RELATED: What size home battery do I need?
Warranty and cycle life
Two numbers set the standard. The warranty, usually 10 years, and the cycle rating, usually around 6,000 cycles. Most warranties read as 10 years or 6,000 cycles, whichever comes first.
A cycle is one full charge and discharge. If you cycle the battery once a day, 6,000 cycles is over 16 years of use. Most UK homes do less than one full cycle a day, especially in winter, so the calendar tends to run out before the cycles do.
The chemistry matters here. Modern home batteries use lithium iron phosphate, often shortened to LFP. It holds up far better over time than the older lithium types, and the UK climate helps. Batteries dislike heat, and heat is not something we get much of.
How capacity fades
A battery does not hold the same amount forever. Capacity drops slowly, around 2% to 3% a year in normal use. That fade is gradual, not a cliff.
At the end of a 10 year warranty most batteries still hold 70% to 80% of their original capacity. The warranty itself guarantees a floor, commonly 70%, so if the battery falls below that inside the term it is covered. A 10kWh battery holding 7kWh to 8kWh after a decade is still doing real work every evening.
Where the battery sits makes a small difference. A unit in a cool utility room ages slower than one in an unheated loft that swings hot and cold. We advise on the best spot at survey.
Real life beyond the warranty
The warranty is not the finish line. Field data from UK installers now shows LFP batteries running usefully for 12 to 18 years, and some reaching 20 in mild conditions with moderate use.
Replacement is a judgement call, not a breakdown. Most people think about it when capacity drops toward half the original, because the evening cover starts to fall short. Until then the battery keeps saving money quietly in the background.
Every battery we fit is covered by that 10 year warranty as standard, and we are not tied to one manufacturer. We fit the unit that suits your home and back it for the long term.
