Welding Thickness of Sunkko Welders

Posted by Binshan on Jan 16th 2019

Today we will talk about the welding thickness of Sunkko battery spot welders. I believe everyone has noticed that we have a brief introduction about the welding thickness in the title and description of each product listing. However, this is not comprehensive enough, so I would like to publish this article for people who is interested in more detailed information regarding the topic.

Two points that need to be highlighted at the beginning:

1. Local power system has a great influence on the welding thickness of Sunkko welders. So please power your Sunkko welder through an outlet directly, not through a patchboard, and turn off other high-power household appliances if possible during the welding process.

2. The materials of poles for different batteries are different. Most of them are made of stainless steel, iron plated nickel or iron. In terms of the degree of weldability, stainless steel > iron-plated nickel > iron, that is to say, under the same welding settings, a 0.15 mm pure nickel sheet can be welded to a battery’s pole made of stainless steel easier than a pole made of iron.

Some users will make some large-capacity battery packs to meet their equipment. In this case, the specifications of the nickel strip connected to the battery need to be adjusted according to the discharge current of the battery pack. We generally adopt the following two methods:

1. Increase the thickness and width of nickel sheet;

The following two tables show the relationship between different sizes of nickel tabs and the current that can pass through.
Table 1(nickel plated steel):

current \ length 0~5cm 5~7.5cm 7.5~10cm 10~15cm
<5A 0.1x3mm 0.1x5mm 0.1x8mm 0.15x8mm
5~10A 0.1x8mm 0.15x8mm 0.2x7mm 0.2x8mm
10~15A 0.2x7mm 0.2x8mm 0.2x9mm 0.2x10mm
15~20A 0.2x9mm 0.2x10mm 0.25x10mm 0.3x10mm

Table 2(pure nickel):

current \ length 0~5cm 5~7.5cm 7.5~10cm 10~15cm
<5A 0.1x2mm 0.1x4mm 0.1x6mm 0.1x9mm
5~10A 0.1x6mm 0.1x8mm 0.15x5mm 0.15x7mm
10~15A 0.15x5mm 0.15x6mm 0.15x8mm 0.2x7mm
15~20A 0.15x8mm 0.2x7mm 0.2x9mm 0.25x9mm

For example, if you need to use a 5cm pure nickel sheet to connect battries, and the nickel sheet needs to withstand a current of 12A, and you can choose the standard of 0.15x5mm.

Table 3 is the welding thickness of most Sunkko welders.
Table 3:

Series 737 787 788 709 797
Model 737G 737G+ 787A+ 788H 788H-USB 709A 709AD 709AD+ 797DH
Fixed head for nickel plated steel(mm) 0.2 0.35 0.2 0.3
Fixed head for pure nickel(mm) 0.15 0.25 0.15 0.25
Mobile pen for nickel plated steel(mm) 0.15 0.2 0.15 0.2
mobile pen for pure nickel(mm) 0.1 0.15 0.1 0.15

2. Welding multiple layers to connect battery cells;

This is a good way to increase the current that passes through, but keep in mind that there are two problems with multi-layer spot welding:

  • Since the surface of the first layer is no longer smooth, when the user welds the second layer to the first layer, there will be a problem of poor contact and insufficient pressure between the two layers. The welding thickness that Sunkko welders can handle will be significantly thinner.
  • Loss of energy: The working principle of Sunkko welders combine the factors of power supply system throughout the region, voltage transform, electrical conductivity, physical properties of various metals and other factors. And we will talk about how electrical conductivity influences the welding thickness.
    At the beginning, Sunkko welder generates a huge current by its internal voltage transformer, and the current goes to the copper welding rods of fixed welding head or mobile welding pen. Due to the electrical conductivity of copper, nickel and the material of battery's pole, when the copper rods contact nickel and battery's pole, the current is transformed to heat that melts nickel to stick with battery's pole and the welding process is done. However, when a user tries to weld a second layer to the first layer, some of the energy will be lost between the first layer and the battery's pole. A small part of energy will stay between the second and the first layer, that's why most Sunkko users cannot weld a second 0.2 mm pure nickel to a battery that is already welded with a 0.2 mm pure nickel.

Regarding the specific loss ratio of energy between the first layer and the battery's pole, and the thickness of second layer that Sunkko welder can weld, we will publish our data in the next blog after our specific test. In addition, we will talk about the working principle between Sunkko welder and the power supply system in later articles.
At the end, thank you for taking time to learn Sunkko product.