Cordless miter saws have benefited from the move leading power tool brands have made to increase battery voltage. Thanks to the improved efficiency this provides, the best cordless miter saws can now compete with corded equivalents. This review is going to delve into the spectrum of fantastic cordless miter saws currently available on the market. There are quite a few of them.
In my opinion (and that of many experts), the DeWalt FlexVolt 60V is probably the best cordless miter saw. This is one of the few 120V cordless tools in the DeWalt FlexVolt range. Using two 60V batteries connected in series, the 120V DeWalt FlexVolt cordless miter saw is as efficient as a corded machine. It has the additional advantage that it can be used as a corded or cordless saw. Truly the best of both worlds.
There is only one issue with the DeWalt FlexVolt cordless miter saw. It’s really expensive. The FlexVolt 60V/20V batteries, as amazing as they are, also cost quite a bit more than other batteries. This means that you not only have to dig deep into your pocket for the saw, you’ll have to spend even more buying additional batteries.
There are now more cordless miter saws available on the market than there were a couple of years ago. This is great news for anyone wishing to buy one. A greater variety means you have the best chance of finding the right tool at the right price.
This review is going to present the latest and greatest developments in the industry. DeWalt may be the undisputed champions in this arena when it comes to super-efficiency and extra power, but they have some stiff competition from other major brands like Makita, Bosch, and Metabo. These more affordable cordless miter saws are really capable machines, making them incredibly attractive options.
Bosch GCM18V-12GDCN / 12”
Axial Glide Compound / Best Cordless Miter Saw with Advanced Electronics
- Surgeon PROFACTOR performance – for a truly mobile jobsite solution, this saw provides light weight and pro capacity
- Axial-Glide™ system – has an articulating arm, for wider cross-cuts enhanced alignment, and smooth glide while taking less space
- Large cutting capacity – features a cut capacity of 3.5 In. depth and a 13.5 In. width/crosscut
- BITURBO Brushless Technology – featuring a brushless high-performance motor and drive-train system engineered to take full advantage of the additional power generated by CORE18V PROFACTOR batteries (sold separately)
- Convenient portability – weighs only 59.3 Lbs. (tool only, not including battery)
- ECO mode – extends the battery runtime by up to 20%, for getting work done
- Connectivity (module sold separately) – link to connected device via Bosch Toolbox App to customize settings and receive detailed feedback
- Integrated base extensions – extend material support up to 43 In.
- Tall fence design – supports taller material for accurate cuts with 4-3/4 In. fences
- Accurate laser guide system – precisely aligns the cut line to the blade
- Upfront bevel control – located to make bevel adjustments easy left to right, keeping the user’s hands away from the blade
The engineers at Bosch have been busy of late, developing new battery and motor technology to keep up with likes of DeWalt, Makita, and Milwaukee. Their marketing guys have been just as busy creating catchy trademarks for all this great technology. This gives the 18V Bosch cordless miter saw a long official title, sounding more like an Italian high performance car than a cordless power tool.
Ladies and gentlemen, I present to you: The Bosch PROFACTOR Surgeon 18V BiTurbo Axial Glide compound Miter Saw. Now that’s a mouthful! The big question is what does all this mean? It’s time to dissect each of these new developments, with… er… Surgical precision?
Bosch has always been an innovative tool manufacturer. Though they started lagging behind other major brands when it came to battery-powered tools. Batteries that did not provide the best working times and outdated electric motors, meant that Bosch cordless tools weren’t as competitive as other big name brands. In a bid to catch up with the pack, they have developed new battery technology and the “BiTurbo” brushless motor.
The new PROFACTOR batteries have higher ampere-hour (AH) ratings than the previous generation Bosch lithium-ion batteries. This obviously provides longer working times. That is not all they’ve done to improve on the old batteries. The battery cells and configurations have been totally reworked, making the new batteries more compact with an increased power to weight ratio. They have also improved battery cooling, increasing battery efficiency and lifespan. Along with the new intelligent battery system, Bosch have developed a new rapid battery charger with an equally catchy name – the HELL-ION intelligent rapid battery charger.
