Trying to workout out what size battery you need for a 1000 watt inverter?
It can all be very confusing when people start talking about amp-hours, watts, and volts.
To be honest, there are lots to take into account.
That’s why I’ve created this super-easy guide to help you find the right size battery for your 1000 watt inverter.
In this article, we will go through battery size and how long they will last, the best battery for 1000W inverter, and what you can run.
Battery Size for 1000 Watt Inverter
For a 1000 watt inverter, you’ll need at least a 100Ah battery.
Anything smaller than this and you will run out of energy very quickly.
To understand the best battery size for you, let me explain the factors to consider.
Battery sizes are measured in Amp-hours (Ah), this is the total amount of energy they can store.
So all you need to do is find out how much energy your inverter uses per hour to know how long your battery will last.
Here’s a simple formula to work out how much energy your inverter uses. For this example, we will say that your inverter is drawing a full load of 1000 watts. (It is likely that you won’t regularly be using that much power, so you can adjust the formula accordingly.)
The formula to find your inverter Amps (A) is Watts ÷ Volts = Amps
Drawing 1000 watts from a 12 volt battery would result in this:
1000W ÷ 12V = 83.3A.
At full load, a 1000 watt inverter uses 83 Amps per hour.
So if everything is working perfectly at full load, a 100Ah battery would last for over 1 hour.
How Much Power Are You Drawing?
The explanation above uses the assumption that you will be drawing full load from your inverter. Full load means always using 1000 watts!
Generally, you won’t be using the maximum capacity of your inverter all the time.
When working out your battery size, you should consider how much power you will actually be drawing from the inverter most of the time. If you are only running lights, TV, and a mini-fridge then you might only be drawing 300 watts!
You can quickly use the formula again to find your energy usage:
300W ÷ 12V = 25A. So a 100Ah battery would last up to 4 hours.
If you want to know how many watts your appliance uses then get yourself a wattmeter for exact readings.
Battery Types & Discharge Capacity
The other thing to consider is your battery’s discharge capacity.
Regular lead-acid batteries shouldn’t be discharged more than 50% as it causes damage. This means for lead-acid batteries you should double your battery size.
More modern lithium batteries don’t have this problem and offer far better performance and charging abilities – it doesn’t matter if you deplete them. (It’s the same sort of battery as in a smartphone). Of course, this performance is more expensive.
1000W Battery Size Inverter Chart
Below I have put together a handy table for you to compare battery sizes and runtime.
It will quickly help you find out how long a 12v battery will last with a 1000 watt inverter.
Plus compares the difference between lead-acid and lithium batteries.
| Runtime 1000 Watts | Runtime 500 Watts | Lead Acid (50% Discharge Capacity) | Lithium (100% Discharge Capacity) |
| 1 hour | 2 hours | 200Ah | 100Ah |
| 2 hours | 4 hours | 400Ah | 200Ah |
| 5 hours | 10 hours | 1000Ah | 500Ah |
| 10 hours | 20 hours | 2000Ah | 1000Ah |
| 15 hours | 30 hours | 3000Ah | 1500Ah |
| 24 hours | 48 hours | 4800Ah | 2400Ah |
What Can You Run With 1000W Inverter and Battery
1000 watt inverters are very popular because they allow you to run a wide range of electronics without breaking the bank.
For many people, it is enough power to keep the essentials running during a blackout or use in a small RV, car, or truck. You could easily charge your gadgets like smartphones, tablets, laptops, digital cameras, headphones, and portable games consoles.
Adding to this, there are a number of home appliances you can run with a 1000 watt inverter too including refrigerator, lamp, computer, fan, speaker, TV, and much more.
Here’s a table of common appliances you could run and their average wattage:
| Appliance | Average wattage |
| Phone | 5 |
| Tablet | 10 |
| Digital camera | 15 |
| Laptop | 30-60 |
| Fan | 40-70 |
| Lamp | 60 |
| Mini-fridge | 40-70 |
| TV | 50-80 |
| Games Console | 100-200 |
| Refrigerator | 300-500 |
| Microwave | 700 |
| Toaster | 1200 |
| Washing machine | 1000-2000 |
| Coffee maker | 1000-1500 |
To know if you can run all the appliances you simply need to add up the total running wattage of everything. For example, TV (70W), phone (5W), laptop (40W), lamp (60W), fridge (300W) = 475 Watts.
You can find the wattage of any electronics by checking the manual/technical information, with a wattmeter, or using a wattage calculator.
A Word on Inverter Efficiency
I just want to write a quick word on inverter efficiency. Power inverters are not 100% efficient. They vary between 85% and 95% efficiency depending on the quality of the inverter.
During the conversion from DC to AC, you will lose energy. Adding to this, inverters use power to run internal systems such as safety guards, cooling fans, and screens. That means an inverter will still use power when not drawing any load. So be sure to switch it off when not in use!
The calculations above are not set in stone, it is impossible to perfectly calculate the exact energy usage of your appliances.
This is because efficiency and the power levels of most electronics go up and down depending on the task you are performing. For example, a games console uses a different amount of energy to play games compared to streaming Netflix.
Final Words on Battery Size for 1000W Inverter
In my experience, you need at least a 100Ah battery for a 1000 watt inverter.
And to be honest, I’d recommend going much bigger than this for a good experience.
Take the time to consider how much energy you will be using and how long you need to go without charging your batteries.
You can use the chart above to get a rough idea of how long your inverter will run.
Thanks for reading.
