The facts about lithium batteries in caravans

Lithium batteries have been in the news a lot recently, usually blamed for unexpected fires and explosions.

If you own a lithium battery-powered RV or have one on order, you might be wondering if you have made the right decision.

In this article we clear up the confusion.

Lithium batteries are lighter, physically smaller, charge faster and last longer than conventional lead-acid batteries, which is why they have become so popular in many off-road campers and caravans.

However, the word “lithium” has been increasingly in the news recently, with spontaneous fires caused by faulty, dodgy and poorly maintained items destroying cars, scooters and storage sheds.

It’s potentially worrying if you have an off-road caravan or camper trailer on order, as most likely it will be fitted, or optioned, with a lithium battery. But here is the news that will make you sleep easier.

If it’s an RV from an established manufacturer or dealer, the battery will almost certainly employ Lithium Phosphate LiFePO4 architecture that is not associated with these spontaneous combustion fires.

Moreover, if you take delivery of your lithium LiFePO4  equipped RV after November 2023 you are further protected by the new Australian Standards AS/NZS 3001.2022 for connectable electrical installations which requires any lithium battery to be mounted in a way that prevents the egress of gases to the habitable space of the structure.

Manufacturers installing lithium batteries to caravans built after November 18 2023 will need to comply to this new standard. Caravans built or modified prior to November 18 do not need to comply to this new standard as the standard is not enforceable retrospectively.

First, some background. Lithium batteries work on the same principle as lead-acid batteries, but the chemistries are different. There are many different types of lithium-based batteries used for different applications. The type you are most likely to find used in RV lithium batteries is Lithium Iron Phosphate which is written as LiFePO4.

In all lithium-based batteries, the cathode or positive side of the battery is made of some kind of lithium-based metal oxide and the negative side or anode is typically made of graphite. There is a separator between them preventing the metals from touching and an organic compound is used as the electrolyte.

As well as being smaller and around 30 per cent lighter, another benefit of LiFePO4 batteries is increased lifespan. Some RV lithium batteries are rated to last up to 5000 charging cycles which is 10 times longer than lead-acid batteries. They can also be charged much faster. 

If you're planning to convert an older caravan from lead-acid to lithium battery power, the same rule applies. Get it done before November or it must comply with the latest regulation.

The main fire culprits are not LiFePO4 RV batteries, but other types of lithium batteries, many of which are found in mobile phones, power tools, laptops and electric scooters that given their use have often been designed with lightweight high density lithium battery chemistries which aren’t as stable as LiFePO4.

So how do you tell if your RV battery should give you any cause to worry? 

An easy way is to look up the battery manufacturers for their battery fitment guide or recommendations and if their cells comply to AS IEC 62619. Speaking with your specific caravan manufacturer is also a great idea to ensure they’re working within the new AS/NZ 3001.2.2022.

If the only contact details you can find is an email address and not a phone number, this is an immediate red flag.

More worrying for the caravan industry is the other portable lithium batteries taken with us traveling. Often these batteries are dropped or left out in the sun for extended periods of time which can compromise the batteries and lead to issues when recharged, sometimes resulting in fire.

The recommendation here when charging is to position them as far away from the van or tow vehicle as possible – in a box on the A-frame or on the back bumper in the case of the bikes and in a fireproof box inside the RV or at the end of a power extension cord if this isn’t possible.

However the best advice is to turn off charging and disconnect the AC power charging source if you can’t keep the charging item in sight.

It's also advisable to keep any batteries or battery-powered appliances at room temperature eg. 20 and 25 degrees C. As batteries, being heavy, are usually stored low and in special compartments in RVs, they usually maintain their temperature within this range.

Another tip is to think about using higher-capacity lithium-ion batteries for portable drills, rather than carrying a spare. Also, avoid completely discharging lithium-ion batteries, and use fresh batteries when possible because lithium ion ages from the moment it leaves the assembly line. If possible, look for the date stamp on any battery powered item you intend to buy and try get the freshest possible.

So, why is fire an issue? Lithium is a reactive metal. It’s so reactive, it will react with water. What that means is if the electrolyte ever dries up and the two metals inside come in contact, the battery could explode or at least catch fire.

This all sounds scary, but there's nothing dangerous about keeping your RV Lithium Ion batteries charged overnight in a caravan. The internal BMS in quality reputable lithium batteries and modern chargers monitor and protect the cells in the battery while discharging and recharging. Which allows for safe autonomous recharging and maintaining without any human intervention.

Batteries that will be stored for longer than four weeks should be fully charged and then isolated from the system completely. Check and recharge them once every three to six months.

Given their potential problems, is going lithium worth all the trouble and additional cost?

Batteries, at their basic level, are simple devices. They contain two types of metals submerged in an electrolyte solution. A separator keeps the metals from touching, but ions and the electrolyte solution can still flow freely. Connecting the two plates together with a wire causes a chemical reaction in the battery, which makes electrons flow from one plate to the other.

There are two types of lead-acid batteries typically used in RVs. Starter batteries deliver a large burst of power quickly. Deep cycle batteries give off a lower amount of power over a longer amount of time. Deep cycle batteries have thicker plates in their cells. They can stand being discharged to a lower percentage and can be recharged more often than starter batteries without damage.

That is why deep cycle batteries are most commonly found in RVs.

LiFePO4 Phosphate-based batteries offer superior chemical and mechanical structure that does not overheat to unsafe levels.

Lithium phosphate cells are incombustible, which is an important feature in the event of mishandling during charging or discharging. They can also withstand harsh conditions, be it freezing cold, scorching heat, or vibrations over rough terrain.

When subjected to hazardous events, such as collision or short-circuiting, they won’t explode or catch fire, significantly reducing any chance of harm. If you’re selecting a lithium battery and anticipate using it in a hazardous or unstable environments, LiFePO4 is likely your best choice.

It’s also worth mentioning, LiFePO4 batteries are non-toxic, non-contaminating and contain no rare earth metals, making them an environmentally conscious choice.

Lead-acid batteries do offer some advantages when used in cold weather environments allowing discharge and recharge in sub-freezing conditions. Lithium batteries are capable of discharging in sub-freezing temperatures but do require greater than zero Celsius temperatures before they will begin to recharge.

It might seem that cold weather campers are stuck with a lead-acid battery, but some companies are finding ways around the cold flaw of RV lithium batteries and use a built-in battery heater. The heat generated by the charging circuit is used to warm up the battery before charging in freezing temperatures.

The energy density of lithium batteries is much higher than that of lead-acid batteries, which means more energy can be stored in a smaller space. It also means an RV lithium battery is much lighter than a lead-acid battery of an equal power rating.

Also consider that the materials used to construct a lithium battery are lighter by nature, so storage in an off-road caravan or camper is easier.

Let’s put all this in perspective. Millions of lithium-based batteries are manufactured each year and very few malfunctions happen. You're more likely to wreck an RV on the road than have your cell phone or a lithium battery spontaneously combust.

Most RV lithium batteries come with a battery management system (BMS) built into them that protects them from excessive discharge or recharge, over or under voltage events and under or over temperature events.

However, make sure that you take care not to expose your lithium-ion batteries to water, as this will cause damage to the battery and reduce the lifespan of the battery.

Also, avoid overcharging. Many lithium-ion batteries charge in three to four hours, and overcharging can cause irreversible damage and reduce service life. The best way to avoid overcharging is by using a good-quality charger with the correct settings for the lithium battery.

What's more, if lithium batteries are not stored properly and kept in a charged state over long periods of storage batteries can be rendered unusable. Batteries will slowly discharge monthly which can lead to over discharge to the point the batteries cannot be recovered.