Like Makita, and other top Battery manufacturers, Bosch batteries include an intelligent battery management system (BMS). This means that intelligent computer monitoring ensures that the battery performs optimally whilst charging and discharging. It also protects the battery from potential dangers that may result from over (or under) charging, by tracking current and voltage, as well as protection from short circuit.
Along with all these creative names for technology that is similar to what the other top brands have been doing for some time, the Bosch marketeers decided to throw in the word “Surgeon” to spice things up even more. Though, I believe this title is quite fitting. The Axial Glide system is the best thing to happen to compound sliding miter saws. In fact, this is not a sliding miter saw at all. It is genuinely a glide saw. To my mind, this technology is the true glory of this cordless miter saw. One could say it allows you to work with surgical precision.
Okay, before we move onto the full review of the Bosch GCM18V-12GDCN cordless miter saw, allow me to recap on the rather long introduction I provided.
Bosch have improved the battery, motor, and charger to make this tool more competitive when compared to the cordless tool market leaders – DeWalt, Makita, and Milwaukee. The latter three brands have been working on battery cooling, rapid charging, and brushless motors for quite a while. Bosh have now caught up and that’s a good thing.
The real magic behind this tool is the axial glide system. Instead of conventional rails, which are bulky and can become problematic over time, Bosch invented an ingenious glide system that eliminates the need for cumbersome, high-maintenance rails.
The Bosch saw slides, or rather glides, on an arm with heavy-duty hinges. It resembles the robotic arms used in automated factory assembly lines. This gives the Bosch axial glide miter saw a sublimely smooth and accurate movement. It is also incredibly durable and will remain accurate for the lifetime of the tool without the need to check and realign the arm as one would need to do with most rail systems. By substituting rails for the axial glide system, the Bosch GCM18V-12GDCN has yet another great advantage – improved capacity for cross cuts. The axial glide arm is able to extend further than the restricted limits of a conventional rail.
DeWalt may have the market cornered with their fantastic FlexVolt battery and 120V cordless tools, but no one can compete with the incredible axial glide arm developed by Bosch. When I reviewed the corded version of this model, I rated it as the best sliding compound miter saw ever built. Perhaps the same can be said for this cordless miter saw. The new batteries are great, as is the fantastic brushless BiTurbo motor. Unfortunately, though, DeWalt still have the monopoly on high-power and super efficiency. Nothing can touch the FlexVolt 120V tools for their reputation as cordless power tools. At least, this is true when for their use of battery power to provide maximum, almost fade-free power.
The Bosch axial glide system is certainly its most impressive attribute. All the other specifications provide even more compelling reasons to rank this amazing machine amongst the very best cordless miter saws.
The 12” blade, with a convenient transparent blade guard is as capable and convenient as it gets. This gives the saw a maximum cutting depth of 3½” at 0° bevel. With the blade angled at 45° to the left, you have a 2” depth capacity, and 1½” when the blade is set 45° to the right. You can adjust the bevel up to 47° left or right.
Width capacity is incredible. For straight cross cuts, it can reach a maximum of 13½”. When performing miter cuts at 45°, cutting width is still very reasonable – 9½” to the left and right. It also has built-in table extensions, able to provide 43” material support.
The general design is great, maximizing working efficiency and ease of use. The fence is solid, providing excellent support. It extends to both sides of the blade, with accurate markings for quick measurement reference. The bevel adjustment knob is situated directly behind the fence, with quick access from the front and clearly visible markings. There is no need to lean over the machine to set bevel angles. It is also one the quickest and easiest bevel adjustment systems I’ve seen – just turn it to the desired setting, and it locks automatically. The cam lock miter adjustment is just as convenient with a knob at the front and easy to use scale markings. Positive bevel stops (0°; 33.9°; 45°; 47° L/R) and miter indents (0°; 15°; 22.5°; 31.6°; 45° L/R, and 60° right only) complete the list of wonderful user functions.
A workpiece clamp slots into position either side of the blade to secure the board for a little extra peace of mind. With everything set up quickly and easily, all you need do is grab the large handle, squeeze the trigger switch, and feel the easy glide motion for effortless accuracy and a superb cut. A laser guide makes it really easy to check your cut line. The Bosch cordless miter saw is truly a pleasure to use.
