Two batteries can both say “10 kWh” and behave very differently
Energy capacity answers how much energy a battery can store. Power capacity answers how quickly that energy can be delivered. The U.S. Department of Energy makes the same distinction at grid scale: storage is characterized by both energy capacity and power capacity. For a home, that difference determines whether a battery can simply run lights and electronics or also support heavier loads.
The battery numbers that change real-world use
| Check | Why it matters |
|---|---|
| Nominal vs usable kWh | Reserve limits and depth-of-discharge rules can make usable energy lower than the label |
| Continuous discharge power | Sets the sustained load the battery can support |
| Peak / surge limits | Relevant to motors, pumps, compressors and short-duration high loads |
| Battery voltage | Must match the inverter architecture |
| BMS communication | Closed-loop communication can improve charge control and state-of-charge reporting |
| Parallel limits | Determines how far the bank can be expanded later |
| Cycle-life test conditions | Cycle claims are not meaningful without DoD, temperature and end-of-life conditions |
| Warranty throughput / retention | A “10-year warranty” may include energy-throughput limits and capacity-retention conditions |
Why LiFePO4 is common in stationary storage
Lithium iron phosphate (LiFePO4/LFP) is widely used in stationary battery products. Buyers should still compare the complete battery system rather than chemistry alone: cell quality, BMS design, current limits, enclosure, thermal management, certifications, warranty support and inverter compatibility can matter as much as the chemistry label.
Runtime is a load problem, not a battery-label problem
A rough runtime estimate starts with usable energy divided by average load, with an allowance for conversion losses. A 10 kWh nominal battery operated to 90% usable depth and through a 92% efficient conversion path would not deliver the entire 10 kWh to AC loads. Use the battery runtime calculator to make those assumptions explicit.
Do not assume a 48 V battery and a 48 V inverter are automatically a supported pair. Check the manufacturer’s current compatibility list, required firmware and communication protocol.
Warranty questions worth reading before checkout
- How many years are covered?
- Is there an energy-throughput or cycle limit?
- What capacity retention is guaranteed at the end of the period?
- What operating-temperature and installation conditions can void coverage?
- Is labor or shipping included in a claim?
- Who provides support in your country?
Primary sources and further reading
Melnti uses primary or institutional sources where they are available. Always confirm current rules, tariffs and equipment documentation before purchasing.