Miller Bobcat 250 Review

If you are a welder, then you know the importance of having a dependable power supply for every job you are on. In today’s review, we are going to take a look at the Miller Bobcat 250 and the performance that provides as one of the best welding generators on the market. In our review, we are going to take a look at the specs of the Miller Bobcat 250 and why many welders continuously rate it as one of the best welding generators. At Throughout our review, we will have a detailed pros and cons outline of what you need to consider when you are shopping for this welding generator. Before we get into our review, let’s take a quick look at the Miller Electric brand, the makers of the Miller Bobcat 250 generator. Check PriceBuy on eBay

Miller Electric: Behind the Brand 

The Miller Electric company started out with humble beginnings in the year 1929. The brand creator, Neil Miller, was the designer behind the small arc welder that was used for stick welding.  The arc welder he crafted was a lot smaller, lighter, and cost-effective than the then popular DC rotary units that were primarily used. This innovation was the starting point of Miller leading the way in the welding industry. It was not long after that the innovative brand crafted the first ever high frequency stabilized AC industrial welder. This welder became popular in factories and construction sites all over and it certainly changed the way that manufacturing companies  welded different pieces of metal together. 

Today, the brand is recognized as one of the leading companies in the welding industry. Because of that, the Miller Electric company has gone on to provide a variety of heavy duty high performance welders for the general public. Additionally, the brand specializes in creating other pieces of machinery essential to welding. Everything from generators to accessories for better performance with your current welder is things that the Miller Electric Company can provide. Today, we are going to be breaking down the ins and outs of their most popular generator, the Miller Bobcat 250.

Now that you have an understanding of the brand, let’s begin our review of the Miller Bobcat 250 welding generator. 


  • Highly versatile
  • Constant current and constant voltage
  • Both AC and DC capable
  • Accu-rated power
  • Heavy-duty construction
  • Reversed generator airflow
  • Quiet
  • Great duty cycle
  • Simple control panel w/ digital meter
  • Easy to maintain
  • Several models available


  • Welding leads sold separately

What’s Good?

Highly versatile

The Miller Bobcat 250 is, hands down, the most versatile engine driven welder on the market today. With 11000 watts of peak power and 9500 watts of continuous power, if you’re serious about fabrication this is the only machine you’ll ever need to buy. Here’s a list of processes it’s capable of:

Stick welding (SMAW)

Flux-cored welding (FCAW)

MIG welding (GMAW)


Non-critical AC TIG (GTAW)

Air carbon arc cutting (CAC-A)

Plasma cutting and gouging

And that’s just the fabrication related processes it can do. This beauty is capable of powering almost any tool in your shop if you need it to. From air compressors to circular saws to refrigerators to sump pumps. Furthermore, if you live in areas with frequent storms, it just makes sense to have a generator on hand, so why not get one that is essentially superman in generator form. With its Kohler 23 HP motor and 12 gallon capacity gas tank, the Miller Bobcat 250 will easily power your entire house in the event of a power outage. Under a continuous 4000 watt load this machine will run for about 14 hours before you need to refill the tank. That’s at least enough power to keep the lights on and your food from spoiling. miller bobcat 250

Constant current and constant voltage

The Bobcat 250s’ ability to handle so many different welding processes is partly thanks to its multi-output capability. It features both constant current (CC) and constant voltage (CV) power sources. MIG welding and Flux-cored require CV while Stick welding and TIG require CC.
What’s the difference?
Welding has two main variables: current and voltage. Most welders will supply both but are only able to constantly maintain one while the other is maintained by some other means.


Constant voltage is used by welding units that are considered automatic processes like MIG and Flux-cored. It provides a constant preset voltage which maintains a constant preset arc length (voltage is directly related to the length of the arc). The current then, is determined by adjusting the wire feed speed, wire diameter and wire stick out. For example, set at 22 V the MIG machine will have an arc length that remains the same but as you increase the feed speed you increase the current.


Constant current is used by machines that are considered manual processes like Stick and TIG. These units will have a current that remains constant. Since these processes are manual the voltage is determined by the proximity of the electrode to the material. The closer to the material you’re welding the more voltage is used. That’s why you see welding equipment typically grouped together like a MIG/FCAW welder or a TIG/Stick welder. With the Miller Bobcat 250 you can easily switch between CC/CV using the knob on the front control panel so no matter what type of welding you need to do, the Bobcat can handle it.

Both AC and DC capable

Did I mention this unit is versatile? If you’re reading this review you likely already know all about AC vs DC +/- polarity so I wont get into it here – just know that the Miller Bobcat 250 offers both. DC is used most of the time. Some of the benefits include smoother, more stable arcs, easier starts, less spatter, fewer arc outages and easier out-of-position welding. AC is used when TIG welding certain materials like aluminum and magnesium. In addition, it’s also used when stick welding to prevent arc blow.

Reversed generator airflow for better cooling and reduced noise

The cooler the engine, the longer you’ll be able to work, which is something the Bobcat 250 does very well. Millers’ unique design operates cooler and more efficiently by rotating the engine towards the front to create better airflow. The air is then exhausted through the top away from the machine so that it can intake fresh, cool air. Hot air recirculation is effectively eliminated, especially when mounted in tight spots, keeping the machine at an acceptable temperature for maximum performance. Additionally, the design and engine placement of the Miller Bobcat 250 reduces noise by up to 33% compared to previous models. This not only makes work more comfortable, it also offers better communication on the job for a safer more efficient work environment. miller bobcat 250

Accu-rated power

Accu-Rated is basically Millers patented name for saying this unit is no bullsh*t – when they say it provides 11000 watts of peak power, they mean it. It means when you need to use peak power the Bobcat 250 will deliver it, for a minimum of 30 seconds – unlike some lesser companies that tend to inflate their numbers for advertising purposes. This is beneficial when you need to run power intensive equipment like plasma cutters, power-heavy welders or starting engines. Not only will it perform to its maximum potential, but it’ll maintain that power for longer and more consistent than its competitors.