In addition to all cutting edge technology, the 12” Bosch cordless miter saw has one more party trick. The Bosch Bluetooth Connectivity Module (sold separately) allows you to use an app on any Bluetooth enable device to access a bunch of advanced features.
Despite the really solid feel, this not a heavy machine, weighing a very reasonable 59.3 pounds. The saw rests on four solid metal feet with bolt holes that secure it to the work bench if needed. It has a dust port behind the blade with a dust bag included. If you want to extend your working time, which is already good, the Bosch cordless miter saw has an eco-mode. While this will limit the peak power output, it can make a big difference toward the end of the day when you want squeeze the last bit of power out of your tired battery.
Bosch have really hit the mark with their axial glide system. This is what makes the Bosch GCM18V-12GDCN such a remarkable cordless miter saw. It oozes the sophisticated precision engineering that the Germans are renowned for. The improved battery, and incredibly powerful brushless motor, make this a saw that can compete head on with any corded miter saw or the best cordless machines.
Visit the Bosch site to learn more.
Review : Bosch / GCM18V-08N14
8.5” Sliding / Best Mid-Range Cordless Miter Saw
The 8½” Bosch GCM18V-08N14 is not only smaller than the exceptional GCM18V-12GDCN reviewed above, it does not have the wow factor of the larger Bosch cordless miter saw. This can be seen as the budget option. Great German engineering and solid quality, without much of the fancy stuff.
Apart from the smaller blade size (8½” vs 12”), along with an expectedly smaller table, the most notable difference between this saw and the larger Bosch model is the absence of the axial glide arm. The Bosch GCM18V-08N14 utilizes a conventional rail that extends to the back. This means it does not have the compact footprint of the Bosch GCM18V-12GDCN. Not to mention all the other great advantages that make the more expensive Bosch saw such an extraordinary feat of modern engineering. Though, when compared to any of the best miter saws, this dual rail system is good as the rest of them.
Another thing that makes this a less accomplished saw is that it only has a single bevel, tilting the blade to the left 0° to 45°. The bevel adjustment mechanism is also not as cool as the Bosch GCM18V-12GDCN. It has a simple screw that locks with a single stop at 45°. Probably the greatest disadvantage is that you have to move to the back of the saw to set the bevel angle and the markings aren’t as comprehensive as the more expensive Bosch miter saw.
Having delivered the bad news, the rest is all good. The table is just as magnificent as that of the larger model. Although the fences, while equally good, don’t have measurement markings – a minor inconvenience. As a miter saw, it just as capable. A fantastic cam lock handle allows you to effortlessly swing the table to the left or right (0° – 47°) for miter cuts. It has convenient detents, providing positive stops at 0°, 15°, 22.5°, and 45° to the left and right.
Obviously, being an 8½” miter saw, it won’t have the same depth capacity as the 12” model and the conventional rail setup means it doesn’t have the extra width cutting advantage. Though, for a miter saw of this size, the Bosch GCM18V-08N14is perfectly up to scratch. Maximum cutting depth at 0° bevel is 2¾”. At a 45° bevel, this capacity is reduced to 1½”. The rail travel allows for a maximum cutting width of 10⁵⁄₈” – not at all bad for such a compact little miter saw. When performing 45° miter this cuts this is understandably less – 7½”.
A laser guide is included to save you time and improving accuracy. It has the same dust port as the larger Bosch miter saw and a dust bag is included.
The Bosch GCM18V-08N14 takes full advantage of the new innovations that boast such illustrious names. It has the super-efficient BiTurbo brushless motor, and the extended time provided by the upgraded PROFACTOR battery.
An advantage to using a smaller 8½” cordless miter saw would be the improved portability. The Bosch GCM18V-08N14 weighs only 31.5 LBS. Portability is enhanced by strategically placed carrying handles.
