Battery performance and warranties: Look for these seven things in your battery warranty’s fine print

battery warranty fine print

Beyond merely setting guidelines for battery repair and replacement, battery warranties can serve as a valuable buyer’s guide for your next energy storage project. As the old adage advises, “it’s all in the fine print!”

Indoor vs. outdoor installation location

If the warranty specifies coverage limitations related to the temperature in which the batteries are installed, you know that you’re limited to an indoor installation location, which may present challenges in terms of available space in a home or garage. Temperature limitations can also limit the regions in which certain storage technologies can be deployed, as well as the use cases for which they are suitable.

Thermal controls

Many battery warranties require that the ambient temperature surrounding the batteries be maintained in a narrow window of ~75℉. To “prove” these conditions are met and protect the warranty, thermal monitoring equipment is required, which adds ancillary system costs. In addition, because many batteries are rated at 75℉, operating outside this temperature range can affect the number of cycles warrantied.

Data collection

To protect the terms of the warranty, monitoring equipment may be required to record battery performance and environmental data in real time to be sent to the manufacturer and stored in the cloud. For example, if there is a battery failure and the manufacturer does not have access to data that proves the ambient temperature window has been maintained, the warranty is void. Installation of monitoring equipment adds complexity, points of failure and additional expense to a project.


A warranty may include scalability restrictions or specify that the initial battery bank cannot be expanded. If a customer is anticipating that his or her family or business will grow over time, it’s important to deliver an energy storage solution that can grow with the customer’s energy needs.


Some battery chemistries pose a risk of thermal runaway and toxicity. To mitigate that risk and safeguard an intrinsically unsafe, unstable and toxic chemical base, warranties for these batteries require cooling, fire suppression and monitoring equipment. These requirements add cost, complexity and potential points of failure to an installation. Plus, customers may object to the idea of storing clean energy in a toxic battery.

Performance profile/metrics

Pay close attention to what’s warrantied vs. what’s specified. The battery spec sheet or other marketing material might promise that a battery will last 10,000 cycles. But the truth can be found in the warranty, which often indicates a far different lifespan. Consider this typical warranty statement: “You will get 10,000 cycles at X depth of discharge if you maintain the battery at 75 degrees.”

End of life

If the EOL is warrantied at 60%, that tells you that the battery’s throughput and amount of usable energy decreases significantly over time.

Though marketing materials and spec sheets may be misleading, the warranties reveal the truth, providing a great tool for installers to leverage when choosing their energy storage solution.

This post and the entire 12 Days of Storage was contributed by SimpliPhi.

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