The secondary battery is the foundation of any dual battery system, and having reliable power is essential for a stress-free adventure. But how do you choose the right battery?
Let’s take a closer look at battery types, sizes, and charging options to help you decide which setup is right for you.
CHOOSING THE RIGHT BATTERY SIZE
Choosing the right battery size is all about balance.
- Too small, and you’ll run out of power quickly. With limited capacity, your fridge, lights, and other accessories won’t last long before you’re looking to recharge.
- Going big ensures you have plenty of capacity, but you’ll need the space to install larger batteries and a correctly sized charging system that can keep up.
- The best way to choose the right sized battery is to start with the basics: understanding the differences in battery chemistry as, they all have different performance, weight and lifespans.
LEAD ACID VS LITHIUM BATTERIES
Different battery chemistries all have different performance, weight, and lifespans.
- Lead Acid Batteries: Popular for their affordability, reliability, and ability to withstand the heat of an engine bay. On the downside, they are heavy, have shorter lifespans, and only offer 50% of their stated capacity. For example, a 100Ah lead acid battery provides only about 50 usable amp hours.
- Lithium Batteries: Lighter, longer-lasting, and able to handle deeper discharges with nearly 100% usable capacity. This means you get more power from the same rating, with a lifespan up to four times longer than lead acid. The only limitation is that lithium batteries can’t be mounted in an engine bay.
- Lead acid may be the way to go if you’re on a budget, have space in the engine bay, and only require limited power.
If you want lighter weight, faster charging, and a longer lifespan, lithium is the smarter choice.
WORKING OUT YOUR POWER USAGE
Once you’ve chosen your battery chemistry, you need to work out how much power you’re going to use to determine what size battery you need.
Take one of the most common appliances: a 12-volt fridge.
- On start-up, it pulls about 5 amps.
- Once cooled, it cycles on and off, running for around 20 minutes each hour.
- Power draw is influenced by fridge type, how often it’s opened, ambient temperature, and settings.
- On average, a fridge will draw 2 amps, or roughly 48Ah over a 24-hour period.
This means:
- A 100Ah lead acid battery will run your fridge for one day.
- A 100Ah lithium battery will run it for two days or more without recharging.
CHARGING AND SOLAR OPTIONS
Recharging is just as important as battery size. Adding a DC-DC charger, such as a REDARC BCDC, allows you to charge your battery from both solar and the vehicle while driving.
To stay off-grid longer, adding solar panels is a great option. REDARC Solar Panels come in fixed and portable styles, helping keep your batteries topped up throughout the day.
EXPANDING BEYOND THE BASICS
Once you add more loads or high-draw accessories like inverters, the calculations become more complex. Check out our full video on calculating power draw for more detailed information.
THE RIGHT BATTERY FOR YOUR ADVENTURE
The right second battery comes down to three key factors:
- Install location
- What you’re running
- How you’re charging it
Wherever you’re headed, REDARC has the power to keep you going.
