Calculating Your Campervan Battery Bank Size

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How much power will I use when I live in my campervan? How large should my campervan battery bank be? When it comes to our campervan electrical system, we all ask ourselves these same questions.

In this article, we will not only discuss how to properly size your campervan battery capacity, but we will also provide our own real life data showing our daily power usage. We hope you can take this information to make an accurate assessment on your own energy needs for your own campervan build.

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Table Of Contents

Why Is Electricity Important In A Campervan?

A campervan electrical system is the life-blood of any mobile home. Electric wires literally run all throughout our DIY campervan like veins in our bodies.

We use electricity in our van to power our most basic needs, like our lights, our ventilation fan, and our phones/laptops. But we also use electricity to run our more luxury items, like our fridge, diesel heater, water pump, and Instant Pot.

Whatever your needs and requirements are for van life, whether basic or luxurious, we believe, at the very least, a minimum amount of electricity is needed to live and travel comfortably in your campervan.

So how do we figure out just how much electricity we actually need?

How Much Electricity Do You Need?

Campervan Electrical System - Computer Work With Lights

The amount of electricity that you require in your campervan is entirely up to you. And no two campervan use exactly the same amount of power. Therefore, it’s important to calculate and estimate your electricity needs before your van build.

Why It's Important To Calculate Your Usage

It is important to estimate the energy needs for your campervan electrical system for the following reasons.

By calculating your power requirements, you will better understand how many batteries and how many solar panels you will need. You can then design your campervan interior to build around these electrical requirements.

Without calculating your electricity needs, you risk building an electrical system that cannot sustainably meet your energy demands on a daily basis. You risk depleting your batteries and running out of electricity when you need it.

Batteries that have been discharged too low and for too many times will degrade faster and eventually die prematurely. This means additional costs are needed to purchase new batteries to replace the ones that have died.

Which Electrical Devices Consume The Most Energy?

Different devices also demand and consume different amounts of power. We put together a list below of the most common electrical devices in a campervan and sorted them by estimated total power consumption. This list takes into account not only the instantaneous power demand, but also the estimated duration of use.

So, for example, even though a hairdryer consumes a large amount of instantaneous power, it is only used for 5-10 minutes per day (and maybe not used every day), and so the hairdryer is not, overall, a major power draw.

On the other hand, an efficient 12v fridge may not consume much instantaneous power, but because the fridge is always on 24/7, it ends up consuming more power than a hair dryer on a daily basis.

High Consumption

Mid Consumption

Low Consumption

Of course, the total power consumption of a device depends entirely on your own usage and can vary wildly to another person’s.

How To Calculate & Estimate Your Energy Needs

It can be tedious but creating an energy usage table can help you to estimate your daily total power consumption.

In order to estimate your daily energy usage:

Each device is called a “load”

This is measured in “watts”.

This is the “time”. It is measured in Hours (h). Fractional amounts are OK, too.

This is your device’s “daily energy usage”. It is measured in watt-hours (Wh)

Don't Know Individual Power Requirements? Use Our Data.

If you don’t know each of your device’s power requirements, you can use our data below for the devices we use in our own camper van. You simply need to multiply each device’s watts by the amount of hours they will be used per day.

Electrical DeviceConsumed Watts
LED Lights (6 Puck Lights)13
Ventilation Fan (low speed)2
12v Fridge55
Water Pump (low pressure)57
Diesel Heater20
Laptop (when charging)65
Instant Pot750
Electric Tooth Brush1
Inverter (Only)13
Hair Dryer800

Review Our Own Energy Usage Table

Below, we created a table of our own daily energy usage. We listed all of our electrical devices and calculated their energy demands.

If you are unsure how to proceed with your own energy usage table, use our table below as a reference and starting point.

AsoboLife Energy Usage Table

LoadCurrent (W)Time (h)Daily Energy Usage
Ventilation Fan2202
LED Lights1376.67
Fridge556 (on 1/4 of time)17.76
Smartphone 11221.4
Smartphone 21221.4
Laptop 16527.5
Laptop 26513.75
Water Pump570.170.35
Instant Pot7500.125 (30min every 4 days)7.25
Diesel Heater (winter only)20510.42
Hair Dryer8000.0422.35
Electric Toothbrush150.08
Total:1011.6 Wh

According to the above table, we estimated that we will use about ~1011.6 Wh of power per day. This estimate is for the winter time when we use our diesel heater.

During the summer months, we expect to use less energy.

In the next section below, we recorded our actual energy usage data over four days during the winter Let’s see how our real-world figures compare to our estimate.

How Much Electricity Do We Actually Use?

For 4 days, we disconnected our solar panels from our campervan electricity system and we measured the flow of amps out of our batteries using our Victron Battery Monitor. We wanted to see how our real-life energy usage compared to our calculated estimation.

Below is a table showing our results.

DayPower Consumed
Jan 15, 2021 @10pmStart
Jan 16, 2021 @10pm864.00 Wh
Jan 17, 2021 @10pm784.08 Wh
Jan 18, 2021 @10pm999.36 Wh
Jan 19, 2021 @10pm747.96 Wh

From the above data, it looks like our calculation was quite close to our real-world energy usage. Figures do vary from day-to-day for a variety of reasons, but it’s encouraging to see that within +/- 163 Wh (+/- 16%), we are keeping within our calculated budget.

What Size Battery Bank Do I Need?

Once you have estimated your Daily Energy Usage you can begin deciding how many batteries are required to sustain your energy needs.

