How Long Will a Battery Last

Most home batteries sold in the UK are warranted for 10 years or a set number of charge cycles — typically 6,000–10,000 cycles — whichever comes first. At one cycle per day, 6,000 cycles is over 16 years.

What the warranty covers

A standard battery warranty guarantees the battery will retain at least 70–80% of its original usable capacity by the end of the warranty period. A 10 kWh battery under a 70% end-of-warranty guarantee still provides 7 kWh of usable capacity after 10 years — enough for most evenings' needs.

What affects how long a battery lasts

• Depth of discharge (DoD) — regularly cycling to 0% shortens life compared to keeping above 10–20%. Good BMS systems manage this automatically.
• Operating temperature — extreme heat accelerates degradation. Batteries in uninsulated south-facing garages in summer can degrade faster than those in cool, shaded utility rooms.
• Charge rate — fast-charging at maximum rate every day stresses cells more than a moderate rate. Properly managed hybrid inverters avoid this.

What happens after the warranty period

The battery does not stop working at year 10. Degradation is gradual, and most batteries continue operating at reduced capacity well beyond the warranty period. Replacement batteries are becoming cheaper as the market matures — prices have fallen roughly 40% in five years.

Should degradation put you off?

Not if the numbers still work at degraded capacity. Even at 70% after 10 years, a battery generating £700/year in savings at full capacity generates £490/year — still a meaningful contribution. Run the numbers on degraded capacity, not peak capacity, when assessing long-term value.