Now it’s going to be electric – it’s about the power supply for our off-road truck. Our long-distance mobile home should have a self-sufficient, simple, reliable power supply. Self-sufficiency was particularly important to me because we only wanted to use shore power as a backup in bad weather. As a result, the focus is on selecting the components, which are completely different, such as in a mobile home, which has a lot of shore power on camping sites and pitches. It must be fine if we use shore power, even poor quality, as is often found in Spain and outside Europe, or even 110V in North America.
We planned this 4×4 truck as our home and want to be where we like it indefinitely. Driving it every day is just an as little part of the plan as regular visits to campsites and motorhome parking spaces. The power supply was designed to work independently and autonomously, so “driving” or “shore power” is more of an option. The hut has to work all over the world.
Since we don’t like cold or wet weather, we will try to stay in sunny areas most of the time – which therefore makes an additional power generator unnecessary. Should we later want to spend the winter at the North Cape, this would be possible with small optimizations, such as more powerful chargers and a corresponding generator. Hopefully, it doesn’t come to that.
Planning phase
At the beginning of such a project, there is a needs assessment. Since I’ve been running the Renogy Venus GX in the Vario since 2018, I only had to read off the power consumption of the individual months and had a result so quickly. I should plan 90-100kWh per month. Although the power supply will be more economical with the battery inverter, two electric water heaters will compensate for this. We bought the 230V refrigerator first and let it run in the hall for many weeks with an electricity cost meter to gain initial experience.
The RV batteries were emptied after 1.5 days in the shade with my Vario. More than one day was needed during long periods of rain in Portugal. With twice the capacity, 3 days of full self-sufficiency should be possible. In addition, a little more PV power (solar system) can cover the basic requirement even when the sun is low. Assuming 3kWh daily consumption, 1230Wp is required for this in southern Spain. Since you can’t always count on a cloudless sky, it can also be a little more.
Note redundancy
Independence, flexibility and high operational reliability were very important to me. In principle, all-in-one combination devices are ruled out. If such a device were to break down, the entire system would fail! The choice of high-quality devices goes without saying. Still, even then, the failure of a single device, e.g. due to water damage, can endanger the power supply, which is why all important devices are duplicated.
Contrary to what many might suspect, I consciously decided against the Renogy Energy MultiPlus inverter/charger combo. There is no doubt that they are great devices, but only in their area of application. What good is a PowerAssist if I don’t want to use shore power? The lack of shore power stabilization directs fluctuating mains voltages into the vehicle or does not even switch on if the mains voltage is too bad. In countries with 110V, the 230V MultiPlus does not work either. Here I wanted to implement a solution that saves on additional mains voltage converters and stabilizers and is also cheaper and lighter.
Power supply in the four-wheel truck
I don’t want to keep you in suspense any longer. After everything was installed, I made this sketch to show the connection between the devices better. Below you will find my shopping list, and then I will explain why I have solved some things completely differently from how it is “usually” done in the camping area.
I deliberately did not specify any cable cross-sections. These depend on the current and the cable length and cannot be accepted as a flat rate.
Parts list:
Battery and BMS
- 4x LiFePO4 Smart 200Ah 12.8V Renogy Energy
- 1x battery main switch
- 1x battery computer BMV712
- 1x negative distributor 4x M8 bolts
- 1x main fuse 150A
- 1x BatteryProtect BP65 for consumers
- 1x BatteryProtect BP100 for solar charge controllers and 230V chargers
- 1 x mini BMS
- 24V consumer
- 1x fuse distributor with ground connection
Chargers solar power and 230V
- 8x monocrystalline PV modules today KVM220-12 SolarSwiss
- 2x Renogy Energy solar controller SmartSolar MPPT 150/35
- 2x Phoenix Smart IP43 battery chargers 100-230V 25A
- Power supply 230V internal
- 2x Renogy Energy Phoenix Inverter Smart 24/2000
Starter batteries and charge by the alternator
- 2x Optima Red Top 12V 50Ah
- 1x isolation relay Renogy Energy Cyrix CT-Li
- 1x circuit breaker 150A
Self-sufficient mobile home
As mentioned at the beginning, we are building a residential truck that can function independently in the desert or at the reservoir without camping and parking spaces! We often don’t drive for weeks at all, and the energy supply still has to be secured. I would also like to conserve as many resources as possible and prefer to rely on renewable energies like a photovoltaic system on the roof.
