Grinding Performance:
Performance is hard to measure on a grinder because there are so many variables from user applied pressure, disc grit count, quality and thickness, ETC. with that said I’ll try to give you a good idea of what this thing can do.
Like I said above, grinding performance is nearly impossible to measure without a lab, which is slightly outside my budget at the moment. What I can say with absolute certainty is this grinder is noticeably more powerful than the previous brushless model. With 2,100 RPM more than the previous model, it’s impressive that the power is so much better while still maintaining a higher speed.
One thing to note is the box that my grinder came in, as well as the press release, said this grinder has a no load speed of 10,000 RPM. But upon looking through the manual and looking at the specification sticker on the tool itself, it would seem this grinder actually produces 10,600 RPM, which puts this grinder at or near the top for cordless 4.5” grinder speed here in North America with the Ryobi 18v brushless grinder right behind it at 10,400 RPM. Whether this inconsistency is because my grinder was ahead of release, or simply an error at Ridgid, I’m going with the rated speed on the tool and in the manual.
Anyway, back to actual performance. This grinder easily removes heavy rust from steel and has good power to grind down welds quickly. You’ll still find more power from some larger 4.5” corded grinders but this unit is right there or even more powerful than smaller 4.5” corded grinders.
For testing I used an old wagon axle that I pulled out of a creek bank and hauled back to the shop. It’s 2” solid square steel and beyond bringing back so it makes an excellent testing piece. Upon testing I found this grinder to be able to quickly remove years of heavy rust that was quite deeply pitted and hard to get back to flat, bare metal. This wagon axle also served well as a thick piece of steel to do runtime testing on, which will be the next section of this review.
One thing I would recommend when doing heavy grinding, don’t let the red flashing light fool you. This grinder will keep running with the red light flashing, which is supposed to indicate overload.
Let me explain my opinion on this feature. I’d call it more of a heavy load indicator rather than an overload indicator. I say that because the grinder doesn’t stall out right away but will keep running with the red light flashing. If you apply enough pressure to make the light flash and maintain that pressure, it will continue to run just fine. If you apply more pressure once the light is flashing, then it will stall out and the red light will flash for a couple seconds or until the slide switch is cycled off. This light originally made me think it wasn’t as powerful as it is, but once you get a feel for the tool you start to “somewhat ignore” the light and only watch it when the tool significantly slows down or stalls. With that, hopefully, you have an idea of why I call it a “heavy load indicator” rather than an “overload indicator”.
During all the grinding I’ve done so far, the motor has barely gotten warm, and the gearbox has only been warm to the touch, which is an improvement over the previous brushless model on which the gearbox gets hot during extended use. To be fair most of my testing has been done in my shop, which is currently about as cold as Mount Everest is, so heat is obviously going to be reduced. Still the motor only got slightly warm, so I’m quite confident that even in the summer this grinder won’t have an issue with overheating.
Grinding Runtime:
First off, let’s get something straight. The runtime testing I did is just short of torture testing on both the tool and the batteries. Most people will not be doing continuous grinding like I did and if they are they’ll probably still use a corded grinder for the unlimited runtime. The reason I did this testing was to find out where the batteries or the tool would “call it quits”. I can say from personal experience that you will see much better runtime if you aren’t doing continuous grinding and if the batteries have time to cool down for a few minutes between uses and are allowed time to recover some. With that said I’ll give you a rough idea of what you can get done with several sizes of batteries.
For this test I went back and forth on the wagon axle I mentioned earlier and did my best to apply consistent pressure through all the tests. I tested Ridgid’s Hyper Lithium Ion batteries as well as their Hyper Octane batteries, some at different temperatures to see how they would perform.
Grinding Runtime with Hyper Lithium Ion Batteries:
This grinder will run on any 18v battery Ridgid has ever made, but it will not be as powerful when used with non-Hyper Octane batteries. The Hyper Lithium Ion batteries still work well and will get the job done if they’re all you have on hand.