The Bosch GCM18V-08N14 may seem pretty average when you compare it the extraordinary GCM18V-12GDCN. A more realistic comparison, pitted against any other 8½” sliding compounds miter saw, this machine has it all. Good power, provided by a brushless motor, with all the bells and whistles to make your life easier. It’s lightweight compact design make it wonderfully portable, perfect contractors who don’t need the larger capacity. For jobsite work, cutting moldings and the like, this is a tough little beast with all the precision that you could possibly want.
Review : Metabo HPT 36V MultiVolt / C3610DRAQA
10” Sliding Compound / Best Cordless Miter Saw for the Money
Metabo have taken a leaf from the DeWalt playbook with their new MiltiVolt, backwards compatible battery. Like the DeWalt FlexVolt 20V/60V battery platform. You can use the MultiVolt battery to power their more advanced 36V cordless tools and the previous generation 18V tools. However, the voltage difference between the DeWalt 120V cordless miter saw and the Metabo 36V model is something that can be debated. If you’re unsure what this voltage difference means in reality, I’ll be discussing the importance of battery voltage for cordless power tools after the product reviews.
Metabo HPT (a merger between Hitachi and Metabo) is a downright good value brand. These are robust, well-engineered machines that typically cost less than most equivalents from rival high-end brands. This, I believe, is the real attraction offered by the Metabo HPT C3610DRAQA cordless miter saw. It has the build quality and advanced technology to compete with any of the top saws, without a prohibitively high price tag. If you’ve been shopping around for the best 10” cordless miter saw, I’m sure this one will catch your interest.
The dual rail system that extrudes to the front, instead of the rear of the saw, has it’s advantages if you have limited depth on your workbench. You don’t need to allow for that extra space behind the saw. Another interesting thing about these rails is the offset angle. Instead of perpendicular rails, these are at an angle. I’m not entirely sure of the actual physical dynamics involved, but I think this gives the rails improved stability and longevity. The Makita miter saws use the same principle and I’m sure there must be a good reason for this. Regardless of the science, I’m pretty impressed with this setup. It’s durable and the saw has a very accurate cut along the width.
The 10” blade, with ⁵⁄₈” arbor, provides a 3½” depth of cut at a 90° bevel, regardless of miter angle. As you tilt the blade, your depth capacity will obviously decrease. Using the saw for a 45° left bevel angle, cutting depth is 1¾” and 1” for a 45° right bevel. The saw has a very practical bevel adjustment knob, accessible from the front, with excellent markings. Setting the bevel angle is quick and superbly accurate. Using the spring action knob it’s a simple matter of of pull and tilt, no screw handles to tighten. You have the convenience of a bevel adjustment that goes beyond the expected 45° range. (48° left and right).
The beautifully machined table is just as impressive. It has a very easy to use flip lever cam lock system for adjusting miter angles. It also has the full range of miter capacity – 55° to the left and 60° to the right. Ease of use is accented by front access and great scale markings. Common angles are a synch, thanks to positive detents at 0°, 15°, 22.5°, 31.6°, and 45°. Another aid to improving working efficiency is the adjustable laser guide for the cutline.
The tall fence is great for crown moldings and is wonderfully sturdy. It doesn’t have inch markings on the fence, but this is not something that bothers me. The extensive use of aluminum, means that the solid fence and table don’t add much weight. The Metabo C3610DRAQA weighs only 45.5 pounds and has a great carrying handle that allows you transport the machine easily.
An AC adapter is sold separately, allowing you to connect the Metabo Miter saw to a regular 120V outlet. When you have access to a generator or grid power, you don’t have to rely on batteries. While this means using a transformer, the power loss is negligible, and the brushless motor is as efficient as any of the best cordless power tools.
The Metabo C3610DRAQA is a highly accomplished cordless miter saw at a pretty reasonable price. This alone, should have many convinced that it’s a great deal. When we add the 5-year warranty into the picture, it becomes even more irresistible. There is no sacrifice between affordability and quality. This saw has all the features and advanced technology that you’ll find on any of the best models from top brands.
Makita XSL07Z 18V X 2 / 12″
Sliding Compound / Best Cordless Miter Saw for Durability & Robustness
In order to meet the increased power demand for a cordless miter saw, Makita has taken a very practical approach. Instead of developing a new battery system, they have simply doubled the voltage using 2 X 18V LXT batteries connected in series. This means a highly efficient 36V saw without the need to buy new batteries. Since the 18V LXT battery platform has proven to be one of the best, there really is no need to make expensive changes.
