The Only Battery Size Chart You’ll Ever Need

Are you planning on purchasing a battery system? Then you’ve come to the right place; this battery size chart is going to come in handy!

It’s always a good idea to do some research before making a big purchase; an energy storage system is undoubtedly a big one. This system will shoulder the responsibility of your energy needs for years to come.

There is no shortage of batteries available in today’s market, but you need to make sure that you choose the right type and size according to your energy demand.

Cut corners while doing your research (or lack thereof), and you’ll end up with a battery bank that’s either too small or too large for your needs; that’s money and time down the drain.

This article will help you understand the different battery sizes and provide you with a complete battery size chart. By the end of it, you’ll learn how to size your battery bank according to your energy demand.

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Understanding Different Battery Sizes

To understand the different battery sizes, let’s first review a few key concepts:


Voltage

Also referred to as potential difference, is the force that pushes electrons around a circuit. Without voltage, electrons move randomly in any direction. By applying voltage, free electrons move in the same direction, creating current. The unit used for voltage is Volts (V).


Current

Current measures the flow of electrons passing through a certain point. The unit used for current is Ampere (A).

Batteries are used to store and provide electrical energy. They consist of one or more electrochemical cells where chemical reactions take place. 

The basic components of a rechargeable battery are:

  • Cathode 
  • Anode
  • Electrolyte
  • Separator

Reduction and oxidation reactions occur between the electrodes. These reactions convert chemical energy into electrical energy (and vice-versa). 

In a battery, the amount of material that can suffer oxidation is directly proportional to the amount of energy this battery can store (and provide). 

In other words, the more material a battery contains, the more chemical energy it can store. 

Following this logic, it’s easy to understand that varying material quantities (that can suffer oxidation) create different battery sizes.

As a result, you’ll find batteries with different capacities, such as 10Ah, 50Ah, 100Ah, 200Ah, 300Ah, etc.


Important Note

In this article, the phrase “battery size” refers to a battery’s capacity, not its physical size.

Moreover, we’ll discuss the three main types of batteries used in solar battery banks: LiFePO4 and sealed lead-acid (SLA), namely AGM and Gel.

We’ll also limit our discussion to 12V batteries. 12V is the most common voltage for batteries used in standard energy storage systems. 


How Do I Know What Size Battery I Need?

The size of your battery bank depends on how much energy you need to run your appliances; your battery system’s energy capacity should always be greater than your energy demand.

But how do you calculate your power demand?


Step 1: Estimate Your Energy Demand

What do you wish to power with your battery bank?

Each appliance has its voltage (in volts) and current (in amps) specifications. Applying a higher value than the recommended voltage and current can damage your appliance.

Another way to express these ratings is using power (in Watts). In physics, power is the product of voltage and current:

Power (W) = voltage (V) x current (A)

Once you’ve calculated the power that each appliance requires to function, you need to determine the amount of time (in hours) you wish to run each load.

For example, you usually run a fridge 24h a day. Considering that an RV fridge requires 70W on average, you’ll need 70W x 24h = 1680 Wh = 1,68 kWh to power this fridge for 24h.

The above calculation determined the fridge’s energy demand, expressed in watt-hours (Wh). You can calculate every load you wish to power with your battery bank. You just need to check the load specifications and use:

Energy required (Wh) = Power (W) x time (h) = voltage (V) x current (A) x time (h)

You also need to estimate your desired hours of autonomy

Continuing with our fridge example, if you wanted to run this fridge for two days before having to recharge your battery, your total energy demand would be 1,68kWh x 2 days = 3,36kWh.

Knowing this, you now need to find a battery with compatible specifications.


Step 2: Determine Your Battery Size

Batteries are rated by voltage and Amp-hours (Ah), as shown in the image below:

A 12V LiFePO4 battery with a capacity of 100Ah.
A 12V LiFePO4 battery that we used as part of our battery size chart.

There are two ways to express battery capacity: its charge capacity (in Ah) or its energy capacity (in Wh).

Charge capacity represents the amount of current the battery can deliver in 1h until its voltage drops to a point where it can no longer “push” enough electrons (produce current). You calculate this using:

Charge Capacity (Ah) = Current (A) x time (h)

You probably won’t need to calculate amp-hours because your battery always shows this value on its case.

In turn, energy capacity expresses how much energy can be stored in/provided by a battery in 1 hour until the battery is depleted. You calculate this using:

Energy capacity (Wh) = Voltage (V) x Amp-hours (Ah)

After calculating your total energy demand (in Wh), you can find a battery that meets your energy demand by calculating the battery’s energy capacity (using voltage and amp-hours specifications).


Step 3: Consider Your Battery’s Usable Energy

You can discharge LiFePO4 batteries to 100% and AGM and Gel batteries to about 80% without causing much damage. However, doing this can shorten your battery’s lifespan.

Manufacturers usually recommend an 80% discharge ( 20% state of charge) for LiFePO4 batteries. And a 50% Depth of Discharge (DoD) for AGM and GEL batteries. Respecting these recommendations maximizes the number of cycles your battery will perform.