1.5AH Hyper Lithium Ion Battery tested at roughly 70° F:
Ran 1 minute 45 seconds to overheat, after cooling a few minutes ran another 25 seconds at which point it needed to be charged.
Total runtime: 2 minutes 10 seconds
This battery is the smallest of the bunch in size and capacity, which makes it more vulnerable to overheating. I will also note that even when fully charged this battery performed poorly when more than a little pressure was applied, which is typical of compact batteries.
4.0AH Hyper Lithium Ion Battery tested at roughly 70° F:
Ran 4 minutes to overheat, after cooling a few minutes ran another 1 minute and 44 seconds at which point it was ready to be charged.
Total runtime: 5 minutes 44 seconds
With another row of cells providing power, the 4.0AH battery had a noticeable amount more power. Even though it did have 1 overheat, it ran for almost 2 more minutes before needing to be charged.
5.0AH Hyper Lithium Ion Battery tested at roughly 70° F:
Ran 4 minutes 26 seconds to overheat, after cooling a few minutes ran another 3 minutes at which point it was ready to be charged.
Total runtime: 7 minutes 26 seconds
Not only is the 5AH the highest capacity non Hyper Octane battery Ridgid offers, it also did very well in power (being the closest to the power of a Hyper Octane battery). Although it hit overheat only a few seconds after the 4.0AH, it achieved a good bit more runtime after cooling off.
If you only have Hyper Lithium Ion batteries on hand, they will still get the job done, but with less power and runtime.
Grinding Runtime with Hyper Octane Batteries:
Ridgid claims more power under heavy loads when you use their Octane tools with Hyper Octane batteries. Not only are the Hyper Octane batteries the highest capacity that Ridgid offers for the size, they also have the benefit of communicating with the Octane tools (which Ridgid says will allow the tool and battery to endure heavier loads without stalling).
3.0AH Hyper Octane Battery tested at roughly 0°, 50°, and 70° F:
At 0° F: 3 minutes 15 seconds to overheat, after cooling a few minutes ran another 1 minute before needing to be charged.
Total runtime at 0° F: 4 minutes 15 seconds
At 50° F: 3 minutes to overheat, after cooling a few minutes ran another 1 minute before needing to be charged.
Total runtime at 50° F: 4 minutes
At 70° F: 2 minutes 54 seconds to overheat, after cooling a few minutes ran another 1 minute 7 seconds to second overheat. After cooling a few more minutes ran another 16 seconds before needing to be charged.
Total runtime at 70° F: 4 minutes 19 seconds
What’s really impressive with the 3.0AH Hyper Octane battery is that it was able to surpass the Hyper Lithium Ion batteries in both power and thermal management. That surprised me since compact batteries, as shown with the 1.5AH, typically have a good bit less performance and heat up quicker. Not only did the the 3.0AH handle the heat very well for its size, it also maintained much more power than than the 1.5AH battery through the test, which is impressive to say the least.
6.0AH Hyper Octane Battery tested at roughly 0°, 50°, and 70° F:
At 0° F: 6 minutes to overheat, after cooling a few minutes ran another 2 minutes 10 seconds before needing to be charged.
Total runtime at 0° F: 8 minutes 10 seconds
At 50° F: 4 minutes 55 seconds to overheat, after cooling a few minutes ran another 4 minutes 50 seconds before needing to be charged.
Total runtime at 50° F: 9 minutes 45 seconds
At 70° F: 4 minutes 58 seconds, after cooling a few minutes ran another 2 minutes 50 seconds before needing to be charged.
Total runtime at 70° F: 7 minutes 48 seconds
The 6AH Hyper Octane battery is a good choice for good runtime while still keeping the weight on the lower side. As the medium size battery in the Hyper Octane line up it performed well in both thermal management and runtime and provided excellent power throughout the testing at various temperatures.
9.0AH Hyper Octane Battery tested at roughly 0°, 50° and 70° F:
At 0° F: 13 minutes to stop, did not overheat, but after resting a few minutes ran another 30 seconds before needing to be charged.
