Understanding Your Battery: Terms to Know

Posted April 08, 2021

Understanding the basics of battery ratings and terminology is important when comparing and selecting the right type and number of batteries for your application to ensure you have enough energy to meet your energy goals. The batteries we will focus on in this blog are classified as deep cycle, for applications where endurance is necessary. Common deep cycle applications include providing power for recreational vehicles, electric vehicles, boats, or camping. In the following, we will use our RB100 lithium deep cycle battery as an example. It’s one of our most popular batteries that work in many deep cycle applications.


relion rb100

Batteries are made up of multiple electrochemical cells. Several predominant chemistries exist, including lead-acid and lithium. Lead-acid batteries have been around since the late 1800s and have multiple varieties - the wet flooded variety, sealed Gel, or AGM type. Lead-acid batteries are heavy, contain less power than lithium batteries, are short-lived, and are easily damaged by improper maintenance. Conversely, lithium iron phosphate batteries (LiFePO4) are about half the weight of lead-acid, contain more energy, have a longer life, and require no maintenance.


A volt is a unit of electric potential or electromotive force. RELiON lithium iron phosphate batteries have an operating range between 2.5 and 3.65 volts per cell. As they discharge, voltage declines from 3.65 volts when full down to 2.5 volts when empty. 3.2 volts per cell is the nominal voltage for lithium iron phosphate batteries because it is the mid-point or average operating voltage. The RB100 is composed of four banks of 3.2V cells connected in series making the total nominal voltage of 12.8V. Because different battery chemistries have different operating voltages that vary slightly, voltage is usually summed up in general by just saying 12 volts instead of 12.8.


An amp is a measurement of electric current or the count of electrons flowing through a circuit.

relion rb100

Amp Hour

One way to measure capacity is in amp-hours which is the amount of current that a battery can deliver for a particular length of time. Drawing a one-amp current for one hour equals one amp hour. The RB100 is a 100-amp hour battery, which means its approximate runtime to 100% depth of discharge can be estimated by dividing its 100-amp hour capacity by the amp load of the DC devices you plan to power. For example, if you are running a 5-amp load, the 100Ah capacity will last roughly 20 hours, if you are running a 10 amp load it will last 10 hours, etc. Regardless of how slowly or quickly you take it out, RELiON lithium batteries provide their rated capacity. This is different than a lead-acid battery where the total capacity could be reduced by up to 30-40% depending on how quickly it is discharged.


A watt is a measurement of power either generated or consumed. Watts = Volts x Amps.

Watt Hour

A watt-hour is a measurement of stored energy. Volts x Amp Hours = Watt Hours. Watt-hours are another way to measure the amount of energy a battery holds. Watt-hours are the nominal voltage multiplied by the capacity. The RB100 is a 1280-watt hour battery (12.8 volts x 100 amp hours = 1280 watt-hours). Most electronic devices are rated in watt-hours, so similar to how you measure amp-hour capacity, you can divide battery energy in watt-hours by the summed watt-hour rating of all devices you plan to power to see how long a battery could provide power.

Battery Management System (BMS)

RELiON’s batteries are all equipped with an internal BMS which protects against potentially damaging circumstances. The conditions the BMS monitors include over-voltage, under-voltage, over-current, over-temperature, short circuit, and cell imbalance. The BMS will disconnect the battery from the circuit if any of these events occur.

Understanding this terminology will help you in the next step to determining the right battery for your energy needs - sizing your battery bank, which can be found here. If you have any questions please don’t hesitate to call, email, or reach out to us on social media.

About the Author:

Chi Woodruff

Chi Woodruff is a Sr. Product Manager at RELiON Battery. Chi's experience includes product management in distribution and manufacturing industries along with a history of analysis, product launches, rebranding and life-cycle management in the battery industry. In his free time, Chi is an avid runner and pacer at many races in Southern California. Keep up with Chi on LinkedIn here.