HOWEVER, batteries are most commonly marketed in “amp-hours (Ah)”, not the “watt-hours (Wh)” you calculated previously. Therefore, it’s easier if you take your estimated Wh and convert it to Ah.

To convert Wh to Ah, you’ll need to devide the Wh by the voltage of the battery. Since most batteries are 12v batteries, you’ll need to device your estimated Wh by 12.

In our case, 1011.6Wh/12 = 84.3Ah.

Some batteries can be either 5-volts or even 24-volts. So make sure you know the voltage of the battery you want to buy.

Which TYPE Of Batteries Will You Get?

AGM vs Lithium-Ion Batteries
Lithium Battery vs. Lead Acid (AGM)

There are two major battery chemistries on the market today that serve the campervan community.

1. Lead Acid (AGM) Batteries: These batteries are cheaper to purchase initially (starting at ~$170), but have several drawbacks, including that you can only safely discharge these batteries down to only ~50% without seriously degrading the battery’s health.

2. Lithium-Ion Phosphate (LiFeP04) Batteries: These batteries have a much higher upfront cost (ours cost $950), but have a significantly longer lifespan and can be safely discharged passed ~90% without any serious degradation to the battery’s health.

Important Take Away

Due to the drastic differences in safe discharge amounts, even though a 100Ah lead acid battery has the same amount of stored energy is a 100Ah lithium battery, the EFFECTIVE usable Ah of a lead acid battery is only roughly half that of a lithium battery.

In effect, a 100Ah lithium battery would have the same EFFECTIVE usable Ah as 2x100Ah lead acid batteries.

To keep your lead acid batteries healthy over the long run, you would need to buy twice the number of lead acid batteries as you would lithium batteries.

To learn more about properly maintaining healthy batteries, read our Battery Charging Best Practices.

Our Battery Bank Recommendation

From our 2+ years on the road, we have a strong understanding of our own electrical usage tendencies. Some days require more power usage than others, and some days our solar panels bring in more electricity than other days.

Based on our experiences, we can recommend a robust battery bank sizing strategy for your campervan, but it depends on which type of battery chemistry you will ultimately go with.

If Going With Lithium Batteries...

If you decide to purchase lithium batteries to provide your power needs, the battery calculation is straight forward.

Take your estimated Daily Energy Usage, double it, and round up to the nearest 100Ah.

Example 1: If your estimated Daily Energy Usage is 35Ah, doubling it will result in 70Ah. Then rounding up will give you 100Ah. You would be safe in simply purchasing a single 100Ah lithium-ion battery.

Example 2: If your estimated Daily Energy Usage is 80Ah, doubling it will result in 160Ah. Rounding up will give you 200Ah. You would be safe to purchase 2x100Ah lithium-ion batteries.

If Going With Lead Acid (AGM) Batteries...

Deciding to purchase lead acid batteries instead will make the battery calculation just a bit more tricky. But still simple enough.

Take your estimated Daily Energy Usage, double it, double it again, and round up to the nearest 100Ah.

Example 1: If your estimated Daily Energy Usage is 35Ah, doubling it will result in 70Ah. Doubling it again will result in 140Ah. Then rounding up will give you 200Ah. You would be safe in purchasing 2x100Ah lead acid batteries.

Example 2: If your estimated Daily Energy Usage is 80Ah, doubling it will result in 160Ah. Doubling it again will result in 320Ah. Rounding up will give you 400Ah. We would then recommend buying 4x100Ah of lead acid batteries to supply your energy needs.

Overestimating Your Battery Bank Is Good

By following the above rules, you will be overestimating your battery bank to supply your energy needs.

Overestimating your battery bank is a good thing because there will be days where you won’t be able to charge your batteries back to full. Either it’s a shady day with no solar potential, or you’re boondocking with no shore power. Either way, overestimating your battery bank will help reduce your risk of running your batteries down to 0% and being without power.

Recommended Battery Products


Batteries are the foundation of any campervan electrical system. If your budget allows, we recommend buying good quality batteries, whether they are Lead-Acid (AGM) or Lithium-Ion based.

Best Lead Acid (AGM)


Not the cheapest on the market, but this heavy duty AGM is built with solar charging in mind. Longer lifespan than usual lead acids at at 125Ah, more storage capacity than normal.

Best Lithium-Ion


Quickly becoming a campervan favorite, we have three of these in our campervan and love them. 2+ years on the road and they still work great and provide solid power to all our devices.

Connecting Your Batteries To Your Solar Panels

Camper Van Electrical System - Fig 5.1: Connecting Solar Panels To House Batteries
Visit our electrical system installation guide to learn more

We created a 100% FREE resource detailing the installation process of a campervan electrical system.

Step-by-step, from start to finish.

Our guide is full of click-able pictures leading you directly to the product’s Amazon page.

Or, to start from the very beginning, visit our Comprehensive Electrical Guide.

Campervan Electrical System Installation Guide
Read Our Campervan Electrical System Installation Guide

Conclusion: Size Your Campervan Electrical System In Advance

We hope this article has helped inform and inspire you to begin building your own campervan electrical system.

In this post, we discussed WHY having an electrical system in your campervan is important and HOW to begin calculating your daily energy usage. Most importantly, from this information, we discussed how BIG of a battery system you will need.

Once you have properly sized your battery bank, you may be wondering how many watts of solar panels you need to help keep your batteries regularly and sufficiently charged.

We discuss this in our next post: Determining The Size Of Your Solar Array.

If you have any questions or comments after reading our campervan battery and solar post, please let us know in the comments below!

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