How Long Will A 12V Battery Last With A 1000 Watt Inverter?

12V Battery With A 1000 Watt Inverter

Since an inverter draws energy directly from the bank of batteries, it’s vital in RVs and off-grid solar systems. With the power of a 1000 watt inverter, you can run many appliances. How long will the battery that is 12V last on it? The answer is contingent on a variety of aspects.

A battery of 12V 100AH with 50% discharge can last for 30 minutes with a full loaded 1000 watt inverter. A similar battery loaded with a 300 watt load will last for 3 hours using the 1000 watt inverter.

How Long 12V Batteries Last On 1000W Inverters

Battery and Inverter
How Long Batteries Last On Inverters?

The following examples employ 100ah batteries since it is among the most commonly used. When talking about 12V batteries, it typically refers to 100AH, which we’ll use in this article.

The formula can be described as:

total watt load + battery voltage/inverter effectiveness = amps/hour.

If you know the amps per minute, It is simple to estimate the length of time that the battery will last.

First Example

Choose a battery with a capacity of 100AH/12V and a 1,000W inverter with an efficiency rating of 85. Like solar cables, inverters also lose energy during conversion. Therefore, it is necessary to add that.

If you have an efficiency of 85%, and your inverter comes with one with an 800- watt charge, then a 100AH battery should last from 65 to 70 minutes, or a half-hour, 10 mins. Using the calculations above:

800 watts/12 voltages or .85 is 78 amps hours.

An 800-watt load draws 78 amps per hour, which means a 12V 100AH battery can last one hour and a 10-minute timer (1.1 hours) give or take.

Second Example

Here’s another illustration. This battery is used with a load of 250W and an efficiency of 90% inverter.

250 watts/12 voltages + .90 equals 23.1 amps

A 250W load will draw 23 amps in an hour so that you can round that up to 25 amps, and the battery will last for 3 to 4 hours.

What is the reason we are saying 3-4 hours? If we make 23 hours round, this would mean 25 amps. 25 x 4 equals 100 amps, do you think?

The load decides the amount of amps that the inverter draws. When the voltage drops, the inverter will draw more current to maintain the voltage, which will drain the battery faster. Therefore, the battery might not last longer than you imagine.

Battery capacity can be measured using 5 amp 20-hour cycles. In other words, If a load is drawing 5 amps per hour, the battery can last for 20 hours. However, 10 amps per hour are not necessarily 10 hours because the more amps are drawn, the more quickly the battery’s capacity is depleted.

Which Battery Will You Use With The Inverter?

The kind of battery you choose to use with the inverter will determine how long it will last under the load. Some batteries have higher discharge times than others, and certain types are more efficient when working with inverters.

Lead-acid batteries have a discharge rate, which means a 100ah battery can only use 50ah in the inverter. When using lithium-ion batteries, you can use up or 90% of their capacity to support your watt load.

Example with batteries

Let’s take the same example as before. There is an inverter that can handle 1000W. Inverter with an efficiency of 85%, you need to power up 800 watts from a 100AH 12V battery.

Let’s say it’s a lead-acid battery having 50 percent of discharge.

800 watts/12 voltages 800 watts / 12 volts .85 is 78 amps hours.

78 amps/hour is sufficient in 1.1 hours. However, our battery has 50% capacity usable, and we must split 1.1 hours by 2 that’s 35 minutes, or that’s.

If you have a large lithium battery and an efficient inverter result, it will appear like this:

800 watts/12 Volts * .90 equals 74 amps

The load can draw 74 amps in an hour. However, the biggest difference is in the lithium battery. If it has an efficiency of 90, it is possible to run the battery until it’s almost empty. Also, the battery will run for around an hour.

Lithium Vs. Lead Acid Battery

Lithium Vs Lead Acid Battery
Lithium vs Lead Acid Battery.

A lithium battery could last twice more than an acid lead battery operating the same load with an identical inverter, even if inverters had the same efficiency. The lithium battery would last longer because of its higher discharge rates.

