Calling in the Reserves: A Guide to Battery Reserve Capacity

A senior man recycling a car battery

JD Power’s 2017 Reliability Study revealed that 44% more vehicle owners reported battery failure than in the previous year. Technological issues are bringing down battery ratings, but too many owners also don’t understand essential battery basics related to maintenance.

Battery reserve capacity is one of the most important measures to consider. It relates to the amount of time a battery can be discharged and maintain its voltage.

Knowing the battery reserve capacity of your vehicle is an important part of maintenance. It can help you determine how long your battery will last.

Read our guide to understand what reserve capacity is and how to use it to keep your battery lasting as long as possible.

What Is Battery Reserve Capacity?

It’s important to answer the question of what reserve capacity on a battery is so you can start using it to your advantage.

Reserve capacity is the amount of time measured in minutes a fully-charged battery can be discharged at 25 degrees Celcius at 25 amps before the voltage drops to 10.5 volts.

A reserve capacity rating tells you the reserve capacity of a battery. The higher it is, the longer it can sustain voltage.

An example measure for reserve capacity would be RC @ 25A = 160 minutes. This means that at 25 degrees Celcius, the battery can supply 25 amps for 160 minutes before the voltage drops.

There are several terms to know for proper vehicle maintenance, and battery reserve capacity is only one of them. For more important definitions, check out our glossary of battery terms.

Why It Matters

The battery is one of the most crucial components of any vehicle. If it’s not functioning properly, other measures of performance will suffer too. That’s why it’s important to know as much about your battery as possible.

Not every vehicle owner knows why they need to know about reserve capacity. It matters because of what it helps you determine.

Battery reserve capacity can help you decide whether a battery is useable. It should be able to reach at least 25 amps before the voltage drops. Anything less than this is usually a low-quality battery.

In vehicle engines, the alternator sends a constant voltage to run the wiper, lights, and other important accessories. If it fails, the engine starts to use electricity. This is where you’ll need to use reserve capacity to determine how long it can sustain itself.

Knowing reserve capacity can keep you from overrunning your vehicle and harming the engine. If you know how long it can sustain its amperage, you won’t run it longer than that.

Reserve capacity also helps you choose the best possible battery for your vehicle.  Higher battery ratings are usually better. Knowing these types of measures ahead of time can help you avoid the battery issues that are plaguing more and more vehicle owners.

The more information you have about your vehicle, the better you can maintain it. That’s why it’s important to be aware of battery measures like reserve capacity.

Other Measures

There are several measures mechanics and owners can use to determine the quality of vehicle batteries. It’s important to understand the differences between them so you don’t get them confused.

Battery reserve capacity is similar to but not the same as amp hours. A battery amp hour rating determines the maximum current a battery can draw for 20 hours of service. Reserve capacity determines how long batteries last at specific draws or loads.

Both reserve capacity and amp hours can be used to determine how long a battery will last but in different ways. That’s why it’s important to know both.

Another measure that’s often confused with reserve capacity is cold cranking amps or CCA. They both relate to energy delivery but measure it in different ways and for different periods of time.

CCA is a short-term measure that determines how long an engine takes to start in cold weather. Battery reserve capacity is a long-term measure of how energy is delivered over time.

The more information you can get about a battery you’re considering purchasing, the easier it’ll be to determine if it’s worth your money. Battery reserve capacity is just one important consideration.

Ask for as many details as you can from a dealer before purchasing a new battery. For more tips on how to get the best one, find out everything you need to know before purchasing a new battery.

How Long Your Battery Will Last

Using battery reserve capacity to determine how long your battery can provide sustained amperage isn’t an exact science. It’s still a worthwhile process because it can keep you from running out of battery power on the road.

Battery measures are non-linear, with capacity decreasing as current draw increases. This means that you won’t get a consistent number for how long your battery lasts, as it changes based on how it’s being used.

Knowing your battery reserve capacity is still an important part of maintenance. It determines how long the battery can supply energy to your vehicle’s accessories when the engine isn’t running.

There are plenty of effective ways to keep your vehicle running well regardless of its battery reserve capacity. Check out our 7 battery maintenance tips to learn some of the best methods.

Where to Get High-Rated Batteries

Battery reserve capacity determines how long a vehicle’s battery can sustain its amperage before the voltage decreases. It’s different from other measures of battery quality but just as important.

Battery RC provides a measure of how long a battery can sustain its amperage. It helps you choose the best, longest-lasting battery.

Battery reserve capacity isn’t the only factor to keep in mind, however. One of the most important things to do is choose the best provider to get your battery from.

We have a range of battery types, including dry charged automotive and more.

We offer options for all types of vehicles, from motorcycles to cars to boats. Browse our effective options, learn more about us today, and see how we can help you get the best possible batteries for all of your vehicles.