The brushless motor further helps to improve power and efficiency. Taking this to the next level, Makita engineers have developed an ingenious Automatic Speed Change system. This adjusts the power output to keep the blade running at 4,400 RPM. It conserves power when it is not needed and provides a boost when the motor begins to labor. This not only provides a consistently smooth cut, but also extends battery time. A really wonderful invention.
Power from the motor to the 12” blade is delivered using a direct drive gearbox. No hassles with belts or the chance of a belt slipping. There is also no power loss, further increasing efficiency, resulting in even better working time from the batteries. This also includes a soft start and an electric brake, which is great.
The dual rails are incredibly strong. This makes for a very reliable and accurate saw. The rails are designed for a minimal footprint, you don’t need to allow for additional space behind the saw. As always, I’m amazed at the super durable build that Makita delivers without fail.
The extra tall fences are superbly crafted with convenient measurement markings. It has a very practical, metal workpiece clamp – about the best I’ve seen. The table is simply magnificent, and it has retractable extensions on both sides, allowing for extra material support. Again, I’m awestruck by the durable metal construction, with every detail precision engineered.
Bevel and miter adjustments are easily done from the front. Quality metal plates have scale markings with all the positive stops and detents one could possibly want. The blade has a bevel capacity of 48° (left and right), with a miter capacity of 60° to the left and right. It includes a laser guide for hassle-free accuracy.
Capacity is as good as it gets. The large 12” blade has a maximum 3⁵⁄₈” depth of cut. Width capacity is 15” for a 90° miter cut and 10½” for a 45° miter. Using dual dust collection ports (with a bag included), the Makita XSL07Z is one of the best cordless miter saws for a clean, dust-free working environment. The large, soft grip handle is another winning attribute.
I don’t believe you’ll find another cordless miter saw with as much solid metal throughout its construction. This is one of the toughest tools around. Of course, the extensive use of ultra-durable materials is not the best when looking at portability. This is one of the heaviest cordless miter saws, weighing just over 69-pounds including the batteries.
The Makita XSL07Z has to take first place for exquisitely crafted durability. I’m truly enthused, in this day and age of cheap plastic products, to see a machine this brilliant. Every detail is as close to perfection as is humanly possible. Truly awe inspiring. Makita has a reputations for manufacturing indestructible tools and this cordless miter saw tops the charts in that regard.
Makita Portable Stand: WST01N
There are a lot of portable jobsite stands available for miter saws. I don’t think that any of them can quite match the Makita WST01N. This is not the only option available for Makita miter saws. They manufacture cheaper stands, but this one really stands out as being one of the very best.
This is a heavy stand, weighing 79-pounds. While it is not something I would like to carry too often, this extra weight provides a lot of stability. Something that is very important when you consider that extensions make it possible to accommodate boards that are 9-feet long with an incredible weight capacity of up to 220 LBS. When you’re dealing with this type of material, the extra stability offered by a heavy stand is imperative. You don’t want those large heavy boards to tip the stand over.
Clever design has made it really easy to move this large heavy stand. It is, despite the extra weight, a portable miter saw stand. Using two heavy-duty springs, collapsing and erecting the stand takes virtually no effort. It folds into a reasonably compact format, measuring 50½” X 21½” X 15¾”. This allows you to move the stand about quite effortlessly, using a large loop handle with generous rubber padding. Solid rubber 12” wheels make light work of rough terrain. It can be stored in an upright position, reducing the overall footprint when no in use.
Using the Makita WST01N has several advantages on a jobsite or in a home shop. Long pieces rest sturdily on the extensions, which have enough vertical support to provide a perfectly stable platform. Infeed rollers on the extensions mean that the boards slide effortlessly. A strong, perfectly flat table, with bolt holes in all the right places, means that you can secure the miter saw for maximum safety and ease of use.
Just by looking at the huge, sturdy Makita WST01N miter saw stand one can tell that this is not a cheap accessory. For this type of quality and versatility, I would expect to pay extra. For a professional contractor, the benefit of increased productivity will definitely be worth the investment.
