Milwaukee HD High Demand vs DeWalt FlexVolt Batteries

Without a doubt, two of the biggest battery-related news items this year have been the DeWalt FlexVolt and the Milwaukee HD High-Demand batteries. It’s reignited the debate between the need for higher voltage and greater amp-hour capacity to extend runtime and power on the jobsite. When it comes to Milwaukee HD High Demand vs DeWalt FlexVolt batteries, we figured the best way to see which was the reigning champ was to test them head to head.

To accomplish this, we grabbed a Milwaukee RedLithium High Demand 9.0Ah battery pack and a DeWalt FlexVolt 3.0Ah battery. The DeWalt FlexVolt battery also works as a 9.0Ah pack at 20V. That makes these two batteries a fairly even match-up.

Milwaukee HD vs DeWalt FlexVolt Battery Capacity

The Milwaukee High Demand 9.0Ah RedLithium battery extends capacity while staying on Milwaukee’s original M18 platform. A simple multiplication problem of nominal volts multiplied by the amp hours will tell you that the Milwaukee 9.0 amp hour battery has a total capacity of 162 watt-hours packed into 15 lithium-ion cells (it’s also written on the underside of the pack). This the only battery currently shipping on the market to reach 9.0 amp hours for handheld power tools.

Milwaukee HD9.0 battery pack

The DeWalt FlexVolt battery has the ability to switch between 20V Max and 60V Max voltages. These are maximum voltages at the highest charge state and translate to 18V and 54V nominal. At 20V Max, the battery runs 6.0 amp hours. At 60V Max, it runs at 2.0 amp hours. There isn’t any other battery available that has the ability to switch voltages. In that, the FlexVolt is truly unique. Dewalt is also planning a 9.0Ah FlexVolt battery pack in early 2017. Do the same math problem we did with Milwaukee, and you’ll find the total capacity of 108 nominal watt hours packed into 15 lithium-ion cells.

Milwaukee 9.0 Vs DeWalt FlexVolt

So when we look at the battery capacity in terms of watt hours (total power availability), we see that Milwaukee has the advantage. However, DeWalt does have a 162 watt hour FlexVolt battery in the works that we expect to be released early next year.

Milwaukee High Demand vs DeWalt FlexVolt Voltage vs Amp Hours

There’s a complex debate between voltage and amp hours that involves a lot of physics and chemistry geek speak. We’re not going to get into all of that right now, but the bottom line is that you have to have both to produce power. Increasing either the voltage or the current flow will increase your available power. Let’s look at this simple equation:

Power = Current x Voltage

To get the same power you can either increase current…or increase voltage. Take your pick. In this way, the higher voltage does not necessarily equate to a higher power tool. That’s especially true given the limitations of a battery pack’s total capacity (measured in watt-hours (Wh). The Milwaukee HD vs DeWalt FlexVolt batteries come pretty evenly matched.

Model Voltage Amp-hours Watt-hours
Milwaukee HD9.0 48-11-1890 18V 9.0Ah 162Wh
DeWalt FlexVolt 9Ah DCB609 20V/60V 9.0/3.0Ah 162Wh

In theory, if you give two tools identical tasks it should require the same amount of work from both regardless of the volt/amp configuration. So let’s plug in some actual numbers for these batteries:

Milwaukee HD 9.0 Pack Power = 9.0 Ah x 18V = 162 Wh

DeWalt FlexVolt Power = 2.0 Ah x 54V (nominal) = 108 Wh

DeWalt FlexVolt 9.0 Ah Power = 3.0 Ah x 54V (nominal) = 162 Wh

or using the battery in series mode at 20V Max…

DeWalt FlexVolt 9.0 Ah Power = 9.0 Ah x 18V (nominal) = 162 Wh

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

That’s exactly what this Milwaukee HD vs DeWalt FlexVolt comparison aims to find out in order to help you decide!

Milwaukee HD9.0 vs DeWalt FlexVolt: The Test

I’ve taken the DeWalt FlexVolt angle grinder and Milwaukee M18 Fuel angle grinder (Model 2781) and put identical 5-inch cutting wheels from Diablo on them. I’ll see how many cuts I can make through rebar with a fully charged battery.

We will be happy to hear your thoughts

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