Connecting lithium batteries involves joining multiple battery cells or packs together to achieve a desired voltage or capacity. The method you use depends on whether you need more voltage or more runtime (capacity).
To connect lithium batteries, you primarily use two configurations: series and parallel. The specific method described in the provided reference details connecting batteries in series.
Series Connection
Connecting batteries in series increases the total voltage while keeping the capacity the same (relative to a single battery). This is useful for powering devices that require a higher voltage than a single battery can provide.
Based on the reference:
While connecting the batteries in the series, you must connect the negative terminal to the positive and then connect it to the system you want to power.
Here's a simple breakdown:
- Step 1: Take the negative terminal of the first battery.
- Step 2: Connect it to the positive terminal of the second battery.
- Step 3: Repeat this process for any additional batteries you want to add in series (negative of battery 2 to positive of battery 3, and so on).
- Step 4: The remaining positive terminal of the first battery and the negative terminal of the last battery in the chain become your main positive and negative outputs for connecting to the device or system you want to power.
Key Result: In this way, you can connect as many batteries as you want, but keep in mind that it will only increase the voltage, not the capacity. For instance, connecting two 3.7V, 2000mAh batteries in series results in a 7.4V battery bank with 2000mAh capacity.
Parallel Connection (For Increased Capacity)
While the reference doesn't detail parallel connections, it's the other primary method for combining batteries. Parallel connection increases the total capacity (runtime) while the voltage remains the same (relative to a single battery).
- Method: Connect all positive terminals together and connect all negative terminals together.
- Result: The voltage remains the same as a single battery, but the capacity is the sum of the individual battery capacities. For example, connecting two 3.7V, 2000mAh batteries in parallel results in a 3.7V battery bank with 4000mAh capacity.
Series vs. Parallel: A Quick Comparison
Understanding the difference is crucial when deciding how to connect your lithium batteries.
| Feature | Series Connection | Parallel Connection |
|---|---|---|
| Voltage | Increases (sums individual voltages) | Remains the same (voltage of one battery) |
| Capacity | Remains the same (capacity of one battery) | Increases (sums individual capacities) |
| Wiring | Negative to positive of adjacent batteries | All positives together, all negatives together |
| Purpose | To achieve higher voltage | To achieve longer runtime (higher capacity) |
Important Considerations
When connecting lithium batteries, especially in series or parallel, it is highly recommended to use batteries of the same type, age, and capacity. Mixing different batteries can lead to imbalances, reduced performance, and potential safety issues. Using a Battery Management System (BMS) is also crucial for safety, balancing cells, and protecting against overcharging, over-discharging, and over-current.
Connecting lithium batteries involves joining them in series for higher voltage or in parallel for higher capacity. The series method involves connecting the negative terminal of one battery to the positive terminal of the next, increasing voltage but not capacity.
