How long will a 20kW battery last? This is the first question that comes to mind when considering the purchase of 20kW batteries. However, there is no definitive answer to this question, as battery runtime can vary depending on several factors. Additionally, 20kW is not the complete specification that could be used to determine battery timing.
This number just indicates the power a battery can supply in a short duration. If you’re a newbie, understanding the difference between 20kW and 20kWh is crucial to understanding how long they can last. In this article, I’ll discuss everything related to 20kW batteries and their runtime. So, let’s begin!
What is a 20kW Battery?
The 20kW batteries offer power supply of up to 20 kW for a shorter duration. This 20kW indicates the rate of energy delivery. Suppose you have an electrical setup that requires 20kW of power. In such cases, these batteries will fit the needs. However, the battery’s runtime in your specific setup cannot be determined by 20kW.
If you go into the market and see a 20kW rating, you’ll never be able to know how long it will power your devices. Instead, this specification will only inform you that this battery can provide a maximum of 20 kW of power. If you want to know how long a 20kW battery lasts, you must see the parameter kWh of that battery.
Don’t know what this kWh is? Worry not, as I’ll explain this unique aspect in the section below.
Difference Between kW and kWh
kW and kWh are two different units. If you only know the specification of the battery in kW, you cannot determine how long this battery will last. The kWh indicates kilowatt-hours, meaning the amount of power that can be used in one hour. This unit indicates the storage capacity of the BESS system.
For example, you have a 20kWh battery; this battery’s power can be used in one hour. Your device, which uses 20,000 watts of power, will run for one hour on a 20 kWh battery. However, the kW indicates the maximum power of the battery. It tells how powerful appliances can run on 20 kW batteries. A 20 kW battery can power a device rated for 20 kW or less.
Here is a table showing the key differences between kW and kWh.
| kW (Kilowatt) | kWh (Kilowatt-Hour) |
| Measures power rating and indicates how much energy a battery can deliver. | Measures energy and indicates storage capacity |
| Tells how fast electricity is used or delivered. | Tells how much electricity is used or stored over time. |
| Example: A 2kW device uses 2 kilowatts of power. | Example: A 2kW device running for 1 hour uses 2kWh of energy |
| Used to describe appliance power ratings or battery output. | Used to describe energy battery storage capacity |
How Long Will a 20kW/20kWh Battery Last?
Do you want to know how long a 20kW battery lasts? In such a case, you must consider the storage capacity of the battery, which is measured in kilowatt-hours (kWh).
- 20 kW only informs about the power a battery can deliver.
- 20 kWh indicates the amount of energy a battery can store.
Knowing the storage capacity of the battery allows you to estimate its runtime. Generally, when people say a 20kW battery lasts, they mean that the battery has 20kWh specifications. Let’s discuss how long a 20kWh battery lasts.
20 kWh batteries come with energy storage of 20 kilowatt-hours. Suppose your home consumes 10kWh. In such a case, a 20 kWh battery will last only for two hours. If your home’s power consumption is 5 kWh, these batteries will last up to 4 hours. Remember, the 20kWh battery’s lifespan mainly depends on power consumption.
Suppose you have one air conditioner with a power rating of 1500 watts. Suppose you run this AC on the 20kWh battery. In such a case, the battery will last for around 13 hours. Different appliances have different power consumption, affecting how long 20kWh batteries last. Here is a table showing different appliance, their power rating, and the runtime of these batteries:
| Appliance | Average Power Rating (W) | Estimated Runtime on 20kWh Battery |
| LED Lights (whole house) | 200 | 100 hours |
| Refrigerator | 300 | 66 hours |
| Ceiling Fan | 70 | 285 hours |
| Washing Machine | 500 | 40 hours |
| Microwave Oven | 1200 | 16.6 hours |
| Air Conditioner (1.5 Ton) | 2000 | 10 hours |
How to Calculate Lasting of 20kWh Batteries?
As I said earlier, different appliances have different power ratings. It means they can consume different powers from each other. Here is a formula that you can use to find how long a 20kWh will last when powering different devices:
Battery Runtime (lasting) = kWh ÷ power rating of device (consumption).
Suppose you have an air conditioner with a 2000-watt rating running on a 20 kWh battery. Remember that 20kWh is 20,000 watts, as the letter’ k’ represents kilo (1,000). In simple terms, 20Wh means 20,000 watt-hours.
