The ultimate guide: Converting motorhomes to a lithium battery

Lithium - atomic number 3, symbol Li - is one of the most exciting elements in the periodic table: it is the lightest of all metals, so reactive that a simple touch causes severe burns and was first mined in large quantities in the 1950s to build the hydrogen bomb.

Today, however, we know the element primarily as the most important component of modern rechargeable batteries, which are used everywhere from smartphones to caravans. A good 74 percent of the lithium mined worldwide is used in battery construction and has long since overtaken AGMs and lead batteries.

In this article, you can find out why it is worth converting to a lithium battery in your motorhome, what you need to look out for when making the switch and which lithium battery is the best choice for you.

Converting a motorhome to a lithium battery: why do it at all?

The first question that arises is, of course, why you should upgrade your motorhome with a lithium battery. After all, the good old lead-acid battery works reliably and even if it gives up the ghost at some point, lithium batteries are apparently much more expensive to buy.

Wrong, my friend! Because calculated over its entire service life, a lithium battery is not only cheaper than other batteries, it also has numerous advantages:

Lower weight with higher capacity

Lithium batteries weigh only about a third of the weight of a conventional battery with the same nominal capacity. While an AGM with a capacity of 100 Ah weighs around 30 kilograms, the lithium battery weighs only ten kilograms.

20 kilograms difference in weight doesn't sound very impressive? Then we would like to point out that you can only ever use half the nominal capacity of an AGM without damaging the battery. So 100Ah here means only 50 usable Ah and you need two batteries to really get to 100Ah. A lithium battery, on the other hand, can be drained down to the last ampere hour without any concerns.

So we are actually talking about 10 kilograms versus 60 kilograms, i.e. a weight difference of 50 kilograms. This corresponds to the mass of two e-bikes that you could carry around with you instead.

Smaller volume

Lithium batteries are also much more space-saving than AGMs. With the same capacity, lead batteries have three times the volume and this can quickly become noticeable in the limited space of a motorhome:

The compact dimensions of a lithium battery not only make installation easier. Above all, you can easily install several batteries and thus significantly increase your energy supply and still have enough space to install a charging booster.

Faster energy absorption

Speaking of charging: Lithium batteries charge much faster than AGMs. So you don't have to spend endless hours at the mains just so the kids can watch Sesame Street in the evening.

The best thing is that lithium batteries maintain this charging speed over their entire life cycle. While lead-acid and AGM batteries absorb less and less energy over the years, the lithium counterpart absorbs power as it did on the first day, even after thousands of charging cycles.

No deep discharge

AGMs are still regarded as little divas. Do not charge too quickly, it is better to gently massage in the energy. And always take care not to be too greedy when discharging, otherwise there is a risk of the dreaded deep discharge and the battery will be gone faster than a French gendarme can give you a parking ticket.

The situation is different with a lithium battery: an intelligent battery management system (BMS) monitors energy consumption and extraction, which is usually controlled directly from the smartphone via Bluetooth. It prevents deep discharge and at the same time allows you to use every ampere hour stored in your lithium battery.

Long service life

Finally, lithium batteries are particularly long-lasting. Although the expected maximum charging cycles vary from manufacturer to manufacturer, you can expect at least 5,000.

Mind you, we are talking about cycles when the battery is completely discharged. If you don't drain the batteries down to the last ampere every time, but charge them back up to their maximum at around 50 percent full, the service life is multiplied again.

Source of danger: How safe are lithium batteries?

As you can see, from a technical point of view, a lithium battery is far superior to a lead-acid or AGM battery. But perhaps you have completely different concerns and images of burning electric cars are flashing before your inner eye. After all, you don't want to set your motorhome on fire when you convert it to a lithium battery.

We can give the all-clear here. Modern lithium batteries that work with lithium iron phosphate (LiFePO4, more on this in a moment) are considered non-flammable. Their maximum operating temperature is up to 85° Celsius, above which the BMS switches off the battery. If your motorhome ever reaches such temperatures, please put it in reverse and leave the sauna you have just rammed into.

