Battery Welding & Weld Tabs : Explained [2021]

Battery welding is the welding process you use when you are out on a trail and needed to weld. Using weld tabs will make the welder work flawlessly.

Here’s the deal:

To get started you just need a battery, a set of jumper cables, and vice grips.

And of course your welding safety equipment.

Not covered on the internet well, I made this guide with newbies and established welders in my mind.

Let’s get started.

Resistance Spot Welding with weld tabs and battery welder.
Battery Welding

How does Battery Welding Work?

Batteries are an integral part of modern life. You can’t avoid them at any cost.

Why not utilize them instead as a temporary or permanent solution.

In battery welding, you connect multiple batteries in series for the purpose of welding. 

That is, the positive terminal is connected to the negative terminal and so on depending on the number of batteries you are using.

Taking an example of the typical automotive battery of 12V, with multiple 12 V you can connect them in series to get one 24V battery or even 36 V battery(via connecting 3 batteries).

A 24V-36V battery is enough to power your basic welding needs on the road.

Connecting Batteries in Series for Battery Welding.
How to Connect Batteries in Series

While you are on the road, you might have jumper cables with you. 

These can be used to connect the batteries in series if you don’t have designated cables.

Be careful, only connect the positive terminal to the negative and vice-versa.

Connecting to the same terminal will cause irregularities in the weld along with other damages.

However, if you have other options it is better to avoid jumper cables and replace them with welding cables.

Welding cables are often preferred for Battery welding since they are highly flexible and are capable of handling voltage fluctuations well.

They are made with fine copper wires which are insulated, and thus its highly flexible nature.

If you don’t want to go through all this hassle, you can buy a portable welding kit like Trail weld.

They come with dedicated cables specifically made for welding and safety equipment, with which you can easily connect multiple batteries and weld.

The tab-to-terminal connection is the other important method that is commonly used. This method is known as Tab Welding.

Weld Tabs and Tab Welding

As discussed in the last section, tabs are used with batteries to ease out the connection between two terminals and are known as tab welding.

Weld Tabs act as a conductor and thus are usually made of highly conductive metals such as copper or aluminum. 

The weld tabs and the whole tab welding depends upon the thickness of both the terminal and tabs along with the material.

Tab Welding is mainly used with lower voltage batteries or small batteries and not automotive batteries.

That is, they are mainly used with

  • Cylindrical batteries
  • Large prismatic batteries
  • Lithium polymer batteries

But, weld tabs are also used for a whole lot of other purposes.

Flat Weld tab used for batter welding
DIY Battery Welding using Weld Tabs

Uses of Weld Tabs

We have already seen how we can make use of weld tabs in battery welding.

But, weld tabs are used for a lot of different purposes as well.

Weld Tabs are originally used in the fabrication of pressure vessels or any other mechanical parts which go through RT(Radiographic Testing).

Typically used in the beginning or the end of the weld, the weld tabs make sure that the weld is smooth and clean.

Without weld tabs in serious welding jobs, it may result in incomplete fusion which leads to weak weld joints.

The incomplete fusion can be easily spotted with the naked eye, to make sure it’s not a mistake welding tests are done too.

Penetrant test or Radiographic testing is done on the weld to find the weak weld often resultant from incomplete fusion.

When it’s the time to submit the weldment for testing, the tabs are mentioned in the weld map.

Hence, tabs are used to reduce the risk of defects related to incomplete fusion.

However, they don’t eliminate the defects completely, instead, they allow the arc to stabilize itself, confining the areas of risk to a very small portion.

Another important use of tabs is to use them as an attachment over a tube.

Since they come in different types(explained below) and are identified by the different purposes they are used for. 

Types of Weld Tabs

By now, I hope you have understood how weld tabs are used. 

There are many types of Weld Tabs available in the market. I have tried to list down the popular ones to make it easy for you guys-

Flat Tabs: By the name itself, they are flat and made up of premium mild steel. Generally used for basic welding processes.

