In our ongoing efforts to revolutionize battery systems for maritime applications, it’s important to spotlight some of the standout features offered by the SEABAT concept. While these features may not be entirely new, the true contribution of SEABAT lies in demonstrating their feasibility within a larger ship system.
- Elimination of Large DC-DC Converters
The SEABAT system eliminates the need for bulky DC-DC converters between the battery system and the DC grid, simplifying the overall architecture. - Versatile Battery Usage
The same battery system can accommodate various DC bus voltages, ranging from zero to the maximum design voltage, enhancing flexibility and adaptability. - Controlled Output Voltage
When connected directly to a DC link, the system maintains a controlled output voltage. Connected converters are not required to be rated for a wide voltage range due to the voltage variations that occur between fully charged and discharged batteries. - Advanced Power Flow Management
The SEABAT system can effectively control power flow both in and out of individual modules within the same string, as well as manage power flow in each parallel string. This capability allows for the maintenance of equal state of charge (SOC) across all modules, regardless of factors such as aging or other performance variations. - Compatibility with Diverse Cell Types
The system can seamlessly integrate parallel strings with different cell types—such as those with varying voltage profiles or C-rates—allowing for greater versatility. It can also accommodate cells with different aging profiles, which is particularly relevant for second-life applications. - Utilization of Varied State of Health (SOH)
The SEABAT system allows for the use of modules with differing SOH within the same string, maximizing the capacity of each individual module. This feature is crucial for second-life utilization. - Temperature Management
The system can account for differences in cell temperatures, automatically reducing power flow in modules that exhibit higher temperatures, thus enhancing safety and efficiency. - Reduced Standby Losses
In larger systems, it’s possible to minimize standby losses by disabling certain strings when they are not needed. - Simplified State of Charge Management
There is no need to equalize the state of charge before closing bus ties or reconnecting batteries, which is a common requirement in current applications that directly connect batteries to DC buses. - Improved Capacity Utilization
In traditional battery systems, the overall capacity is limited by the single cell (or parallel connection of cells) with the lowest capacity. In contrast, the SEABAT system allows only the module with the weakest cell to be limited, thereby optimizing performance. - Onboard Capacity Testing
The SEABAT battery system allows for capacity tests—full charge-discharge cycles to verify exact storage capacity—without taking the vessel out of operation. This means one or a few strings can be tested at a time while the others continue to meet the vessel’s demand, resulting in significant operational cost savings for vessels required to perform such tests regularly. - Low Short Circuit Current
The system features low or insignificant short circuit currents in the event of an external short circuit, enhancing safety. Additionally, the easy scalability of energy capacity means that adding more strings only results in a minimal increase in worst-case short circuit currents. - Simplified Precharging
There is no need for extra hardware for the precharging of the DC bus when connecting the battery and DC bus. This function is managed by the modular converters. - Efficient Shore Charging
Charging from the shore can be accomplished using a simple diode rectifier, with the modular converters controlling the charging current or power.