Review : Makita XSL06PT 18V X 2 / 10″
Sliding Compound / Best VALUE Cordless Miter Saw from Makita
The 10” Makita XSL06PT can be viewed as a better value deal if you don’t need the increased depth capacity of a 12” blade. This 10” cordless miter saw is a little more compact and lighter than the 12” Makita XSL07Z. It also includes two 18V LXT (5AH) batteries and a dual port rapid charger.
Apart from the smaller blade diameter, there is another noticeable difference between the 10” and 12” Makita miter saws. The more affordable Makita XSL06PT does not have the same exquisite table extensions as the top of the range 12” model. This smaller saw has much more conventional, lightweight extensions that don’t provide the same type of additional material support. The net effect of these changes results in a reduced weight of only 60 LBS.
Essentially, the Makita XSL06PT is a smaller, lighter cordless miter saw, with a less accomplished table extension setup. In all other aspects, the cheaper Makita miter saw has all of the exceptional technology as the larger model.
This means it has a super-efficient brushless motor with a direct drive, soft-start, and electric brake. The smaller blade has an obvious reduction in cutting depth capacity – 3⁵⁄₈” at a 90° bevel. It has the same great dual rails system, requiring no additional space behind the saw. Though, the rails are slightly shorter than those on the larger model. As a result, the Makita XSL06PT has a reduced cross cutting ability cutting of 12” at 90°, and 8½” for a 45° miter cut.
Bevel and miter adjustments are the same as the Makita XLS07Z, giving you the ability to perform bevel cuts at 48° to the left and right, as well as miter cuts up to 60° (left and right). The cam lock miter adjustment is the same, as is the easy to use bevel adjustment knob. Both are easily accessible from the front.
The tall fence is also the of the same high standard, including equally great measurement markings. It has positive miter stops at 0°, 15°, 22.5°, 31.6°, 45°, and 60° to the left and right. The Makita XSL06PT has the same great dual port dust extraction system and a laser guide.
The Makita XSL06PT is, at its heart, a sophisticated high-quality cordless miter saw, true to everything we expect from this top power tool brand. It is cheaper and lighter than the range topping Makita XSL07Z. Though this does not mean much compromise. I was mighty impressed with the extraordinary table extensions fitted to the more expensive Makita saw, whereas the cheaper model has more conventional extensions. For the rest, the only real difference is the smaller blade diameter and slightly reduced rail capacity. It’s an amazing cordless miter saw, none the less.
Understanding Batteries – Does More Volts Mean More Power
Throughout the best cordless miter saw review, the difference in the voltage requirements for the various models probably raised some questions. Is it beneficial to use a higher voltage for cordless tools? Does this actually make the saw more powerful?
To understand the importance of battery voltage, we have to get down to the basics, starting with electrical engineering 101. We will begin with the formula that all engineers use to determine power vs current: Power = Volts X Amps (P = VA). You may remember this from school science classes and probably thought you’d never actually need it in real life. Well, now is the time to make sense of this forgotten knowledge.
As we unpack the information derived from applying the P=VA equation to cordless tools and batteries, we need to keep another important fact in mind. When dealing with electrical efficiency, heat is the enemy. This will help us understand how volts and amps affect the power delivered by a cordless power tool.
The first step would be to compare the various batteries mentioned in the cordless miter saw review, using the power vs volts vs amps equation. Of the tools featured in this review, three different voltages are used for the different models:
- The Makita and Metabo HPT miter saws operate at 36V.
- The Bosch saw uses an 18V battery.
- DeWalt uses 2 X 60V batteries to provide 120V.
How does this affect the power to current ratio? For the purpose of this example, we need to assume that we will be using these three battery systems to power a 500W. By using the same watts for each voltage we can make a definitive comparison.
Using a 36V battery, or 2 X 18V batteries connected in series:
- Power = 500W; Volts = 36; Amps = 13.89
Using an 18V battery:
- Power = 500W; Volts = 18; Amps = 27.78
Using 2 X 60V batteries in series (120V):
- Power = 500W; Volts = 120; Amps = 4.17
One thing should be clear, any amount of power can be achieved, regardless of the voltage. As we increase the volts, the amperage is reduced.
