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How to Calculate and Compare Volts, Watts, Amps, Ohms?

Are you someone new, finding lithium batteries for your RV? Or someone who wants to upgrade to lithium batteries from AGM or SLAs? Or want to learn about these incredible batteries?

Oh yes! Today, one of the most popular battery types is the 'Lithium Batteries.' So, why not upgrade to this latest technology or learn about this technology - A technology that comes with tremendous advantages that you must have heard from people around you. And, why not? These batteries are the hot topic of the town, isn’t it?

Lithium batteries are found to be one of the most extraordinary batteries possessing several advantages over other types, such as longer life, lighter weight, faster charging, and a long list to go.
If you're eager to know about these batteries in-depth, you must learn about some important units related to these batteries, such as volts, watts, amps, ohms, etc. When researching more about these batteries, you'll come across these terms many times.

In this blog post, we will discuss some of the most important units you need to know to understand lithium batteries clearly and how to calculate and compare those terms. Without further ado, let’s dive in.

Some Important Units Related To Lithium Batteries

There are some basic and important units related to lithium batteries, so let me describe those terminologies in simple language to get started with the article. So if you're not a physics person, that's not a problem! Just read on till the end, and you'll definitely enjoy learning these terms.

There are three basic units when we talk about electricity and they are voltage (V), current (I), and resistance (r). The unit of voltage is volts, the unit of current is amperes, and the unit of resistance is ohms. Following the table for reference:

What are Volts?

Volt is the unit of electromotive force. It’s a standard unit that measures the electrical potential difference between two points, which means it can be used to measure the voltage across an electric circuit or volts across components in the same circuit. It is measured in volts (v).
The battery possesses a fixed voltage. It can be 12 volts, 24 volts or 36 volts, and so on. Our 12V 100Ah lithium batteries possess 12.8 volts, which is works wonderful for a camper. Here it is to be noted that the RV appliances working on 12 volts need a battery with a supply of 12 volts.

What are Amps?

Amperage is the unit of electric current and is the number of electrons passing through the cross-sectional area. It is measured in amperes, amps or A, where one amp equals 6.24 x 10 ^ 18 electrons per second, passing through an area of one square centimeter perpendicular to the direction of flow.

Current I (A) = Voltage (V) / Resistance R(ohm)

Simply it can be said that amp is the amount of electric current flowing through the device. Voltages of your electrical appliances in RVs are fixed, but it depends on how many amps they draw from the battery.

Let's take the example of an RV air conditioner. The startup on an air conditioner takes ~ 12-15 amps while the running RV air conditioner draws ~13-16 amps from our 12v 100ah LiFePO4 deep cycle battery.
Since lithium batteries are capable of delivering high currents, amps are a more useful unit for specifying the capacity of these batteries.

What are Watts?

Watt describes the power of electricity, in other words, battery’s power. It measures electrical energy over time, and it's measured in watts (W). One watt equals to one volt multiplied by one amp.
This unit is used to calculate the energy consumed by appliances that are being run on your RV battery. Volts are fixed but amps are variable.
Let me give you an example of how to calculate watts. The basic formula for calculating watts is volt multiplied by amps:

Power (W) =Voltage (V) ×Current I (A)

So, if you have a 12v bulb that draws 8.3 amps, the power consumption is 99.6 watts.

What is Ohm?

Ohm is a unit used to measure resistance. It indicates the ability to impede the flow of current. Which means it can be used on circuits with components that are connected in series or parallel. Its SI-derived unit is I.

R (Ω) =Voltage (V) / Current I (A)

It is measured in ohm or kilo-ohm, where 1 ohm equals to one volt divided by one ampere.

What Is Amp-Hours?

Amp-Hours (Ah), a unit to describe the discharge capacity. More precisely, it's the amount of current passing through a circuit over time, where one amp-hour equals passing one-ampere current for one hour. The name suggests how much amp the battery can deliver in one hour.

For example Aolithium 12 V 100amp hours lithium battery can deliver with capacity 100 Ah can deliver 100 Ah to a 12 V device.

Amp-hours is a more useful unit for calculating the energy consumed by your appliances.

What is Watt-Hours?

It’s a unit used to describe energy. It is the product of watts applied for one hour. Thus, if you have a 100-watt bulb that has been lit for 10 hours, it would mean that the light bulb has used 1kWh of energy.


The Relationship of Volts, Amps, and Watt-Hours in Lithium Batteries

Now that I've discussed some terminologies related to batteries let me get you started with building more knowledge on lithium batteries. So let's get down to basics- Viewing the relationship among volts, amps, and watt-hours.

As discussed in the article above, amps is a unit of electrical current, whereas a watt is a unit of power that describes amount of energy consumed by a device, precisely how powerful it is. Now, if you know about these two units, then it's easy to understand watts per hour or watt-hours, which is a unit of energy.

You can simply say that watt-hour is the product of watts and time; thus, it is the energy will the battery expend in one hour. For instance, if you have a 100-watt light bulb that has been lit for 10 hours, then by simple calculation, you can calculate the energy it has consumed.
So, 100 watts x 10 hours = 1000 watt-hours or 1kWh of energy.

