Difference Between 18v and 20v Drill: Key Features and Performance Variations

Difference Between 18v and 20v Drill

You know how a professional sports team can, on paper, appear to be better than another professional sports team?  How many times have we read that about a team we are considering placing a friendly wager on for this week’s game?  

In truth, though, what may appear on paper to be so clear can also disappoint when the game is actually played.  That’s why the games are played, rather than simply giving up because of what it said about them on paper.  One speaks to potential, while the other speaks to reality.

Such is the case with lithium-ion batteries and their voltage ratings.  

Key Points:

  • The main difference between 18v and 20v drills is the voltage rating of the battery, with 20v being slightly higher than 18v.
  • In practical use, the difference in voltage may not have a significant impact on the performance of the drill, and a less expensive 18v drill may provide better value and performance than a 20v drill.

Lithium-Ion Batteries On Paper

It used to be nickel-cadmium batteries were the thing, but that all changed with the fairly recent lithium-ion battery technology development.  They are what we use now on our cordless tools:  they are easy to recharge and contain battery cells of 1.2 volts, 1.5 volts, and 3.6 volts.  

Groups of 5 cells are connected and wired in a series, and in the case of cordless tool battery packs, and every group of 5 cells is connected through a wire in parallel.  This ensures the battery will have a high number of amp hours, as well as a good volume of watt-hours.

Some simple math tells us that 5 cells, each of which is 3.6 volts, add up to 18 volts.  The cordless drill I used yesterday is an 18v tool, certainly powerful enough for all of my household and woodworking shop uses, and it is powered by a battery pack that has 5 cells of 3.6 cells wired together to give me the voltage the cordless drill needs.

All cordless power tool manufacturer sources the cells from third parties and then assembles them in their own battery packs.  The battery slots on the power tools and the branded battery charger are made such that they fit the branded battery pack well and tightly, resulting in a power tool that is effectively and efficiently powered for use.

In addition, branded battery packs are manufactured to communicate well and smoothly with the motors in the branded power tools.  This enhances the efficiency of tool operation.

Lithium-Ion Battery Cells

A string of 5 cells, each of which is 3.6 volts, as we calculated, has a total of 18 volts and powers 18v tools.  But this is where the “on paper” and “on the field” comes in.  

Each individual battery cell has a maximum voltage, its full potential, of 4 volts.  That’s the “on paper” number.  Again, simple math tells us that 5 cells in a group times 4 volts each is going to equal 20 volts.  This represents the potential or maximum voltage of the batteries.

However, batteries aren’t used “on paper”: we use them in the real world.  Each cell has a real-world or what is referred to as a nominal voltage rating of 3.6 volts, and the math has already told us that 3.6 times 5 is 18 volts. This nominal voltage is what we get from the battery when we pull the trigger and use our cordless tools. 

Maximum voltage and nominal voltage, then, are what we need to understand, one on paper, one on the cordless tools we use.  In fact, these are just words, words that are used in marketing and labeling “on paper.”

The only difference that matters, then, is the manner in which manufacturers label and promote their batteries, and not in the actual way in which the batteries perform.  Promotions of 20V Max batteries, though, are limited to the United States; outside of the US and Europe, for instance, companies are required to use the nominal voltage rating of batteries and not the maximum voltage rating.  

Sure, 20v sounds like more than 18v, and on paper, it is.  But, “the proof is in the pudding,” to use another old expression – the truth of something being judged on actual experience with it, on its results rather than its potential.

Yet, some will argue that 20V batteries are more powerful than 18v batteries, and they can “feel” it in the use of their cordless power tools.  They will have paid more for the battery and the cordless tool they use the battery with, under the belief it will give them more juice and more torque (the turning power) of the tool.

For myself, I know my 18v drill is equally powerful whether I’m using a 20v Max battery or an 18v battery.

The DeWALT 20v Max Battery Truth

We don’t mean to muddy the water on this discussion, but DeWALT has introduced some mud, if you will, in both its line of batteries to power its lines of cordless power tools and in its marketing of both its batteries and power tools.

It maintains a 20V Max platform of batteries and tools, its FlexVolt system, and its Battery Stack batteries. We’ll demystify this for you to help you make better-informed decisions on what to purchase, at least as it relates to 20v vs. 18v batteries and tools.

Battery Stack batteries are designed to run longer and cooler and deliver more power than its other battery lines.  The Battery Stack 20V Max has a 25% smaller footprint than the 20v Max while offering half-again the power of the 20v Max and double the lifespan.  We don’t want to get too far afield from the original question of this article, but these batteries are designed and manufactured differently than either of the other battery lines from DeWALT.

