Dewalt recently introduced a new FlexVolt 15Ah battery that works with their 20V Max and 60V Max cordless power tools.

To some people, the 15Ah part is all that matters.

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But to many – and the industry – the deeper details hold much significance.

The popular community theory is that the new Dewalt battery pack is equipped with (30) 18650-sized battery cells, each with 2.5Ah charge capacity.

If you do the math, 3.6V x 30 x 2.5Ah = 270 watt-hours.

This could also potentially be a 15-cell battery pack built with 21700-sized Li-ion battery cells, each with 5.0Ah charge capacity. But, the size and weight of the new battery suggests that it’s built with (30) 2.5Ah 18650 cells.

The math with 21700 cells would be: 3.6V x 15 x 5Ah = 270 watt-hours.

According to Dewalt’s published specs, the new FlexVolt 15Ah battery weighs 4.5 lbs. Dewalt has provided dimensional specifications for the new battery: 6.8″ length x 3.4″ width x 3.9″ height.

In comparison, Dewalt’s Flexvolt 20V/60V Max 12.0Ah battery weighs 3.2 lbs and measures 5.4″ in length and 3.8″ in height.

The new Dewalt 15Ah battery is larger and heavier than all of the brand’s existing 20V Max and FlexVolt cordless power tool batteries, including their soon-to-be second highest capacity 12Ah battery.

While longer, the new FlexVolt battery should be widely compatible with existing tools given that it nearly matches the height of other high capacity FlexVolt batteries.

In the other post, Big Richard was the first to suggest that this could be a 30-cell battery with 18650 cells, rather than a 15-cell battery with 21700 Li-ion cells.

**Why is this important?**

The battery cell size, count, and configuration largely dictate its theoretical and practical power and performance output levels.

While power and performance of a tool and battery pairing depends on many factors, it’s convenient to simplify things for the sake of discussion. Following are two generalizations.

If you have a 5-cell battery rated at 3.0Ah charge capacity, and a 10-cell battery also rated at 3.0Ah, the 10-cell battery can drive heavier duty tools and higher demands for longer.

Similarly, if you have a 10-cell 6.0Ah battery with 18650 cells, and a 10-cell battery 6.0Ah battery built with 21700 cells, the 21700 cell-equipped battery will usually be higher-performing.

Here are deeper discussions about battery basics:

Revisiting What an Amp-Hour Means for Cordless Power Tool Batteries, and Other Tidbits

Milwaukee’s Next-Generation Battery Tech (Advanced Discussion)

As for 18650 and 21700, these are industry stands that describe the diameter (18 or 21 mm) and length (65.0 or 70.0 mm) of Li-ion cells.

(In case you’re wondering, a rechargeable lithium-ion battery cell in AA sizing would be 14500, and a rechargeable Li-ion cell in AAA sizing would be 10440.)

Brands shifted to 21700-sized Li-ion battery cells from 18650 because several tech and performance ceilings were reached.

Going by memory, the best 2.0Ah cells from a few years ago topped out at ~25A max current output, the best 2.5Ah cells topped out at ~20-22A max current output, and the best 3.0Ah cells topped out at ~15A max current output.

Heat becomes a greater challenge with higher charge-density cells.

Consider a room that’s filled with kindergarteners to 60% capacity. The kids all had some chocolate and are then asked to leave the room, fast. There’s going to be a lot of energy in that room, and for the most part they’ll exit the room at a comfortable pace. Now fill that room to 100% capacity. If you try to hustle them through the door at the same rate, there might be more pushing, shoving, distractions, and a lot more resistance.

So what do you do if you want to cram even more energy into a room? You build a bigger room.

In 2015, we talked about the end of the road as far as traditional cordless power tool batteries could go. At that time, 15-cell batteries and batteries built with 21700 cells weren’t announced yet.

18V Batteries are Now at 6.0Ah – How Much Higher Can They Go?

It’s amazing when you think about it, that just 6 years ago 18V cordless power tool battery packs were at their limits and none of today’s higher output or higher voltage options were even announced.

