Making Custom Battery Cables

Steps

1. 1

   Step 1: Choosing cable lugs

   Many cheap cable lugs are available on online stores like Amazon, Temu, or AliExpress, but they are very thin-walled with a thin lip. In contrast, connectors from brands like Klauke are made of much thicker material. Thick-walled connectors have less resistance, can carry more energy without getting warm, and do not tear open easily.

   What I used

   Item	Amount	Notes
   AliExpress cable lugs	various	Thin-walled and cheaper
   Klauke cable lugs	various	Thick-walled and high quality

2. 2

   Step 2: Why crimping is better than soldering

   Many people say soldering is better, but I completely disagree for a few reasons. Soldering is a chemical connection where tin must flow into the wire and the inside of the connector, which is very hard to control because copper and the lug conduct heat so well. If the cable ever gets warm for any reason, the tin can melt and the connector can come loose from the cable.

   When you press a cable lug with a crimper, the copper wire inside is squeezed together into one solid lump of copper and the lug is pressed tightly onto it. This creates a very low resistance so the connector does not get warm. Even if it ever gets warm for some reason, a crimped connection will never let the cable go.

3. 3

   Step 3: Selecting a hydraulic crimping tool

   Small hand crimpers are fine for thin wires, but they are not powerful enough for thick cables like 35, 50, or 70 square millimeters. You do not need extremely expensive professional gear, as a simple hydraulic crimping tool works super well. The hydraulic crimper I use costs about 40 euros and comes with different dies for 4, 6, 8, 10, 16, 25, 35, 50, and 70 square millimeter cables.

   This tool lets me make practically any cable I want, including the 70 square millimeter cables I used for my MultiPlus setup.

   • 4 mm2

   • 6 mm2

   • 8 mm2

   • 10 mm2

   • 16 mm2

   • 25 mm2

   • 35 mm2

   • 50 mm2

   • 70 mm2

   What I used

   Item	Amount	Notes
   Hydraulic crimper	1	Costs about 40 euros, includes dies up to 70mm2

4. 4

   Step 4: Preparing and crimping the cable

   To start, I take the cable and an M10 cable lug to check how far the cable fits inside. I strip the outer jacket a little bit further than needed so a tiny bit of wire sticks out the back rather than falling short. I make sure all the strands stay neat together.

   Next, I close the valve on the hydraulic crimper and pump it until the dies close. I insert the M10 cable lug into the tool so it holds it in place, which gives me an extra free hand. I push the stripped cable all the way into the lug, pushing it an extra little bit, and start pumping until the die is fully closed. Because it is hydraulic, it takes quite a bit of strength to close it completely.

   What I used

   Item	Amount	Notes
   Hydraulic crimper	1	Used to press the lug
   M10 cable lug	1	Fitted onto the cable end
   Cable	1	Stripped for crimping

5. 5

   Step 5: Double-crimping and smoothing the edges

   After the initial crimp, I usually set the tool right next to the first crimp and pump it again to get a larger contact surface. Because the crimping creates small standing lips on the sides of the lug, I do one final light press by opening the valve, turning it just a tiny bit, and giving it one quick touch over. This pushes the standing lip flat so there are no sharp edges that could cut into my heat shrink tubing.

   The finished cable lug is pressed on extremely hard and sits securely all the way to the end of the barrel.

   What I used

   Item	Amount	Notes
   Hydraulic crimper	1	Used for the second press and flattening the lip

6. 6

   Step 6: Applying heat shrink tubing

   I take pieces of black and red heat shrink tubing and slide them over the cable lug. I push the tubing so it sits just a little bit over the neck of the lug, while making sure the flat contact surface of the lug stays completely clean and free of tubing.

   Using a lighter, a heat gun, or anything else that gets hot, I heat up the tubing. The heat causes the tubing to shrink and clamp tightly around the cable lug.

   What I used

   Item	Amount	Notes
   Heat shrink tubing	2	Black and red pieces
   Lighter or heat gun	1	To heat and shrink the tubing

7. 7

   Step 7: Benefits of making your own cables and length rules

   Pre-made cables with lugs are usually much more expensive because of the labor involved in pressing them. Making them yourself is cheaper, and you can make them to the exact length you need to run from your busbar to your battery.

   When you connect simple battery cables, the exact length is not super critical. However, if you have MultiPlus units connected in parallel with two units on one phase, they must work together and it is very important that their cables have the exact same length so one cable does not have less resistance than the other.

8. 8

   Step 8: Takeaways

   • Thick-walled cable lugs carry more energy without getting warm and have less resistance than thin-walled ones.

   • Crimping creates a solid lump of copper with low resistance, making it much safer than soldering.

   • A budget hydraulic crimper from AliExpress is powerful enough to press thick cables up to 70 mm2.

   • Flattening the standing lips of a crimped lug prevents it from cutting into the heat shrink tubing.

   • Cables connecting parallel MultiPlus units must be of exact equal length to ensure equal resistance.