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We have been struggling with leisure batteries in our Sprinter 4×4 for some time now. I have previously written about this in modifications. We were relatively satisfied with our current Optima Blue Top batteries but with only 150 Ah the capacity is too low, especially in winter when the solar panel is not really contributing.

We were looking for a LiFePO4 lithium battery as it charges faster, weighs less than a third of the equivalent lead acid battery and it can be discharged down to 5% of the capacity instead of 40% for the Optima’s. In the following text I will refer to LiFeP04 lithium batteries when I use the word lithium.

Actual setup with the two Optima Blue Top 75 Ah batteries.

Although the lithium batteries have a lot of advantages there are some disadvantages as well. The high price is one of them and everyone should calculate for themselves if it is worth it in their situation. Another big disadvantage (in our case) is the fact that these type of batteries do not cope well with cold. Most of them cannot be charged  at temperatures below zero C. and although they generally perform better than lead acid batteries at low temperatures, most lithium batteries are not designed for use in extreme conditions.

As we are travelling in freezing conditions a lot this was a real dealbreaker for us. We know that there are some suppliers that offer a lithium battery with a ‘built-in-heater’ but I have heard mixed stories about this, mainly that this is a marketing gimmick instead of a real solution for extreme freezing temperatures.

Heated batteries use the initial charge current to heat up the battery cells using an internal heating element. When it gets back above zero, the charge current is then used to charge the batteries. The problem is that this is like putting a frozen chicken into a frying pan, the heat is not evenly distributed and it cannot be good for the long life of the cells. It also means that all the initial charge current (from solar or alternator) is used for heating and not charging the batteries.


Typical camping spot for us.

So we were unconvinced that a lithium battery would be the best solution for us until our friend Niels pointed us towards Roamer batteries. This is a UK based company that designs and sells a range of lithium batteries specifically for campervans. The website looks very professional, the battery specs are excellent and they even provide a 10 year warranty on their products. Prices are very competitive as they only sell directly to customers not via resellers or distributors.

I came in contact with Steve from Roamer and we had a call scheduled to discuss our needs. We had a great talk and Steve pretty much confirmed that a ‘normal’ lithium battery would not work for us. Instead he recommended the Roamer Xtreme, a new battery in their line that was especially designed for extreme environments. The key difference with this model is the special low temperature LiFePO4 cells which allows the battery to be charged at temperatures down to minus 40 degrees . These cells have been used in military vehicles for many years but Roamer are the first company I’ve come across that are using them in a leisure battery. We’ve seen the lab reports and the performance of these batteries looks outstanding but we’re looking forward to testing in the real world!

The service was also excellent from Roamer.  Steve has a lot of knowledge concerning batteries but also about the whole electrical setup in a Van or Expedition truck as he is a long term vanlifer himself and Roamer also design and supply full electrical systems for campervans, based on Victron equipment.

Roamer 200X

We asked Steve some more information on the Roamer 200X so we could see for ourselves if this would indeed be the solution for us. We even received  a document with actual test results in extreme winter conditions and it all looked very promising (although really technical for us).

The advantages of the Roamer 200X are basically:

  • The battery can be charged at 100A at temperatures down to minus 40 without any heating elements.
  • The battery performance will not be affected by temperature in the same way as lead acid or standard LIFeP04 cells.
  • Even at very low temperatures and discharging at 200A the battery will deliver almost full capacity. They will not ‘crash down’ or loose voltage.
  • The cells can be discharged at 3C which is 600A continuous but the BMS limits to 200A so we will be nowhere near maxing out.
  • The cells are capable of being charged and discharged continuously at rates up to 3C (600A for our 200Ah battery). The BMS limits this to 200A so it’s reassuring to know we will be nowhere near maxing out.
  • They were tested with 800 charge and discharge cycles at -20C and the capacity was still 96% of the original.

It basically means that we will be able to access the full 100% of the battery capacity and charge/discharge at high rates without losing voltage. We simply never need to think about the temperature of the battery.

Opening everything up to prepare for the installation of the Roamer 200X.

So we decided to order the Roamer 200X as we have a lot of faith in Steve’s knowledge and commitment and the 10 year warranty as a back-up. 

Steve also advised to remove the Victron Cyrix as the charging voltage will be too low for the lithium and it can also damage the alternator. Instead he advised us to use one or two Victron Orion Tr-smart (non-isolated) 12 | 12 – 30 DC to DC charger with a 60A fuse.

We decided to start with one Orion and see if it charges fast enough for our needs.

Installing the Victron Orion with the 60A fuse.

It took some time to re-arrange everything but thanks to the installing diagram – schedule that Steve supplied, it was all crystal clear.

The Roamer 200X fits perfectly in the 'reserved' spot.

After installing everything we adjusted the Victron BMV 700 to the new battery specs and we checked the loading pattern of the Victron Orion. It is very convenient that both appliances communicate via Bluetooth – Victron Connect app.  The Roamer battery also has Bluetooth and we can view and monitor the internal battery status from an app.

When the engine is off, both batteries are isolated from each other (thus making sure that the starter battery is always full). The moment the engine runs, the charging of the Roamer starts as well.

First test

Two days after installing we left for a powder trip to Austria as there was a real snow dump in Upper-Austria and Styria. We went to Tauplitz (-17 C. during the night) and Krippenstein (-9 C. during the night). 

At several times we had the Webasto heather on full force, the fan, the refrigerator, lights on and the 3000 watt inverter making coffee on a Nespresso machine. In the past, the batteries would have a hard time and struggling giving the power, the Roamer 200X did it effortless.

The battery was charged swiftly when on the road, so at this moment we do not feel the need for an extra Victron Orion charger.

Fantastic powder in Tauplitz.

So far, so good after this ‘minimal’ test. There will be more roadtrips this winter and also in the other seasons as well. We will regularly post an update on the ‘behaviour’ of the Roamer 200X. It will be most interesting to see how the Roamer performs over time and how long it will last, only time can tell!

For now we are impressed by the battery, but especially Steve. This man stands behind his product 100%, knows his business and is really willing to help. 

Therefore we have asked Steve to advise on how to ‘electrically manage’ our future Mountain Yacht. He already came up with some strong ideas including a 48V battery system and 3000W alternator charger, so more to follow in the near future!

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