How Many Car Batteries to Power a House?

How Many Car Batteries to Power a House

Do you live in an area where power outage is a common occurrence, especially during bad weather?

Are you looking to purchase car batteries offering backup to the home energy system to the key energy supply of your home?

You might be thinking, “How many car batteries do you need to power a house,” right?

In this article, I will elucidate the answer to this question.

So, keep on reading until I finish the article.

Details – Using car batteries to power a house?

Home Battery Power System

I own an average-sized house. A few months back, an electrical outage happened in my locality.

That time, I chose to use car batteries to power my house. And 90 kilowatt hours of energy consumption happened in 3 days.

I used 38 pieces of 6-volt batteries rated at 400Ah. Each battery delivers 2.4 kilowatt hours of power.

Let me share the whole perception in detail.

As per the calculation of the US Energy Administration, in a month, the average energy consumption by an American household is – 901 kWh or 30 kWh per day.

So, for 3 days, the consumption will be 90 kWh.

This is a practical idea of the number of backup power systems required to disrupt the home’s main power supply.

Moreover, this is also an estimate of 2.4 kWh of power per battery. The batteries are rated ah or amp-hour and available in 3 different voltage options: 6V, 8V, and 12V.

To calculate the battery’s energy consumption, multiply the battery operating voltage and rating and divide it by 1000.

A 6V battery with a 400 Ah rating has around 2.4 kWh of energy capacity (6 V X 400Ah / 1,000 = 2.4 kWh).

And to learn the number of battery pieces, divide 90 by 2.4 KWh: (90/2.4 = 38).

Benefits of Using a Home Battery Power System

A home battery power system has recently gained popularity because of its excellent performance.

You will get electricity from a battery bank if the leading power supply service is unavailable.

A home battery power system will deliver many benefits during severe weather conditions like a hurricane.

Because of climate change and increasing temperatures, the sea level is rising, and intense hurricanes are damaging coastal areas.

In 2012, destructive hurricane Sandy caused much damage in the District of Columbia. After the hurricane, electricity was unavailable in 7.9 million households and business places.

Moreover, many days after Sandy, 67% of the New York City gas stations were out of gas to sell, leaving home and business generators almost unusable.

Homeowners who own battery backup systems are more fortunate because they will be able to save valuable time. And at the very least, they can use lights on until the grid comes up with the help of a battery backup system.

Why Picking a Battery Backup System instead of A Generator?

Battery Backup System instead of A Generator

Habitants who use an electricity backup system know the importance of the backup system during an extended power outage.

Which one should I pick, a generator or a battery-powered electricity backup system?

Undoubtedly, a battery-powered backup system is a newer, better, and cleaner backup power option over a generator. However, the purposes are similar in a battery power backup system and a generator.

In this section, I will compare a generator and a battery backup system to make a precise purchase decision.


To determine the cost of a battery backup system, you must know how much power you require for your home.

As I already stated, 90 kWh is the electricity requirement of a medium-sized house for 3 days, and to get the power, 38 pieces of 6 V battery are needed, rated at 400 Ah. Such a type of battery will cost you $300 – $500. Your advance cost for a battery power backup system should be $11,400 – $19,000.

You will have to cost $4,000 – $8,000 for diesel generators to get the same electricity backup. It will run on fossil fuel, diesel. As long as you are using the generator, you will always have an operating cost for fuel.

But for a battery power backup system, a power outlet or solar power will assist you in getting them charged.

A battery backup system is much cheaper than a generator in price or cost.

Power Source

The power source of a backup power system plays a vital role in operating them.

Generators are powered by fuel, natural oil, or propane. As long as you run a generator, you will need assistance from these options continuously. If these options are unavailable after a hurricane like Sandy, the generator will not be used.

The battery backup system runs with the help of electricity. You must connect the system to an electric source to give it a full charge. Once the system is fully charged, you will get full support from the system.

You also can use solar energy to power the battery backup system. For this, you have to install a solar panel system. During the day, you can quickly charge the battery backup system with the help of the solar panel.


Generators create much sound and emit fumes while operating. Since they run by taking assistance from oil, they emit harmful gases.

But battery backup systems create less noise and don’t emit any gas. The truth is they are an eco-friendly system.

How Long Will a Car Battery (12v) Power a TV?

So, how many car batteries are needed to power a house?

  • It would take many car batteries to power an entire house. A typical car battery stores around 50-100 amp hours (Ah) of energy. An average household uses around 30 kilowatt hours (kWh) of electricity daily. So you’d need about 300-600 car batteries to store enough energy to power a house for a day.
  • Car batteries are 12-volt DC batteries, whereas household electricity is 120/240 volt AC power. So you’d need an inverter/charger system to convert the DC power from the batteries into AC to run household appliances.
  • Deep-cycle lead-acid batteries like those used in RVs or for solar power storage would work better than standard car starter batteries. They are designed to handle repeated discharges better without damage.
  • The batteries would need to be periodically recharged, either by solar panels/generators or by plugging them into grid power when available. So, it’s not an entirely off-grid solution.
  • There are some significant setup costs and maintenance requirements. You’d need a large space to house all the batteries, temperature control, ventilation, monitoring systems, etc.
  • It’s not the most efficient or cost-effective way to power a home compared to grid power or residential solar panels. But it could provide backup power if designed properly.


For those planning to install a battery backup system in their house, “how many car batteries to power a house” – is a common question. These systems are cheap and easy to install, operate, and maintain.

Check out the calculation and install a battery backup system per the requirement.