Signs a Home Battery Has Reached the End of Its Life

Batteries wear out slowly, not suddenly. Over their lifespan, batteries degrade, which reduces cyclable charge, the energy you can cycle in and out¹. A battery that runs for less time than it used to isn't necessarily dead, and it isn't necessarily fine.

What "end of life" means on paper

For lithium-ion batteries, manufacturers typically specify cycle life as the number of cycles until capacity falls to 80% of its rated value¹. A cycle is one full charge and discharge. So "end of life" on a spec sheet is often a line drawn at a loss of capacity, not the moment the battery stops working. A battery past that line can still run, only for less time.

Chemistry changes the numbers. LFP chemistry offers a considerably longer cycle life than other lithium-ion chemistries, and under most conditions it supports more than 3,000 cycles². Your own product's rated figure is in its manual or spec sheet, and that figure is the one to use.

Signs that point to wear

None of these alone proves a battery is finished. Together they're a reason to ask.

• Shorter runtime. The unit carries your loads for less time than it did when it was new, which fits the gradual loss of capacity described above¹.
• It falls short of its rating. If the maker states a percentage of rated capacity at end of life, compare against that.
• Repeated error or fault messages. Check what your manual says each code means.
• Lead-acid only: abuse history. For lead-acid, repeated deep discharges will result in capacity loss and, in time, premature failure³.

Signs that mean stop

Some signs aren't about wear. A swollen, dented or leaking case is a damage problem, not a wear problem. If you see it, stop using the battery and go to the damaged-battery page.

Finished or just needing service?

You usually can't tell from the outside. EPA notes that not all batteries are removable or serviceable by the user⁴. Follow your manual and contact the maker or the company that installed the battery⁴.

So read the manual first. Then contact the maker or the installer, who EPA says to contact for energy storage equipment⁴. A hard-wired home battery should only ever be opened or disconnected by a licensed electrician.

When the answer is "finished"

Don't put the battery in the trash. Cover the terminals and hold it the way the storage page describes, then choose where to take it with the help of this guide to collection sites. If the warranty or a take-back scheme applies, ask the maker before you do anything else.