Deep Cycle Batteries: Lithium and AGM

Deep Cycle Batteries are arguably the most important addition to your off-grid setup or RV. Although it is possible to go camping without any power, not everyone feels the need to go full Bear Grylls. At Outback Equipment, we stock the largest range of batteries in all different sizes to suit everyone's needs. Whether you're powering an off-grid home or need a power pack for a hike, we have the battery for you.

Portable Batteries & Power Stations

Portable power is crucial for road trips. There will be times you can’t bring your vehicle but still want 12V accessories. We offer portable power packs from top brands like Companion, Projecta, Hulk, Dometic, and Coast to Coast.

Deep Cycle Batteries

Deep cycle batteries are designed to be charged and discharged in cycles. They are designed to provide steady power over extended periods. If discharged to about 10V, they must be recharged to complete the cycle. Unlike car batteries, which discharge all at once to start a car and then recharge off the alternator, deep cycle batteries are built to be discharged and recharged repeatedly. They are used in rechargeable systems like solar set-ups or as auxiliary batteries in dual battery systems with a DC-DC battery charger. This type of battery is designed for durability and long-lasting performance.

AGM/Gel Batteries vs. Lithium-ion Batteries

Upfront cost is the main difference between AGM (Absorbed Glass Mat) and lithium-ion batteries. Lithium-ion batteries have become more affordable and popular recently. Spending more on lithium can save you in the long run. AGM batteries are cheaper due to inexpensive, widely available materials. Lithium batteries use pricier materials, and lithium is harder to find. The main advantages of lithium batteries are their longer lifespan, high discharge rate, depth of discharge, and their weight.

• The more you discharge an AGM battery, the fewer cycles it has in the long run.
• AGM batteries are generally recommended to be discharged to only 50% of their capacity to maximise their cycle life. This means if you want more power, you need more batteries wired into a battery bank. This leads to higher upfront costs and a considerable increase in weight.
• A lithium (LiFePO4) battery boasts a much longer cycle life with a depth of discharge around 80-90%. Fewer batteries are required to achieve your desired capacity, resulting in less weight, less space, and more power.

Lithium batteries have many advantages, but AGM batteries are useful in different situations. AGM batteries can charge in freezing temperatures, while lithium batteries need temperature regulation for sub-zero conditions. Lithium batteries are usually half the weight of AGM batteries and save volume and weight in your RV or caravan. We recommend AGM batteries for occasional RV use and lithium batteries for long-term off-grid living.

AGM Benefits

• Can be used as a starter battery (most lithium batteries can’t)
• Can still charge in colder conditions
• Lower upfront cost

Lithium-ion Benefits

• Higher charging efficiency
• Up to 50% lighter than AGM
• A longer lifespan
• Deeper depth of discharge (80-90%)
• Higher quality technology for what you pay

In Series vs. In Parallel

Think of series as "two batteries acting as one." Wiring batteries in series increases voltage output from 12V to 24V or 36V, mainly in larger vehicles. This makes the current run faster and more efficiently, reducing stress on wiring cables. A 24V system can easily run a 5000W inverter with normal gauge wiring. However, larger set-ups require sophisticated monitoring systems, higher-quality fuses, bigger shunts, and consistent wiring gauges.

Wiring batteries in parallel increases amp hours. We've tested Baintech Slimline Lithium batteries in parallel, achieving 220Ah of power. This increased the current flow from 100A to 200A, allowing us to run a 2000W inverter, which handled the current draw of a small microwave, perfect for our caravan set-up.

Frequently Asked Questions

If an auxiliary battery goes flat, can it be recovered?

Remove all output sources and switch off the LED voltage meter or battery box it’s housed in. Apply a battery charger to a 240v source and trickle charge until full. This may take about a day, and depending on the quality of the battery, you may have to replace the battery if it continues to discharge too quickly. It is very hard to ‘recover’ a battery to what it was before being completely flat, however a lithium-ion battery generally has an internal battery management system which would still allow the battery to last a few years.

How do I get the most life out of a battery?

For the best possible longevity, keep your auxiliary battery charged at above 13V. Check the battery once a month if not being used.

How to store a Lithium battery

Do not operate or charge a lithium battery when the temperature is less than zero or above 45 degrees Celsius, doing this can affect the lifespan of your battery as freezing temperatures will drain the battery 10x faster than normal.

What is a battery management system?

If your lithium battery has a battery management system in-built then it will have a low voltage disconnect at around 11v, so the battery should never fully discharge or go completely flat. It is an electronic solid-state circuit board which manages the cells and protects the battery from overcharge and over-discharge. If your battery drops this low, your BMS will automatically cut power and you will be able to recharge without damage once or twice. More than this, and it will start to affect the longevity. The idea is to keep it always charged at a minimum of 13v for the best results.

How to mount/install a battery

Always mount an AGM battery standing up as most AGMs need to vent. A lithium battery can be installed in any position; however, upside down is not recommended by some manufacturers, especially Baintech slimline batteries. It’s best to read the instructions carefully, as each manufacturer will be different.

Why shop with Outback Equipment?

• We’re Australian owned and operated – We’re based right here in the south of Brisbane. If you ever need help with an order or a product, you can call straight through to our friendly local team.
• Plenty of payment options – You can pay via PayPal, MasterCard, Visa, zipMoney, Afterpay, and direct deposit – whichever is most convenient for you.
• Delivered to your door – You don’t have to worry about darting across town to grab your order. We deliver your goods straight to your door to save you time and energy.

Order Your Auxiliary Batteries Today

Stay in complete control of your power grid with our range of deep cycle AGM batteries and Lithium-ion batteries. For the best dependable power solution, shop online to find the finishing touches for your recreational vehicle today.