Milwaukee High Output Battery vs. DeWalt FlexVolt Battery

Without a doubt, when comparing Milwaukee and DeWalt, we have to turn to the batteries that each brand uses to run its core power tools. For the reds and yellows, it comes down to the Milwaukee M18 RedLithium High Output Battery and the DeWalt FlexVolt. It reignited the debate over the need for higher voltage and greater amp-hour capacity to extend run time and power on the job site. When it comes to Milwaukee High Output vs DeWalt FlexVolt batteries, we have two ways to compare them. The first ranks the available batteries to compare capacities. The second involves testing them head-to-head.

DeWalt FlexVolt vs. Milwaukee High Output Battery Capacity Comparison

Remember, with DeWalt Flexvolt, you have two ratings. When using DeWalt FlexVolt batteries with 20V tools, you get a higher Ah rating. When used with 60V FlexVolt tools, the lower rating will take over. The packs haven't changed in terms of capacity — just what we've called them when testing similar products:

• FlexVolt 60V/2Ah = 20V/6Ah
• FlexVolt 60V/3Ah = 20V/9Ah
• DeWalt FlexVolt 60V/4Ah = 20V/12Ah
• DeWalt FlexVolt 60V/5Ah = 20V/15Ah

Here's how to match the Milwaukee High Output and DeWalt FlexVolt battery packs. Remember we are only comparing 60V FlexVolt specific packages from DeWalt:

Milwaukee M18	DEWALT FlexVolt (60V)
CP3.0 high output	no comparable packaging
XC6.0 high output	FlexVolt 6Ah
XC8.0 high output	FlexVolt 9Ah
HD12.0 high output	DeWalt FlexVolt 12Ah
no comparable packaging	DeWalt FlexVolt 15Ah

Milwaukee high output with DeWalt FlexVolt battery capacity

For visual comparison, we used a Milwaukee M18 RedLithium High Output HD12.0 battery pack and a DeWalt FlexVolt 4.0Ah (20V/12Ah) battery. While DeWalt also has a 5Ah (20V/15Ah) FlexVolt battery, its size makes it unsuitable for many handheld power tools.

According to the picture above, the Milwaukee high output 12Ah M18 RedLithium battery has extended capacity while maintaining its original 18V platform. A simple multiplication problem of nominal volts times amp-hours yields a total capacity of 216 watt-hours, packed into 15 lithium-ion cells. You can find the total watt-hours on the bottom of almost any battery pack.

DeWalt FlexVolt batteries are capable of switching between 20V Max and 60V Max voltages. These are the maximum voltages at the highest state of charge, which translates to 18V and 54V nominal voltages. At 20V, if the FlexVolt battery has 12.0 amp hours, it has 4.0 amp hours at 60V.

The DeWalt and Metabo HPT MultiVolt have the only batteries on the market with switching voltage capability from a major tool manufacturer. This makes the DeWalt FlexVolt and Metabo HPT MultiVolt batteries truly unique.

Milwaukee High Output vs DeWalt FlexVolt – Who Makes the Biggest Battery?

Ok, so when considering Milwaukee High Output vs DeWalt FlexVolt, who makes the biggest battery? The Milwaukee tops out at 12Ah, while the Dewalt has a 15Ah FlexVolt battery pack. Multiply the nominal voltage by the amp-hour capacity, and you'll find that the DeWalt 15Ah monster battery has 270 nominal watt-hours. It gets its power and capacity from 30 individual 18650 lithium-ion cells. This offers more capacity than the 216Wh found on Milwaukee's current flagship 12Ah battery pack.

So when we look at battery capacity in terms of watt-hours (total available power), we see that the DeWalt FlexVolt currently has a clear advantage over the Milwaukee High Output. But when it comes to batteries you're likely to stick to hand tools like impact drivers, drills, or angle grinders, Milwaukee and DeWalt are neck and neck.

Milwaukee High Output with DeWalt FlexVolt Volts and Amp Hours

There is a complex debate between voltage and amp hours, involving a lot of lectures from physics and chemistry geeks. We're not going to go into all of them right now, but the bottom line is that you have to have both in order to generate electricity. Increasing the voltage or current will increase the available power. Let's look at this simple equation:

Power = Current x Voltage

To get the same power, you can increase the current…or increase the voltage. Take your pick. As such, higher voltage does not necessarily equate to a higher powered tool. This is especially true given the constraints on the total battery pack capacity measured in watt-hours (Wh). The Milwaukee HD is a good match for DeWalt FlexVolt batteries.