Battery’s Runtime = 20000 ÷ 2000 = 10 hours
Suppose you have more than one device running simultaneously. In such a case, you will need to add the power ratings of all the devices. Once done, you then divide 20000 by your added value and get the exact lasting 20kWh battery in hours. You can refer to the user manual of each device to determine its power rating (consumption).
Is a 20kWh Battery Enough to Power a House?
Yes, the 20kWh batteries are potent and can easily power a house. However, it still depends on the house’s energy consumption.
As I said earlier, 20kWh batteries offer 20000 watts of power. A smaller house with lesser power consumption can be run by a single 20kWh battery. However, if you have a large house with high power consumption, the 20kWh batteries may not be perfect in such a case. On average, a mid-sized home with basic appliances consumes around 5 kWh of power in a day.
In such a case, the 20kWh will last four days powering that mid-sized home. Remember, the appliance used in the house determines whether the 20kWh battery is used or not. Here is how long a 20kWh battery will last as per home size (active appliance):
| Home Usage Category | Typical Appliances
Running |
Estimated Power Use (kW) | 20kWh Battery Runtime |
| Simple Use (Basic Load) | LED lights, ceiling fans, fridge, TV, Wi-Fi, laptop | 1.0 – 1.5 kW | 13 to 20 hours |
| Normal Use (One AC) | All basic items + 1 air conditioner (1.5–2 Ton) | 2.5 – 3.5 kW | 5.7 to 8 hours |
| High Use (Larger House) | Multiple rooms with ACs, washing machine, oven, water heater | 5.0 – 7.0 kW | 2.8 to 4 hours |
In short, yes, the 20kWh batteries can efficiently run houses of different sizes and loads. However, the runtime of these batteries will vary depending on the home’s power usage. A single 20 kWh battery can power a home for several days if the overall power consumption of the house is very low. You can reduce power consumption to achieve a longer runtime from the 20kWh battery.
Factors that Affect Runtime of 20kWh Batteries
Many factors can affect the performance and runtime of 20 kWh batteries. Considering those factors is crucial if you want better performance from your batteries. Here is their list:
- Battery Efficiency: The battery energy storage efficiency should be high (over 85%). During charging and discharging, such batteries will undergo minimal energy loss. As a result, more energy will be stored, thereby improving the battery’s runtime. I recommend using lithium-ion batteries as they offer around 90% of energy efficiency.
- Power Consumption: Suppose you use 20 kWh batteries to run appliances with a higher power rating. In such cases, your battery will drain out quickly. On the flip side, if your appliance consumes less power, the 20kWh batteries can last for many hours. The power consumption is a significant factor that determines how long a battery will last.
- Simultaneous Usage: Do you run multiple appliances simultaneously? If so, this will reduce the runtime of the 20kWh batteries. If you want to get better runtime from the battery, you should never run many appliances simultaneously. For example, turn off the AC if you plan to use the washing machine.
- Battery Health & Age: The old batteries have lower energy efficiency. Their storage capacity decreases to 60-70%. It means they can hold lower amounts of energy. As a result, they will drain out quickly. You should keep the battery maintained and check its electrolyte level. This will increase the runtime and overall performance of the battery.
Frequently Asked Questions
How much does a 20kWh battery cost?
The cost of 20kWh batteries depends on their brand and types. High-quality lithium-ion batteries (20 kWh) can cost around $10,000 to $20,000. However, lead-acid batteries are slightly cheaper, but their performance is compromised.
Can I run my AC on a 20kWh battery?
Yes, you can efficiently run AC on a 20kWh battery. If your AC has a 1500-watt power rating, this battery will run your AC for around 13 hours. You can even use more than one AC on a 20 kWh battery, but this will reduce the runtime and lifespan of the battery.
How long will a 20 kWh battery power a house?
It depends on the power consumption of a house. The battery will power the home for five days if the home consumes 4 kWh per day. If the power consumption is more aggressive, battery runtime will decrease and vice versa.
Conclusion
20kWh batteries are very popular due to their excellent power storage. However, when it comes to the runtime of these batteries, many seem to be confused. In this article, I’ve explained everything about these batteries.
This article also discusses the key factors to consider if you want to increase the runtime of your 20 kWh battery. In summary, the runtime of 20kWh batteries depends mainly on their power consumption. If you manage power usage effectively, it will significantly increase the battery’s runtime.