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Choose the most suitable lithium battery for your RV


Self-sufficient travel is our goal, but to achieve that we need more power storage. An underseat LiFePO4 battery for RVs was soon part of the concept for us. In addition to the battery, we also upgraded the power supply system in our Adria Twin Supreme 640 SGX van with solar panels, charging booster and inverter. In this first report on the power supply, we present our purchase considerations for the battery and our ultimately chosen Renogy 100Ah12v lithium ion battery w/ Bluetooth.

Underseat LiFePO4 lithium battery for RVs – our requirements

Very soon we had to realize that our free standing options are severely limited without shore power. As an example of the electricity consumption of our Adria 640 SGX, let’s mention a normal 24-hour day in February on the Mediterranean when it rains. Our van already needed 39 Ah of electricity from the battery to operate the diesel heating, refrigerator, light, water pump, charging cell phones and a cup of coffee from the machine. In the summer it would probably be less, since the fan for the heating would not have to run almost all night. But even then, if you use electricity sparingly, you won’t have more than 2-3 days of free time with a 100 Ah AGM battery.

Our planned travel destinations extend from the North Cape to Morocco or even ship the van overseas. Of course, the greatest possible self-sufficiency is required in order to be able to survive longer dry spells without external infrastructure. No matter how good a solar system and booster may be, in the end there must also be sufficient electricity storage available. Standing alone with a solar system yields little in cloudy weather or in the winter months. Therefore, the battery storage capacity plays an important role. So more RV batteries are needed!

AGM battery versus LiFePO4 lithium battery

With a 3.5 t vehicle, payload is always an issue. You can learn more details about what is an agm battery here. The 100Ah AGM battery installed by Adria in the 640 SGX already weighs 27 kg. A second AGM battery would go under the passenger seat and bring the storage capacity to a nominal 200 Ah. But AGM batteries should not be discharged more than 50% for long life. This reduces the effectively usable capacity to just 100 Ah with a weight of a whopping 54 kg. In our real example as mentioned above, this would be enough for almost 3 days. For the health of the second AGM battery, it should also be noted that there is not a great difference in age and charging cycles that have already been carried out compared to the first battery. The service life of an AGM battery is around 500 charge cycles – lithium batteries tolerate > 3000 – 5000 charge cycles.

Underseat LiFePO4 lithium battery for RVs – the advantages

You can already find a lot of information about the advantages of a lithium battery in blogs and forums. Many charging cycles, high discharge rate, fast charging, extremely resilient, low weight compared to AGM batteries and no memory effect are just some of the advantages. Just 1-2 years ago, the high price was rightly seen as a major disadvantage. But the prices for a 100Ah lithium battery have now fallen below EUR 950.00.

A cost-effectiveness calculation in comparison with an AGM battery (approx. EUR 310.00 for 100 Ah) shows that over the entire service life of a LiFePO4 battery, this will be the cheaper variant. When comparing comparable Ah yields (LiFePO4 battery with 100 Ah versus 200 Ah AGM batteries), the pure price difference turns out to be only 1/3. The fact that the LiFePo4 batteries can be charged at least four times over shows their economic superiority. The weight saving is also considerable with us at 25 kg. Of course, if my mobile home has a service life of 4-5 years or you are almost exclusively connected to shore power, then AGM batteries are still the first choice.

Understanding how to use a DC power supply properly can significantly enhance the efficiency and longevity of these batteries.

Actually, the WoMo manufacturers should offer the buyers the option of upgrading to a lithium battery right from the start. We hope that Adria reads this point carefully :). Because the AGM battery that is often sold with the “must have” packages becomes useless when it is exchanged… then it’s better to offer a lithium battery as an option right from the start.

Underseat LiFePO4 lithium battery for RVs – technical aspects

In principle, LiFePO4 batteries, like AGM or gel lead batteries, know their suitable characteristic curve for the charging process. For this reason, corresponding characteristic curve settings for different battery types can also be found on electroblocks (EBL), solar controllers, charging boosters and pure sine wave inverter. The Schaudt electronic block (EBL 211) installed in the Adria 640 SGX does not yet have a setting for lithium batteries, for example. However, there are already lithium batteries on the market that can be replaced 1 to 1 with lead-acid batteries using advanced battery management systems (BMS) and should be able to cope without changing the AGM/GEL charging/discharging structure. PS: the Schaudt EBL has been paralyzed in this area and the battery charging is managed by charging boosters, solar regulators and inverters for shore power with optimal LiFePO4 characteristics.

  • Underseat LiFePO4 lithium battery for mobile homes – The offer is large!

If we read the blog and forum posts on this topic 1-2 years ago on the Internet, then we have to realize that a lot has happened around LiFePO4 lithium batteries. On the one hand, the supply has become very large, prices have fallen by almost 50% and the number of batteries equipped with modern battery management systems (BMS) has increased significantly.

Underseat LiFePO4 lithium battery for mobile homes – Our list of criteria

Due to our requirement for high self-sufficiency, we aimed for a total capacity of the new lithium battery of at least 200 Ah. But that means that no provider is eliminated today – so create a catalog of criteria. The following aspects were important to us:

  • 200 Ah it must be possible to install the underseat (to fit under the seats of a newer Fiat Ducato, Peugeot Boxer, Citroën Jumper). The factory-fitted AGM battery measures (L x W x H) 33.5 x 17.5 x 19 cm – 2 pieces could be placed under the seat.
  • LiFePO4 battery must be protected by battery management (BMS).
  • high cycle time.
  • good price / quality ratio.
  • Battery Bluetooth interface.
  • APP for querying battery status & charging/discharging current.
  • Good values in the minimum temperature range (charging / discharging).
  • warranty period.
  • Support from the manufacturer and repair options in the event of a defect.
  • Battery data must reliably support the performance data of our charging booster and inverter.

Underseat LiFePO4 Lithium Battery for RVs – Our selection process

When comparing the data sheets and pictures, we noticed that some batteries may be manufactured in the same factory. The requirement for the right dimensions for the underseat installation in the Adria 640 SGX already took one or the other supplier out of the running. The criteria for a BMS, Bluetooth interface and APP shortened the list further. But if we had dropped the criterion for a Bluetooth interface, for example, then the batteries would have been even cheaper.

Underseat LiFePO4 Lithium Battery – Renogy Battery Experience

Although the battery fits perfectly under the passenger seat, the seat has to be removed for installation. Ideally, you put the battery connections on an Adria Twin to the front. Because when installing the charging booster, it turned out that the connections for the cables to the rear are a bit cramped for the mounting board for a booster and the battery connections are hidden behind the board. So ideally, don’t mount it the way it is shown in our picture – but mount the connections at the front of the seat:

For test purposes, we also connected an induction hob via the inverter and drew the full wattage of the 3000w power inverter from the battery for 10 minutes. The battery did the job without hesitation and delivered 3 pans of sparkling hot water.

Underseat LiFePO4 lithium battery for RVs – Conclusion

If you need more power storage, you will no longer be able to consider a lithium battery. A separate list of criteria will certainly help to find the right product from the variety of providers. We would give security and functionalities such as APP a good place in the list of criteria. Prices will definitely fall further and thus carry the advantages of this battery technology even deeper into the camper market.

Other articles from totimes.ca – mtltimes.ca – otttimes.ca

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