Milwaukee’s 15-cell M18 HD batteries were first announced in mid-2015, and Dewalt’s FlexVolt system was announced in mid-2016 with their larger form factor batteries hinted but not formally announced or released until later.

Since then, the trend for professional cordless power tool brands has been to move towards higher voltage systems (e.g. Dewalt Flexvolt, Metabo HPT MultiVolt, Milwaukee MX Fuel) and 21700-equipped batteries (M18 High Output).

This is where things get complicated.

Metabo has a 10.0Ah battery pack:

New Metabo 18V 10Ah Power Tool Battery is “World’s Most Powerful” of its Size

Dewalt also has a 10Ah battery:

New Dewalt 20V Cordless Mowers, Powered by Dual 10Ah Batteries

Dewalt *could* have introduced a FlexVolt 15Ah battery built with 5.0Ah cells. And they still can. But it appears that they went with 18650-sized 2.5Ah cells.

Let’s look at some specs.

**18650 Cell Max Discharge Current**

- Samsung INR 18650-25R (2.5Ah): 20A

**21700 Cell Max Discharge Current**

- Samsung INR21700-30T (3.0Ah): 35A
- Samsung INR21700-40T (4.0Ah): 35A (w/o 80°C temp cut)
- Samsung INR2170050E (5.0A): 9.8A
- LG INR21700M50T (5.0Ah): 14.55A at 10-25°C

Updated:

- Samsung INR21700-50S (5.0Ah): 20A (w/o 80°C temp cut)

The LG 5Ah discharge current plummets below 10°C (50°F) and above 25°C (77°F). There could be better 21700 5Ah cells, but these are the best high-discharge ones I could find.

*Update: The Samsung INR21700-50S is rated at higher discharge compared to the -50E, but it’s still not quite as high-performing as lower capacity cells.*

If you ignore cooling considerations, 2X 18650 2.5Ah cells in parallel can deliver approximately the same max current as 1X 21700 3.0Ah or 4.0Ah cell.

This is why some brands’ larger form factor compact (5-cell) battery packs can deliver the power of their higher capacity (10-cell) 18650-based battery packs. For example, a Milwaukee compact M18 4.0Ah battery can be used in place of an M18 XC 4.0Ah battery without power or performance compromises.

Dewalt’s FlexVolt batteries have 15 cells, and can be paired with their 60V Max or 20V Max cordless power tools. But, for the battery to be FlexVolt-compatible, you need 15 cells or multiples of 15.

With each 3.6V cell described as a 4.0V Max cell, 4V x 15 = 60V Max.

Doubling that would give us a 30-cell battery with 20V Max and FlexVolt tool compatibility.

Ignoring cooling and any other considerations, (2) of the aforementioned Samsung 2.5Ah cells could potentially deliver 40A of combined max discharge current, which would approximately match the maximum discharge current ratings of individual 3.0Ah and 4.0Ah cells used in Dewalt’s 9.0Ah and 12.0Ah battery packs.

On paper, (5) Li-ion cells arranged in series deliver 18V and the rated max current capacity. Real-world and engineering limits will be lower.

(10) cells arranged in a 5-series 2-parallel configuration give you 18V and double the charge capacity, but there is also a theoretical doubling of the max discharge current (again, ignoring real-world limitations).

(15) cells arranged in a 5-series 3-parallel configuration give you an additional boost in capacity and max discharge potential.

Since tools are designed around a performance standard, they won’t always be able to take advantage of the extra overhead, but that higher power capacity also means the batteries will run cooler even in demanding use.

**New FlexVolt Battery Implications**

Now we have 30 cells, does that mean this is a 5-series, 6-parallel battery pack when used in 20V Max tools? This could provide a current and charge capacity boost, possibly even compared to even existing FlexVolt options.

If the battery is switching contacts in the same way as for existing FlexVolt tools, as they physically switch from 20V Max to 60V Max configurations depending on the tool they’re connected to, this would reflect new engineering accomplishments by Dewalt.

When paired with a FlexVolt/60V Max cordless power tool, the 30-cell battery would be arranged in a 15-series, 2-parallel arrangement. In a 20V Max tool, the configuration would likely be 5-series, 6-parallel.

Other brands could potentially follow suit.

