The Schaudt Elektroblock is an all-in-one power distribution, control and battery charging system for Motorhomes & Caravans – predominantly fitted to German built vehicles. Our’s recently started misbehaving on a recent trip to Europe, and while it was sent away and repaired by a specialist after the trip it made me lose some faith in the 20 year old components it is made from!
I started thinking about whether it would be possible to replace the whole unit with a plug-and-play DIY solution (our version – an EBL 4-105 – is not available anymore, and current versions (which wouldn’t be a direct swap anyway) are over £500….)
On reviewing the Schematics and poking about inside the unit it became clear that there is not actually all that much to them, most of the intelligence is in the battery charger bit and by separating out the functions I could use an off-the-shelf battery charger and create a separate power distribution system that plugs straight into our motorhomes wiring.
This is the inside of the unit – the large transformer and lower circuit board make up the battery charger, the upper circuit board is the power distribution, fuses, relays etc. The rest of it is fresh air!
The first step is to select a suitable battery charger that can be left permanently connected to the leisure battery – I selected this 11amp automatic unit from Absaar (similar capability to the 10amp unit in the original Elektroblock)
Note: I ended up not using this particular charger, as it makes an annoying loud buzzing noise when it is operating! – but it’s useful for showing the process I went through in integrating it to the motorhome
To prepare the mains side of the wiring I replaced the original 3 pin plug lead on the charger with a ‘kettle’ type socket. This allows the motorhome wiring to plug straight in.
This is the Elektroblock in it’s original location inside a cupboard on the right hand side of the cab, the metal angles on the bottom slot in channels in the wood.
Adding some 90 degree metal angles to the sides of the new charger allows it to slot into the exiting channels
Next step was to design a distribution and fusing system to handle the rest of the Elektroblock functions, based on the original schematics for the EBL 4-105. This is the schematic for the new system:-
The main functions are as follows:
- Relay for split charge (to charge the leisure batteries when the engine is running)
- Relay for the fridge (to power the fridge from 12V when the engine is running)
- 12V systems relay (to turn the 12V supplies on when switched on from the control panel)
- A shunt to measure the current going in/out of the leisure battery, to drive the ammeter on the control panel
- Fuses to protect all the circuits
- Plugs to connect to the original motorhome wiring (1x input mate-n-lok, 2x output mate-n-lok, 1x solar connection mate-n-lok, 1x 8-way panel connector)
- Connection points for the 12V feed from the charger
- Flyback diodes for the relays, and a diode to prevent the leisure batteries from back-feeding the alternator
This is the control panel as fitted to the motorhome that interfaces to the Elektroblock. It contains a voltmeter for starter and leisure batteries, an ammeter for current in/out of the leisure batteries, and a switch to turn the 12V circuits on/off
The two relays for the split-charge and fridge are switched from theT alternator D+ terminal, so I used standard automotive 40A relays. To house these I picked up a combined relay/fuse box that holds 2x relay and 8x automotive fuses, and comes complete with all the necessary terminals to wire it up:-
Fuse and relay box, cost just £7.59 delivered
The relay for the switched 12V circuits needs to toggle between on & off when it receives a momentary signal from the control panel, so a more specialised relay is required here. I used a Finder DPST DIN rail mount 12V latching relay. This has the added benefit that it can be actuated manually, so should the control panel/switch/wiring fail, the 12V circuits can still be switched on/off by pressing the button on the front of the relay:-
Finder 12V DIN rail mount relay
For easy access I opted to mount all the distibution components to a wooden board that will go above the charger unit in the cupboard. The fuse box and shunt are screwed directly to this board, and a din rail is added to hold the Finder relay and some DIN rail mount distribution blocks for the various circuits. Here is the fusebox, finder relay and shunt mounted up and the first bits of wiring connected:-
Here is the board with all the wiring added, ready for the plugs to be terminated:-
The flyback diodes for the relays in the fusebox are connected directly to the coil terminals – you can see them here in the fusebox wiring:-
The flyback diode for the finder relay is connected to the coil terminals (top and bottom of the relay) and lay down the left side of the relay itself
Next job was to start terminating the plugs. For the panel connector I could only find the mating half in a PCB mount version, so I soldered it onto a piece of prototyping board and added an 8-way PCB mount screw terminal connector to wire it up:-
In the original motorhome wiring the starter battery sense line and the two shunt sense lines are directly connected to batteries and fused at 30A – too high for the wiring to the panel. To protect these circuits I added inline fuses holders to the wiring to the panel connector with 800mA glass fuses:-
Next job was to add all the pins and sockets for four main Mate-n-lok connectors:-
This is it all terminated and ready to go:-
Here is a top view of the fuse & relay box with the lid removed, showing the fuses and relays in place:-
Here is the new system connected to the wiring in the motorhome and ready for final installation
And the final installation inside the original Elektroblock cupboard:-
The new system works perfectly, with the added bonus that the solar regulator can now charge both the starter and habitation batteries.
In case you want to create something similar yourself, here is a bill of materials – total cost £105.66 (note – the piece of wood and a few small lengths of different colour wire are from stock I had lying around, so aren’t included in the BoM, I also haven’t included the charger in the BoM as you can pretty much use any charger you like as long as it is designed to be permanently connected to a battery – I ended up using a CTEK unit)
I’m pleased with the outcome and it’s a saving of many hundreds of pounds over a new Elektroblock! Let me know what you think – is it a good idea?, have I missed anything? Also, let me know if you want a copy of the schematic – I’m happy to share it.
Thanks for reading!
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