motor running, we mainly use it for a storage battery.


Not only the LiFePO4 battery can power your daily use during your traveling, but also can power the travel trailer RV. More and more RVers are replacing their lead-acid house batteries with lithium-ion options. They are lightweight, but they have a higher energy density. Without toxicity, they are also friendly to our environment. Compared with the lead-acid battery, we don’t need to spend our time maintaining the LiFePO4 battery.


We recommend the 25.6V 150Ah LiFePO4 battery pack for your RV traveling. Do you want to be a battery DIYer? We’d like to share the full process of lithium-ion battery assembly in the following post. Check the following post now!


*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 150Ah LiFePO4 battery cells (8 pieces)
  • BMS (Battery Manage System, 1 piece)
  • Connectors (About 8 pieces)
  • Others: Epoxy boards, 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. Laser welding is a process used to join together metals or thermoplastics using a laser beam to form a weld.


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 tape. (Made of hot melt adhesive and forms a stronger tape that is resistant to tears and has better temperature tolerance than regular tape.)

Step 2: Cut the Signal Line to an Appropriate Length

Tidy up the messy lines, then cut them into an appropriate length.

Step 3: Connect the Positive and Negative Wires With Connecting Pieces

Step 4: 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 cooling. 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 5: Put Battery Pack Into Shell and Fill EVA Cotton

EVA cotton can be shockproof, fireproof, and insulated, which can protect the LiFePO4 battery cells well.

Step 6: Secure BMS With Thermally Conductive Tape

Thermally conductive tapes are designed to provide preferential heat transfer between heat-generating electronic components and cooling devices such as fans, heat sinks, or heat spreaders. They are also used for the thermal management of high-powered LED’s which can run at high temperatures, thus increasing the efficiency and reliability of the system.

Step 7: Connect B- of BMS to 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 8: Connect Positive Power Line

Step 9: Connect the Positive and Negative Power Lines to the Cap

Step 10: Check the Signal Lines in the Correct Order

The wrong sequence may cause BMS to burn out!

Step 11: Plug Signal Acquisition Wires’ Port Into Interface

Step 12: Test Voltage of the Battery Pack

In this step, 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 24 volts battery will indicate about 25.6 volts when it is fully charged.

Step 13: 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 150Ah should provide 150A for one hour.

Step 14: 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.