It’s unclear how some brands are able to produce competitive 10Ah battery packs, but presumably there are some cells that can deliver the necessary discharge current levels with sufficient cooling considerations. But, based on datasheet specifications for available 21700 5.0Ah cells, the ones we looked at are bested by 2.5Ah cells in parallel.

Is this the way forward? Might other brands have to go to 20-cell 2.5Ah cell arrangements to get to 10Ah, or 30-cell arrangements to get to 15Ah?

What becomes possible at that power level?

An 18V or 20V Max 12Ah battery would be rated at 216 watt-hours. This 15Ah battery is rated at 270 watt-hours, which is a 25% increase in energy.

Are we going to see more 120V Max cordless power tools from Dewalt? Maybe 2x M18 tools from Milwaukee?

**At the least, this is a new way to achieve a higher charge capacity for longer runtime.**

But, consider what happened in the past when similar advancements were made. What happened when brands stepped up from 5- and 10-cell battery packs to 15-cell batteries? What happened when brands found a new way to push past a charge capacity ceiling to reach new levels?

Milwaukee M18 HD, Milwaukee M18 High Output, Dewalt FlexVolt, Metabo MultiVolt, Makita 18V X2, Bosch CORE/Profactor – every time a battery advancement was made within a cordless system, it paved the way for new cordless power tool developments.

Going from 12Ah to 15Ah in this way is nothing like the bump-up from 3.0Ah to 4.0Ah or 4.0Ah to 5.0Ah just a few years ago.

Think about it – if you’re a user that wants more runtime with fewer interruptions, you can work within your cordless system’s limitations and just buy more batteries and faster chargers.

This *could* just be about bumping up runtime from 12Ah to 15Ah, but with added size and weight? And, don’t forget that fresh engineering efforts must have gone into these batteries.

There’s going to be more about these batteries. I don’t know what, yet. Maybe a cordless 10″ table saw? Full-size 120V Max dust extractor? Dewalt’s first cordless snow blower?

If this is indeed a 30-cell battery, Dewalt has taken things to a new level, and there’s a good chance they designed it around new cordless power tools or innovations.

And, even if they didn’t, this represents a direction that other brands could go in. Dewalt is raising the ceiling just a little bit, but possibly enough to allow for their next generation of cordless power tool tech.

Back in October 2019, I wrote about how their compact 4Ah battery wasn’t really a big deal. It was welcome, but it wasn’t a huge development since they were already using similar cells in larger battery packs and they already had a compact 3Ah battery.

Even with the exact Li-ion battery cell and engineering specifics as of yet known, the DCB615 battery’s geometry, size, and weight still convey that it’s a different breed compared to any of Dewalt’s current 20V Max or FlexVolt battery packs.

Everything about this battery screams “this is a big deal!”

Mike

I’m sure you mean 65.0mm or 70.0mm for the length of the battery cells. Otherwise they would be very long!

Stuart

Yes – thank you! *fixed*

Nathan

so could it be 21700 cell based with extra spacing and heat sinking to allow for better thermal loading?

as one thing that keeps poping up in my head when I see it – is alot of surfance area for potential heat movement.

and another is that extra black piece in front of the latching rails. I think regardless it’s an interesting device – and honestly the tool I really want to pair it with is that new Dewalt Attachment capable Flexvolt trimmer.

another odd thought – might it have cooling gel in the body? I doubt it – but then again it’s the new thing to do.

Big Richard

With the 5000mAh 21700 cells DeWalt used in the 10 cell 10Ah 20v pack, they did have to add some additional cooling tech into the pack, and as a result it is slightly larger and a couple ounces heavier than their other 10 cell 21700 packs (6Ah and 8Ah).

So that was my original thought with this 15Ah battery, that it is a little bit bigger for the same reasons, as it must also be using the same 5000mAh 21700 cells. It makes sense that it would be slightly larger and heavier than their other 15 cell 217000 batteries (9Ah and 12Ah).

