How Long Will a 10kwh Battery Last?

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A 10kwh battery is a considerable investment, but it is worth it for many people especially if you deal with constant power outages. The question now becomes, how long can you depend on a 10kwh battery? Well the answer depends on various factors but overall, it should last a while.

A 10kwh battery is going to last for 10 to 12 hours, assuming the system uses 1000 watts an hour. If you only run a few appliances the battery runtime is going to increase.

Is a 10kwh Battery Right For You?

The average home uses 750 to 1000 watts an hour during a power outage. If you maintain this usage a 10kwh battery bank will run out in 10 or 12 hours.

10kwh is enough to run a refrigerator, TV, lights, microwave, coffee maker and other small appliances except a central AC. It is sufficient to meet the power requirements of a medium sized household.

If you want to run most or all appliances during a power outage, a 10kwh battery is the best option. Keep in mind that a 1000 watt an hour load will empty the battery in 10 hours, so this is ideal for a single day power outage only.

Of course you can make this battery last more than 10 hours by reducing the load. If you only use an energy efficient refrigerator , the TV or laptop, lights and some kitchen appliances, consumption is going to be around 3000 to 4000 watts an hour. If you add a window air conditioner to the basic appliances, consumption will be from 6000 to 7000 watts.

As you can see there are a lot of variables involved here. The size of your household, what appliances you consider essential and how long you expect the power outage to last are all factors .

How to Estimate a 10kwh Battery Runtime

How long a 10kwh / 10000 watt battery will last comes down to usage. The following assumes you will only use the battery and not rely on a solar array.

10 kwh / hourly wattage consumption = runtime

If you run a 1500 watt load, a 10kwh battery is good for 6 and half hours.

10000 / 1500 = 6.6

The next step is decide what type of battery to use. Due to inverter inefficiencies, voltage losses and battery discharges, you should round off the results.

There are two basic battery types to choose from, lead acid and lithium. Each one is sized differently.

10kwh lead acid battery calculation. 10kw x 2 x 1.1 = 22kwh

If you need 10kwh and will use lead acid batteries, you have to get 26kwh to make up for the 50% depth discharge. The 1.3 in the calculation is for system inefficiencies and energy losses.

10kwh lithium battery calculation. 10kw x 1.1 x 1.07 = 11.7kwh

Lithium batteries have an 80% to 100% discharge rate. For best results, you should discharge between 80% to 90%, which is what we assume in this calculation.

As we stated earlier you should round off the results. For the 10kwh lead acid battery that means getting 2kwh and for lithium 12kwh.

This is the minimum capacity that you should get. You can always adjust the calculations based on your power consumption.

The point is if you need 10kwh a day, the battery backup power needs to be more than that. In the case of lead acid batteries you have to double it.

10kwh Battery Price and Features

A 10kwh battery costs $12,000 to $15,000. You can buy a single large 10kwh or two 5kw batteries, or you can combine several smaller batteries. The advantage of buying a single 10kwh or two 5kwh is you save space.

These batteries are becoming more common as prices drop. Features vary but they are all designed for heavy duty use.

Parallel configuration. You can buy several batteries and connect them in parallel to increase power. If you have three 5kwh batteries, you can set up a parallel connection and get 15kwh. This is a great option if you need lots of energy.

If you prefer regular 300ah lead acid or lithium batteries, you can also join them in parallel until you get 10kwh. If space is not an issue these batteries will get the job done.

How to Calculate Your Battery Backup Needs

The following is a simplified guide that explains how to determine your battery power needs.

Add up your daily power usage. Check your monthly power bill and look for the kilowatt hour usage. Divide the figure by 30 and multiply by 1000.

How long you expect to be without power. If you expect to be without power for 2 days, will 10kwh be enough?

There is no single answer for this because it depends on what situation you face. This also depends on what appliances you want to run and for how long.

If you want to have access to all or most appliances, a 10kwh battery will be enough for a day. If you need more power or want to run an AC, you have to double the capacity.

You also have to consider recharging options. Once the battery runs out you have to recharge it with AC power. You can only do this once the power is back on though.

Before you even buy a 10kwh battery, add the watts for all essential appliances you will need. This will tell you if 10kwh is too much, too little or just right.

When it comes to solar power and batteries in general, it is better to have reserve power. You will never know when you might need to run another device so it is best to be prepared.

Is a 10kwh Battery Enough to Power a House?

10kwh is enough to run most household appliances for a day. But if you want to run an off grid house, it is going to take more than that.

A 10kwh battery is just like a large solar generator. It is designed for backup power use. You can run it for 1 to 3 days depending on how much power you consume daily. If you want to go off gird you will need a large battery bank, solar array, an inverter and charge controller.

You probably won’t find off grid homes that consume 10kwh a day. But even so you cannot rely on a 10kwh battery alone.

For an off grid home you might need 800 amps or 20kwh plus a large solar array. Your inverter must also be large enough to meet the needs of your appliances.

What Affects Affects 10kwh Battery Performance?

The best way to maintain a battery is to follow the instructions for its use. However there are some general guidelines that are applicable to most deep cycle batteries. Do these and your battery should last several life cycles.

  • Temperature. deep cycle batteries are designed to run under a specified temperature range. If the battery operates 5 degrees above it, performance could deteriorate by as much as 30% or more.
  • Overloading. If you overload a battery, this will damage the internal components. You should only run the battery to its stated maximum capacity.
  • Wear and tear. Even the best batteries eventually get worn out. This is natural. When your battery gets old and no longer holds a charge like before, it is time to get a replacement.
  • Proper maintenance. Lead acid batteries have to be refilled with water every few weeks. They must be recharged at 50% as well. Not following these could result in poor performance.
  • Ventilation. Lead acid batteries need ventilation, so make sure they are installed somewhere with ample space.
  • Proper use. Do not mix and match lithium and lead acid batteries.
  • Use the right components. If you buy a 10kwh battery, use the cables and connectors that came with it. If you have to buy, make sure it is designed for that particular battery.


For some, a 10kwh battery might be too much, and for others it may be just enough. It really comes down to what you need. By determining how much power you require, you can figure out if this battery is worth it or not.