Making and Routing 70 mm² DC Cables for Victron 3-Phase System

Steps

1. 1

   Step 1: Choosing cable lugs and hydraulic crimping tools

   I use 70 mm² cable between the MultiPlus units and the busbar. I advise against cheap Chinese cable lugs and recommend proper Klauke cable lugs instead. For crimping, I use a proper hydraulic tool and warn against small Chinese tools that lack strength.

   Warning

   Do not use cheap Chinese cable lugs or undersized crimping tools.

   What I used

   Item	Amount	Notes
   70 mm² cable	several	Used between MultiPlus and busbar
   Klauke cable lugs	multiple	Recommended over cheap alternatives
   Hydraulic crimping tool	1	Must be a sturdy tool; smaller tools require two crimps

2. 2

   Step 2: Marking stripping length, stripping the mantle, and placing the cable lug

   I mark up to where the cable needs to be stripped. Then I remove the mantle and slide the cable lug into place. Using the correct steps helps me get a neat and proper connection.

3. 3

   Step 3: Testing cable length in the duct and discovering it is too small

   I lay the cable in the cable duct to find the ideal length. I notice I have not put heat shrink tubing on yet because the Chinese shipment was delayed, but I will add it later. I realize that six of these thick cables will take up way too much space in the 6040 cable duct I used.

   Because the cable and duct take up so much room, I will have to order a larger cable duct and replace the current one with a thicker version. I probably need to move from a 6040 size to about a 6080 size. Now that I can see exactly where the cable ends, I cut it to length and put a nice cable lug on the other side using my advanced nail scissors method and two crimps for good measure.

   What I used

   Item	Amount	Notes
   6040 cable duct	1	Too small for all six thick cables
   6080 cable duct	1	Planned replacement size

4. 4

   Step 4: Cutting cables to final length and attaching second cable lugs with double crimps

   Now that I can see exactly where the cable ends in the duct, I cut the cable to final length. I put a nice cable lug on the other side using my advanced nail scissors method. Finally, I add two crimps for good measure to make sure it is secure.

5. 5

   Step 5: Replacing cable ducts with wider 6080 ducts

   Two days later, the new cable ducts have arrived and I have already installed them. I now have significantly more space to run the thick 70 mm² cables through. It was a big job to get the old ducts out, and I had to temporarily disconnect and untie cables that were neatly zip-tied to keep track of incoming and outgoing power.

   Now I have to zip-tie everything back together to keep it neat and organized. For now, I continue making the thick cables to size, doing them one by one until all three negative cables are done.

   What I used

   Item	Amount	Notes
   6080 cable duct	multiple	Replaced the old smaller ducts
   Zip ties	several	Used to organize incoming and outgoing power wires

6. 6

   Step 6: Connecting negative and positive cables to the Lynx Distributor

   All three negative cables are now connected to the Lynx Distributor. I have not tightened them down with a torque wrench yet, but just put them on loosely to check cable lengths before crimping and adding heat shrink. The first positive cable is also in, and the new wider cable duct allows it to run straight through the side without pushing the lid away.

   All three positive cables are now mounted in the Lynx Distributor, where four cables run next to each other. Battery cables will also need to run here soon, which takes up even more space. I point out the mega fuses here and remind viewers from an earlier video that I will replace them with EF3 fuses because they have a higher AIC rating and handle short circuits better.

   What I used

   Item	Amount	Notes
   Lynx Distributor	1	Used to connect negative and positive cables
   Mega fuses	multiple	To be replaced with EF3 fuses

7. 7

   Step 7: Using the April hydraulic tool and introducing the thermal camera

   Before anyone asks, I use an April hydraulic tool that costs 35 euros on AliExpress. If you want to spend 35 euros well, get this tool because its dies are interchangeable, it can crimp from 4 to 70 mm², and it has about 5 to 6 tons of force. You just close the valve, pump it to crimp with incredible force, and open the valve to release it automatically.

   I also show a thermal camera that I will use later in the project to test the set. I will load the entire set to the maximum for both charging and discharging to see what it does to system temperatures, fuses, and cables, helping me find any bottlenecks.

   Tip

   The April hydraulic tool from AliExpress is a great affordable tool for crimping 4 to 70 mm².

   What I used

   Item	Amount	Notes
   April hydraulic tool	1	Bought on AliExpress for 35 euros, 4 to 70 mm capacity, 5-6 tons force
   Thermal camera	1	To be used later for testing maximum load temperatures

8. 8

   Step 8: Applying heat shrink tubing to all DC cables

   I disconnect all power cables from the set to make it easier to work with the heat shrink tubing since there is no voltage on them yet. I let the heat shrink tubing overlap the cable mantle by a few centimeters and run it all the way to the front of the cable lug, then cut it. This tubing has glue inside, making it harder to shrink, but once it is on, it stays on.

   I slide the tubing over the cable lug and warm it up using a lighter, a hair dryer, or whatever works, as long as I do not burn it. This leaves less exposed metal, and I make sure not to get any heat shrink tubing on the contact surface. With all DC cables done, I head back to the shed to mount them.

   What I used

   Item	Amount	Notes
   Heat shrink tubing with glue	multiple	Overlaps cable mantle and reaches front of cable lug
   Lighter or hair dryer	1	Used to heat and shrink the tubing

9. 9

   Step 9: Reinstalling the DC cables and protective caps

   The negative cables are now all connected. I removed the protective caps to make screwing them down easier, and I have not used a torque wrench yet because I do not have it on hand, but I will do that later. I put the protective caps back over the connections to prevent cables from touching each other and ask viewers to let me know if they know the exact reason for these caps.

   With that, the last direct current cables are in place.

   What I used

   Item	Amount	Notes
   Protective caps	multiple	Prevent cables from touching each other

10. 10

    Step 10: Overview of AC and DC system wiring

    Power comes in through the main switch and goes straight to the residual-current devices (RCDs) and groups, with an extra RCD added. A 5-core 6 mm² cable runs from the meter cupboard to the shed, entering through a main switch so I can safely cut power to the set. From the main switch, power goes down to feed each MultiPlus with a phase, while neutrals go to a block and split to separate bottom neutrals.

    On the AC output, all neutrals combine in an upper collection block and go to a 25 A circuit breaker, while a phase from each MultiPlus goes up to the circuit breaker and into the consumer unit. Later, a bypass switch will be added to connect the main switch directly to the house without going through the shed. On the direct current side, the 24V input from each MultiPlus goes down to the distribution, which connects to the SmartShunt, then to the Power In where the battery pack in the steel cabinet will connect.

    What I used

    Item	Amount	Notes
    5-core 6 mm² cable	1	Runs from meter cupboard to shed
    Main switch	2	One in meter cupboard/shed input, one for bypass later
    25 A circuit breaker	multiple	Receives AC output phases from MultiPlus units
    SmartShunt	1	Connected between distribution and Power In
    Power In	1	Connects to the battery pack in the steel cabinet

11. 11

    Step 11: Takeaways

    • Always use quality Klauke cable lugs and a strong hydraulic crimping tool instead of cheap alternatives.

    • Plan for sufficient cable duct space, upgrading to 6080 ducts when 6040 proves too small for thick cables.

    • Use heat shrink tubing with glue inside to protect cable lug connections without getting material on contact surfaces.

    • EF3 fuses should be used instead of mega fuses for a higher AIC rating during short circuits.

    • A thermal camera is a useful tool for testing system temperatures under maximum charge and discharge loads.