How to DIY LiFePO4 Car Battery

By Henry, Updated on January 29, 2024

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The LiFePO4 car battery is made in two main steps.The first step is the manufacture of lithium battery cells. The second step is to connect the lithium cells one by one in series or parallel, to achieve the desired voltage and capacity of the lithium battery pack for electric vehicles, as well as charging and discharging requirements.

Part 1. LiFePO4 car battery lithium battery cell manufacturing

The basic steps of the manufacturing method of lithium battery cell are as follows:

Stirring and mixing of raw materials: mix the electrode active materials, binder and solvent together, stir and disperse them thoroughly, and make them into slurry.
coating of positive and negative electrode sheets: coating the slurry intermittently and uniformly on the surface of the transport collector for drying. The positive and negative pole pieces are made into rolls respectively.
Cold pressing of positive and negative electrode sheets: after coating the positive and negative electrode sheets, the positive and negative materials are relatively loose. It is necessary to give a certain pressure to the pole piece. Compact the positive and negative materials to a certain range.
Cutting and slitting: According to the model of battery, it is necessary to slit the positive and negative electrode sheets into corresponding widths.
Stacking of positive and negative pole pieces: small positive and negative pole pieces and isolation film are stacked and combined to form a bare battery cell.
Shelling, spot welding, vacuum drying: the bare core is wrapped with packaging foil and thermally encapsulated on the top and sides. In addition, and then after a high vacuum high temperature baking, a small amount of water drying, so that the lithium battery performance is guaranteed.
Liquid injection: add the electrolyte into the cell and seal the cell completely.
Formation: the assembled battery is given a certain current to activate its internal positive and negative substances, the battery can only be used as a power source after formation.
Capacity Separation: In the manufacturing process, the actual capacity of the battery is inconsistent due to the process, and the battery is classified according to its capacity through certain charging and discharging tests.
Forming: The shape of the battery cell will be done for final processing.

After the above steps, a LiFePO4 battery cell is manufactured successfully. The next step is to form the LiFePO4 cells into a LiFePO4 battery pack.

lifepo4 car battery cell

Part 2. How to assemble LiFePO4 battery cells into LiFePO4 battery pack?

Connect the LiFePO4 battery cells one by one in series or parallel to achieve the desired LiFePO4 car battery (LiFePO4 car battery pack).

How to make a LiFePO4 car battery

LiFePO4 batteries are not only safe, but also have a lot of battery cycles. If you want to make your own 48v 20ah LiFePO4 car battery pack, you can buy LiFePO4 battery first. With 3ah 26650 LiFePO4 battery, 16 series 7 parallel can achieve 48v 20ah LiFePO4 car battery pack. then buy 16 series LiFePO4 battery protection board. Control current normal 6a, max 12a, instant 18a will be fine.

Prepare materials, including stainless steel battery box.
20 LiFePO4 battery cells assembled into a string. A total of 8 strings.
8 strings of lithium batteries connected in parallel, and then use the spacer and tape to do a good job of insulation.
tape fixed, series welding protection line.
LiFePO4 car battery is very harmful if short circuit. So we should use heat shrink film to insulate the series welded lithium battery package. Connect the protection board, good insulation to prevent short circuit.
heat shrink film wrapped battery, LiFePO4 car battery assembly is complete, put it into the car.

diy lifepo4 car battery

Part 3. DIY LiFePO4 car battery production tips

1. LiFePO4 car battery inspection

Check the quality of all connections during the disassembly of the battery. Also check whether the fuse holder, charging socket, and EV lithium battery lead wire contact is normal and reliable, and tighten all connections. Those that need to be replaced should be replaced, and should focus on examining their reliability, and those that are unreliable should be replaced.

2. LiFePO4 car battery installation

LiFePO4 car battery should be installed according to the instructions in the battery box. In fact, most of the batteries inside the battery box each battery is connected in series. Use copper wire to solder each battery together with a soldering iron.

Finally, there are two output terminals, positive and negative, which are soldered to the two terminals of the output socket. Be careful not to connect the reverse, must correspond to the positive and negative poles on the charger.

3. LiFePO4 car battery trial

After installing the LiFePO4 car battery, use a multimeter to measure the voltage of the battery output port. The actual voltage of the battery should be 2~5V higher than the standard voltage, and it can be put into normal operation only after it is normal.

Part 4. FAQs

Can I use a LiFePO4 battery in my car?

LiFePO4 batteries can be used in cars as a replacement for traditional lead-acid batteries, providing benefits such as longer lifespan and higher energy density.
Can LiFePO4 batteries be used in electric vehicles?

LiFePO4 batteries can be used in electric vehicles, offering advantages such as higher safety, longer cycle life, and better performance in extreme temperatures.
Can a car alternator charge a LiFePO4 battery?

A car alternator can charge a LiFePO4 battery, but it may require a compatible charging system or a specialized LiFePO4 battery charger for optimal charging.
What are the disadvantages of LiFePO4 batteries?

Disadvantages of LiFePO4 batteries include higher cost compared to other lithium-ion chemistries, lower energy density, and slightly lower specific power compared to some alternatives like lithium-nickel-manganese-cobalt oxide (NMC) batteries.