Can you Run a Welder off an Inverter?

Note: The information provided in this post is only intended as a guide. Always consult the manufacturer of your welder or inverter manufacturer first before you connect any welder to an inverter

If you do remote jobs that require welding then you might want to consider a light power source that does not take up much space on your truck as a generator does.

You can use a power inverter to run power drills and grinders but can you power a welder using an inverter?

And if so, what size of inverter should you use for a welder?

This post sheds some light on whether you can and should run a welder using power from an inverter, the advantages and disadvantages there are if any, and what alternative power sources you can use instead of an inverter.

Can you run a welder off an inverter?

Yes, you can run a welder off an inverter provided it is able to supply the surge and continuous power requirements that the welder requires.

In practice though, powering a welder using an inverter is suited for light welding jobs for short periods because of a combination of the limited capacity of available batteries and the high current draw of the welder.

What size of inverter for a welder?

This largely depends on the power requirements of the welder.

Before you connect a welder to any inverter, consult the welder manufacturer if you can use an inverter and the recommended inverter capacity to use with it.

Even then, it should be limited to light jobs that require limited weld time to minimize the likelihood of damage to your inverter.

For example, you may be able to use a 3500 watt + good quality pure sinewave inverter with a 20 amp, 120V TIG welder.

Always start with a low welding current first and ramp it up slowly while monitoring the inverter for any unusual behavior – noises, smoke, temperature.

Always remember to consult the welder manufacturer if you can and should use an inverter.

In addition to the inverter, you’ll need a power source for the inverter. This might be a large enough battery bank or a high-power alternator.

For the 20 amp, 120V, or 2,400 watt welder, assuming an alternator output voltage of 13V, the alternator needs to supply about 184 amps.

You’ll need a high amp alternator and it’ll probably need to be run at high idle. Should you choose to use a battery bank, it should be large enough to supply 184 amps for the duration of the weld!

For a 4-hour weld, you’d need 184 amps x 5 = 920 Ah battery bank or greater at 24 V.

Alternatives to using an inverter for a welder

If there is no available power source for the welder:

  • consider using a long extension cord of the appropriate gauge to extend power close enough to the repair site.
  • Can you transport the points to repair? It might work out to be cheaper than investing in a battery-powered alternator
  • You can use battery-powered arc, tig, or MIG welder kits
  • You can also purchase a high-output welding alternator
  • You can use a generator instead to power the welder – it should be appropriately sized thought.

If using a 20 amp welder at 115V, with an estimated power draw of 2,300 watts, consider using a 5 kW generator.

The generator solution will likely be more affordable than the investment you’d have to make in batteries, inverter, or an alternator upgrade.

It will also give you more weld time compared to an inverter battery solution. The disadvantage is it takes up space, requires maintenance, and can be noisy.

Can a 3000-watt inverter run a welder?

A good quality 3000-watt pure sine wave inverter should be able to run a small 120V, 15 amp welder.

In addition, you’ll need to power the inverter from a battery bank (size dependent on the estimated weld time) or an alternator.

The alternator would need to supply about 140 amps dedicated to the welder.

So, it might work but you’re probably better off considering the alternative power solutions.

Final Word

While you can run a welder from a power inverter, it is probably not the best power solution for the welder.

Inverter solutions unlike generators require investment in battery banks and charging sources for that battery bank.

Given the limited storage capacity of the batteries, you’ll likely be limited to a small welder (to keep the costs down) and limited weld time compared to using a generator.

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