Total runtime at 0° F: 13 minutes 30 seconds
At 50° F: 14 minutes 30 seconds before needing to be charged.
Total runtime at 50° F: 14 minutes 30 seconds
At 70° F: 10 minutes 34 seconds to overheat, after cooling a few minutes ran another 2 minutes 26 seconds before needing to be charged.
Total runtime at 70° F: 13 minutes
The 9.0AH Hyper Octane battery was by far the best performer in power, heat management, and runtime. With a third row of cells providing power it took far longer to overheat than any of the other batteries tested, and even managed to not overheat at all in the 0° and 50° F test, running nonstop for 14.5 minutes on it’s best test. It also provided more consistent power throughout the testing at various temperatures, which makes it an excellent choice for cold and hot weather work. The only downside to this battery is the weight, which can be factor when doing continuous work. However, the added runtime is worth the extra weight and power.
Ridgid did provide some of their runtime testing numbers and they did get quite a bit more work done. However, due to the difference in the numbers below, you’ll can see that my testing was applying more load. While my testing was a heavier load, Ridgid’s testing was more scientific so I’ll give you all the details:
“All 3 of Ridgid’s tests were done with a type 27 grinding wheel, with a 7 lb. load and at a 15 degree angle.
- On a 3AH Hyper Octane battery you can expect between 6 and 7 minutes of continuous grinding.
- On a 6AH Hyper Octane battery you can expect between 10.75 and 14 minutes of continuous grinding.
- On a 9AH Hyper Octane battery you can expect between 19.5 and 22 minutes of continuous grinding”.
Ridgid did not provide any runtime numbers for cutting.
The Hyper Octaner batteries provide this grinder with a noticeable boost in power under heavy loads, and they also give excellent runtime thanks to their higher capacity. I can definitely say the claims of more power when Octane tools are used with Hyper Octane batteries is true for this grinder.
Flap disc performance:
Just like grinding performance, flap disc performance will vary somewhat by disc quality, user applied pressure, and the material grade. What I can tell you for sure it this grinder has good power when using flap discs.
You can bog it down easier than with a grinding wheel when using a very coarse grit disc but a coarse flap disc will remove more material faster than with a traditional grinding wheel (which will put more load on the motor). If you let the tool do the work it will still remove material very quickly without issue. Flap disc runtime should be close to the same as grinding runtime.
Concrete cutting performance:
This grinder, when equipped with an abrasive concrete cutting disc, cuts through cinder blocks like butter. The high rpm and better torque really make it a breeze to use for cutting thin concrete.
The dust screens at the back also help keep the larger concrete particulates out of the motor, which should help it last longer. I didn’t have enough concrete discs or cinder blocks to do runtime testing but the grinder didn’t bog down much at all so you should get quite a bit of concrete cutting done per battery.
Wire wheel performance:
For this test I used an almost new twisted wire cup wheel. This grinder has plenty of power for removing rust without damaging the surface metal and is excellent for cleaning slag off of stick and flux core welds. I did a quick test for pictures on a piece of rusty ⅛” thick steel plate and it had no lack of power.
Metal cutting performance:
For cutting thinner metal you won’t see a huge difference in power from the previous model, but step it up to anything thicker than ¼” steel and you’ll notice how much faster the Octane model is thanks to more torque and higher RPM. The Octane model has no problem making a full depth cut into solid steel, and compared to the previous model it cuts through 2” of solid steel to its full cut depth much faster and with less vibration than the previous model. It also has no problem cutting various thicknesses of flat stock, angle iron, round stock, small pipe, sheet metal and rebar. Overall this grinder is an excellent performer in the cutting category.
Metal cutting runtime with Hyper Lithium Ion batteries:
Just like with grinding runtime, cutting runtime will vary due to factors such as disc quality and grit count, material thickness and grade, and user applied pressure. With that said I did my best to make consistent cuts through ½” rebar with a variety of batteries. For each battery I started with a new 4.5” aluminum oxide cutting disc. Also worth noting is that just like with the grinding runtime testing, you’ll get better runtimes if you’re not doing continuous cutting and allow the battery to cool down and recover a bit.
