The lifespan of energy storage batteries varies depending on several factors, such as battery type, usage cycles, and operating conditions. Here are some estimates based on the search results: Residential energy storage batteries can last anywhere between 5 to 15 years. The life expectancy of a solar battery is mostly determined by its usage cycles, and most solar batteries are generally deep-cycle batteries, which allows them to discharge up to 80% of their stored energy before recharging. The useful life of a battery is typically said to be at the end when it fails to meet around 60% of its nominal storage capacity. The timing of battery replacement or supplementation can be affected by the amount of system capacity overbuilt on the front end of a project. It’s important to note that these numbers are estimates, and the actual lifespan of an energy storage battery will depend on factors such as battery type, usage cycles, operating conditions, and maintenance.