**Quick Answer**

**A 2000 watts inverter would require a 1000ah 12V battery. The 3000 watts inverter requires at least a 1500ah battery, and the 4000 watts inverter requires 2000ah. And finally, the 5000-watt inverter will support by a 2500ah 12V battery. Ensure you choose compatible batteries.**

## How many batteries do I need for a 2000watt inverter?

**Battery capacity is calculated based on the load backup duration.** This is a very important point that you need to be aware of. So remember, the inverter capacity would not be deciding factor in battery capacity. The battery should have sufficient charge to meet the maximum power supply of the inverter.

For example, if your batteries deal with the load of 1200W on your inverter at 12 volts, 200ah may generate 2.4kWh energy that can power the appliance for an hour.

For this calculation, we are considering the max 50% utilization only. Moreover, there will be some wastage of energy during electricity transmission from one device to another.

Let’s assume your inverter input DC voltage is 12 volts only then you may require one or more batteries connected parallel to control the loads to the device.

If the batteries are starting working with 24 VDC, then you may require two batteries of 12 V.

Ensure that you offer the input of 24 volts or use the two different sets of the 4 batteries to meet the requirement.

Pair it according to prescribed by the inverter manufacturer. Control the voltage limit to 24v for improving the backup duration of the battery.

## How many batteries do I need for a 3000-watt inverter?

The 3000-watt inverter with a 20 amp battery will produce 12 volt DC to 110 Volt AC. As a thumb rule, the flooded cell batteries will require double the charge which is 6000 watts. The efficiency of the battery plays an essential role.

Few battery manufacturers offer significant battery component that lasts longer. It would be hard to find batteries that can handle the constant discharge rate of C1.

The battery with the C1 indicates, the battery draws 3KW from 3KW batteries and has a shorter life span.

## How many batteries do I need for a 4000-watt inverter?

Several factors affect the battery’s efficiency. The number of batteries required for the inverter will depend on the rated supply voltage of the inverter.

Let’s say you want to run a 4000 watts inverter which is a 4kW energy supply. It will draw a good amount of energy in the amps at 12 volts and 24 volts.

Presumably, you will connect the inverter to the 48 volts. Thus you may require 4 x 12-volt batteries in the series of connections to power the 4000 watts of the inverter.

## How many batteries do I need for a 5000-watt inverter?

It would be best to consider various factors while calculating the need for the batteries to power the 5000-watt inverter, such as the battery capacity, voltage, and active duration in the hours.

It is vital to know how long you want to run the inverter. Batteries will have limited capacity.

It starts draining quickly once you connect the inverter. Even if no appliances are connected to the inverter, still the battery will keep drawing.

Comparative to the small-size battery backup, the large inverters are used for emergency purposes.

The battery requirements are determined by how many hours the whole system is active and supplying the energy.

### Formula:

Hours needed x watts = total watts/volts = battery amps.

By using the above formula, you can identify the battery amp’s capacity. Based on the figures, you can decide how much battery backup you would require to keep the system running.

## How to calculate the batteries required for the 5000-watt inverter?

When you know the battery amps, it will become easy to identify the energy requirement of the inverter. A 5000-watt inverter would require a minimum 450 to 500 ah 12 V battery.

Alternatively, you can have two separate batteries of 210ah 12V that would power the system for 30 to 45 minutes.

If you demand to run the inverter for 1 hour, you would require 750ah 12 V batteries. As you extend the hours, more power supply would be needed in the backup.

The 4 hours of the operating system may need a 2500ah battery. Remember that you have to double the capacity each time you do not want to discharge the battery fully.

## Batteries for Inverter Calculation Method

In the following example, we explain how the battery is consumed when connecting the inverter to the system. Let’s say you have a 5000-watt inverter with 12 V input.

The 5000-watt inverter would generate approx 416 amps an hour of energy. It is calculate as 5000W / 12 V = 416.

With this formula, you can tell how many amps you would require to power the inverter. Based on the figures, we can assume a 450 to 500 ah battery can comfortably run the system for an hour.

Remember that the efficiency of the battery, inverter and whole system would decide the final output. Some batteries are highly efficient in transferring energy.

The result may be slightly different from what we have presented in this example.

Additionally, during the transition process, some energy will be lost. The energy level decreases consistently, reducing the number of hours the system can run when connecting the 5000-watt inverter.

So, in this case, the battery that should sustain for one hour may work efficiently only for 30 to 45 minutes. Also, the figures changes when you consider the 24V, 36V, or 48V battery.

**Battery Size Chat:**

The inverter chart will tell you how much optimum capacity would have the particular size of the inverter. You can compare the values with the other inverters and choose a suitable size for your home equipment.

Energy drawn by the inverter varies depending on the size. The chat explains how much energy a particular inverter will draw.

The table is developed after analyzing the total capacity of the inverter. We are assuming that the battery is fully charged.