Heavy-duty construction

Ruggedness is the name of the game with the Miller Bobcat 250. After all it needs to be able to withstand the harsh conditions and unpredictable terrain of being transported to and from remote job sites – which is what this beast was meant for. It features copper winding and iron generator components for the ultimate in reliability. The heavy internal leads are lugged, rather than soldered, for increased durability out in the field. The shell/casing on the Bobcat is incredibly tough to protect the internal components from damage. It’s practically meant to be battered around. Finally, the door panels are heavily protected with thick armour to protect the weld studs and receptacles as required by OSHA.

Great duty cycle

With a duty cycle of 100% at 250 amps for MIG and flux-cored welding and 60% for TIG and stick the Miller Bobcat 250 is a real powerhouse. That means you’ll be able to weld MIG/FCAW all day long without taking a break and only minimal downtime with TIG/stick. However if you want to keep powering through and don’t need to to weld at full power, it’s capable of 100% duty cycle at 225 amps for TIG and stick. Who needs a break anyways?

Simple control panel w/ digital meter

Despite its wide range of functions and abilities the Bobcat has a surprisingly easy control panel. There are 4 basic controls you need to consider:

1. Power – Thats the one located nearest the bottom of the panel.

Within the power knob there are 4 options: start, run, run/idle, and off.

To start it hold the choke for a few seconds and then turn the knob to start. When it fires up set it to run and you’re all set to start welding.

2. Process selection – on the left side of the control panel is the process selection knob.

Your choices are: wire +/- (MIG/FCAW), stick, TIG and AC weld.

3. Voltage/ amperage range selector – in the middle you have the voltage and amperage range selector.

The part in blue is for MIG/FCAW.

It allows you to set the voltage range from low to high. 17-22 and 20-28.

Next to that is the amperage range selector. Your choices are 40-100, 60-140, 80-200 and 100-250.

4. Voltage/amperage fine tuning – finally on the right you have the knob for fine tuning the voltage or amperage, depending on what process you’ve selected.

This lets you hone in on the exact amperage/ voltage you need to lay down the perfect bead.

The dial goes from 1-10 so you might have to try a few settings before you get it just right.

Finally at the very top right corner of the panel you have the gas gauge and an hour indicator. The gas gauge should be pretty obvious but the hour meter indicates how long you’ve used the machine over its lifetime. It’s used to keep tabs on how long its been since it’s had an oil change so you can keep your machine running as smooth as possible. It’s recommended you change the oil after every 100 hours. miller bobcat 250

Easy to maintain

Speaking of oil changes, the Miller Bobcat 250 is incredibly easy to maintain. To refuel, simple unscrew the gas cap at the back left on the top of the machine and pour it in. There’s an indicator near the bottom side that tells you how much gas you’ve put in so you don’t have to worry about overflow. Furthermore, thanks to its tool-free panels all you do is press the levers and the panels pop right off for easy access to the insides. The top panel allows you to check and fill the oil as well as changing the air filter. The side panel pops off just as easily so that you can easily drain the oil and change the filter. miller bobcat 250

Several models available

The hardest part about decided on an engine driven welder/generator is what model of Bobcat you’re going to get – let’s face it, the Bobcat is the best in almost every aspect. All of the models are nearly identical except for a few key differences.

Bobcat 250 – This is the base model which I just reviewed.

Bobcat 250 GFCI – This model includes GFCI receptacles, which stands for Ground Fault Circuit Interrupters. It’s designed to prevent electrical shocks by shutting down when it detects the current is flowing along an unintended path such as water or a person.

Bobcat 250 w/ Electric Fuel Pump – This model includes an electric fuel pump which allows for smoother starts, especially when working at higher altitudes.

Bobcat 250 EFI – EFI stands for electric fuel injection and is the King of the Bobcats.

It works by optimizing the air/fuel ratio which results in lower operational costs, fewer emissions, longer runtime and better performance.

Additionally the EFI model puts out an extra 1000 watts of peak power for a total of 12000 watts.

What’s Bad?

Welding leads sold separately

I can’t really find anything wrong with the Miller Bobcat 250 when it comes to functionality and usability. It’s a truly impressive machine. But if I have to have a con it’s that it doesn’t come with any welding leads. For the cost I would expect at least a stick electrode holder and ground clamp but in reality, if you’re considering an engine driven welder it’s likely that you already have your own so it’s probably not that big of a deal.

The Verdict

The Miller Bobcat 250 is a remarkable piece of equipment. It’s the Jack-of-all trades in the fabrication world – capable of MIG, TIG, stick, flux-cored, air-carbon and plasma cutting – it’s the only machine you’ll ever need. The Bobcat is considered the most popular engine driven welder in the industry and it’s easy to see why. With its 11000 watts of peak power, its rugged design meant for the most unforgiving job sites, its easy maintenance schedule and its unmatched versatility the only thing you’ll regret is that you didn’t buy one sooner.

Specs and Features



Type: Kohler CH 730

Size: 23.5 HP

Speed: 3600 RPM


Power: 11,000 W

Amperage: 40-250

Duty Cycle: 60% @ 250 A

Processes: Stick/TIG/MIG/FCAW/Gouge

Tank Size: 12 gal.

Size(LxWxH): 41 x 20 x 28″

Weight: 501 lbs

Warranty: 3 year

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