But then I saw the 15Ah’s dimensions and weight. It is almost an 1.5″ longer and over a pound heavier. That is a much bigger difference than the aforementioned 10Ah vs 6Ah/8Ah difference. It’s specs are fairly close to another SBD 60v battery, Craftsman’s 5Ah V60 battery. Which just so happens to be a 30 cell 18650 battery. Add in to the equation that Makita recently announced a 5Ah 40v XGT battery that uses 20 18650 cells in lieu of 10 21700cells, and it just got me thinking DeWalt may have done something similar.

I can see it both ways, and the more I think about it the more unsure I am about which direction they took.

Iginio Romero

Dewalt flexvolt 20/60V 15/5Ah = Dewalt 40V 7.5Ah XR, same 30 cells 3.6V 2.5Ah battery

Rob

I have not once found that a “compact” 21700 based 4ah battery pack allows a tool to perform as well as it does on a standard double row 18650 configuration. This even applies to low wattage stuff like drills, impact drivers and OMT’s. I haven’t used Milwaukee though. Is that the exception?

Stuart

I don’t recall Dewalt making any claims, but Milwaukee says their High Output batteries can be used for next-level-up power requirements, and I haven’t experienced any contradictions to this yet.

philip s john

Don’t think so. M 18 is done on bigger stuff. The 12 and even a 15 will trip out with continued use on some big tools. They need new line.

Tom D

I’ve not noticed a performance difference between any of my M18 batteries beyond run time – but I may not be a heavy user.

The biggest thing I’ve noticed is some tools just don’t seem balanced unless you put a heavy battery on them (sawzall for example).

philip s john

Try a 12 amph on a big grinder or big chainsaw for continuous use. You will see the biggest battery trip out.

Travis

Would I be better off using one 12 ah flex volt or two 6ah Flexvolt batteries for my dewalt 60v chainsaw? Would the higher ah give more power?

Big Richard

The 9Ah and 12Ah FlexVolt batteries will give more power than the 6Ah FlexVolt battery. All of them are 15 cell batteries, but the 9Ah and 12Ah use 217000 sized cells that have a higher discharge rate (more Amperage) and run cooler. Which means more power is possible.

From a cost perspective, you are better off running two 6Ah FlexVolts, as a 2pk is $179 at the moment, while the 12Ah is $249 and out of stock everywhere. Plus with two 6Ah batteries, you can run more continuously as you will always have the spare on a charger.

Ideally, two 9Ah is the way to go, as you get that extra power and near continuous runtime.

Phil

I agree. With the 9 at 60v. Having 2 6 bats is like a 2x 18v combo tool. So much battery and charger maintenance. Switch out cooling down. Etc. Also like m18v HO they trip out to early from heat. Then cooling becomes paramount… because you can keep re starting the tool but with several trip outs in a row and ruin a Milwaukee amph at 18v. 60v 9 runs with no issues and higher tool performance.

macfox

Bosch explicitly claims their 4Ah ProCore (21700-based) battery provides the same power as the old 4 and 5Ah 18650-based batteries. This seems correct, as the 4Ah ProCore can provide 810 watts sustained power, while 5S2P 18650 packs with premium high-current cells deliver about the same.

Lyle

Technically 18mm x 65mm for 18650 and 21mm x 70mm for 21700. There’s an extra 0 at the end. A 700mm long battery wouldn’t be practical for handheld tools 😀.

Stuart

Whoops! Thanks – fixed! (Forgot my decimal points.)

Evadman

They have to be 21700 cells or pouch cells from what I can see. I have tons of 18650 batteries laying around,and I can’t organize 30 of them in any configuration and hit the size listed. Pouch cells can be fit with much less wasted space than a can cell.

Stuart

It’s possible, but are pouch cells as impact and shock-resistant as cylindrical Li-ion cells? Cooling might also be more complicated.

Dayton

They can be extremely resilient with the proper compression applied while packing more wh per square inch

Ben

Food for thought. 10 cells 18 mm wide in a row is 180 mm or a bit over 7 inches. This new battery is 6.8 inches long. The battery thus can’t have rows of 10 cells.

DeWalt list the new battery as 1/10 of an inch taller than the current 12 ah battery. So 2.5 mm taller. Switching from 21700 cells to 18650 cells saves you 3 mm in height per row. Combines you have 11.5 mm of height. To fit a fourth row of cells DeWalt would need to come up with 6.5 mm of height savings inside the battery pack.