If you plan to recharge the battery up to 50%, then double the capacity for each column. We have considered the optimum capacity for four hours, and comparatively, the minimum capacity would be one hour.

Depending on the type of battery you will be using for the system, the depth of the discharge range will change. We have considered DOD at 100% capacity.

It is possible with lithium batteries. In lead-acid batteries, the DOD drops significantly. You will get only 50% DOD to use.

These kinds of inverters and batteries are generally used in a solar-powered home. They offer a great facility to store and supply energy smoothly to the house.

It is noticed that these batteries are less frequent in RVs.

You may find the batteries in large-size RVs, but small-size RVs may not be suitable for them. Ensure that the battery generates sufficient charge and is ideal for the camper.

Do the calculation of voltage required to find the total energy requirement. If your consumption is higher, you may have to carry a pair of batteries to meet the demands.

## What are the ways to decide on battery inverter size?

It is essential to know the actual consumption of the energy during peak hours. Your battery should have the capacity to supply the needed energy. Get the specific answer to your question with the help of the following information.

### 1) Total Charge Requirement:

We are assuming that you have a 5000W inverter to power the device. First, ask the question to yourself, do you need this size of the inverter? Remember that every inverter consumes some amount of energy which is a loss to the owner.

The inverter itself requires 20% of energy to operate.

Calculate the total load requirement by adding the watt usage of each piece of equipment. Consider all the home appliances and devices you want to connect to the inverter.

While calculating the wattage, remember that large appliances such as refrigerators and air conditioners would have surge power requirements. So consider the extra energy to compensate for the additional energy demand.

### 2) Inverter input voltage:

Most of the inverters would have 12V or 24V input. Some inverters may have 36V, 48V, and 96V as well. So first, you need to check what inverter input voltage your inverter supply.

Check whether your battery matches the input. Your battery doesn’t have to be a specific match. Ensure that the total matches with the inverter.

**Example:**

48V inverter will work efficiently on the 12V battery pack. You may have to combine batteries in 12 x 4 = 48 series.

Remember that compatible batteries are required. Else, they will not support the system. Your inverter will not be able to generate the AC power, and the whole system will fail.

Hence, you should consult with the manufacturer to know the compatible battery type before buying it.

### 3) Hours to run the inverter:

The duration is crucial. Energy supply is calculated based on the number of hours the battery runs. Find out for how many hours you are going to run the inverter.

Is it for a couple of hours, 10 hours or 12 hours, or even more? The watt will be calculated based on the number of hours, and you can decide the battery capacity.

Let’s say you have a 5000 Watt, 48V inverter. You plan to run the inverter for the approx 6 hours.

If we consider the power load factor as 0.8, then there are chances that the volt-amperes (VA) may value at 130 amperes.

Therefore, your connected battery should generate a minimum of 130 amperes of power.

The challenging part is the 48V 130 amperes are very uncommon, so you may have to adopt the alternatives where you will connect the 200 amperes instead.

### 4) Battery Storage Capacity:

The battery capacity shows how many hours the system will run and supply the energy. The battery capacity is measured in amp-hours.

Based on the above calculation, the system would require 200ah or 220ah of batteries. These batteries are more efficient in running the 5000w inverter. It will continuously run the system for more than 8 hours.

The 5000w inverter system may require a significant power back. In the case of the RVs, the needs are minimal, and calculating the energy requirement is primarily easy.

You can calculate the total number of appliances with the required wattage and connect the system that powers the entire RV.

## Why battery overhead and discharge rate is imperative?

The 5000W battery could produce 416 amps which is sufficient to power the equipment. As a thumb rule, when connecting the batteries to the inverter, always add 50w extra to support the depletion rate and surge power. So, in this case, the overhead would be 460 amps.

You can choose inverters with the 460 ah or, for better performance, a 500ah inverter. The discharge rate of the battery determines the battery bank life cycle.

The battery with a slower discharge rate reduces the consumption. A 460ah battery runs the inverter for more than 30 minutes. Decrease the inverter load, and the battery depletion rate will get reduced.

If you reduce the load from 5000w to 3000w, the battery depletion rate will decrease, and you will experience it last longer than what 5000w was producing.

You can apply this technique to any inverter. However, you should first test the system and then take the decision based on the output.

When you calculate the total load requirement of the equipment, if the count has a big difference, then you can reduce the inverter wattage would help the battery consumption.

Also, there will be less energy loss which will reduce the cost to store the power.

If your system is connected to the primary power grid, the system will cost more than what you consume daily.

So always make decisions based on your total consumption of energy. Do not use high wattage inverter if you don’t require more energy.

Eng. Matthew Joseph Nandirio is the Founder of walkingsolar.

After graduating from the University of Houston in 2002, matt started working as a Solar Electrical Engineer for several multi-national solar energy companies.

He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research.

He now shares his 20 years of expertise through his articles on the walkingsolar website.

Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.