Example:, for a 12V 200Ah AGM battery, the usable energy would be:

Energy (Wh) = 12V x 200Ah = 2400Wh.

Considering 50% DoD, the usable energy = 2400Wh x 50% = 1200Wh.


Misleading Info

Another relevant observation is that battery capacity rating standards can be misleading. This means that the Ah advertised by manufacturers expresses the battery capacity in ideal conditions.

For example, a battery rated 200Ah can deliver 200A for 1h in ideal conditions.

Likewise, it can theoretically deliver 100A for 2h, 50A for 4h, 10A for 20h, 2A for 100h, etc.

In reality, though, these numbers aren’t accurate. Several factors decrease the rated battery capacity, such as temperature, rate of discharge, and Peukert’s Law.

In addition, for lead-acid batteries, the Ah rating is usually given at a “20-hour rate” or less often at a “10-hour rate”. This means that a 100Ah battery can only provide its 100Ah capacity during a 20h period (5A for 20h). If you connect the same battery to a 100A load, it might only last for a few minutes instead of the theoretical 1h.

With that in mind, we advise that you always account for capacity loss when determining your battery size demand. For instance, if you’ve done your research and calculated you need a 12V 360Ah battery bank, consider getting a bigger size battery bank (400Ah), so it will compensate for potential losses.


Battery Size Chart

Usable Energy Capacity

This first table shows the usable energy (in Watt-hours) for 12V LiFePO4 and Sealed lead-acid (AGM and Gel) batteries, rated for 10Ah, 50Ah, 100Ah, 200Ah, and 300Ah.

Additionally, it shows the energy capacity of each battery, taking into account the recommended depth of discharge (DoD) of each battery (80% for lithium batteries and 50% for lead-acid batteries):

10Ah50Ah100Ah200Ah300Ah
12V LiFePO4 (DoD 80%)96Wh480Wh960Wh1920Wh = 1,92kWh2880Wh = 2,88kWh
12V AGM or Gel (DoD 50%)60Wh300Wh600Wh1200Wh = 1,2kWh1800Wh = 1,8 kWh
Energy capacity (in Watt-hours) for each battery. Recommended DoD is taken into account.

Appliance Runtime Chart

Next, is a battery size chart showing how much time each battery can power a particular appliance. This chart considers the battery’s energy capacity (in watt-hours) and common appliances’ average power ratings (in watts).

Again, this battery size chart already considers the depth of discharge recommended to each battery. (Respecting the recommended DoD ensures your battery performs more cycles, this way, it lasts longer).

However, it doesn’t take into account the energy required by the inverter, to convert the DC (provided by battery) into AC (usually what powers appliances). So, if you want to get a more precise estimate, you should consider the energy your inverter requires to function properly.

BatteryPhone charger (5W)1 LED Light (9W)WiFi Router (10W)Drone / Camera (40W)Laptop (60W)Ceiling Fan (70W)Medium size TV (70W)Water Filter and Cooler (80W)RV Water Pump (100W)Refrigerator (170W)Power Tools (1000W)Coffee Maker (1400 W)
12V LiFePO4 100Ah192h106h96h24h16h13h13h12h9h5h0,9h0,6h
12V LiFePO4 200Ah384h213h192h48h32h27h27h24h19h11h1h1h
12V LiFePO4 300Ah576h320h288h72h48h41h41h36h28h16h2h2h
12V SLA (AGM and Gel) 100Ah120h66h60h15h10h8h8h7h6h3h0,6h0,4h
12V SLA (AGM and Gel) 200Ah240h133h120h30h20h17h17h15h12h7h1h0,8h
12V SLA (AGM and Gel) 300Ah360h200h180h45h30h25h25h22h18h10h1h1h
*Considering the usable energy for each battery and average power ratings of common appliances

What Will a 10Ah Battery Run?

A 12V 10Ah AGM battery and 12V 10Ah LiFePO4 battery.

A 12V 10Ah battery has an energy capacity of 12V x 10Ah = 120Wh

Considering the recommended depth of discharge for each battery, here are their energy capacities:

12V 10Ah LiFePO4, 80% DoD: 12V x 10Ah = 120Wh x 80% = 96Wh*

12V 10Ah AGM or Gel, 50% DoD: 12V x 10Ah = 120Wh x 50% = 60Wh*

*The same calculation applies for different values of battery capacity (in Ah)


Example Appliances & Runtimes

Appliance12V LiFePO412V AGM or Gel
Phone charger (5W)19h12h
1 LED Light (9W)10h6h
WiFi Router (10W)9h6h
Drone / Camera (40W)2h1h
Laptop (60W)1h1h
Ceiling Fan (70W)1h0,8h
Medium size TV (70W)1h0,8h
Water Filter and Cooler (80W)1h0,7h

What Will A 50Ah Battery Run?

A 12V 50Ah LiFePO4 battery and a 12V 50Ah Gel battery.

