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What is the capacity of a battery?

Views: 326     Author: Ubest     Publish Time: 2023-09-25      Origin: Site


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What is the capacity of a battery?

Batteries frequently have a ton of technical specs and jargon, whether they are used in your smartphone or portable power station. It can be difficult to compare and contrast different battery-powered device models without having a basic understanding of the concepts.

One of the most important specifications to understand when looking for a battery-powered device is storage capacity. Knowing how long your device can go without a charge is essential to determining if it will meet your needs. This goes for everything from laptops to solar generators to electric vehicles. The fact that different specs are used by manufacturers to measure capacity makes it even trickier. No matter what kind of device you're buying, make sure you make informed decisions by reading on to learn the fundamentals of battery storage capacity.

What is the capacity of a battery?

The maximum amount of electricity a device can store when fully charged is referred to as battery storage capacity. Not all batteries can be used until they are completely discharged safely. A lead acid battery should never be discharged below 50% of its total capacity, for instance, as this will reduce the battery's lifespan. LFP batteries are capable of being safely discharged to 80% or less. What determines how long your battery will last is battery chemistry. All batteries, including the smallest ones found in smartphones, whole-house generators, and electric vehicles (EVs), should be given a rating indicating how much energy they can store. Related product:12V 50Ah LiFePO4 Lithium Battery.

How Is the Storage Capacity of Batteries Measured?

Watt-hours (Wh), kilowatt-hours (kWh), milliampere-hours (mAh), and amp-hours (Ah) are commonly used units to describe battery storage capacity. You can always compare two batteries' storage capacities using their respective watt-hour ratings. However, if the batteries are at various voltages, you cannot directly compare two amp-hour ratings.

The formula below can be used to convert a battery with an amp-hour rating only to watt-hours:

Amp-Hours (Ah) x Voltage (V) = Watt-Hours (Wh)

Thus, 1200Wh of energy could be stored by a 12V, 100Ah battery:

Watt-Hours equal 1200 Wh (1.2 kWh) at 12V from 100Ah.

51.2V 50Ah

What Sets Storage Capacity Apart from AC Output (Power) Capacity?

Storage capacity and power capacity are two very different units of measurement. AC output capacity can be even more important to make the best purchase choice if you're buying something like a portable power station or anything designed to operate appliances.

The total amount of electricity a battery can store is determined by its storage capacity, also referred to as its energy capacity. The specification details the amount of electricity a battery can produce overtime before requiring recharging. This measurement is typically given in watt-hours (wH) or, for larger batteries, kilowatt-hours (kWh). Batteries with a 2 kWh storage capacity, for instance, should be able to supply 2 kW of power for 1 hour, 1 kW for 2 hours, or any other arrangement that results in 2 kWh.

Alternatively, you could have a whole-house generator with up to 25 kWh of combined battery storage, which would enable you to run a total of 1 kW of systems and appliances in your home for a full day without running out of power.

The maximum amount of electricity (in watts or kilowatts) that a portable power unit or other battery backup system can produce at once is referred to as AC output or power capacity. Both watts (W) and kilowatts (kW) are used to measure this metric.

When using generators and battery backup systems, you need to understand AC output because it affects which appliances you can run (and which you can't) as well as how many at once.

Your appliances' starting and operating wattages are a crucial additional factor. Many large appliances, particularly those with motors like refrigerators, air conditioners, and washing machines, use a lot more energy to turn on than they do to run. That is unimportant. When connected to a wall outlet, it makes no difference, but if your generator or portable power source can't provide enough starting watts (surge power), your appliance won't turn on.

What Reduces the Storage Capacity of Batteries Over Time?

All batteries gradually lose storage capacity over time if they are in use. The chemistry of the battery is crucial in this situation. A lead acid battery's capacity can start to noticeably decline after only 300 to 500 cycles (charges/discharges).

1. Cycles and Life of Batteries

A battery goes through one discharge and one complete recharge, as was previously mentioned. The majority of manufacturers list "Cycle Life" as a specification to describe a battery's life expectancy based on usage. A lithium-ion or LFP battery that is used once per month will chronologically last much longer than one that is used every day. Li-ion and LFP batteries experience less deterioration over time than lead acid batteries, which eventually results in a reduction in storage capacity.

2. Temperatures

The temperature ranges at which different battery chemistries operate differ as well. Try to charge your batteries between 50°F and 86°F (10°C and 30°C) as a general rule. A battery can be permanently harmed by charging at temperatures that are too high or too low. Most batteries can safely discharge over a much wider temperature range. Again using DELTA 2 Max as an example, it is safe to use it in a range of temperatures from -4°F (-20°C) to 140°F (60°C).

3. Discharge Depth

The percentage of a battery's total storage capacity that can be safely used before recharging is measured by depth of discharge (DOD). Even though the battery will continue to operate below its recommended DOD, it could potentially harm the battery permanently and reduce its cycle life. To avoid premature deterioration, a recommended DOD is provided for each type of battery. The recommended DOD for lead acid batteries is about 50%, whereas LFP batteries can be safely discharged to 80–90%.  To find out the specific DOD recommendations, contact the manufacturer.

4. Increased Discharge Rates

The speed at which batteries discharge can have an impact on how long they last. Operating constantly at maximum power capacity can result in heat damage and a shorter cycle life for devices like portable power stations, where AC output varies depending on how many appliances you are running. Give batteries a break or occasionally let them run on lower electricity loads if you can.


The maximum amount of electricity a device can store and deliver before recharging is called the battery storage capacity. Contrary to popular belief, power (AC Output) capacity measures the total amount of electricity a battery-powered system can deliver at once.

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