BESS round-trip efficiency decay
Falling round-trip efficiency as internal resistance rises.
Round-trip efficiency (RTE) decay is a gradual fall in the ratio of energy out to energy in, driven by rising internal resistance, ageing, or auxiliary (HVAC) load. A drop below ~85% RTE means more energy is lost as heat on every cycle — directly eroding arbitrage and ancillary-services margin.
Symptoms
- Measured RTE trending downward cycle-over-cycle.
- More heat generated per cycle (rising auxiliary cooling demand).
- Lower net throughput for the same charge energy.
SCADA signatures
- RTE (energy discharged ÷ energy charged) declining toward the 85% line.
- Internal-resistance proxy rising; voltage sag under load increasing.
- Auxiliary/HVAC consumption climbing as a share of throughput.
Root cause
Increasing cell internal resistance from ageing, degraded electrical connections, BMS miscalibration, or a growing parasitic auxiliary load. Each lost percentage point of RTE is energy you paid to store and never sold.
Financial impact
On an arbitrage asset, a 2-point RTE loss is a direct hit to spread margin on every cycle, compounded across thousands of cycles a year. It is also a diagnostic signal — rising resistance often precedes other cell-level faults.
How NuraVolt detects it
NuraVolt computes RTE per cycle, trends it, and projects days until it crosses the efficiency floor. It separates cell-resistance-driven decay from auxiliary-load growth so the fix is targeted (connections/BMS vs. HVAC) rather than guessed.
Frequently asked questions
See also
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NuraVolt turns your SCADA and BMS data into early fault detection, degradation-aware BESS analytics, and audit-ready reporting. A fixed-scope audit shows you what we’d find on your portfolio.