12V 50Ah LiFePO4, 80% DoD: 12V x 50Ah = 600Wh x 80% = 480Wh

12V 50Ah AGM or Gel, 50% DoD: 12V x 50Ah = 600Wh x 50% = 300Wh


Example Appliances & Runtimes

Appliance12V LiFePO412V AGM or Gel
Phone charger (5W)96h60h
WiFi Router (10W)48h30h
Drone / Camera (40W)12h7h
Laptop (60W)8h5h
Medium size TV (70W)6h4h
Water Filter and Cooler (80W)6h3h
RV Water Pump (100W)4h3h

What Will A 100Ah Battery Run?

A 12V 100Ah Gel battery and 12V 100Ah LiFePO4 battery — battery size chart.
A 12V 100Ah Gel battery and 12V 100Ah LiFePO4 battery.

12V 100Ah LiFePO4, 80% DoD: 12V x 100Ah = 1200Wh x 80% = 960Wh

12V 100Ah AGM or Gel, 50% DoD: 12V x 100Ah = 1200Wh x 50% = 600Wh


Example Appliances & Runtimes

Appliance12V LiFePO412V AGM or Gel
1 LED Light (9W)106h66h
WiFi Router (10W)96h60h
Drone / Camera (40W)24h15h
Laptop (60W)16h10h
Water Filter and Cooler (80W)12h7h
RV Water Pump (100W)9h6h
Refrigerator (170W)5h3h
Coffee Maker (1400 W)0,6h0,4h

What Will A 200Ah Battery Run?

A 12V 200Ah LiFePO4 battery and a 12V 200Ah AGM battery — battery size chart.
A 12V 200Ah LiFePO4 battery and a 12V 200Ah AGM battery.

12V 200Ah LiFePO4, 80% DoD: 12V x 200Ah = 2400Wh x 80% = 1920Wh = 1,92kWh

12V 200Ah AGM or Gel, 50% DoD: 12V x 200Ah = 2400Wh x 50% = 1200Wh = 1,2kWh


Example Appliances & Runtimes

Appliance12V LiFePO412V AGM or Gel
Drone / Camera (40W)48h30h
Laptop (60W)32h20h
Ceiling Fan (70W)27h17h
Medium size TV (70W)27h17h
RV Water Pump (100W)19h12h
Refrigerator (170W)11h7h
Power Tools (1000W)1h1h
Coffee Maker (1400W)1h0,8h

What Will A 300Ah Battery Run?

A 12V 300Ah AGM battery and 12V 300Ah LiFePO4 battery — battery size chart.
A 12V 300Ah AGM battery and 12V 300Ah LiFePO4 battery.

12V 300Ah LiFePO4, 80% DoD: 12V x 300Ah = 3600Wh x 80% = 2880Wh = 2,88kWh

12V 300Ah AGM or Gel, 50% DoD: 12V x 300Ah = 3600Wh x 50% = 1800Wh = 1,8kWh


Example Appliances & Runtimes

Appliance12V LiFePO412V AGM or Gel
WiFi Router (10W)288h180h
Drone / Camera (40W)72h45h
Laptop (60W)48h30h
Medium size TV (70W)41h25h
Water Filter and Cooler (80W)36h22h
RV Water Pump (100W)28h18h
Refrigerator (170W)16h10h
Power Tools (1000W)2h1h
Coffee Maker (1400W)2h1h

Final Thoughts

When it comes to sizing your battery bank, there are different types of batteries and capacities to choose from. Moreover, it can be confusing to determine what battery size you need for your specific needs.

We hope this battery size chart helps make this process easier for you by showing the most common battery sizes and some examples of appliances they can power – and most importantly – for how long.

With this information in hand, you’re now ready to find the perfect battery for your needs!

Ana Lejtman

Ana Lejtman

Ana is a Research Chemist with a strong background in Environmental chemistry. She's deeply interested in how chemistry can be applied to the development of green technologies. Her passion for sustainable chemistry and the environment led her to join the Climatebiz team, writing informative articles on renewable energy/green technologies related topics.

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Andrew

Hello and thanks for the very informative article. I’m curious about the different ratings on batteries of the same type. For example, why would a manufacturer sell (and a consumer purchase) and AGM 50AH battery instead of a 100AH battery? Or a 100 versus a 200 or 300 AH battery?
In various articles, there seem to be reasons for these decisions that I cannot seem to find an explanation for. It doesn’t appear to be price, as some 50AH batteries and priced higher than 100AH of the same type.
Taking the difference in capacity as a given, what is the REASON for the difference and why a solar planner might opt for one over the other? Does a 50 last longer than a 100? for example?

Kyle Browning

Hi Andrew, I’m glad you enjoyed our article. Generally, people purchase batteries based on their power requirements. Ah stands for ampere-hour or amp-hour. An amp hour is simply a measure of how long a battery can provide one amp of power per hour.

Therefore, a 50Ah battery will not last longer than a 100Ah battery.

Batteries with higher capacity tend to cost more than those with less capacity. So, a 100Ah battery will always cost more than a 50Ah battery (assuming both have the same cell chemistry).

With this in mind, it stands to reason why people opt for the battery capacity best suited for their power requirements. Why pay more for a larger battery when you don’t plan on using all its stored energy.

I hope this clears things up for you Andrew?

In this article we cover solar battery cost in detail. Here you can see that lower capacity batteries always cost less than batteries with higher capacity.

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