Should you repair or replace your home battery?
Updated August 2026
← Every repair-or-replace call
A home battery is a sealed unit, so a failed pack is a replacement rather than a repair: $8,000–15,000 installed, and frequently free while the roughly 10-year warranty still runs. Before accepting that number, make the installer prove the cells are the fault. The gateway, the hybrid inverter, and the communication boards fail more often than the pack does, and those are $500–2,000 serviceable parts. Batteries also do not die all at once. Most warranties promise about 70% of original usable capacity at the end of the term or a stated energy throughput, so the normal end state is a battery that works but stores less than you want.
The short version
The usual repair-versus-replace arithmetic does not apply to a sealed lithium pack, because there is no partial repair to price. Ask three questions instead. Is it still in warranty, roughly 10 years or a stated throughput on most systems? Is the fault in the battery at all, or in the gateway, hybrid inverter, or comms board? And is the remaining capacity still useful to you? A pack faded to 70% is not broken, it is smaller. A 13.5 kWh unit at that level still delivers around 9 kWh, enough for overnight essentials, which is why many owners keep an aging battery on light duty and add a second one rather than spend $8,000–15,000 starting over.
Your situation, decided
| Situation | Verdict | Why |
|---|---|---|
| Under warranty, app reports a pack fault or capacity loss | Warranty claim | The manufacturer supplies the pack; confirm labor coverage |
| No output, gateway or hybrid inverter throwing a fault code | Repair | A $500–2,000 electronics fault, not dead cells |
| Out of warranty, usable capacity below what your loads need | Replace | Sealed pack, no cell-level service; $8,000–15,000 installed |
| 9 years old, holding near 70% capacity, still cycling daily | Keep it | Reduce what it backs up, or add a second unit later |
| Swelling, heat, or a burning smell at the enclosure | Shut it down now | Safety outranks cost; call the installer the same day |
What each path costs
Repairs typically run $500–2,000; a replacement is $8,000–15,000 installed. Home batteries carry a warranty of about 10 years or a set throughput, ending near 70% of original capacity. Warranty status, not age, drives the decision on a sealed pack. Price your own number on the home maintenance cost calculator before you commit either way.
The repair-or-replace call is easy when you know the unit's age and service history. OnOtto keeps both, plus the maintenance that delays this decision for years.
Start your home's service log, freeFrequently asked questions
What does a 70% capacity warranty actually mean?
It sets a floor, not an expiration date. Most home batteries are warrantied to retain roughly 70% of original usable capacity after about 10 years or a stated total energy throughput, whichever arrives first. A 13.5 kWh pack ending the term at 70% still delivers around 9 kWh, which may cover a refrigerator, lights, and a well pump overnight but not central air. Dropping below the promised figure inside the term is a claim. Dropping below it afterward is simply an old battery, and you decide whether what remains earns its space on the wall.
How do I tell whether the battery or the gateway failed?
Get the fault code before anyone quotes you a pack. The gateway, hybrid inverter, and communication boards are separate serviceable parts in the $500–2,000 range, and they cause a large share of the outages owners blame on the cells. Symptoms pointing away from the battery include a system reporting full charge that will not discharge, a unit that vanished from the app while still backing up loads, and errors that clear after a power cycle. Ask for the diagnostic log. Our home battery primer explains which box does what.
Does the warranty cover labor to swap the pack?
Often not in full, so read the terms closely. Manufacturers commonly cover the battery for about 10 years while removal and reinstallation labor is limited, prorated, or excluded after the first few years. Expect $500–1,500 in labor even on an approved claim, plus any permit or utility re-approval your area requires for storage equipment. Registering the system at install and filing the commissioning paperwork makes the claim far smoother. The maintenance checklist includes keeping those records somewhere you can actually find them.
Is adding a second battery better than replacing the old one?
Frequently yes, if the first one still cycles. A pack at 70% is not scrap, and pairing it with a new unit restores total usable energy with less disruption than a full swap. Two limits apply: manufacturers restrict mixing generations and firmware, and your panel may need space or a service upgrade to support more storage. Price both paths, because a second battery at $8,000–15,000 is not automatically the cheaper move. Review expected battery life before you invest in an aging system.