Degradation curve
Also known as: Warranty Curve
A graph showing the projected decline in battery State of Health (SoH) over time or equivalent full cycles. The shape of the curve depends on the load profile — number of cycles per day, depth of discharge, C-rate, and operating temperature. OEMs provide contractual degradation curves as part of performance warranties, guaranteeing minimum SoH at defined intervals throughout the project lifetime.
In energy storage
OEM degradation curves are typically provided for a specific load profile (e.g. one cycle per day at 0.5C, 25°C, 90% DoD) — operating outside these conditions may void or alter warranty terms. An independent engineer verifies actual degradation against the contractual curve through periodic capacity tests, and the gap between the curve and measured SoH determines whether a warranty claim or augmentation is triggered.
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