With some inexpensive retrofits we have made our Oasi 540N quite independent from shore power.
First, a very compact high-performance 150-watt solar module from Offgridtec was mounted on the roof, featuring a so-called “back contact” design, which has an extremely high efficiency level of the 22%.
The back of this module is also coated. I did the assembly myself, no tricks with the glued montage modules.
The system is completed by a Votronic MPP 250 solar controller with a corresponding display from the Votronic solar computer S.
At first glance, an expensive investment of around € 750 is required for a very reliable Lifepo 4 lithium-ion battery with 120 Ah from Robur. The price, however, is put into perspective when considering the duration (much longer than a lead-acid battery) and the performance data.
The battery weighs about 16 kg compared to the almost 60 kg of the 2 previously used 95 Ah AGM batteries, which in practice deliver only 95 Ah of power because they can only be discharged to the 50%, as opposed to the 100% potential of the lithium battery.
This makes much more power available than the two relatively huge and super heavy AGMs combined. Incidentally, it fits easily under the driver's seat and leaves room for the CBE charger.
An inverter for operation, e.g. of a coffee machine is easily operated by this battery.
We have replaced our trivalent refrigerator with a 90-liter compressor refrigerator from the Italian manufacturer Vtitrifrigo. So you always have a cold beer, no matter how inclined our Oasis is. The power consumption of 45 watts and the noise level are minimal.
The solar module fully charges the battery during the day, so staying charged independently for a few days is no problem. Even in relatively cloudy weather, the modern solar controller contributes to self-sufficiency with a decent charging capacity.
A 300 watt inverter is available to charge the eBike batteries and while the engine is running, a charge booster (40 A) from Votronic charges the battery in record time.
The charging process is considerably faster than conventional batteries with the same charging technology.
The Robur Lifepo4 battery has the advantage that the existing charging technology can continue to be used one by one without restrictions and therefore additional costs.
Another source of self-sufficiency are the two 12 kg Alugas cylinders, which make the transport of gas cylinders and the search for replacement stations superfluous.
Many filling stations offer LPG and on considerably more favorable terms than gas. At first I was a bit afraid of the refueling process, but now it has become a routine like filling up with diesel.
We have come to appreciate these changes in everyday life and we don't want to lose them anymore.
In the next post I will show how 4 comfortable beds can be created in the compact OASI 540 N with minimal effort.
Figure 1 Lifepo4 Battery
Figure 2 charge booster
Figure 3 Bottles of the Alugas tank