Running multiple air conditioners on battery power sounds simple—until the numbers hit. Many people buy a 15kWh lithium battery hoping it can handle heavy AC loads overnight. But can it really run 4 AC units for 10 hours?
No, a 15kWh lithium battery cannot run 4 air conditioners for 10 hours.
In most real-world cases, it won’t even come close.
Here’s why
Four ACs typically consume far more energy than a 15kWh battery can store, especially when startup surge and real usage are considered.
How much power does 1 AC actually use?
Before jumping to battery math, we need realistic AC consumption.
Average power use of one AC
- 1.5 ton inverter AC: 1.2–1.5 kW (running)
- Non-inverter AC: 1.6–2 kW (running)
- Startup surge: 2–3× higher for a few seconds
To stay conservative, let’s assume:
- 1 AC = 1.5 kW average
Power needed for 4 ACs over 10 hours
Now the simple math.
Total load
- 4 AC × 1.5 kW = 6 kW continuous load
Energy required
- 6 kW × 10 hours = 60 kWh
Battery capacity comparison
- Battery capacity: 15 kWh
- Required energy: 60 kWh
➡️ Battery shortfall: 45 kWh
Even with perfect efficiency (which never happens), the battery only covers 25% of what’s needed.
What about inverter ACs and ideal conditions?
Some sellers claim inverter ACs use “very little power.” That’s partly true—but only in mild conditions.
Best-case scenario
- Inverter AC throttles down to ~1 kW
- Indoor temperature already cool
- No peak heat load
Even then:
- 4 AC × 1 kW × 10 hours = 40 kWh
Still nearly 3× more than a 15kWh battery can supply.
Battery losses you must account for
Battery systems are never 100% efficient.
Typical losses
- Inverter efficiency: 90–95%
- Battery depth of discharge limits
- Heat and cable losses
Usable energy from a 15kWh battery
- Real usable energy: 12–13.5 kWh
That makes the situation even worse.
What can a 15kWh battery realistically run?
Here’s a more practical view.
Possible runtime scenarios
- 1 AC (1.5 kW) → ~8 hours
- 2 ACs → ~3–4 hours
- 4 ACs → ~1.5–2 hours max
And that’s without other household loads like lights, fridge, or fans.
Pros & cons of using a 15kWh battery for AC loads
| Pros | Cons |
|---|---|
| Silent power backup | Not enough for multiple ACs |
| No fuel or emissions | High surge demand |
| Good for short outages | Expensive per kWh |
| Works well with solar | Limited runtime for cooling |
Real-world example
A homeowner in a hot climate installed:
- 15kWh lithium battery
- 5kVA inverter
- 2 inverter ACs
Result:
- Battery lasted ~3.5 hours at night
- Could not add a third AC
- Upgraded later to 40kWh storage
This is a common outcome, not an exception.
FAQs (People Also Ask)
Can solar panels help run 4 ACs with a 15kWh battery?
Solar can help during daytime, but at night the battery is still the limit. You’d need much larger battery storage.
How big a battery is needed for 4 ACs for 10 hours?
You’d need 60–70kWh of usable storage, depending on AC type and efficiency.
Can a high-capacity inverter solve the problem?
No. A bigger inverter handles power, not energy. Battery capacity is the real bottleneck.
Is it cheaper to use a generator instead?
For long AC runtimes, yes. Batteries are better for short, silent backup—not all-night cooling with multiple ACs.
Final verdict
A 15kWh lithium battery is not designed to run 4 air conditioners for 10 hours.
It’s physically and mathematically unrealistic.
If your goal is long AC backup:
- Increase battery capacity
- Reduce the number of ACs
- Combine solar + battery + grid or generator
Bottom line: Match your cooling expectations with real energy numbers—not marketing promises.