1.5AH Hyper Lithium Ion battery tested at roughly 70° F:
Made 12 ½ cuts in ½” rebar before overheating, after which made only another ½ cut before needing to be recharged.
Just like in the grinding runtime testing, the 1.5AH Hyper Lithium Ion Battery performed a good bit below the other batteries tested in both power and runtime, as well as heat management. Making only 13 cuts total makes this battery a poor performer in runtime which means it’s really only good if you need just a few cuts.
4.0AH Hyper Lithium Ion battery tested at roughly 70° F:
Made 46 cuts in ½” rebar before needing to be recharged.
The 4.0AH Hyper Lithium Ion battery performed much better than the 1.5AH in power, heat management, and runtime, which makes it a good choice for punch list jobs where you don’t need a ton of runtime or power. If you have some 4.0AH batteries around they work pretty well, just not as well as the 5.0AH or Hyper Octane batteries.
5.0AH Hyper Lithium Ion battery tested at roughly 70° F:
Made 54 ⅔ cuts before needing to be recharged.
The 5.0AH Hyper Lithium Ion battery is the best performer that Ridgid offers that isn’t part of the Hyper Octane family of batteries. It has more power than the 4.0AH battery and also has better runtime thanks to the higher capacity cells. Just like with the 4.0AH, this battery runs the Octane grinder well, but with less power than the Hyper Octane batteries.
Metal cutting runtime with Hyper Octane batteries:
3.0AH Hyper Octane battery tested at roughly 70° F:
Made 37 cuts before needing to be recharged.
Just like with the grinding test the 3.0AH battery performed very close to the same level as the larger battery tested in power, heat management, and runtime. With a very respectable 37 cuts it got close to the runtime of the 4.0AH Hyper Lithium Ion battery.
6.0AH Hyper Octane battery tested at roughly 70° F:
Made 79 ¾ cuts before needing to be recharged.
If you’re doing a lot of smaller cutting tasks, such as rebar or smaller steel (less than ¾”), the 6.0AH is an excellent middle ground in runtime while keeping the power up and the weight down. With a very impressive 79 ¾ cuts this battery is a great choice for cutting purposes.
9.0AH Hyper Octane battery tested at roughly 70° F:
Made 117 ⅔ cuts before needing to be recharged.
If you’re doing a lot of heavy cutting or a ton of smaller cuts the 9.0AH battery is definitely going to get the job done. The only downside is that it’s pretty big and heavy compared to the other batteries tested, but it more than makes up for it in runtime and power. Just like the grinding test this battery maintained the most power throughout the test making it the best option, in my opinion, for heavier and longer cutting tasks.
Room for improvement:
I wouldn’t change much on this grinder, but if I could add a couple features I’d include a variable speed dial for lighter work, and make it so the gearbox can be unscrewed and rotated on the motor for a better grip for people doing lots of cutting. In addition, a vibration-absorbing side handle would be nice and I’d gladly pay another $10 or so if one was included. The only other thing I would do is make the overload indicator less sensitive and make it come on closer to the grinder’s actual stalling point.
Final thoughts:
Overall the new Octane grinder is an excellent option for anyone in the Ridgid battery platform who does lots of work with metal, or even tile and concrete. The value is excellent at $129 for the bare tool and it’s probably got the best power per dollar on the market. There are no kits available yet but I hear there’s something big coming to the Octane line in May of this year (2019), so hopefully we’ll see an even better value with some batteries included. It’s a noticeable upgrade from the previous version in power and ergonomics. Outside of the overload indicator being too sensitive for my taste, there’s not much I don’t like about this grinder. If you’re in the market for a great grinder, I highly recommend the Ridgid Octane 4.5” grinder to anyone who is already in the Ridgid battery platform or who is looking for a new battery platform that features an excellent 4.5” grinder.
Please leave a comment and let me know what you think of this grinder and its performance!
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