On-Board vs Off-Board Chargers: What OEMs Should Know
The electric vehicle market is in overdrive, and along with it, the serious choice of the charging infrastructure. In the case of OEMs involved in the development of electric two-wheelers, three-wheelers, and light commercial vehicles, the basic differences between on-board and off-board chargers determine the success of the product and its customer satisfaction.
Understanding the Two Charging Architectures
On-board chargers are designed to be embedded directly in the automobile to transform AC power that is supplied in regular electrical outlets to DC power that is used to charge the battery. These miniature power electronics systems accompany the vehicle, enabling it to be charged anywhere there is AC power.
Portable chargers or external chargers are off-board chargers, which are independent of the vehicle. These are freestanding charging stations that can be more powerful and do not add weight to the vehicle itself,f but they need specific infrastructure.
Key Considerations for OEMs
- Power Density and Vehicle Design
Chargers should be on board without infringing space in the chassis of the vehicle. The latest solutions apply modern power electronics to provide a high rate of charging in a very small space. Weight-to-power ratio is essential in the case of electric two-wheelers and three-wheelers.
Off-board chargers have no constraint on the space, thus can have a higher power output and can charge faster. This, however,r involves an investment in infrastructure and constrains flexibility.
- Charging Flexibility and User Experience
The charging systems are done on board with maximum convenience. The vehicle owners can charge it at home, at work, or anywhere with AC power. This is beneficial in markets where charging infrastructure is emerging.
The off-board systems can charge more quickly, but the charger has to be carried or used at special stations, which causes logistics problems for fleet operators.
- Cost Implications
On-board chargers would be a single manufacturing cost that can be found in the bill of materials of the vehicle. This will add to the upfront cost of the vehicles, but remove the need to purchase separate charging equipment.
Off-board systems can lower the cost of the vehicle but need to invest in charging infrastructure. Total cost of ownership is more complicated in the case of fleet operators who utilise a number of vehicles.
Technical Specifications That Matter
- Power Output and Charging Time
Electric two-wheelers and three-wheelers have on-board chargers of between 1kW and 6kW. A typical 3kWh battery can be charged in a matter of one hour using a 3.3kW on-board charger.
The off-board fast chargers may be used to supply 6kW to 10kW and above, which greatly minimizes the charging time. Nevertheless, the battery management system should have the capability to enable such increased charging rates without reducing the battery life.
- Efficiency and Environmental Durability
Contemporary on-board chargers include power factor correction (PFC) and high efficiency conversion circuits with efficiencies of more than 90%. These systems should be able to work between -35 C and +65 C and that should withstand road vibration and weather conditions. IP67 sealing protection is used to resist dust and water intrusion which is essential under a variety of operation conditions.
- Communication and Intelligence
Modernized on-board chargers have CAN communication, where real time data transfer is possible between the charger, the battery management system, and the vehicle controller. This integration assists in adaptive charging depending on the temperature of the battery, diagnostic, and firmware upgradability.
Similar intelligence can be implemented with off-board chargers though standardized communication protocols between the charger and vehicle systems are required.
- Safety and Regulatory Compliance
Both architectures of charging will be required to adhere to the IS 17017-1 (ICAT), AIS 039 and IEC 61851 standards. Such safety measures as overcurrent, overvoltage, short-circuit, and thermal protection should be provided. On-board systems have the advantage of being more closely integrated into the safety architecture of the vehicle.
Making the Right Choice
In the case of the mass-market electric two-wheelers and three-wheelers with individual consumers as their target, on-board charging will provide the best balance of convenience, affordability, and experience. AC charging eliminates major obstacles to EV adoption since people can charge anywhere.
In commercial fleet usage where operations are centralized a hybrid method is effective, in which vehicles are fitted with on-board chargers to conduct overnight charging, and off-board charging of higher power at depot points.
Solterra’s Approach to Charging Solutions
Power electronics designed at Solterra are optimally tailored to the challenging electric mobility needs. The combination of IP67-sealed and harsh construction with smart power management makes our on-board and portable charging systems reliable and available in the most extreme operating environments.
Having all the solutions, including small on-board chargers, high-power mobile chargers, etc., we can assist OEMs in making the right choice depending on the target market and platforms of particular vehicles. Our engineering-based strategy guarantees a smooth level of integration with battery management systems and vehicle architectures.
Conclusion
The option between on-board and off-board charging is determined by the target market, situations of use and the overall cost of ownership. The insights of these factors will inform the best charging strategy of the electric vehicle platforms.
In the case of OEMs making such difficult technical choices, collaborating with knowledgeable power electronics suppliers who are well aware of the challenges in engineering as well as realities in the market places are sure to help them to have charging solutions that will meet the present needs yet be flexible to meet future innovations.
About Solterra Technologies
Solterra is a technology-based power electronics firm that is developing rugged connected and reliable energy systems in EV and electrification ecosystems. Having extensive knowledge in on-board chargers, portable chargers, and power modules, Solterra is an engineering partner of OEMs and infrastructure developers constructing electric mobility.