Lithium battery – Campervan leisure battery bank

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We upgraded our leisure lithium van life battery bank

Why we upgrade our leisure lithium battery bank from 100 ah to 400 ah

When we first built our van and chose a leisure battery bank, we went with a 100AH 12V lithium battery, we had built the van so we could add one extra lithium battery in the future when we had the economy. Lithium batteries are great but they are more expensive than AGM batteries, we paid around 962 euros for one 100AH lithium battery, including shipping. We thought that the 100AH leisure lithium battery bank would be enough for us, and during the summer in Sweden it was. Almost endless sun and our flexible 300-watt solar panels did the trick, but then our lives changed.

Well, the season changed first. As we drove our campervan to the south of Europe, chasing the sun and escaping the winter in Scandinavia, the days also became shorter. By the time fall came to visit, we were both full-time students with 2 laptops, 3 camera batteries and a drawing tablet that needed charging almost every day with a very limited amount of sun hours. And let’s not forget about our already high-consuming 12V fridge and various power outlets like LED lights, diesel heater and phone chargers. Our 100 amp leisure battery bank was FAR from enough for our needs.

It was time to upgrade!

Wait.. What does 100AH mean? And what are the 12V doing?

This is a little more technical segment, if you’re not interested in that just click here to continue reading our story.

When you’re getting into van building, or any type of building really, there is so much new information that you need to process and learn. Electricity is right at the top of the most difficult and scary ones so here is a little electricity lingo dictionary so you know what we are talking about.

Electrical dictionary for beginners

  • A (Amperes/amp) – The amount of electricity that flows per second.
  • AH (Amp-hour) – The capacity of your battery is measured in amp-hours. For example, your 100AH 12V battery can provide one of your 12V devices with 1 amp for 100 hours when fully charged, 2 amps for 50 hours, 4 amps for 25 hours and so on.
  • V (Voltage) – The amount of energy given to an electronic device. A 12V device is always given 12 volts from the battery and a battery always has a fixed voltage, for example, 12V or 24V.
  • W (Watt) – Watt is power and it tells you how much energy a device consumes. To calculate the Watt you multiply voltage with the amp.

If you are interested in learning more about the electrical lingo click here.

Why choose Lithium battery VS AGM battery?

This is a constant battle and people will have different opinions, but we prefer the lithium battery and this is why:

  • Lithium batteries are less sensitive to the depth of discharge. This means it’s possible to discharge the battery more without damaging the cycles it has. For an AGM it is the opposite, for example, it’s recommended to not discharge an AGM battery less than 50% so out of your 100AH you can only use 50AH. Lithium can be discharged to 80-90%.
  • The size and the weight of the lithium batteries are MUCH better. So if you want to keep your campervan light, a lithium battery is the best option. A 100AH AGM battery weighs around 30kg while 100AH lithium only weighs around 15kg which is HALF of the AGM.
  • Lithium batteries have around a 15% higher charging efficiency. Which means that they charge faster.
  •  Lithium-ion batteries have a smaller energy footprint to build than lead-acid. In fact, a Stanford study found that lithium-ion batteries are 5 times better than lead-acid when considering the energy needed to make the batteries compared to the energy stored over its lifetime.
  • A lithium-ion battery can typically be warranted for up to 15 years, whereas other battery types generally are warrantied for only a maximum of 1 year.

So while the price of lithium might intimidate you at first it could very well be the cheaper option in the end.

Can I connect old lithium batteries with new lithium batteries?

We started our quest to upgrade our leisure battery bank, we were looking for another 100AH or 200AH lithium battery to connect and pair with our existing battery. Our electrical guy in Sweden said that this would be no problem, something we learned not to be true while we were browsing and talking to the staff at caravan shops in France. This might be obvious to some of you and I understand that, but we had never touched electrics in our life before we converted our van and installed our electrical system, and I know there are more like us out there.

It is NOT recommended that you connect your old lithium battery with a new lithium battery or any lithium battery with a different age at all.


It’s always recommended that the batteries are the same brand, same size and the same age.
If they are not the same brand, size or age there will be different voltages, a different state of charge and you will end up with one lithium battery trying to charge the other which will create all sorts of headaches which is best to avoid.

Roamer batteries 400 amp campervan leisure battery bank
Roamer batteries 400 amp lithium battery

Where we bought our lithium battery

Our quest to find a new lithium battery in the shops failed, we were looking online for any kind of option within our budget but all hope looked lost… Until Roamer Batteries emerged like a hero at the end of a movie and saved the day!
Not only were the prices WAY better than all the batteries we had been looking at, both online and in the shops, but the size and weight were also ridiculously good AND they ship all around Europe.

Tap this link to head straight to Roamer vans and check out their batteries and what they offer.

One of the best prices in Europe on lithium batteries

Like most people, when you see something on the internet that looks too good to be true, you become suspicious if this is for real and if it is, how is the quality?

But, from one hero to another, it was our good friend Tom from tinybuildelectrics who recommended Roamer to us and we would trust our entire build with Tom and his company. He is such a LEGEND and has helped us so much when we have had problems with our electrical system, trying to figure out the cable area and other stuff that we don’t really know how to do.

So there was no question about it, we sent Roamer Batteries an email to get some help and recommendations about what lithium battery they think would suit our needs the best, and WOW! From the first email, all the way until we received our leisure lithium battery, they did everything and beyond to make sure we were happy and got our lithium battery delivered to us as quickly as possible.

We quadruple our leisure battery bank

Because Roamer Batteries was so much cheaper than all the other lithium batteries we looked at we decided to spend a little bit more money and end our struggles once and for all! Instead of just upgrading to a 200AH we went big and got ourselves a MONSTER!

400AH lithium of raw power!

We paid LESS than we would have done for one 200AH of the same lithium battery we had before, and we got double the amount of power with our new 400AH lithium battery and that’s including shipping! Also, just because we quadruple our battery bank our new leisure battery bank isn’t quadruple in size or weight, the dimension is 640mm L x 240mm W 220 H and it only weighs 39kg.


The battery bank upgrade + Bluetooth app

Not only did we quadruple our leisure battery bank, it also came with an app where we can monitor everything that’s going on with the battery. Instead of going to the front of the van, opening a door to be able to read the percentages of our lithium battery I can now, with a slide of my finger, open the app on my phone and see everything. I can see the remaining AH, temperature of the battery, how much the battery is charging, how long it will take until it’s fully charged and much more!

The one thing that could be better

We are super happy with our new lithium battery but there is one thing that we would like to see improved, the Bluetooth app. It definitely works and it works great but sometimes we have a little bit of a problem with the app crashing when we try to open it. We then have to close it, open it, close it and then open it again before it works. This is not something big or something that has affected our battery or our usage at all, just thought that it could be worth a mention.

If you want professional help with your electrics

Make sure to contact Tom from tinybuildelectricsThey help you to design, supply and support you with:

If you want top-shelf LiFePO4 Batteries for your CampervanMake sure you go to Roamer Batteries website by clicking here, they have 10 years of experience from van life adventures so they know a thing or two about living off-grid!



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Joel Larsson

Joel Larsson

Joel Larsson is one of the 2 founders of Onthefreeside. He is a professional photographer and video creator, as well as content writer. Joel lives together with Indie in their self-converted van, traveling the world and building a tiny house in the Swedish countryside.

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