Converting your motorhome to a lithium battery: it's that easy

So: lithium batteries are not only powerful and long-lasting, but also safe. But what about the installation? If it costs you a few thousand euros, the fun will soon be over.

Don't panic! Installing a lithium battery is not a major challenge. Professionals just follow the instructions: take out the old battery, put in the new one, done. People who are less experienced simply follow these steps:

1. Safety is paramount. This means that you should wear safety goggles and gloves and remove all metal jewelry. Sparks can fly and you are working with a strong current. Also use insulated tools if possible.
2. Next, make sure that neither the shore power nor the solar system are plugged in. Be sure to disconnect all cables or switch off the solar charge controller or inverter. Also switch off all consumers and disconnect them from the mains where possible.
3. Now you can disconnect the terminals of the old battery. Important here: Always disconnect the negative terminal (black or blue) first, then the positive terminal (red). Not the other way round!
4. Now remove the old battery from its holder. The batteries are usually fixed in place with a simple tensioning strap, more rarely with an elaborate snap system. Caution: Lead batteries are heavy. You may need help carrying them.
5. The next step is to connect the lithium battery. Pay attention to the sequence again! The following applies: First connect the positive terminal (red), then the negative terminal (black or blue)so exactly the reverse of the removal procedure. The terminal adapter and terminal clamps usually also fit the new battery. Also take care not to short-circuit the battery by touching the positive and negative terminals at the same time with the wrench!
6. Then secure the new battery, which in most cases means simply tightening the tensioning strap.
7. Finally, you must adjust your charge controller and, if necessary, the solar charge controller to the new battery. A look at the operating instructions is essential, as the settings can vary greatly from manufacturer to manufacturer. Operation at 14.6 to 14.7 volts is ideal.
8. That's it. You're done. Give yourself a pat on the back.

If you're not comfortable with all this, it's not an insurmountable problem. Any workshop will be happy to do the installation for you (if they have the capacity). As this involves little effort, the bill is usually not particularly high.

Tangled cables: Do I need a charging booster?

If your battery has a connection to your engine's alternator, converting your motorhome to a lithium battery will be a little more complicated. This is because, compared to a lead-acid battery, a lithium battery can be charged with a much higher current - and the alternator can supply it. However, the wiring is not always designed for such high currents.

This is where the charging booster comes into play. Because contrary to what its name suggests, this device limits the current in the mains circuit to an acceptable level. Put simply: With a charging booster, you don't have to worry about the cables and can also charge the battery via the alternator while driving.

Difficult choice: Which lithium battery is right for me?

Before you strap on your tool belt, you need to decide how many amp hours your new lithium battery should have. After all, you don't want to suddenly find yourself in the dark in the middle of your vacation, nor do you want to invest in a battery capacity that you don't even need.

First a word about:

LiFePO4: What is it?

LiFePO4 (or LiPO for short) is the common abbreviation for the latest generation of lithium batteries and stands for lithium (Li) iron (Fe = ferrum) phosphate.

The biggest advantage of LiFePO4 is already in the name: Lithium batteries used to be called lithium cobalt oxide batteries by their full name - and surely you know that cobalt is not only rare and therefore damn expensive, but is also usually mined under hellish conditions for people and nature in the poorer countries of our planet. So by buying a lithium battery, you are simply contributing to greater sustainability.

However, a LiFePO4 also has a whole range of other advantages.

The advantages of a LiFePO4

• High level of safetyDoes not burn, can be disposed of in an environmentally friendly way.
• High power density: Provides continuous high power without fluctuations.
• High charging current: Charges quickly.
• High cycle stability: Is fully operational even after many charging processes.
• High electrical efficiency: The energy inside can be almost completely utilized.
• Insensitive to deep dischargesDoes not break down.
• Wide operating temperature rangeWorks at -45 to +85° Celsius.
• Low self-discharge when not in useCan be charged, stored and used later.

