Tool Reviews 0
by Kenny Koehler
On June 21st, 2016 at 8:30 A.M in Baltimore, Maryland, we witnessed the unveiling of DeWalt FlexVolt technology. It brought never before seen hybrid-voltage battery technology to the table and opened up even more tools to the cordless world. We’ve heard a lot of confusion about FlexVolt, so this article goes over the key details and features of the technology so you know why you may or may not want to take a closer look.
Hybris battery voltage makes DeWalt FlexVolt so revolutionary. Each FlexVolt battery supports outputting either 20V Max or 60V Max. The tool tells the battery which mode to operate in, so it’s completely automatic for the user. Electronic controls have given DeWalt the technology to wire the FlexVolt battery both ways to either extend run time in 20V Max tools or deliver more power in 60V Max (and the occasional 120V Max) tools.
FlexVolt batteries currently exist in four different sizes:
- 2Ah 60V FlexVolt (6Ah @ 20V)
- 3Ah 60V FlexVolt (9Ah @ 20V)
- 4Ah 60V FlexVolt (12Ah @ 20V)
- 5Ah 60V FlexVolt (15Ah @ 20V)
20V Max and 60V Max from the Same Battery – How?
The idea of battery pack wiring is fairly straightforward. You wire lithium-ion battery cells in a series to increase the voltage. Wiring rows of cells in parallel delivers greater amp hours.
Wired For Greater Amp Hours
You get a 20V Max pack (or an 18V nominal pack) by wiring sets of five lithium-ion cells in series. Each cell produces 4V Max (3.6 volts nominal) and the series connection multiplies it to make 20 volts. The ~2.0 amp-hours in each cell don’t combine in any way, so the battery is a 20V Max, 2.0 amp-hour battery—also known as a DeWalt compact battery.
You can then wire a second set of five cells to the first using a parallel connection. Now the voltage remains the same, but the amp hours double. This creates a DeWalt 20V Max 4.0 amp hour battery. Add a third row of cells wired in paralleland you get 6.0 amp hours in your 20V Max battery.
Wired for Greater Voltage
If you were to remove the two parallel connections between the five cell sets and replace them with series connections, you’d get a 60V Max, 2.0 amp hour battery. That concept is what has driven higher voltage systems, like 40V Max in DeWalt’s OPE and the 56V and 80V Max batteries on other platforms.
Before DeWalt FlexVolt, you had to choose a hard configuration for your battery to perform in. If you wanted a higher voltage battery, you had to move to a completely new platform incompatible with the lower voltage system. Another solution was to combine multiple batteries with a series connection between them to double the voltage.
If you look inside the DeWalt FlexVolt battery pack, you’ll find 15 lithium-ion cells along with wiring configurations for both 20V Max and 60V Max power supply. Electronic communication between the tool and the battery tells the cells which set of wiring to run on. The DeWalt 15Ah FlexVolt battery uses even more cells—but the same principle.
DeWalt FlexVolt – Why?
Corded tools draw different amounts of power. A drill may get all the torque it needs from a 6 amp motor while a miter saw requires a 15 amp motor to perform well. Each motor has an amperage rating, but the power consumption is actually measured in watts (your power bill always shows kilowatt-hours used).
With FlexVolt, tools that draw fewer watts for their smaller brushless motors use the 20V Max configuration. When higher watts are required by larger brushless motors, you can put the battery into FlexVolt (60V Max) tools.
You can think of a lithium-ion battery like a gas tank. It has a set capacity of potential energy available. In the case of DeWalt FlexVolt batteries, that’s 108 nominal watt-hours (nominal voltage times amp hours). The 9.0 amp hour FlexVolt will have 162 watt-hours when it’s released. That gas tank is drained by a combination of voltage draw and amp-hour draw (current). Multiply the two values together to get power measured in watts. DeWalt found in its research that the larger brushless motors run better at 60V Max and 120V Max than they do trying to push a higher amp currentthrough at 20V Max. At the same time, there are all the tools they’ve developed that run just fine at 20V Max.
The idea behind FlexVolt is to create a cordless jobsite where there’s no compromise on power and performance no matter what tool is used without forcing the user to be tied to multiple battery systems.
A Note About Air Travel Safety
108 and 162 nominal watts (and higher) actually create an issue for distribution and travel by air. At 100 watts capacity, restrictions kick in based on the inherentrisk associated with lithium-ion cells’ thermal runawayshould they overheat and catch fire, usually due to a short. We can carry smaller lithium-ion batteries onboard if they are installed in a device or properly packaged.
DeWalt developed a simple, but effective workaround. By locking the DeWalt flightadapterin place on the battery, the 108 watt-hour system is divided into three 36 watt sections and certified safe for air travel. Its connection to the terminals helps prevent shorts in addition to creating the cell separation required by the FAA.
Do FlexVolt Tools Work with 20V Batteries?
No. One thing to know about DeWalt FlexVolt Tools is that they only work with FlexVolt 60V Max battery packs. While FlexVolt batteries can fit on and power DeWalt 20V Max tools, the opposite is not the case. DeWalt FlexVolt tools require the 60V output that only FlexVolt battery packs can produce.
DeWalt has a variety of tools lined up for the FlexVolt line. They announce more and more each year. Here’s a small sampling of some of the initial FlexVolt cordless power tools along with MSRPs:
DeWalt FlexVolt 120V Max Tools
- DHS716AB/T2 Fixed Blade Miter Saw with Adapter Cord: $499/$649
- DHS790AB/T2 Sliding Miter Saw with Adapter Cord: $649/$799
DeWalt FlexVolt 60V Max Tools
- DCS575B/T1/T2 Circular Saw: $179/$299/$379
- DCS388B/T1/T2 Reciprocating Saw: $179/$299/$379
- DCS485B/T1 Table Saw: $379/$499
- DCG414B/T1/T2 Grinder: $179/$299/$379
- DCD460B/T1/T2 Stud and Joist Drill: $279/$399/$479
DeWalt FlexVolt 20V Max Tools
- DCL070/DCL070T1 Area Light: $399/$499
- DCK299D1T1 Hammer Drill & Impact Driver Kit: $379
DeWalt FlexVolt Batteries, Chargers, Radios, and Adapters
- DCB606 FlexVolt 20/60V Max Battery 6.0 Ah: $149
- DCB606-2FlexVolt 20/60V Max Battery 6.0 Ah 2-Pack: $199
- DCB118 Fast Charger: $79
- DCA120 120 Volt Adapter: $49
- DCR025 Bluetooth Radio Charger: $199
- DCB1800B Portable Power Station: $399
- DCB1800M3T1 Portable Power Station with (3) 4.0 AH 20V Max Batteries and (1) 6.0 AH FlexVolt Battery: $599
Shop FlexVolt at Acme Tools
