20V Max vs 18V Battery News & Opinion

20V Max Vs 18V: Setting the Record Straight

When it Comes to 20V Max Vs 18V Batteries, Which is More Powerful?

“There was a major difference in power when I switched from an 18V system to a 20V system.” Ah, if I only had quarter for every time I heard that one…

The 18V vs 20V Max debate will continue to go on no matter how many times I step into someone else’s conversation and explain it to them. Let me take the drama out of the conversation now: They’re the same. We promise you.

I’d love to stop there, but people will insist on arguing that the 20V Max systems are simply more powerful than 18V because, well, 20 is bigger than 18. *sigh*


Seriously though, I love talking about this stuff, so let’s jump on it. Here in the U.S., manufacturers such as Bosch, Milwaukee, Ridgid, Ryobi, and Makita are all running on an 18V battery platform. DeWalt and Porter-Cable run on their 20V Max systems. A voltmeter is all that it takes to offer some quantifiable data, and a look inside the battery will show you why.

20V Max Vs 18V: Running the Numbers


Inside your battery pack are the individual battery cells. In an 18V/20V Max system, they are always set in groups of 5 wired in a series. Each group of 5 is then wired in parallel to increase the number of amp hours and overall battery capacity in watt-hours. For more on that, check out our feature on Voltage vs. Amp Hours.

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Each one of those battery cells has two voltage ratings – nominal and maximum. The amount of voltage that a battery produces when fully charged is higher than when it begins to discharge, even slightly. It’s actually a chemical characteristic of the lithium-ion system. Each battery cell has a nominal voltage of 3.6 volts and a maximum voltage of just over 4 volts.

  • 3.6 volts (nominal) x 5 cells = 18 volts
  • 4 volts (maximum) x 5 cells = 20 volts

That’s it. That’s the entire difference in 18V vs 20V Max batteries. It’s only a matter of whether the company is using nominal voltage or maximum voltage as its rating.

Milwaukee Battery Cutout

20V versus 18V: What About Higher and Lower Voltage Systems?

This brings up several interesting talking points. First, many European countries are more strict about how a company can advertise. You’ll find that tools are sold by their nominal voltage in most areas. That means 18V high power tools and 10.8 volt lower power tools. From a marketing standpoint, being able to put a higher number on the tool makes it seem more powerful. Putting a nominal voltage on it is a representation of where the battery operated most of the time.

For some reason, 20V Max vs 18V debate only seems to be an issue among these 5 cell group platforms. Everyone advertises their 12V line (3 cells), not their 10.8V families. Jump up to OPE (Outdoor Power Equipment) and we get 40V systems (10 cells) that are taking the place of the 36V platforms of a couple of years ago. So before you leave with a bad taste in your mouth about DeWalt or Porter-Cable, understand that everyone does it somewhere.


20 Volts vs 18 Volts: There’s a Reason It Says “Max*”

Speaking of DeWalt and Porter-Cable, you’ll notice on their packaging that it is marked 20V Max*. That asterisk and the word “Max” points to the documentation that clearly states the voltage is maximum. Is it a marketing tactic? Yes. Is it misleading? Only if you don’t look for an explanation when you see something marked with an asterisk.

Barry Bonds, Single Season Home Run King* – Known to have used performance-enhancing drugs

Double Chocolate Fudge Brownies, bake for 25 minutes* – 18 minutes at higher elevations

20V Max* – 20 volts maximum, 18 volts nominal

So yes, 18V and 20V Max systems have the same amount of voltage power. However, the guts of each battery cell do vary from brand to brand and even within a single brand as technology and chemistry improve. So is DeWalt’s 20V Max line more powerful than their 18V line was? Yes. Because the electronics, motors, and cells are better, but they’re putting out the exact same voltage!

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Gerald Hurst

Everyone is missing the point that power is measured in watts, not volt or amps. And it does not matter whether the current is AC or DC. Power (watts) is volts times amps so if you don’t know the amps drawn or the volts you don’t know the power. An 18 volt drill that draws more amps can easily be more powerful than a 20 volt drill that draws fewer amps.
The manufacturer is misleading the customer via misinformation.

Thomas Reid Smith

I don’t care about the voltage, I just want it to work and do what the old 18 volt did.

Skyler Holman

When will 2170 cells play a role here?

Willie Pienaar

I found the article very interesting as I have a 20V Ryobi drill – angle grinder combo (bought in South Africa). The battery has now stopped charging and Ryobi South Africa does not stock 20V products anymore. Opening the battery unity I saw that they have 5x 18650 Li-On batteries marked as 4V 1500mAh. 18650 batteries are normally 3.7V. Could it be that these batteries are also stating the maximum voltage rather than the nominal? Can I replace the 18650 batteries with other similar batteries of 3.7V and can I use ones with higher mAh for better capacity? Will the… Read more »

David S

I can compare this to the electrical system in an automobile. All automobiles have 12 volt electrical systems, BUT, each cell in the battery has anywhere from 2.1 – 2.2 volts depending on its state of charge. A battery that just came off the charger will have about 13.2 volts or a little more, but as it settles the voltage will drop and be closer to about 13.6 volts. While the engine is running, a good alternator will charge the battery anywhere between 13.6 14.8 or so volts. If an automotive battery manufacturer started marketing a battery as 13 volt… Read more »