Now for the next big question: how important is amps? This is the proverbial million dollar question. Comparing amperage is the most important part of comprehending electrical conductivity and, therefore, electrical efficiency.
Amperage, or conductive impedance, allows us to understand how the electrons move through a conductor. Any conductor will present resistance when a current passes through it. Resistance causes heat. This is the principle used for resistance heaters. However, since heat reduces electrical efficiency, it is not ideal when you want to get the most power from a battery.
As the amperage increases, more heat is generated. If the conductor is not capable of handling the heat it will melt. Hence, a 30A extension cord is twice as thick as a 15A extension cord. More importantly, heat causes electrons to become unstable. This reduces electrical efficiency. In other words, the power provided by a heated electron is less than it would be if the electron were at its normal temperature.
Now we’re able to make a qualitative comparison between the battery voltages for the different voltages used for the miter saws featured in the review:
- 120V (4.17A): lowest amps, less heat, most efficient.
- 36V (13.9A): increased amps, more heat, less efficient.
- 18V (27.78A): highest amps, most heat, least efficient.
We also need to consider battery efficiency. Just as heat affects the power that is produced by the motor, it reduces the efficiency of a battery. As battery temperature rises, voltage is decreased. This produces more heat because a lower voltage means higher amps.
Using this information, we can see that voltage is significant when determining how efficient a cordless tool is. It is possible to provide additional cooling to prevent increased amperage from impacting on electrical efficiency. The Bosch PROFACTOR battery is an example of this. In order to effectively power the Bosch GCM18V-12GDCN cordless miter saw using only 18V, the battery was redesigned to improve cooling. This helps, to some degree, mitigate the unwanted effect of the high amps that result from using a lower voltage. By managing the power supply electronically, efficiency can also be improved.
Even with the best cooling and electronic power management systems, one fact will never change. Lower voltage increases amps which increases heat. The simplest and most effective means of providing the best efficiency for a cordless miter saw is to increase the battery voltage. Essentially the best cordless miter saw has to be the one with the highest voltage as this will be the most efficient, thereby providing the best battery times.
There is a practical consideration that complicates the decision. If it were simply a matter of providing the most efficient battery voltage, then the dual FlexVolt battery setup used by DeWalt makes the best sense. However, in the real world, we need to be practical about the cost involved.
In order to take advantage of the increased efficiency of a high-volt battery, we need to buy new batteries. Most of us have been using cordless tools for many years and have acquired a good selection of tools that we depend upon. It is only logical that we buy tools that use the same battery. People who started out with the DeWalt 20V MAX cordless tool range tend to stick with this battery platform. You’re using the same batteries and charger for all your tools. Even though the DeWalt FlexVolt (and Metabo MultiVolt) batteries are backwards compatible, you still have to buy new batteries and chargers for the new tools that use an increased voltage. You can use the new batteries in the older (low-volt) tools, but you can’t use the older batteries in the new tools.
From a practical perspective, the cost of buying new batteries for high-volt cordless tools may not be worth it for some. Since a low-volt cordless tool can basically do the same job as a high-volt tool, albeit less efficiently, is it really worth paying so much extra for new generation (more expensive) batteries and chargers?
Ideally, the high-volt cordless tools are the best. It really comes down to practical economics. If you have been using cordless tools for many years and have invested a lot of money in a particular range of tools using the same battery, it may not make the best sense to upgrade to the new battery platform. Perhaps, it’s something you may want to consider in the future, but not right now. If you’re only beginning to invest in your cordless tool repertoire, it might make sense to start out with the highest battery voltage from the outset. This is the best way to get the most from your cordless tools and it is certainly the future of battery technology.
The only downside to using a low-volt battery is that they will discharge faster, and you will experience a more rapid loss of power as the battery discharges. You can compensate for the efficiency loss by having more batteries and using a multi-port charger. If you have enough fully charged batteries on standby, you can simply swap out the discharged battery for a fully charged one as soon as you notice a power loss from the tool you’re using.