The battery is thus not long enough for 10 cell wide rows and is too short to have a fourth row of cells. The battery can’t have 30 cells inside.

Stuart

Is it possible the cells are staggered differently? Or, could there be a non-rectangular configuration which might explain the boxy shape, such as 2 cells on top, with 4 rows of 7 cells?

XRH07

if the cells are staggered that way then the pack is too tall and doesn’t fit into legacy tools with a battery cage. Like the 1-7/8″-2″ SDS Max hammers that have been out for 2 years.

4x18mm is considerably taller (~15%) than 3x21mm. And my Flexvolt 9.0s with 21700s are 3-13/16″/3.812″ at their tallest point. Dewalt states this pack is 3.9″ which is in line with existing 21700 Flexvolt packs. This 15Ah pack also has the same width as existing 9/12 Ah Flexvolt batteries too.

The cells are 100% going to be 21700 Samsung 50S spaced out with generous heatsinking. The added length checks out because this is where you need a bulk of the heatsinking to go anyways.

Samsung rates the 50S 21700 similarly to the 40T with a 80deg temp cut,. They’re already in the 10 Ah XR pack and the equivalent Metabo too. They’re going to carry the same cells between 10/15 Ah packs the same way they do the 3/6/9 and 4/8/12 ones.

RyanH

Dumb question: how does Tesla’s battery development (specifically the 4680 cells) affect this? Given Tesla went into battery manufacturing to avoid a shortfall in 2022, could we see Tesla battery cell, or at least the technology, used to provide even better power density? I think its relevant considering the SBD patents that look at moveable batteries for vehicle and home use.

https://cleantechnica.com/2020/09/22/everything-you-need-to-know-about-teslas-new-4680-battery-cell/

Stuart

I really don’t know, but Tesla and EV developments have influenced the industry in the past. It was hinted that this led some brands to go with 21700 cells whereas Dewalt was originally planning to go with 20700 for their higher capacity batteries.

I don’t know true it is, but I read somewhere that 20700 cells were specifically designed for the cordless power tool industry as a potential replacement for 18650 cells.

Morgan

I couldn’t see Milwaukee going backwards to 18650, but perhaps a 4 row 21700. A 16ah battery, used for run time with tools with no weight/size penalty – table saw, lights, etc. That would be 288 watt hours. There seems to be room left in the mold for an even larger battery than the 12ah.

Stuart

Possibly, but for more power-hungry tools they might also consider 2x battery systems to make them more available to a wider range of users. There are lots of downsides to dual battery tools, however, and so it’s hard to say.

Milwaukee has surprised me in the past, and they’ve also not quite reached a new technological ceiling yet. However, I could have said the same about Dewalt.

Milwuakee has MX Fuel for their cordless equipment needs, and other brands need to innovate to better compete in that space. This 15Ah battery could be part of Dewalt’s competitive counter.

Makita’s solution is to go with 18V-sized 36V batteries which can be doubled-up, as well as a 20-cell battery that can also be doubled up, but their XGT system is completely incompatible with their 18V system.

Dewalt designed their FlexVolt system for higher performing tools, but also released new 20V Max core tools that benefit from a performance boost when paired with high output or FlexVolt batteries.

There are a lot of unknowns that need to be worked out and revealed in time.

Nathan

so interesting comment on the 20700 as I’d swear I’d read something similar about 2 years ago but it wasn’t size related as much as it was current throughput related.

In that the EV industry was going to push batteries to longer life – more power density – less weight. which would end up working out well for cell phones, laptop, tablets . . . . . . . and the power tool and other special use cases would push battery development toward more density, higher current throughput, same weight.

The idea being that power tools are looking for that 50C or 70C battery output and EV is looking to stay around 30 but have more density in the same weight. Thus one day you power tool 5AH compact battery will weight the same but be able to draw off significantly higher current like it does from a 2 row/3row battery.

and the EV will have 4000 or even 6000 mAH cells but less current thoughput for longer life.

time it will tell.

