How Long Does a 5kWh Battery Last?

Table of Contents

If you’re considering a home battery, the question “How long does a 5kWh battery last?” actually has two important answers: how long it will power your home in a day, and how many years it will serve you over its lifetime. We’ll break down both.

Part 1: How Long Will It Power Your Appliances? (Daily Runtime)

A 5kWh battery can store 5 units of electricity (kilowatt-hours). How long that lasts depends entirely on what you’re running.
Think of it like a fuel tank: a car with a 5-gallon tank will drive much farther at 30 mph than at 80 mph. Similarly, your battery’s runtime is determined by your power consumption (load).

The Technical Variables: What Affects Your 5kWh Battery Runtime?

Before any calculation, we must first define the three critical technical factors that dictate usable energy from your 5kWh system.

1.Depth of Discharge (DoD) is Key

The Depth of Discharge (DoD) defines how much of the battery’s capacity you can safely use before needing a recharge. This is the biggest differentiator in the storage market.
Traditional lead-acid batteries typically have a safe DoD of only 50%. This means a 5kWh lead-acid battery only provides 2.5kWh of usable energy.
Our advanced LiFePO4 batteries allow a DoD of up to 80% to 90%. This translates to 4.0kWh to 4.5kWh of usable energy, offering significantly better value and performance.

2.Inverter Efficiency

The inverter transforms the battery’s DC power into usable AC power for your home. This process is not 100% efficient, with some energy always lost as heat.
High-quality pure sine wave inverters are typically 90% efficient (η= 0.90). This efficiency loss must be factored into your total runtime calculation.
For the most accurate calculation, we will use a conservative 90% efficiency rate.

3.System Voltage

The system voltage (typically 12V, 24V, or 48V) affects the current flow and heat dissipation.
While all systems can achieve 5kWh, a 48V system is generally more efficient and requires smaller wiring, which is why it is preferred for larger residential storage applications.

The Essential Calculation: Determining Battery Runtime

To accurately predict how long a 5 kWh battery will last, you must use the established industry formula.
We start by converting the total battery capacity into its usable Watt-hours (Wh):

Usable Wh = Nominal Capacity(Wh) × DoD × Inverter Efficiency(η)

The final runtime is then calculated by dividing the usable energy by your total continuous load power (W):

Runtime(h) ≈ Usable Wh / Total Load Power(W)

Example Calculation using LiFePO4:
Let’s assume our 5kWh LiFePO4 battery with a 90% DoD and 90% inverter efficiency:

Nominal Capacity: 5,000Wh
Usable Wh: 5,000Wh × 0.90 × 0.90=4，050Wh

If your household’s combined load is 500 Watts (W):

Runtime(h) = 4050Wh / 500W =8.1Hours

Real-World Scenarios: 5kWh Battery Runtime Tables

The true benefit of a 5kWh battery is demonstrated through practical application. Here, we analyze different load scenarios to give you a clear expectation of your 5kWh battery runtime.

Load Scenario	Devices Running Simultaneously	Total Load (W)	Usable Wh (LiFePO4)	Estimated Runtime
A. Emergency Backup	LED Lights, TV, Wi-Fi Router, Fridge (Cycling)	350W	4,050Wh	11.5 Hours
B. Overnight Essentials	Fridge, CPAP Machine, Several Lights, Laptop Charging	550W	4,050Wh	7.3 Hours
C. Heavy Usage/RV Power	Microwave (on), Small Portable AC Unit, TV, Lights	2,000W	4,050Wh	2.0 Hours
D. Low Critical Load	CPAP Machine, Alarm System, Router	100W	4,050Wh	40.5 Hours

To maximize your 5kWh battery runtime during an outage, identify your critical loads.
Prioritize running only essential items: lights, medical devices (like CPAP), and communications (Wi-Fi). By eliminating high-draw appliances like electric water heaters or ovens, you can easily stretch the power for a full day or more.
A 5kWh unit is excellent for covering a full night’s sleep during an emergency power failure.

PART 2: Strategic Planning: Charging and Product Advantage

Recharging Your 5kWh Battery

Knowing how long your 5kWh battery lasts is only part of the solution; you also need to know how fast it can recharge.
If you have a 3,000-watt solar array (assuming 5 peak sun hours per day), your system produces about $15 \text{ kWh}$ daily. In this scenario, your 5kWh battery can be fully recharged in approximately 2 to 3 hours of peak sunlight.
Matching your solar panel capacity to your storage capacity ensures reliable, day-after-day energy independence.

The Leforsolar LiFePO4 Advantage

Our company specializes in high-quality LiFePO4 energy storage solutions. This chemistry is critical to maximizing the value of your 5kWh investment.
By offering a high DoD (up to 90%), our batteries deliver more usable energy than competitors. Furthermore, LiFePO4 chemistry provides a superior cycle life (often 6,000+ cycles) and enhanced safety.
When calculating the duration of how long a 5 kWh battery will last, choosing our LiFePO4 technology ensures you are always calculating with the highest usable capacity available.

3 Simple Tips to Maximize Your Battery’s Lifespan

Getting the most out of your investment is simple. Follow these tips to ensure your battery lasts for its full potential:

Avoid Constant 100% Depletion: While LiFePO4 batteries handle deep discharges well, regularly draining them to 0% can cause more stress than stopping at 10-20%. Using a smaller portion of the capacity daily can extend its life.
Keep It in a Moderate Climate: Extreme heat is a battery’s biggest enemy. Installing your battery in a garage or basement where temperatures are stable will prevent unnecessary wear and tear.
Use a Compatible, Quality Inverter: Your battery and inverter are a team. A mismatched or low-quality inverter can cause inefficient charging and discharging, which slowly degrades the battery over time.

The Bottom Line

So, how long does a 5kWh battery last?

In a day: It can keep your essential appliances running for several hours during an outage.
Over its life: A quality LiFePO4 model can reliably power your home for over a decade.

The key is to invest in a battery from a reputable brand that uses durable chemistry and provides a strong warranty. This ensures you get every bit of the long-term value and energy independence you’re paying for.
Contact our solar storage experts today for a free consultation and customized system design. We’ll ensure you invest in the right capacity—whether it’s 5kWh or more—to guarantee total energy independence.