Of course, lithium batteries are more expensive, often more than twice the cost of lead-acid. However, if you must utilize 100AH, you could end up purchasing two lead-acid batteries as each battery can be used for 50ah and only. This means that the price could even go up in the long run.

It is entirely up to you. If you find yourself charging lead-acid batteries often to meet demand, Perhaps it’s time for you to switch from lead-acid to lithium. If your battery is in good condition, there’s no reason to upgrade. Lithium batteries are the best choice if you are running large appliances due to their long-lasting life span.

What Is The Maximum Load For A 1000W Inverter?

Inverter 1000 watt
Inverter 1000 Watt.

On paper, it is possible to put 1000 watts of power into an inverter with a capacity of 1000W. Inverter. However, just as solar panels can’t always generate the power they’re rated for, it is the same for inverters.

Since an inverter isn’t 100% efficient, it may not handle an entire 1,000-watt load. Inverters with an efficiency rating of 90% can be loaded with up to the power of 900W. Some compelling devices could run 1000W, which would be too much when used frequently.

There must always be an inverter with a power reserve, solar panels, charge controllers, and batteries. Voltages and currents show peaks and valleys, and sudden surges can cause a spike in watts over 1000 watts.

Suppose your inverter is running at its limits when there’s a sudden surge that causes damage to the inverter and any appliance connected to it. When the power load falls lower than 1000 watts, there is enough power reserve to withstand the rapid surge. An abrupt watt surge could be catastrophic, particularly if the solar panel is not equipped with the appropriate equipment.

Of course, some inverters are more well-designed than others. If the manufacturer claims it’s okay to load an inverter with 1000W, then by all means. Inverter and you believe them, then go with their word. You should have no issues if you are sure that the inverter is covered under the warranty and everything you do is done according to the instructions. It is also helpful to look up customer reviews before purchasing an inverter.

Reminders For Running 12V Batteries With Inverters

1. The runtime duration depends on the battery’s capacity and watt load

It is possible to recharge batteries using electricity. The usable amps are dependent on the batteries. As previously mentioned, the lead-acid batteries are characterized by DODs of 50, some AGM, and gel batteries, which offer higher discharge rates.

2. Do not charge the battery for longer than the recommended discharge

If the battery’s discharge percentage is less than 50%, you should recharge the battery at 50% or greater. The battery used at a lower rate can shorten the life cycle considerably.

3. Verify that the voltages are inline

There are 100AH batteries available in 24V and 48V. Find out if your inverter can work with these batteries because some inverters are built to only function with specific voltages.

4. Don’t overload either the batteries as well as the inverter

Keep the load under the limit, 1000 Watts in the inverter. It is possible to run more than 100 amps of battery, provided that the draw does limit to 100 amps per hour.

5. Pay close attention to the power of surges

Inverters have two crucial numbers, the running, and peak watt capacity. Motors and some appliances such as fridges and AC systems come with surge or starting watts that are three times or more than their operating watt.

A fridge labeled as 600 watts refers to operating wattage only. The initial or surge watt need will likely be 1200 – 1800 watts. Your inverter should be able to provide the surge watt and your battery. This is not only for inverters but also for solar generators too. This applies not only to inverters, but also to solar generators that can power a house.

6. Choose a reliable manufacturer

Inverters that are large and battery aren’t at a bargain, even though prices have dropped. Make sure you get the most value for your money by buying from reputable manufacturers that back their products with support from customers and quality warranties.

7. Battery capacity limitations in the case of an inverter

Certain inverters only support only a limited quantity of batteries. Check the inverter manual to determine how many batteries can be connected to the inverter. Inverters have a charge-current limit, and typically you shouldn’t attach more than twelve times your maximum capacity.


In most solar panel systems that are used, the inverter is only as effective as the battery it’s connected to. Depending on the charge, a 100ah 12V battery will run from one hour to several hours. By planning, you can determine what number of batteries you will need.