Other Parts Discussed in Thread: LM5171, BQ77PL900, BQ78PL114
I plan to connect two 600 watt 3 volt Sodium Ion Battery Cells in Series Parallel and plan to use the LM5171 + bq77PL900 for passive cell balancing bq78PL114. Please keep in mind we want these components to help enable 8000-10,000 Battery Cycles over 20-25 years. Can we combine these two components? We will not use a typical Battery Management System as they only last 5-10 years. Is combining LM5171 + bq77PL900 possible? Our other choice is to use two LM5171 Board at 3 volts where we connect the 200 amp hour 3 volts cells in parallel.
bq77PL900 or a bq78PL114
design a system where the bq77PL900 (used for passive cell balancing within a battery pack) works in conjunction with the LM5171 (which manages power conversion) to optimize battery discharge and then step up the voltage for AC conversion by an Enphase microinverter. Here’s a high-level overview of how this system could be structured:
Step 1: Passive Cell Balancing with bq77PL900
- The bq77PL900 can monitor individual cell voltages within your battery pack and engage passive balancing to ensure all cells are kept within a similar voltage range. This process involves dissipating excess energy from higher-charged cells as heat, thus preventing any single cell from becoming overcharged and promoting longevity and efficiency of the battery pack.
- It's worth noting that passive balancing is more about maintaining cell health and balance rather than actively discharging the battery pack for energy utilization.
Step 2: Voltage Step-Up with LM5171
- Once the cells are balanced and the battery is discharging, the LM5171 can take the output from the battery pack and step it up to the required 22 volts needed by the Enphase microinverter.
- The LM5171 is designed for high-efficiency power conversion and can handle the bidirectional transfer of power, although in this scenario, you are primarily concerned with stepping up the voltage from the battery pack for AC inversion.
Step 3: AC Conversion and Grid Integration
- The stepped-up DC voltage (22 volts) provided by the LM5171 is then converted into AC by the Enphase microinverter, which can then be synchronized and fed into the grid.
- Microinverters like those from Enphase are designed to convert DC to AC at a very high efficiency, and they include the necessary circuitry to ensure that the AC output is in phase and meets the grid's voltage and frequency standards.
Considerations:
- System Integration: This approach requires careful system integration to ensure that the operations of the bq77PL900 and the LM5171 are well-coordinated. While the bq77PL900 will primarily be active during the charging or when balance is needed, the LM5171's operation during battery discharge needs to be efficiently managed.
