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Will lithium batteries (LiFePO4) work in my RV?

Will lithium batteries (LiFePO4) work in my RV?

When we refer to lithium battery in this document, we mean LFP/LiFePO4 and no other lithium technologies.

We are often asked, "will lithium batteries fit in my RV?" The simple answer is Yes ! But there are a few things that are important to keep in mind, as all motorhomes are slightly different:

EBL Elektroblock, Mastervolt, Dometic and other electrical systems

Motorhomes can have several different electrical systems, depending on the chassis and the builder, one thing they have in common is that most of them have a 12V or 24V system. Regardless of which EBL or electrical system you have in your car, you can switch to lithium batteries if you want. If you have a car, where the charger or solar cell regulator does not have lithium settings, that is not a problem either.

EURO 4 and previous EURO classes

If we start with cars registered before September 1, 2009, ie cars with Euro 4 or lower EURO classification.

Make sure your EBL or the charger is set for GEL batteries 14.2 – 14.3V or AGM batteries 14.4V (EBL's usually have no setting for AGM). It is often said that lithium batteries should have a 14.6V charge, but that is a maximum of 14.6V. It works just as well with 14.2-14.4V for charging. You can control or change the charging voltage on most chargers. If you do not have a Gel or AGM mode, then choose, for example, to set the charger to 14.2V - 14.4V or the volt number that is closest to 14.6V. The advantages of lower charging voltage are that you charge the battery a little more gently and that you can charge both the starter and the living area battery with the same charger or EBL. The disadvantage is that it takes a little longer to charge the battery. Exactly the same applies to the solar cell regulator.

If you have a 24V system in the car, exactly the same applies, you set the charging voltage to 28.4V; 28.6 or 28.8V.
Max charge for lithium batteries 24V is 29.2V.

"Is there a risk of burning the generator if I have a lithium battery?" The short answer to that question is "No" and one of the reasons is that lithium batteries do not suck power from the generator, but that it receives everything that the generator can deliver. A generator has a regulator, just as you have a regulator between your solar cells and batteries. The regulator regulates the current output from the generator based on what resistance (inertia) the regulator senses. The chassis builders Fiat, Mercedes, Ford, Renault, etc. build vans (except Mercedes which builds a chassis for motorhomes from 2017) and then you only have a starter battery and the car's system to take care of. The cables from the generator to the battery are far too thin (flimsy) and the resistance will be too high for the generator to catch fire or be destroyed. The problem is more that you don't get more than 18-20A, which means that it takes time to charge the living room battery when driving. If you want to increase the amperage, you can connect a DC/DC charger so that you can get 30 to 50 A depending on the DC/DC charger, or install stronger cables from the generator to the starter battery and on to the EBL and housing battery.

EURO 5 & EURO 6

The EURO 5 class was introduced for cars registered after September 1, 2009 and EURO 6 for cars registered after September 1, 2015. This is to reduce emissions from diesel cars. Part of the solution to achieve the goal was to lower the voltage, when the starter battery is fully charged, on the generator. Because the resistance in the generator causes the car to draw more diesel.

Smart generator

Even if it is said that EURO 5 and EURO 6 cars have a Smart generator, it does not exist and you cannot change to a "stupid" generator, but what the manufacturers do is that the ECU (Electronic Control Unit) (the car's control unit) via a release wheel on the generator reduces the voltage from 14.4V to 12.6V (plus a whole lot of other things) to reduce consumption and meet EURO 5 & EURO 6 requirements. 12.6V is required to keep the car's systems running, such as the ECU, lights and instruments, but 12.6V does not charge a battery. And that the cables are far too thin (skinny), usually no more than 6mm2. This poses a problem for us motorhome owners, because 12.6V is not enough to charge the living room batteries and you cannot get more than 18-20A at 14.4V through a 6mm2 cable. Which means that it takes time to charge the living room battery when driving. If you have an EBL in the car, it is the one that maintains the voltage and charges the battery.

On EURO 5 & EURO 6 cars, it is a bit smarter to raise the voltage to charge the passenger compartment batteries better. Several motorhome manufacturers have fitted a DC/DC charger from the factory, especially on EURO 6 cars. Of course, you can install a DC/DC charger yourself. But it doesn't always help, because if the voltage is 12.6V, then DC/DC cannot get enough of the voltage for the charging to speed up. Shit in/shit out simply. If you want to overcome the problem of too low voltage, make sure to control the DC/DC via D+ on the generator.

Another option could be to install a charge distributor, to "trick" the ECU into thinking that the starter battery is not fully charged and thus the ECU maintains the voltage. You can still only get out about 18-20A and if you want to increase the charge, you can, for example, mount an extra 6mm2 cable from the generator, which means you get 12mm2 (2x6mm2) and thus you can get out about 36A. Even thicker cable will further increase the charge or fit a DC/DC charger.

Solar cells on your motorhome

Do you have a solar cell or cells on your motorhome today? What you need to keep in mind is that the solar cell regulator (MPPT) should be set to a maximum charge voltage of 14.6V, but the lithium battery actually feels better charged with 14.2 to 14.4V, the same as GEL or AGM batteries. You do not need to change the solar cell regulator to change to a lithium battery, if you set the voltage (Volt) to 14.2V or 14.4V the battery will be fully charged, it just takes a little longer.

Wondering something else? Many answers can be found in our battery guide!

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