Amps and Voltages across Parallel and Series Circuit

As discussed earlier, amps describe the electrical current, and voltage describes how much potential difference (electromotive force) is available to drive electrons through the circuit. Now I know you're wondering what does this means, so here is the example. In an old-fashioned Christmas light strings, you'll have a series of bulbs that are typically wired with small wires, so each bulb will have only a few volts passing through it.

However, if you were to wire those lights and connect them in parallel, this voltage across all the lights would be the same. However, the wattage would be different for each bulb because if you use larger size Christmas lights, these will obviously result in more energy.

As such, when people discuss batteries, they use amps and watts to figure out exactly how much power is available. Now let's get back to battery terminology; we know that batteries are capable of storing energy. However, the amp-hour rating for a deep cycle battery is a more useful measurement of its capacity because it’s a measure of how much current can be delivered at a given voltage before the battery reaches 10.5 volts. It indicates that you should know about voltage and amps when using lithium batteries because even if your RV’s appliances have the same amp rating, they do not provide you with similar wattage. Moreover, even if two batteries may look alike (say 100ah), their watt-hours can vary based on volts and currents at which these batteries work.

So let me get this straight; two batteries of equal voltage, but one delivers 4 amps while the other delivers 5 amps, both batteries will provide different watt-hours.

Comparing Watt-Hours to Amp Hours- How to Calculate Them?

Okay, let's compare these two terms- watt-hours and amp-hours.
So, watt-hours describe how much power a battery can deliver over time. However, amps determine how many amps a battery can deliver in one hour. Though both watt-hour and amps are important, amp-hours are like horsepower for an engine since it tells you how much power is available to be drawn by the appliance.

You should know that amps and watt-hours are related, but they don't work in conjunction with each other, as such batteries that have high voltage can deliver a lot of current for a short period of time. However, if you try to draw them continuously, then these will drain faster than batteries that have lower voltage rating.

So, how to calculate them? Let’s have a look!

Calculation of Amp-Hours

Amp-hour is the amount of current a battery can supply in our one. For example, in the case of RV batteries, we would use the term "amp-hour" to describe how many amps a battery can deliver in one hour. Amp-hour has a subunit which is milliampere-hour (mAh).

Theoretically, 1 amp-hour battery should deliver 1 amp in one hour of continuous current to a device, before discharging. And if the same battery delivers 2 amp of continuous current to a device, the time will reduce to half an hour.
In case of our aolithium 12v100ah battery, it will deliver 1 hour of power to a device of 100 amps or half an hour of power to a 200 amps.

To calculate amp-hours we use the formula:

Amp Hour = Current (I) x Discharge Time (T)

If the current drawn by the RV appliance is 10 amps in 5 hours, 5 amp-hours will be delivery by a 100ah aolithium lithium battery.
Calculation of Watt-Hours

If you want to know how many watt-hours are available in a battery, you simply multiply the amps at which it’s being delivered by the volts.


For example, if you have a 12v 100ah LiFePO4 deep cycle battery, Just multiply 12 by 100, and you get the answer 1200 (watt-hours).

Another example, if you have our 100ah 12-volt lithium battery that delivers 5amps, then this means that this battery can provide 600 watt-hours of energy before reaching 10.5 volts.

What Is Battery Run Time And How Is It Calculated?

Now, what is battery run time? Well, it’s actually the time that your appliance will be able to run using your batteries. For example, if the battery is fully charged, it can be affected by three things.

  • The mechanical condition of the battery
  • Current that the load draws
  • The integrity of the system, such as the wiring and the inverter

To calculate it, we have a formula (10 x amps) / 100= maximum run time of the battery.

For example, if your RV runs a 100-watt TV off battery-rated amps for 40 A , by calculating it using the formula, the maximum run time we get is 4 hours.
(10 x 40) / 100 = 4 (maximum battery run time)

Terms to RV Lithium Batteries You Must Be Interested to Learn

 Cycle Life

The cycle life of a battery is the number of times it can be discharged and recharged before its performance drops below a certain level. A battery with a longer cycle life will last longer overall. For example, the cycle life of our 12v 100ah LiFePO4 deep cycle battery is 4000+.

Depth of discharge (DOD)
Depth of discharge is the amount of energy that has been drained from a battery, expressed as a percentage of its total capacity. A battery that has been discharged to 80% of its capacity, for example, has had a depth of discharge of 80%.

Charging Time
The charging time of a battery is the amount of time it takes to fully charge the battery. This can vary depending on the size and type of battery as well as how much power is being drawn from it.

Maximum Charging Current
The maximum charging current of a battery is the amount of electricity that can be pushed into it without causing damage over time or shortening its life span significantly. This value varies depending on the chemistry and capacity of each cell in your pack!

Discharging Time
The discharging time of a battery is the amount of time it takes for the battery to discharge from 100% to 0%. This can vary depending on the size and type of battery as well as how much power is being drawn from it.


To conclude the article, I hope this article was interesting and helpful for you to learn different units and terms associated with lithium batteries. Now, you can easily calculate watts, ah, watt-hour, etc., without any hassle. If you are someone searching to buy a new battery for your RV or are thinking of an upgrade, I'm going to suggest to you that it's the best option for a long-term investment. Not just this, but LiFePO4 deep cycle batteries come with several other advantages such as no rusting, odorless when charging, and it's eco-friendly.

Transform your need with the latest technology and have an amazing trip without caring much about battery charging and recharging issues! Happy traveling!

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