Capacity retention

Also known as Energy retention, Retained capacity, Remaining usable capacity

Capacity retention describes how much of a battery's original usable capacity or nameplate rating remains available after age and use.

Capacity retention describes the usable capacity a battery can still deliver compared with its original usable capacity or nameplate rating. In home battery warranties it is usually written as a retained percentage at the end of a warranty period, after a cycle limit or after a stated energy throughput. The baseline matters because one document may refer to nameplate rating while another uses remaining usable capacity. Temperature, cycling, charge and discharge rates, reserve settings, installation conditions and warranty exclusions can affect how a battery ages and how a warranty claim is assessed. The term matters when reading datasheets, warranties and handover documents because a 10 kWh battery with a 70% retained-capacity level is being assessed against about 7 kWh under the warranty's measurement conditions, not the full original figure.