Round-trip efficiency (RTE) measures energy losses during charge/discharge cycles and directly impacts battery performance across several key aspects:
1. Energy losses
Every 1% drop in RTE translates to lost usable energy. For example, a 90% RTE battery returns 90 kWh for every 100 kWh stored, while a 94.5% RTE battery (like EG4-LL) recovers 94.5 kWh. Lower RTE necessitates oversized storage capacity to compensate for losses.
2. Heat generation
Inefficiencies manifest as heat, requiring thermal management systems to prevent capacity degradation and safety risks. This increases system complexity and costs.
3. Cost-effectiveness
Higher RTE (e.g., 93-94.5% for modern LiFePO4 batteries) reduces operating costs by minimizing wasted energy. Lower RTE systems require more frequent charging to maintain equivalent output, shortening battery lifespan.
4. Application suitability
Grid-scale applications prioritize high RTE (80-95% for lithium-ion vs. 70-85% for older tech) to maximize ROI. Seasonal storage systems may tolerate lower RTE if cycled infrequently.
Key RTE comparisons
| Battery Type | Typical RTE | Key Factors |
|---|---|---|
| Lead-acid | 70-80% | High internal resistance |
| Standard Li-ion | 83-85% | Electrolyte chemistry |
| Advanced LiFePO4 | 93-94.5% | BMS optimization |
| Pumped hydro | 70-85% | Mechanical losses |
Higher RTE indicates better energy preservation, reducing grid strain and improving renewable energy utilization. Battery management systems (BMS) and improved cell chemistry now push RTE boundaries beyond 90%, making modern batteries more viable for high-cycle applications like frequency regulation.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-round-trip-efficiency-of-batteries-affect-their-overall-performance/
