As is well known, 12V lithium iron phosphate batteries are suitable for trolley motors and car emergency starters, but RVs, marine, and off-grid solar systems require batteries with higher power output. This often confuses many business owners and DIY enthusiasts. Hongyitai Technology Co., Ltd. specializes in producing various lithium iron phosphate batteries. We will guide you on lifepo4 batteries in series via 3.2V lithium iron phosphate cells to to form 12V, 24V, 36V, and 48V, eliminating any problems you may encounter during installation.
The purpose of series connection in lithium batteries is to increase voltage. The positive terminal of the first cell is connected to the negative terminal of the second cell, the positive terminal of the second cell is connected to the negative terminal of the third cell, and so on.
This positive-negative connection method ensures that current flows through a single path, and the total voltage is equal to the sum of the voltages of each cell. That is: B1+→B2-, B2+→B3-, B3+→B4-, and the output terminals of the entire battery pack are B1- and B4+.
Wiring LFP batteries in series rules
Before connecting a lithium iron phosphate battery pack, the following safety rules are crucial:
- Cell matching requirements
Each cell must have the same capacity. 50Ah and 100Ah batteries must never be connected in series.
Cells must be from the same manufacturer and batch. Cells from different batches or manufacturers have different chemical compositions; mixing them is not recommended.
Same State of Charge (SOC). Cells awaiting matching must be at the same voltage (±0.05V), properly charged or discharged to the specified voltage range.
Cells from the same production date. Mixing old and new batteries is not recommended.
- Pre-connection checklist
Check cell voltage with a multimeter.
Confirm the BMS (Battery Management System) is compatible with your battery pack power.
Consist the total battery pack voltage is compatible with the inverter and charger.
Wear insulated gloves and safety glasses during the connection process.
- Correct wiring sequence
Connect the BMS first → then connect in series → finally connect the load/charger.
How to connect 4 cells in series to 12V LiFePo4 battery?
The 4S Lifepo4 battery pack is commonly used to replace lead-acid batteries, providing a stable power supply for trolling motors. Taking a 12V 100Ah Lifepo4 battery as an example, you will need the following materials:
4 × 3.2V LFP battery cells, 4 series BMS (supporting overcurrent up to 200A), AGW 6 wires for main power, AWG 18 for balancing, heat shrink tubing, and fuses.
Connection step below:
Place the cells side-by-side, ensuring terminals are in contact.
Connect the series wires: Cell 1(+) → Cell 2(-), Cell 2(+) → Cell 3(-), Cell 3(+) → Cell 4(-)
Install the BMS:
B- Connect to the negative terminal of Cell 1 (total negative terminal)
B1, B2, B3 Connect to the connection points between the cells.
B4 Connect to the positive terminal of Cell 4.
P- As the new system negative output.
Add the main fuse (150A-200A) to the positive output terminal.
Test Voltage: The total voltage should display 12.8V-13.2V; each cell 3.2V-3.3V. View more 12V Lifepo4 battery products in details.
How to connect 8 cells in series to 24V LiFePo4 battery?
Eight 3.2V LiFePO4 cells connected in series can form a 24V (actually 25.6V) battery pack, requiring BMS protection and balancing connections. Taking a 24V 50Ah LiFePO4 battery as an example, you will need the following materials:
Eight 3.2V 50Ah LiFePO4 cells, a 24V BMS (supporting overcurrent up to 100A), pure copper busbars, M8 copper lugs, nylon insulating tubing, a multimeter, and insulating tape.
The specific connection steps are as follows:
1. Arrangement: Place the eight cells horizontally in a straight line, with a 2cm spacing. The negative terminal of cell 1 should face left (system overall negative), and the positive terminal of cell 8 should face right (system overall positive). Secure their positions with double-sided tape to prevent movement.
2. Connect the cells in series: cell1+ → cell2- (busbar A), cell2+ → cell3- (busbar B), and so on.
3. Connect the BMS: B0 → cell1-, P+ → cell8+.
4. Main Output Circuit: System negative terminal: led out from Cell1- (M10 copper lug); System positive terminal: led out from Cell8+ (M10 copper lug); add a 100A fuse to the positive terminal.
5. Testing: Measure the total voltage (25.6V) and the voltage of each cell (3.2V) under no-load conditions.
Click to view more 24V lfp battery products with details.
How to connect 12 cells in series to 36V LiFePo4 battery?
To construct a 36V (actually 38.4V) battery pack by connecting 12 3.2V LFP cells in series, a BMS and balancing connection are also required. Taking a 36V 50Ah LifePO4 battery as an example, you will need the following materials:
12 balanced 3.2V 50Ah cells, a 36V BMS (supporting overcurrent up to 100A), 25mm² pure copper cable (AWG4), a 100A ANL fuse, and M8 copper lugs.
The specific connection steps are as follows:
1. Connect the cells in series: Cell1+ → Cell2- (busbar 1), Cell2+ → Cell3- (busbar 2), and so on, Cell11+ → Cell12- (busbar 11). Total negative terminal: cell1-, total positive terminal: cell12+.
2. Connect the BMS: B0 → Cell1-, P+ → Cell12+ (connect the 100A fuse in series).
3. Insulation: All exposed metal parts are wrapped with heat shrink tubing, and series connection points are wrapped with insulating tape.
4. Testing: No-load total voltage: 38.4V ± 0.2V, voltage per cell: 3.2V.
View more of our 36V Lifepo4 battery products.
How to connect 16 cells in series to 48V LiFePo4 battery?
16S deep cycle batteries are commonly used in residential energy storage and 48V solar systems. They consist of 16 cells connected in series, but because 48V DC can be fatal, additional protection is required: 1000V rated insulated tools, a disconnect switch between the battery and the inverter, an additional protection device between the positive and negative terminals (double protection), and the battery negative terminal should ideally be grounded.
LiFePo4 battery series combination safety & warning
BMS limitations: Regardless of the type of lithium iron phosphate battery, it requires BMS protection for overcharge, over-discharge, short circuit, undervoltage, and temperature.
Passive balancing: a standard configuration of most BMS systems. Before battery cells are grouped together, we check the voltage of each cell and require the voltage difference to be <0.05V.
Choosing the right wire gauge and fuse is also important. The fuse should be installed at the positive terminal of the battery, and it’s best to choose one with a cover to prevent water damage.
| System Voltage | 100A Loading | 200A Loading | Fuse Specs |
|---|---|---|---|
| 12V (4S) | 2 AWG | 2/0 AWG | 125A / 250A |
| 24V (8S) | 4 AWG | 1 / 0 AWG | 125A / 250A |
| 48V (16S) | 6 AWG | 2 AWG | 125A / 250A |
Don’t confuse this with “parallel.” Battery parallel connection refers to connecting the positive terminals of the first and second cells together to increase capacity and extend operating time. Of course, we often see multiple series and parallel combinations; click to see more about series and parallel differences.
FAQs of LiFePo4 Series Connecting
No, if a 50Ah and a 100Ah battery are connected in series, the entire battery can only be charged and discharged based on the 50Ah battery, which may also create a potential risk of damage.
Before connecting the batteries in series, you need to confirm with the supplier whether this 12V lifepo4 battery supports series connection (BMS determines this), and then follow the manufacturer's operating instructions.
One of the most common problems is that the BMS cannot be activated. It is most likely that the voltage of a certain cell is less than 2V, which requires charging that cell to 3.2V separately.