What is Battery Reserve Capacity?

You have a lot of specifications to compare when choosing a battery for your energy system. From amp-hours to voltage to cycle life to efficiency, there are countless factors to consider. It is also important to understand how the battery reserve capacity affects the battery’s lifespan and how it performs under sustained loads. Generally, battery reserve capacity describes how long a fully charged battery can run without dropping below a specific voltage, a crucial information to know if you need a battery to handle consistent loads over time rather than short bursts. Before investing in your next battery, make sure you know what you need to know about reserve capacity.

What is battery reserve capacity?

A 12V battery‘s reserve capacity is measured in reserve minutes. It refers to the amount of time it can be used before it drops to 10.5V, commonly referred to as RC. For example, if a battery has a reserve capacity of 150, it can supply 25 amps for 150 minutes before the voltage drops to 10.5V.

The difference between reserve capacity and amp-hours (Ah) is that amp-hours measure the amount of current, or amps, that can be generated in an hour, whereas reserve capacity measures time. The reserve capacity can also be calculated from amp-hours, but the two are not the same. When compared to amp-hours, RC capacity is a more accurate method of measuring how long a battery will last under sustained loads.

What is Battery Reserve Capacity? Redway Battery

Why is battery reserve capacity important?

It is important to understand your battery’s reserve capacity if you intend to discharge your batteries for a long period of time. It is a great indicator of how long your batteries will last with consistent loads. Knowing your reserve capacity will give you a better idea of how long your batteries will last, as well as how much power they can provide. There is a huge difference in how you use your batteries as well as how many you need depending on whether your reserve capacity is 150 minutes or 240 minutes. In order to time your travel effectively and get home without running out of power if you’re going fishing for a full day, you need to know how much power and time your battery will supply.

The reserve capacity of your battery directly impacts the power it can generate. Power is equal to amps multiplied by volts, so if your battery voltage drops from 12 to 10.5volts, power drops. As energy is equal to power times the length of time used, if the power drops, so does the energy produced. Your battery reserve capacity needs will vary based on how it will be used – for example, for a days-long RV trip, or for a golf cart that you use occasionally.

How does reserve capacity differ between lithium & lead acid batteries?

What is Battery Reserve Capacity? Redway Battery

In the first place, lithium batteries do have reserve capacities, but they are rarely rated in this manner, as they are usually rated in amps or watts. This is due to the Peukert Effect in which the reserve capacity of lead acid batteries decreases with a decrease in discharge rate. However, lead acid batteries have a lower reserve capacity than lithium batteries on average. High-quality lithium batteries are not affected by the Peukert Effect, and their amp-hour rating indicates how much charge they can deliver under most circumstances.

As an example, a 12V 100Ah lead-acid battery has a reserve capacity of approximately 170-190 minutes, whereas a 12V 100Ah lithium battery has a reserve capacity of approximately 240 minutes. By replacing lead acid batteries with lithium batteries, you can save space and weight because lithium batteries offer higher reserve capacity at the same Ah rating.

Find out how to calculate your energy needs and find the best battery for your application and usage by visiting our website. You can get assistance from our experts if you need assistance selecting the right battery for your specific usage – from boating to RVing. Get in touch with our team today.

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