If you are planning to build your own electric vehicle, then you must know about the Daly 4S BMS (Battery Management System). It is a crucial component that helps to protect your battery from overcharging, over-discharging, and over-current. In this article, we will discuss the Daly 4S BMS wiring diagram, which is a blueprint for connecting the BMS with your battery pack, charger, and load.
What is Daly 4S BMS?
The Daly 4S BMS is a small electronic module that monitors and controls the voltage, current, and temperature of your lithium-ion battery pack. It consists of a microcontroller, a voltage sensing circuit, a current sensing circuit, a temperature sensing circuit, and a relay. The microcontroller reads the voltages from the battery cells, the current from the charger and load, and the temperature from the thermistor. Based on these readings, it makes decisions to charge, discharge or balance the battery.
What are the Specifications of Daly 4S BMS?
The Daly 4S BMS has the following specifications:
- Rated Voltage: 14.8V
- Maximum Voltage: 16.8V
- Minimum Voltage: 12.0V
- Balance Current: 45mA
- Charging Current: 20A
- Discharging Current: 20A
- Operating Temperature: -10°C to +50°C
How to Wire Daly 4S BMS?
Wiring the Daly 4S BMS is not complicated, but it requires some basic understanding of electrical circuits and safety precautions. You need to follow the wiring diagram carefully to ensure that the BMS is connected properly and works as intended. Here is the step-by-step guide for wiring Daly 4S BMS:
Step 1: Prepare the Battery Pack
Before wiring the BMS, you need to prepare the battery pack by soldering the nickel strips to the battery cells and connecting them in series. The number of cells depends on the voltage of your application. For example, a 12V battery pack consists of four 3.7V lithium-ion cells in series. Make sure that the nickel strips are clean, flat, and have good conductivity.
Step 2: Connect the BMS to the Battery Pack
The first connection is between the B- terminal of the BMS and the negative terminal of the battery pack. This is the common ground for the BMS and the battery. Then, connect the B1, B2, B3, and B4 terminals of the BMS to the positive terminal of the respective cell in the battery pack. This is how the BMS reads the voltage of each cell individually.
Step 3: Connect the BMS to the Charger
The second connection is between the P- terminal of the BMS and the negative terminal of the charger. This is where the charging current flows into the battery pack through the BMS. Then, connect the P+ terminal of the BMS to the positive terminal of the charger. This is where the charging voltage is applied to the battery pack.
Step 4: Connect the BMS to the Load
The third connection is between the C- terminal of the BMS and the negative terminal of the load. This is where the discharging current flows out of the battery pack through the BMS. Then, connect the C+ terminal of the BMS to the positive terminal of the load. This is where the load voltage is applied to the battery pack.
Step 5: Connect the Balance Wires
The final connection is between the balance wires of the BMS and the balance plug of the battery pack. The balance wires are thin wires that connect the BMS to the balancing circuit of the battery pack. They ensure that each cell is at the same voltage level and prevent overcharging and over-discharging of the battery. There are four balance wires, one for each cell. Make sure that you connect them correctly according to the wiring diagram.
BMS Wiring Diagram
Here is the wiring diagram for Daly 4S BMS:
| BMS Terminal | Battery Pack Terminal | Charger Terminal | Load Terminal |
| B- | Negative | – | – |
| B1 | Positive of Cell 1 | – | – |
| B2 | Positive of Cell 2 | – | – |
| B3 | Positive of Cell 3 | – | – |
| B4 | Positive of Cell 4 | – | – |
| P- | – | Negative | – |
| P+ | – | Positive | – |
| C- | – | – | Negative |
| C+ | – | – | Positive |
BMS FAQ
1. Why do I need a BMS?
You need a BMS to protect your battery from damage and prolong its life. The BMS ensures that the battery is charged and discharged properly, and each cell is at the same voltage level. It also prevents overcharging, over-discharging, and over-current, which can cause fires, explosions or permanent damage to the battery.
2. Can I bypass the BMS?
No, you should not bypass the BMS. It is a safety feature that you cannot afford to lose. If you bypass the BMS, you risk damaging your battery and endangering yourself and others. Even if you think you know what you are doing, the consequences of a mistake can be catastrophic.
3. Can I use a different BMS?
Yes, you can use a different BMS, but you need to make sure that it has the same specifications and functions as the Daly 4S BMS. You also need to follow the wiring diagram carefully and test the BMS before using it with your battery pack.
4. How do I test the BMS?
You can test the BMS by using a multimeter to measure the voltages across each cell, the charger and the load. You should also check the balance function by monitoring the voltage differences between the cells during charging and discharging. If everything works as expected, you can use the BMS with confidence.
5. Where can I buy Daly 4S BMS?
You can buy Daly 4S BMS from online retailers such as Amazon, AliExpress, or eBay. Make sure that you buy from a reputable seller and check the feedback and reviews from other customers. You should also read the product specifications and user manual carefully to ensure that it meets your requirements.