Tube Tabs: Weld tabs used for tubing are called tube tabs and are usually flat. At the bottom, they have a radius, via which they are fitted to a tube. They are welded perpendicularly to the axis of the tube.

Trick Tabs: These weld tabs are also used for welding. They have a unique name since they can fit on any tube of any diameter, hence the name “trick” tabs. Unlike tube tabs, they are welded parallel to the axis of the tube.

Gussets: Used at the corners, they have holes in them which are used to run electrical wires, etc through them.

Flanges: These are used to bolt two pieces of metal tubes together instead of welding them. Can be easily unbolted and thus an easy temporary( or sometimes permanent) solution.

There are several other types of Weld tabs for very specific purposes as well.

Welding Process Used in Battery and Tab Welding

Any of the welding processes out there can be used to weld tabs and the battery together. 

However, resistance welding or resistance spot welding is the widely used process for battery welding.

Although it usually requires large, generally immobile, and expensive machines, electric resistance welding, also known as ERW, is a clean and efficient method of joining weld tabs to battery ends quickly and solidly. 

Resistance Welding

Electric resistance welding is used for some extremely crucial manufacturing processes apart from tab weldings, such as the seam welding used for fuel tanks, large pipes, and other containers. 

The principle behind electric resistance welding, and hence behind electric resistance welding machines, is straightforward but can be applied in several different ways.

Resistance welding machines work by clamping the two pieces of metal that are to be joined between two copper electrodes.

That is the weld tab and the battery end. 

A strong electric current is passed through the electrodes and the metal pieces – generally, a current with fairly low voltage but high amperage. 

The metal’s resistance to the current converts the electric energy into heat energy, which melts both parts at the place where the electrodes are creating a circuit through them. 

The pressure of the electrodes then squeezes the two parts into each other, literally combining their substance at that point, and creating a weld.

The two most common forms of resistance welding are

  • Spot welding
  • Seam welding

Each uses a different type of machine with different electrodes and is used for very different fabrication processes. 

Spot Welding

Spot welding is a type of electric resistance welding that is carried out with two clamping electrodes that complete an electric circuit through the two sheets of metal. 

The maximum level of resistance is at the point where the two sheets of metal are pressed against each other, so maximum heating occurs here as well. 

Heat increases the resistance, which causes more heat, and so on. 

To prevent the electrodes from sinking into the other side of the sheets, the electrodes are water-cooled, so the heat is concentrated at the place where the sheets touch and not elsewhere.

The two areas of the sheets touching each other become molten and flow together, forming a bond. 

As the electrodes continue to clamp down, the heat flows back towards them, then is drained away by their water cooling, hardening the weld. 

There is a possibility of damaging the weld at this point if the heat has been built up too quickly, however, and cannot be drained off in time to prevent the electrodes from squeezing out molten metal from the weld point. 

Spot welding is quick and cheap, but not very strong. It is used frequently in building cars.

Seam Welding

Seam welding is similar to spot welding in general principle but replaces the stationary, clamp-like electrodes of spot welding with a pair of electrodes in the form of copper wheels or rollers. 

These wheels heat the metal plates with an electric current in the same way as a spot welder.

But are in constant motion, simultaneously rolling the sheets forward between them, heating the metal to the molten point with electric resistance, and squeezing them into each other to form a bond. 

Seam welding forms an unbroken seam between the plates – a strong, uniform, continuous weld from one end of the workpiece to the other. 

Unlike spot welding, seam welding is very strong and is used for such important items as fuel tanks.

Whether it is built to carry out spot welding or seam welding, a resistance welding machine takes advantage of the characteristics of electrical resistance to heat and weld two pieces of metal together with a minimum of byproduct heat, fumes, and other peripherals of ordinary welding. 

Conclusion

I hope you got the information you were looking for about weld tabs and battery welding. 

Some wanted this info to make their own DIY welding machine, others were in distress and some even wanted to weld their vehicles frame. I tried my best to pour my knowledge into this post keeping you in mind.

Remember to wear your safety equipment & Happy Welding.