E 40 Electrical system

Because I am not a born electro craftsman, I did a lot of planning before I started the work. I replaced the missing experience by much theoretical knowledge, added with knowledge of users at several internet forums.


I started my planning with considerations about the necessary elements and the systems witch are aviable at the german market. In the end I choosed active components of the german supplier Votronic.
I did a lot of research for the right passive elements, like fuse boxes and terminals. The RV suppliers offer a lot of cheap products for all purposes, but usually the qualitiy is poor.  But the boat and ship suppliers offer the right products and there I found high qualitiy offers.

Then I putted the grown knowledge together in this wiring diagram.

Dexter E3.05

Wiring diagram V3.05

Download newest version:
Wiring diagram V3.05

More information in German


First I calculated the daily power demand.

  • Lighting          80 Wh
  • Fridge            400 Wh
  • Heating           80 Wh
  • Pump               15 Wh

For the further steps I calculate with 600 Wh a day.
Maybe you wonder about missing things like TV or laptops. Normally I do not use such devices during my vacation. If I am outside I want to see the nature, not a flatscreen. But if necessary there are mobile solutions on the market. You would be surprised about the capabilities of a easy ipad.

My scope is to be independent from the grid for two days. This means that the battery needs a usable capacitiy of 1.200 Wh.


The power will be generated in three ways:

  1. Alternator
  2. Solar panels
  3. Shorepower

1. Alternator
I use a charging converter VCC 1212-45 Li. I connect it to the car battery not to the alternator. By wiring like this the alternator do not reduce the charge in case of a full car battery and a empty RV battery.
The charging converter  recognise a running engine and load the RV battery with 45A. The empty RV battery is fully loaded after a little bit more then two houres driving time.

2. Solar panels
I will stick two or three moduls (each 120 W) on the roof. To protect the sandwich against high temperatures some insulation between the panels and the roof will be necessary.
A Votronic MPP430 Duo controller will charge the batteries (both car and RV).
Finding the right capacity of the solar system is not an easy thing. Nobody knows about the sunshine hours of the days I will use the system. Average assumptions will not help on days with less sunshine. Because normally the sun don’t shine continuously (not in Central Europe), the system needs to be larger then the theoretical calculation shows.
The daily demand of  600 Wh is generated within 5 hours of full sunshine.
5 hours x 120 W = 600 Wh
The empty RV battery would be charged fully within 10 hours (or a whole day)
During the charging phase the RV need contiuously power, so it would need some hours more then calculated.
But I think that this isn’t reachable practical. So I will install two of these modules.
For backup reasons a mobile module will be on board as well.

3. Shorepower
With a CEE plug the RV can be connected to any 230V supply. The Votronic Pb1230 Li charge the batteries with up to 30 A. The empty RV battery is fully charged with only three or four hours connection to power supply.

Power Storage

The power storage demand is 1.200 Wh.
Because of the advantages of the LiFePo4 batteries (weight, charging current, cycle stability) I decided to choose this system.
LiFePo4 batteries are allowed to discharge up to 80% resulting in the following dimensions:

1.200 Wh / 12 V / 80% = 125 Ah

On the market are 120 Ah avialable, I choose this dimension. For further expanding needs the space and wiring for a second batterie is provided.

Dexter Stromlaufplan E2.12 Beleuchtung 1

I use LED stripes in aluminium profiles.
The differnt zones of the RV can be switched separatly, eyery zone have an own fuse. I use buttons and for each curcuit an impulse switch.

The impulse switches are located at the central distribution. The switch units are at positions easily accessible (there where you ere staying) positioned. By using the impulse switches, there may be any number of switch positions, without the wiring is confusing.


I manufactured the switch units by myself. The Cover is of PVC plastic (3mm, white) switches, sockets etc. are buyed at Conrad Electronics.

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They are wired and fitted with multi-plugs for easy installation and maintenance.

Central distribution

It is located in one of the benches. Because of the mass of componentes I constructed it with three layers. To maintain the lower level the upper ones are foldable.

  • The battery and the wire passage is in the lower department.
  • On the middle layer are the main fuses an the charging units located.
  • On top are the fuses and relais located.

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To exhaust the warm air from the charging units there is a ventilator installed. It push the air into the garage.


Steckdose für das Ladegerät und Ventilator zur Kühlung

More information in German language


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2 Gedanken zu “E 40 Electrical system

  1. Deine E.insta. sieht wirklich sehr durchdacht und sauber montiert aus! Gratulation!
    Aber, Heiland: „Montage direkt auf Holz?!?“ (Multiplex/Tischlerplatte?)
    Warum hast Du dir denn nicht noch paar 2,0er Aluplatten geholt und alles da drauf montiert?
    Bei dem Aufwand und deinen offensichtlichen Fähigkeiten?!
    Ich hoffe für dich und deine Lieben, dass da nie ´was heiß wird… !
    Allzeit gute Fahrt!!

    Gefällt mir

    • Hallo,
      die Zündtemperatur von Holz liegt bei ca. 280 – 340 Grad Celsius. Es erscheint mir mehr als unwahrscheinlich, dass diese Temperaturen bei den Sicherungsverteilern je erreicht wird.

      Viele Grüße,

      Gefällt mir

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