However, where there is light, there is always shadow. LiFePO4 also has a handful of disadvantages compared to cobalt batteries.

The disadvantages of LiFePO4

• Lower nominal voltageLiFePO4 deliver 3.2V, while lithium-cobalt batteries deliver 3.7V.
• Lower energy densityOlder LiFePO4 batteries only manage 90Wh per kilogram, which is just half of an average lithium-cobalt battery. However, the latest models now achieve 210Wh per kilogram.
• Few different designsThis can make installation more difficult in very angled motorhomes.

Nevertheless, it is clear that LiFePO4 is the future. Not only because we should care about the environment and cobalt will probably become unaffordable in the foreseeable future, but also because the advantages clearly outweigh the disadvantages.

Our first tip is therefore: If you buy a lithium battery, opt for a LiFePO4.

But which one should it be?

The amperage question: How to find the right lithium battery

The one Of course, we cannot make a purchase recommendation. Which lithium battery belongs in your motorhome depends primarily on your daily consumption - and since we unfortunately don't know whether you are traveling alone or with a large family, whether you have to blow-dry your flowing hair every day or prefer to let it air-dry, we can't calculate this for you.

However, we can tell you how many watts typical electrical appliances consume per hour. And don't forget: To convert watts to amps, use the formula

Watt / Volt = Ampere.

A lithium battery from BullTron has a nominal voltage of 12.8 volts, but this can also be increased to 24, 36 or even 48 volts by connecting it in series. So you will need to do a little arithmetic.

Typical consumption values are

• Lamps: 35 watts
• Refrigerator: 75 watts
• Oven: 700 watts
• Heating oven: 1,125 watts
• Hairdryer: 1,000 watts
• Television: 45 watts
• Receiver: 35 watts
• Coffee machine: 700 watts

So everything that gets hot consumes a lot of energy. Consumer electronics, on the other hand, are surprisingly economical. For maximum energy efficiency, we therefore recommend firing up the charcoal barbecue more often in the evening and enjoying the starry sky while the children are busy with the Playstation.

And perhaps a little more seriously: experience has shown that a battery with a capacity of 100 Ah is easily sufficient for a relaxing vacation for two. If, on the other hand, the whole family is on board, including demanding teenagers, you should go for a model with 250 Ah or more.

Rest period: how to store your lithium battery correctly

When the vacation season is over, your battery is free. To ensure that it is fully operational again when the next vacation starts, it is best to disconnect it (observe the sequence!) and remove it.

For a long battery life:

• Always store lithium batteries partially charged (approx. 50 percent full)
• Do not store in frosty conditions: The ideal temperature is 10 to 20° Celsius.
• Avoid direct sunlight
• Never expose to moisture

The usual suspected places such as the cellar, garage or attic are ideal. Also make sure that you never leave your battery unattended for longer than six months. This is because it slowly discharges itself over this period and should therefore be reconnected to the mains after six months at the latest.

Converting a motorhome: if a new battery, then a lithium battery

So let's summarize: If you want to upgrade your motorhome for the future, then a lithium battery should definitely be on board. This is because a LiFePO4 battery is smaller, lighter and more powerful than any AMG or lead-acid battery.

Installation is not just for skilled mechatronics engineers. If you feel reasonably confident with technology, you can do it yourself. Otherwise, head to the nearest garage and simply combine the installation with the due inspection.

To find out which lithium battery is right for you, it's best to estimate your average daily consumption. An excellent choice for reliable and long-lasting home storage systems are, for example, the systems from Voltsmile. And don't forget: You can easily install several batteries if you absolutely cannot do without your home cinema system on your camping vacation.

For all other questions, detailed advice and a sympathetic ear for your concerns about photovoltaics, energy self-sufficiency and lithium batteries, please contact us. Just write to us and we'll help you!