Stuart

When FlexVolt was announced, we were explicitly told that the then-upcoming 9Ah battery would have 20700 cells.

But, it seems that after Dewalt started working on FlexVolt, EV industry interests shifted from 20700 to 21700 sizing, which probably wasn’t too difficult for them to redesign for.

From what I understand, there is more effort being put into 21700 R&D than 20700, as well as greater production capacity and competition. 21700 became the next-gen battery size, and I don’t think anyone gave 20700 a second thought after that.

Big Richard

I haven’t taken apart my 10Ah battery yet, but I’m pretty sure DeWalt is using the Samsung 50S for its 5000mAh 21700 cells, not the 50E or the LG M50T. It is good for 20A continuous, but with enough cooling can peak up to 35A.

Stuart

Thanks!

I couldn’t find official datasheets for the -50S, but you’re right – 20A max discharge w/o 80°C cut-off, and 35A with.

The question is whether Dewalt went with 18650 cells or 1.3 lbs of cooling.

Each cell weighs 72g. That’s ~2.4 lbs for 15 battery cells. The 4.0Ah cells weigh 70g each. Going by on-paper specs, there’s a difference of ~1 ounce.

Weights:

4.5 lbs for this 15Ah battery

3.2 lbs for 12Ah battery

So for 12Ah battery, ~2.3 lbs in battery cells plus ~0.9 lb in supporting plastic, circuitry, and contacts.

For the 15Ah battery, ~2.4 lbs for the battery cells, ~2.1 lbs for supporting plastic, circuitry, contacts, and cooling components?

It’s certainly possible.

But, all that effort, engineering, and cost is going to add up, and the final result would be a 25% higher capacity battery pack that might at best match up to the power output levels of the 9Ah and 12Ah batteries. Would this drive the cost-per-amp-hour costs to disproportionate and unacceptably higher levels? And, there’s also the added battery pack size as well.

Would this be enough to push the FlexVolt tech ceiling even a little bit higher?

Which path would hold more potential for Dewalt and benefits for users, 30x 18650 cells or 15x very cooling-sensitive 21700 cells?

Plain grainy

I guess they fit 4 on a power station? Home Depot has tools today on specials page. I see Rigid belt sander18v. I didn’t know they had a cordless belt sander.

Stuart

It’s not very visible, but it’s been out for a while.

https://toolguyd.com/ridgid-18v-cordless-brushless-belt-sander/

Kent Skinner

I have an M18 (go team red!) 12ah battery, and I’m not sure I’d want more weight than that added to a tool I’m carrying. But for stationary tools, this looks pretty slick.

I also imagine it’s going to be *really* expensive.

ToolGuyDan

Why not 4- or 5- bank configuration, but with bank switching, similar to wear-leveling on SSDs? In a 4-bank configuration, that’s ten seconds on 1,2,3; ten seconds on 2,3,4; ten seconds on 3,4,1. The banks individually discharge near enough to evenly that it’s within the limits of normal cell variation, so it wouldn’t have any impact on battery life or workload, but it gives you substantially more thermal mass and surface area to dissipate the waste heat versus a 3-bank, high-Ah-per-cell design.

Benjamen

Because the cells are directly connected to the terminals, (or in the Flexvolt case to the 20V/60? disconnect mechanical switch). There are no batteries on the market (to my knowledge) that switch through transistors , which is what would be required for your scheme. Although the Metabo HPT Multivolt batteries bring out the two separate banks of cells on separate contacts and the connection to the tool decides it the banks are connected in series or parallel.

Why are the cells directly connected to the terminals and not switched inside the battery? Because of space and heat limitations — the kind of power transistors that you’d need to handle the current are big and require heatsinks.

philip s john

Exactly… and if I am correct this then would also be 7.5 amph… not 15.

ToolGuyDan

Thank you for the detailed response! I’m still a bit confused, though. A Shelly 2.5 is UL-listed for switching 2×10 amps per channel (at both 110 and 220V), and is roughly the size of an Oreo. And you’d only need to do this fancy footwork on FlexVolt loads.

Thinking about it a bit more, you could also pull off a neat trick to reduce how millisecond-accurate your switching would need to be: one third of your voltage per “cycle” could come from two banks in parallel.

