When selecting DC charging power modules, people often assume that the module's rated power should match the required output power—for instance, choosing a 6kW charging module for a system that requires 6kW of power.
However, in actual practice, higher-rated modules are frequently used. For example, a 10kW module might be selected for a 6kW application, while a 20kW module might be chosen when the actual requirement is around 12kW.
What is the reason for this?
Rated Power vs. Actual Operating Power
The rated power of a charging module indicates the maximum output capability under specified operating conditions. It does not mean that the module needs to operate at this power continuously.
For example:
| Required Output Power | Module Rated Power | Approx. Operating Load |
| 6kW | 10kW | 60% |
| 12kW | 20kW | 60% |
| 16kW | 20kW | 80% |
A module operating below its maximum rated output has more available capacity. This can be useful when the charging system needs to operate continuously, when environmental conditions are demanding, or when the actual load can change during operation.
The right question is therefore not simply "How many kilowatts does the system need?" It is also "Under what conditions will the module operate?"
Operating Conditions Matter
A charging module's rated power is normally specified under defined operating conditions. In an actual installation, those conditions may be different.
Ambient temperature is one important factor. Some charging modules reduce their available output power at higher temperatures. If a module is already operating close to its rated capacity, temperature-related derating can have a greater effect on the system's available power.
Other factors can also matter, including:
- Input voltage range
- Output voltage
- Maximum output current
- Ambient temperature
- Cooling method
- Installation environment
- Continuous operating time
This is why module selection should be based on the complete datasheet rather than the kW rating alone.
Does a Higher-Rated Module Always Mean a Better Choice?
No.
Choosing a 20kW module for a 12kW application may be reasonable in one project but unnecessary in another. A higher-rated module can increase the equipment cost and may have different requirements for cooling, installation space, input current, or system integration.
The goal is not to select the largest available module. The goal is to select a module with enough capacity to meet the required output under the actual operating conditions, with an appropriate margin.
For some applications, a module operating at 70–80% of its rated power may be suitable. In other cases, a larger margin may be preferred because of temperature, load profile, or system requirements.
What Should You Check Before Selecting a Charging Module?
Key specifications include:
- Required continuous output power
- Output voltage range
- Maximum output current
- Input voltage range
- Full-power operating temperature
- Power derating curve
- Cooling method
- Communication interface
- Installation environment
- Expected future power requirements
The relationship between voltage and current is also important. A module's maximum power is limited by its available output voltage and current, so the required operating point should fall within the module's specified output range.
One-Stop Sourcing for Charging Power Modules
Choosing the right charging module is not always about finding a single model with the exact required power rating. Different projects may require different brands, power levels, output ranges, and operating characteristics.
Allblue provides access to genuine charging power modules from multiple brands and across a wide range of power ratings, allowing customers to source different module requirements through one supplier.
Whether you need a 10kW module for a 6kW application, a 20kW module for a 12kW system, or modules with different power ratings for a larger charging project, we can help source the appropriate products according to your specifications.
Instead of contacting multiple suppliers for different brands or power levels, customers can consolidate their charging module purchasing through Allblue for more efficient sourcing and supply-chain management.