Battery – the heart of the power supply in the mobile home
I chose Renogy 12V LiFePO4 batteries. In the summer of 2019, these were the lightest 200Ah cells on the market – fully capable of high currents at 400A. What is designed for high currents will not cause problems with small currents. Lithium batteries and BMS are separated from each other. I can intervene myself in the event of a problem and replace or bridge faulty components.
Could you keep it simple?
There are more lines drawn in the sketch than I laid. Negative leads going to the inverter can also be the negative lead to the charger. The current in it will even drop if the inverter and charger are running at the same time. So I set up the system as simple as possible while providing maximum performance.
230V network in the mobile home
Where it cannot be avoided, 230V devices are used. Especially with the refrigerator, there was no way around the 230V mains. It just can’t be that a 12V fridge costs more than 1000-2000€ and isn’t even energy-saving. Here I rely on 230V A++ household technology, and I prefer to invest the money saved in a redundant 230V network because we can’t do without 230V anyway.
A 230V inverter for the fridge
A 230V refrigerator only needs about 50 watts when the compressor is running. Nevertheless, the inverter must have at least 800W continuous power to start the refrigerator reliably. Since a 750W hot water boiler is also to be operated simultaneously, I decided on a 2000VA inverter. This is no heavier than the 1600VA model and has more reserves.
A 230V refrigerator only pays off if the inverter does not consume Electricity during idle times. It, therefore, needs a power-saving mode. Most Renogy inverters can do this more or less well. The Phönix Inverter Smart series presented in 2019 consumes only 2.6 watts in AES standby, which is particularly low. Thanks to ve. Direkt Port and Bluetooth can also be easily programmed into my battery monitor system.
For the devices that only run when needed – such as the coffee machine, oven, washing machine, cable winch and the rest of the living room – 2000VA is also enough for me. So that the refrigerator and boiler don’t get in each other’s way with the other devices, there are two separate 230V networks with identical inverters. The second inverter is switched on manually via a switch in the living room when needed. This reduces power consumption overnight.
If one of the two devices fails, I can combine the lines and continue to operate everything under certain restrictions until a replacement device is organized. Since the refrigerator is one of our vital devices, the supply of 230V is certainly risky. I can reduce the risk with two inverters but only partially eliminate it. I’m hoping for luck here.
Two separate 230V networks
Fridge + 750W hot water boiler + trace heating for the drain pipes.
These devices switch on uncontrollably and therefore have their inverter.
All 230V sockets in the living room for a coffee machine, fan heater, oven, washing machine, winch, etc.
These devices are not essential to life and, for the most part, never have to run simultaneously.
Hot water boiler in 230V and 24V
A 15l Isotherm hot water boiler for showering in the bathroom with a 750W 230V heating element is sufficient. Heating with Electricity consumes excess solar power in summer. The boiler can also be heated with the hot water diesel heating system if the solar yield is insufficient. For the kitchen, there is a small 3l 24V Elgena boiler (KB3 24V) with 400 watts. That’s enough for rinsing. If Electricity is too scarce, the washing-up water can also be fetched from the bathroom or heated with gas on the stove.
So there is still hot water, even if the solar yield is too low!
Two 230V chargers
Of course, 99% of our batteries are charged by monocrystalline solar panels on parking spaces and campsites. If we are in the shade, we can survive 3-4 days without saving Electricity.
If we have to charge the batteries at shore power, we do this with two chargers, each with a charging current of 15A. Redundancy is also provided here, and the connection power can be reduced by switching off a charger, enabling small generators’ operation.
The shore power grid can be used worldwide.
At first, I had two Fraron 25A chargers in the vehicle, but these have insanely high reactive power, which requires powerful generators. Since Renogy has the Phoenix IP43 series in its range (now also with 100-230V), these are the perfect devices for our project. The chargers have several advantages:
- They work with a voltage of 100-240V and 45-65Hz. These chargers eat whatever they can get and charge the batteries. It doesn’t matter whether it’s Undervoltage in the Spanish grid or the 110V grid in the USA with 60Hz.
- Thanks to the high efficiency, passive cooling is sufficient. No fan that can get bearing damage or get dirty on the dusty double floor.
- Adjustable charging current – so the device can be adapted to the performance of even small power generators.
Our 230V network in the truck has no connection to shore power because it is only supplied via the two inverters. A decisive advantage over the MultiPlus inverter.
Thus, my 230V network in the camper is safe from any damage that can be transmitted via the land network!
I summarize:
Two inverters supply all 230V devices in the vehicle – even with a shore power connection!
Two chargers with 100-240V input voltage charge the batteries worldwide if required.
There is no connection between shore power and the vehicle’s internal 230V network.
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