Benjamen

The heat generated is dependent on the current, not the voltage (I^2*R loss). Also you can pull 100A or more current out of a regular Flexvolt at 20V battery for short term and 60A for long term.

And to address Drew M below:

at 60A: 60A*60A *.001ohm = 3.6W

at 100A: 100A*100A*.001 ohm = 10W

That’s not too much wasted energy, but you’d still need to heat sink the FETS and provide the space for airflow around the heatsinks.

It doesn’t have to be too large, but I think you are right that price may be the limiting factor. I’m thinking of RC car speed controllers, they are relatively small, but they cost $100 retail. So even if the bill of materials cost the tool company $20 extra, that would blow the price of the batteries out of the water after markup.

Drew M

There are definitely tiny metal cased FETs that could easily handle this load but they’re pretty expensive and they would need some heatsinking but not nearly as much as you’d think since we’re talking about a Rds_on of ~1mOhm.

MM

Scott wrote:

“It’s amazing when you think about it, that just 6 years ago 18V cordless power tool battery packs were at their limits and none of today’s higher output or higher voltage options were even announced.”

I couldn’t agree more. And I think we can look back even further, it wasn’t all that long ago–the mid 90’s–when cordless power tools were essentially a joke. Compare then to now when many cordless tools outperform their corded equivalents, and others require bind-up protection lest they physically injure their operator. Still others like Milwaukee’s MX compete with internal combustion engines. To make that kind of a leap in ~25 years is amazing to me.

fm2176

Twenty-five years ago the gutter company I worked for was using B&D/DeWalt UniVolt drills with 7.2v and 8.4v batteries (I still have one). We had a hammer drill (forget if it was 12v or 14.4v) for hanging downspouts.

Looking back through ToolGuyd’s archives, you’ll find that DeWalt announced their 2Ah and 4Ah batteries not even 9 years ago: https://toolguyd.com/next-generation-higher-capacity-lithium-ion-batteries/

My first Li-Ion system came with two 1.3Ah batteries. Unbeknownst to me at the time, Porter Cable’s 20v Max system was replacing their 18v tools, but I eventually accumulated 3 more batteries and most of the tools. All of those batteries gave me 6.5Ah of runtime combined. Now I have 6Ah and 9Ah batteries, and the systems I have the fewest batteries in still provide near or exactly twice the Ah.

Bosch: three-4Ah slim packs = 12Ah

MetaboHPT: two-5Ah MultiVolt packs + one-3Ah 18v pack = 13Ah

Grant

I have measured the weight of a few dozen different cordless tool battery packs and compare them to the weight of the cells inside. Cases for DeWalt 20v/60v packs are typically around 30% of the overall pack weight. Ego 56v packs, with their extra overmolding and cooling sleeves, are typically 40% to 50% case, by weight. If this new 15 Ah Flexvolt pack uses (15) 21700 cells with Ego-style cooling sleeves and increased cell spacing like the Ryobi P193 6 Ah pack, the weight of the case would come out to 46% of the overall weight, right in line with the Egos. I think what we’re looking at here is an extra rugged Flexvolt pack, not one that uses (30) 18650 cells.

Some other pack weights, for reference:

DeWalt DCB609: 1457 grams, 28% case

DeWalt DCB208: 950 grams, 26% case

Ego BA1400: 1311 grams, 49% case

Ego BA2800: 2264 grams, 41% case

Ryobi P193: 930 grams, 52% case.

Stuart

This is looking very possible as well.

Frankly, there are pros and cons to both approaches, and it’s uncertain (for now) as to which path Dewalt has taken.

The 1.3 pound difference between 12Ah and 15Ah batteries is more than the entire non-Li-ion cell componentry of the 12Ah battery (~0.9 lbs if my math is correct).

Grant

If my guess of an up-armored pack is correct, DeWalt must have decided the existing 15 cell packs aren’t able to hold up on certain jobsites. Maybe they have some new heavy industry tools in the pipeline, similar to MX Fuel.