Battery	Model	Voltage	Ampere hours	Watt hours
Milwaukee CP3.0	48-11-1835	18V	3.0 ah	54Wh
Milwaukee XC6.0	48-11-1865	18V	6.0Ah	108Wh
DeWalt FlexVolt 6.0Ah	DCB606	20V/60V	6.0Ah/2.0Ah	108Wh
Milwaukee XC8.0	48-11-1880	18V	8.0Ah	144Wh
Milwaukee HD9.0	48-11-1890	18V	9.0 ah	162Wh
DeWalt FlexVolt 9.0Ah	DCB609	20V/60V	9.0/3.0 ah	162Wh
Milwaukee HD12.0	48-11-1812	18V	12.0 ah	216Wh
DeWalt FlexVolt 12.0Ah	DCB612	20V/60V	12.0/4.0 ah	216Wh
DeWalt FlexVolt 15.0Ah	DCB615	20V/60V	15.0/5.0Ah	270Wh

insert numbers

In theory, if you give two tools the same task, they should both require the same amount of work regardless of the volts/amp configuration. So let's plug in some real numbers for these batteries:

Milwaukee HD12.0 battery pack power = 12.0 Ah x 18V = 216 Wh

DeWalt FlexVolt 12.0 Ah Power = 4.0 Ah x 54V (nominal) = 216 Wh

Or use batteries in series mode at 20V Max…

DeWalt FlexVolt 12.0 Ah Power = 12.0 Ah x 18V (nominal) = 216 Wh

The reality is that you can only go so far before putting cells at risk, usually due to heat. So is one battery better than the other in this case?

That's exactly what we want to know. To compare the Milwaukee High Output and DeWalt FlexVolt batteries in a real world scenario, we grabbed a few packs and started testing!

Milwaukee High Output vs DeWalt FlexVolt – Test Pack

We used a DeWalt FlexVolt angle grinder and a Milwaukee M18 Fuel angle grinder with the same Diablo 5" cut-off wheel installed. We wanted to see how many cuts we could make through the rebar on a full charge.

There are several ways to approach this test, but we want to mimic what users in the field are most likely to experience. We chose to find the sweet spot between cutting speed and battery efficiency. This means cutting the rebar as quickly as possible without stalling the tool in the process.

We change the grinders after each cut and make sure each grinder has at least a 30 second rest period before cutting again.

Milwaukee High Output vs DeWalt FlexVolt battery results

The DeWalt FlexVolt Grinder is clearly more powerful than the Milwaukee. It was fast in testing. We found that we could effectively cut by about 2 seconds on average. However, as the cut-off wheel wears, the situation is different. The average cut time for the DeWalt FlexVolt was about 17 seconds, while the average cut time for the Milwaukee was 19 seconds. Each had faster and slower cuts throughout the test.

At no time does the grinder give up due to heat buildup. Also, neither tool (and its battery) will be hot to the touch, which seems to be a danger of shutting down.

After running the Milwaukee High Output vs DeWalt FlexVolt comparison, the FlexVolt grinder finally gave up after 50 cuts. Milwaukee's Fuel grinder lasted 68 years. Keep in mind that you may get different results with different battery packs. On top of that, the tool definitely affects the results more than the battery.

evaluation result

So will the larger battery capacity lead to more cuts? Yes, sometimes.

The power of DeWalt's 60V Max grinder is clearly relevant to our results. Since it doesn't have to work as long as Milwaukee does to make each cut, it gets the job done faster. It becomes clearer when you look at the total time each grinder has to work. DeWalt had to work for about 14 minutes and 10 seconds. Milwaukee worked 21 minutes and 30 seconds — 52 percent longer than DeWalt.

Milwaukee and DeWalt also offer several models of grinders, so your results will vary depending on the tool you use.

The X factor in all of this is that the higher watt-hour Milwaukee high-output batteries are more efficient when using things like cut-off wheels than the smaller DeWalt FlexVolt battery packs. vice versa.

In our tests, we replaced the wheel near the end of its life (but before it was completely worn out) after 30 cuts.

High output and the conclusion of the FlexVolt battery

Both Milwaukee and DeWalt have very valid claims that you need to take into consideration when making your buying decision. First, DeWalt has definitely raised the bar on how much power they can get out of many new tools in the FlexVolt line. The battery is backwards compatible with your DeWalt 20V Max product. They also have a 162 Wh battery on deck. However, you cannot use a 20V Max battery with a FlexVolt tool, so you will need a new battery and tool system.

Currently, DeWalt's 15Ah battery pack definitely has higher battery capacity and runtime. However, the actual use of this battery still requires larger tools and equipment.

Also, with Milwaukee, you don't need to buy a new battery platform to use all your M18 tools. Their 18 volt grinders certainly offer a lot of power, but in our testing, the DeWalt FlexVolt tool easily outpaced that particular grinder. As Li-ion battery technology continues to improve, all of these power issues should disappear entirely.

the bottom line

This is just one of hundreds of tests we can choose from from many different tools. Every user's needs will be different, so it's up to you to use what you've learned here to decide for yourself whether one battery platform is better for you than another.

With the wide variety of tools powered by both batteries, there are a lot of variables at play. At the end of the day, if staying on one battery platform and knowing that all tools will work with all batteries is the most important thing to you, then Milwaukee is the car for you. They also have many more models and sizes available.

But there's also the Metabo 36V 9" grinder… maybe another day.

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