FlexVolt batteries are made to power DeWALT’s 60v and 20v tools.  We can pretty much set this one aside, also,  and deal directly with the 20v Max. 

We’ve written about DeWALT batteries in past articles, and if you want to learn more, you can refer to them.

The 20v Max battery from DeWALT comes with an asterisk on the DeWALT website page devoted to it.  The voltage measurement of 20v batteries is its initial value, and the measurement is taken almost in the abstract – when you first turn on your 18v drill, for instance, and before it is actually doing its work for you – drilling holes, driving screws, etc.

In warm-ups and when practicing my shot, I could easily drill what today would be called 3-point shots one after another as I moved around the arch.  Nobody was guarding me, and it was just me and one of the trainers on the floor.  It was not a real game condition; no pressure, just me, the ball, and the basket.  This represented my potential.

When game times rolled around, though, and I was being guarded, the ball just didn’t fall as it did during practice.  I’d still make baskets, but not with the frequency of unguarded practice.  This was when I was actually doing my work.

Unguarded practice was my “maximum voltage,” and game conditions were my nominal voltage.  You get the picture.

Now, back to the asterisk on DeWALT’s product page.  The text attached to the asterisk makes the same distinction:  Maximum initial battery voltage (measured without a workload) is 20 volts.  Nominal voltage is 18.

Don’t take our word for it, either.  Go here to see for yourself.  

Promoting a 20v Max battery just sounds so much more powerful than promoting the same battery as 18v.  While each is true, maximum voltage and nominal voltage are the “on paper” vs. “on the field” distinction.  One is potential in the abstract, while the other is in the real world, in your hand, drilling a hole or driving a screw with your 18v tools.

Which Should You Buy – 20v Max or 18v?

It depends, to be honest.  There are more considerations than the promoted voltage rating when purchasing cordless power tools and their batteries.  

  • Cost.  Manufacturing quality and reliability come with a cost.  DeWALT, for instance, enjoys a well-deserved great reputation when it comes to power tools, and brand accounts for the prices one pays to own their tools.  Since other brand batteries are not compatible with DeWALT tools, you’ll be purchasing DeWALT batteries to power those tools.  As we’ve shown, though, you won’t be getting greater real-world, actual use voltage from that 20V Max battery.  Choose the power tool that best fits your budget and your intended project usage – you may very well find that a less expensive 18v drill will give you great performance, while a 20v Max tool may not give you what you think it will.
  • Torque.  What kind of torque your drill will give you should matter more than the battery.  More torque means more turning power, and more turning power means more efficient and effective use.  Go for the torque rating.
  • Weight.  Look at the weight of both the power tool and the battery needed to power it.  The heavier the tool, the more fatigue you will feel earlier in the day.  Think about the quality of your work experience because woodworking is supposed to be fun.
  • Bells and whistles.  Settings lights and indicators, sound warnings, and such are nice frills to have on your power tools – circular saws, drills, drivers, etc.  You are better served with an 18v battery that powers tools with these frills than a 20v Max tool without them.

These matter to the enjoyment and use of cordless power tools.  You can easily find an 18-volt drill that will offer you the best combination of these factors, and that will do a terrific job for you in your shop without your needing to base a decision on a battery that sounds better or more powerful.  

Battery Power

The inside of batteries do differ both from brand to brand as well as within a brand’s line of batteries.  We also know that technology always advances – we’ve come from nickel-cadmium batteries to lithium-ion batteries just in my woodworking career.  This will, of course, continue.

In answer to the question of whether the 20v Max battery is more powerful than their previous 18v line of batteries, we’d have to say yes.  But, we attribute this to advances in electronics, motors, and the cells within the battery packs, in addition to the brand quality.  

But, the answer to the question about the voltage output is they are putting out the same nominal voltage.  The 20v Max is a promotional label used in advertising to make them seem more than they are.  The DeWALT product page we referenced earlier and provided the link for says so.  

We found others who have reached the same conclusion and a video of one such examination of voltage output.  It’s only a 4-minute video, but it covers that same analysis and conclusion you’ve just finished reading.

On paper vs. on the field is an apt analogy.  That’s why the games are played, and that’s why what really matters is the tool in your hand and its performance.  As between experiential knowledge and theoretical knowledge, we’ll rely on what we experience with our own senses. 

Your 18v drill will perform very well for you with an 18v battery. You can spend more money on a 20v Max battery, but the power output is identical. The nominal voltage is the same, and that’s that. Never mind what the paper says – play the game to find the answer.

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