Andrew and Peta Murray are full-time travellers. They gather information on outback destinations and review products suited to outback travel, for their website Top Wire Traveller. Their 4x4 Isuzu truck and Wedgetail Camper are both powered by REDARC. We gave them one of REDARC’s new 200Ah Lithium batteries to retrofit into their slide-on camper and to test long-term.
A Lithium Battery Upgrade Makes Sense
Are you thinking of replacing the deep cycle batteries in your camper, RV, caravan or campervan? Then it might be time for a Lithium battery upgrade.
It makes a whole lot of sense, as we’ll explain soon.
You might need to change a few other components, depending on how your dual battery system is set up. We’ll run through what to consider before retrofitting your rig with lithium batteries.
Upgrading Our Off-Grid Capacity
Our Wedgetail Camper originally had a 100Ah lithium battery, fitted from new. It performed faultlessly and gave us over 5 years of loyal service.
The only issue? Limited off-grid capacity when the sun wasn’t shining. While the Wedgetail Camper has a portable solar panel, we also have a 112W REDARC Amorphous solar blanket being able to connect both at once gives us indefinite off-grid capacity when the sun’s shining.
But on those cloudy, rainy days we struggled to keep the battery charged. We’d get about two and a half days before the battery was close to its lower limit.
We needed more capacity. And for us, the solution was to fit a 200Ah REDARC Lithium battery. Another option would have been two 100Ah REDARC Lithium batteries connected in parallel, however they simply wouldn’t have fit in the space we had available.
Now we have closer to 5 days capacity before we need to charge the battery. That’s more than enough for us. if the sun isn’t shining for that long, then we’re out of there!
We’re super-happy with the new 200Ah REDARC Lithium battery. It gives us peace of mind and we no longer need to worry about keeping a close eye on the battery’s state of charge. Before you upgrade, you need to consider a few things.
Let’s start with weight.
Lithium, A Lightweight Option
One of the biggest issues with 4x4s and caravans is weight. With so many people travelling, we’re seeing authorities around the country cracking down on overweight vehicles.
A REDARC 100Ah Lithium battery weighs 11kg. In comparison, an 100Ah AGM weighs around 30-35kg. So a Lithium battery is a third of the weight of an AGM battery.
But this is only part of the story.
An AGM can be discharged down to 50%, meaning a 100Ah AGM can only provide 50Ah. Yes, you can go past 50% discharge. However, this will shorten the battery’s life, especially if you do this repeatedly.
In comparison, a Lithium battery can be discharged down to 20%. When you buy a 100Ah battery from REDARC, it has 100Ah of usable capacity.
Meaning, a 100Ah REDARC Lithium battery can provide the entire 100Ah. How? REDARC make them slightly bigger intentionally, to ensure you can use the entire 100Ah (or whatever the rating).
Say you need 10Ah and it has to last overnight (use REDARC’s handy calculator to figure out how much power you need), This means your AGM will last 5 hours. Hmmm, warm milk for breakfast, anyone?
In contrast, the Lithium battery will last 10 hours between charges under these conditions.
So you’ll need two AGMs, doubling your weight to around 70kg. Yet you only need one 11kg Lithium battery to do the same job. That’s a big difference, especially in a campervan, 4x4 ute or wagon.
And as your system gets bigger, the weights quickly add up. It’s not unusual for modern caravans and RVs to have 400Ah of battery capacity.
But this rating is misleading.
If the batteries are AGMs, then usable capacity is half, 200Ah. You could replace the four AGMs with two REDARC 100Ah Lithium batteries and maintain the usable capacity of 200Ah.
That’s 140kg versus 22kg, a substantial weight-saving. You’ll also potentially save loads of space in your vehicle.
Weight is an important consideration these days. At the same time, we’re all demanding more from our second battery systems – microwaves, pie ovens, sound systems, hair dryers and so on. Unfortunately, more power demand equals more weight.
The only solution is to go with Lithium batteries. Let’s look more closely at what else you should check before considering a Lithium battery upgrade.
What Changes Do You Need to Make?
Whether you’re upgrading a 4x4, RV, campervan, caravan or a camper like ours, you need to look at the existing dual battery system to discover what other components might need replacing.
If your vehicle’s old-school, chances are it doesn’t have a smart alternator. Check with the manufacturer if you’re not sure. With this type of vehicle, you could safely fit a Voltage Sensing Relay (VSR) between the start battery and AGM house batteries.
However, Lithium batteries can take big charge currents. Within reason, they’ll take whatever you can throw at them (although they do have an internal battery management system which protects the battery from damage).
It’s entirely possible you’ll overwhelm either the starting battery, alternator or both if you use a VSR.
To prevent this, use a DC-to-DC charger instead. REDARC have a range of DC-DC chargers known as BCDCs, which limit the output current to protect your start battery and alternator.
And if you step up to REDARC’s Manager30 Battery Management System, you can easily limit the current output from a setting within the Remote Monitor.
The other benefit of a DC-to-DC charger or BMS is their charging profile. They have built-in battery chargers which optimise the charging cycle for your battery to prolong battery life.
In contrast, a VSR simply dumps whatever power is available into your battery.
What if your vehicle has a smart alternator? Chances are, it does. They were introduced as standard quite a few years ago now.
Well, you need a DC-to-DC charger or a BMS. Their internal circuits take the alternator’s lower voltage and boost it to suit the needs of the house battery.
If your system already has a DC-to-DC charger or BMS, check:
- Can you limit the output current to the battery? If so, set it to between 25 and 40 Amps. If not, replace the unit.
- Is it compatible with Lithium batteries? Lithium batteries have a different charge profile to AGM batteries.
Cable sizing is a minefield of confusion and misinformation in the auto industry. We put together a comprehensive cable sizing calculator and guide to help remove the mystery.
In short, your cable sizes must match the current they are expected to carry. If not, you’ll get voltage drops. Worst case if the cables are undersized? Cable insulation can melt and potentially cause a fire.
The next vehicle that burns to the ground due to dodgy aftermarket cabling certainly won’t be the first.
We doubled our battery capacity. But this doesn’t mean we can simply whack a whole lot of new devices onto our system. You need to check the cable sizes first, to make sure they’re large enough to safely carry the increased current.
This is time-consuming and requires some knowledge – which is why we published a cable sizing calculator and guide.
If you’re not sure, then you’re probably best using a reputable installer. REDARC have a list of certified installers who they recommend.
A Lithium Battery Upgrade – A Simple Solution
Most times, you’ll find a Lithium battery upgrade is straightforward. The benefits?
- Less weight for the same battery capacity.
- More usable capacity compared to an AGM battery.
- Potentially more free space in your vehicle.
- Incredibly fast charging times.
If you’re replacing like-for-like (e.g. replacing a 200Ah AGM battery with a 200Ah Lithium battery), then check:
- Does the charging unit have a Lithium charging profile?
- Can you limit the output current of the charging unit to between 25 and 40 Amps?
If the answer is Yes to both, then you’re good to go. If not, then you’ll need to upgrade the charging unit.
If you’re upgrading Lithium battery capacity like we did, then check the above and think carefully before adding devices which can draw high currents. Large capacity inverters are a good example. You may need to upgrade the wiring out of the battery to these devices.
And if you’re not 100% confident, then consider using a REDARC certified installer. You’re far better spending a little more upfront than potentially ending up with a vehicle fire.
You can follow Andrew and Peta’s outback travel adventures via their website and on Facebook, Pinterest and YouTube. If you’re looking at starting a dual battery system build but aren’t sure where to start check out our build your REDARC dual battery system tool.