I certainly agree with your assessment that this pack required some extra R&D, and that must indicate some new applications for Flexvolt. Can’t wait!

philip s john

But this article doesn’t mention how wide this battery is. It looks to be just as wide as a 12 so the 18650 theory would have more room in the form of flex housing..

The flex 6 with 18650 trip out too often.

On the other hand new yellow flex 6amp must have 21700 cells… must have been made for flex advantage tools

Stuart

It seems to be comparable in width, with the length and weight seemingly where the major differences are.

philip s john

I think what you are proposing multi volt is already doing this. If I understand your theory correctly this would make your 30 sell 18 650 7.5 amp hour not 15

philip s john

Some say flex 9 switch from 20700 to 21700. Also flex bat would always need 3 rows for the switching… I think.

Could the 15 be 21 cells. 3 rows of 7 of 20700. 3×7 can do the switch of 20v and 60.

Big Richard

20700 vs 21700 is just the size of the cell, has nothing to do with their voltage. All the cells, whether 18650, 20700, or 21700 are 3.6v nominal (4v max). So 7 cells would be a 25.2v (28v) in parallel mode and 75.6v (84v max) in series mode.

philip s john

I will guess 21700 . 2 rows 7 and on on the end for 15 cells. It’s the dimension of the form and rows that I am trying to make sense of.

If the 9 truly had 20700 or 21700 at 3 rows and the 10 has 21700 at 2 rows … would the form of the 15 have room for 3 rows. I dont think it does… so I also think the 9 only ever had 20 700 possibility sitting in the valley of cells. This affects the hight . The night is at the limit… it’s only getting longer now.

philip s john

Exactly… and if I am correct this then would also be 7.5 amph… not 15.

Stuart

15 cells x 3.6V = 54V (60V Max). Charge capacity would be 2.5Ah.

Consider that 15-cell series configuration as a single battery. Double it up in parallel, and you have 5.0Ah charge capacity.

30 cells x 3.6V x 2.5Ah = 270 watt-hours.

20V Max is 18V nominally.

270 Watt-hours/18V = 15Ah

In 60V Max mode, 270 Watt-hours/54V = 5Ah

20V Max and 18V batteries with 3.6V cells need to have battery sets in multiples of 5 since 3.6V x 5 = 18V.

60VMax and 54V batteries with 3.6V cells need to have battery sets in multiples of 15 since 3.6V x 15 = 54V.

It doesn’t have to be this way, but otherwise you lose energy and increase heat with voltage conversions.

Add a battery cell and you get 24V Max. Take two away and you get 12V Max.

Michael

The ah rating on a duel voltage battery could be very misleading for the average consumer. This battery is only 15ah in a 20v max tool. In a 60v max it is only 5ah

Stuart

Possibly, but the current branding has been made clearer. Using the 20V Max charge capacity as a reference seems fair, otherwise more customers might wonder why a “lower capacity” FlexVolt battery is larger and pricier compared to a “higher capacity” 20V Max battery.

Big Richard

Confirmed from my DeWalt rep, 30 18650 cells. Make of that what you will.

Greg

I would wager based on the rough sizes and possible configuration there are 25x 3A 18650 cells.

a 3P configuration of 3A cells.

There would be 4 layers of cells with a maximum length of 7 cells in a layer.

My guess is:

The top row has 5 cells + room for wiring and switching

The second and third row has 7 cells

The bottom row would have 6 cells

that just my engineering intuition and some rough size comparison based on the photos.

Greg

Well, I am wrong because 60V wouldn’t work in this case.

I just don’t see how they could cram 30 18650 cells in there.

I suspect it will be 15 2170 cells with better cooling to get a higher amp draw.

Greg

8

7

8

7

works but it would be almost 6 inches long.

Iginio

DeWALT FLEXVOLT 15AH battery = DeWALT 40V XR 7.5AH battery

Ron

Torque Test Channel took one apart and verified that there are indeed 30 2.5-Ah 18650 cells in the DCB615. They are oriented vertically instead of horizontally.

Big Richard

Correct, I actually confirmed this with a product engineer back in May2021. As I suspected at the time, and Iginio mentioned above, it is the same configuration as their now discontinued 40v 7.5Ah battery (30 2500mAh 18650 cells).