Caravan Batteries: Just As Relevant As Ever

A solar setup is an essential amenity for anyone that is wanting to get off-grid and venture into the more remote corners of Australia, and batteries are one of the most crucial components of any solar setup. In this Buyer's Guide, we're going to give you an introduction to caravan batteries, the differences between lithium batteries, AGM batteries, and lead acid batteries, and walk you through everything you need to know when it comes to getting your caravan equipped for some off-grid adventures.

What are caravan batteries used for?

Let's get the simple questions out of the way before we start digging into the science, shall we? Caravan batteries (sometimes referred to as deep cycle batteries) are most commonly used to store energy produced by solar panels, although they can also be charged with a petrol generator, wind turbine, or really anything that is capable of producing an electric current.

Whether it's wind, solar, or petrol that is producing your power, caravan batteries allow you to store that energy to use even when its source is no longer producing - that means you can keep the lights on even when the sun isn't shining.

What are the different types of batteries?

When you're looking for batteries online, you're likely to come across two main types: AGM, and lithium batteries.

AGM Batteries

An AGM battery is technically a lead acid battery, with a few key differences. In an AGM battery, mats of fibreglass are sandwiched between the lead plates - AGM stands for Absorbent Glass Mat - and wick the acid solution, as opposed to a flooded lead acid (FLA) battery where the plates are completely submerged in the solution.

Because AGMs are sealed batteries, the chemical reaction that takes place within them creates minimal off-gassing, reducing the need for maintenance and allowing AGM batteries to be placed in confined areas. In addition, AGM batteries have lower internal resistance than FLA batteries, resulting in higher voltage outputs and faster charging times, and they can also be discharged to roughly 20% of their capacity, versus only 50% for FLA batteries. Moreover, AGM batteries will only lose a small amount of their charge if they're left unused for a period of time.

All of these qualities make AGMs incredibly popular for off-grid and solar setups, while FLA batteries tend to be reserved for use in standard cars.

Lithium Batteries

Lithium caravan batteries (or lithium-ion batteries) have become well-known in recent years due to their widespread usage in electric vehicles. Lithium batteries have a different construction to AGM and FLA batteries and are made up of a negative electrode (anode) and a positive electrode (cathode) in an electrolyte solution, with a seperator in between them.

When a lithium battery is charged or discharged, lithium ions flow through the electrolyte between the cathode and the anode, releasing energy in the form of electrons, which flow in the reverse direction through the circuit, allowing us to power our cars, lights, and appliances.

As well as being substantially lighter than AGM batteries, lithium batteries are faster to charge, have a greater usable capacity (being able to discharge approximately 90% of their charge) and have a longer lifespan. For these reasons, lithium batteries are becoming increasingly popular for anyone that is looking to build a long-lasting off-grid setup, either at home or on the road.

Which battery is better for a caravan solar setup?

Most caravan owners will tell you that lithium batteries are the clear choice due to their fast charging, usable capacity, long lifespan and weight savings. However, the main drawback of lithium batteries is their price, with a lithium battery costing roughly twice as much as a comparable AGM battery.

Ultimately, the best choice for your caravan will depend on your budget and needs. If you only use your caravan for a few weeks of the year but want to get off-grid, the savings offered by AGM batteries probably make them a better choice, while lithium batteries are more suitable for owners that plan to live in their caravan full-time or spend extended amounts of time off-grid.

How many batteries do I need?

Once again, there is no set answer for everyone, and you'll have to do some calculations to figure out how many batteries you'll require to meet your storage needs. We explored how to calculate your power generation needs in our Buyer's Guide on caravan solar panels and for the sake of simplicity, we'll use the same figures here. Let's assume you have the following appliances in your caravan:

Microwave: 1000W x 10 minutes per day = 100 Watt hours

Single LED light: 10W x 6 hours = 60 Watt hours

Laptop charger: 100W x 2 hours = 200 Watt hours

Television: 200W x 3 hours = 600 Watt hours

60L caravan fridge: 60W x 24 hours = 1,440 Watt hours

The total number of Watt-hours you would need to generate each day would be 2,400. Once you have your solar panels, you need to be able to store that energy for use at a later date - but batteries are measured in Amp hours, not Watt hours. So what do you do? You divide the wattage of the appliance by its voltage to get its hourly Amp draw, and substitute the resulting number into the equation. Again, for the sake of simplicity we are going to assume that each of the appliances listed above are 12V.

Microwave: 1000W ÷ 12 = 83.3 Amps | 83.3A x 10 minutes per day = 13.8 Amp hours

Single LED light: 10W ÷ 12 = 0.83 Amps | 0.83 x 6 hours = 5 Amp hours

Laptop charger: 100W ÷ 12 = 8.33 Amps | 8.33 x 2 hours = 16.6 Amp hours

Television: 200W ÷ 12 = 16.6 Amps | 16.6 x 3 hours = 50 Amp hours

60L caravan fridge: 60W ÷ 12 = 5 Amps | 5 x 24 hours = 120 Amp hours

This gives us a total of 205.4 Amp hours. In other words, to store enough energy to power all of these appliances for one full day, you will need a little over 200Ah of battery capacity, or just slightly more than one of these BMPRO lithium batteries.

Of course, you will want to have some additional capacity to tide you over in case the sun doesn't shine for a day and your batteries can't charge. Also keep in mind that the figures we've used are very much intended as an example, and in reality your actual daily energy needs will be significantly higher than what we've shown, especially if you plan on living in your caravan full time.

What else do I need for a solar setup?

Once you have panels and batteries sorted, you'll need to add the final accessory pieces to get your solar setup completed. There are different options available depending on how sophisticated you want your setup to be, which we will explore now.

Solar Charge Controller

A solar charge controller is essential for regulating the voltage and amperage of the electricity produced by your solar panels, which can vary widely and be unsuitable for powering your device or appliance. The solar charge controller will monitor the v0ltage of your batteries and reduce the current to prevent them from overcharging.

Battery Monitor

A battery monitor is not essential but is highly recommended for anyone that is serious about their solar setup, and will allow you to know exactly how much charge you have left in your batteries. Here at Shop RV Parts, we stock a range of battery monitors from BMPRO but one of our favourites is the BatteryCheckPRO, which has Bluetooth connectivity so you can monitor your batteries from your smartphone.

If you're considering a solar setup, check out our unbeatable selection of batteries and battery accessories.

Hopefully you now have the knowledge you need to build a solar setup that will let you get off-grid and explore Australia in all of its beauty. If you're interested in learning more, you can read our other Buyer's Guides for information on everything from caravan air conditioning to solar panels and safety essentials.

With an immense range of products from leading brands including Sphere, Dometic, BMPRO and dozens more, we are your one-stop-shop for everything concerning caravans and recreational vehicles. Head over to the Shop RV Parts website today to browse our full selection and find your next upgrade.