At this year’s DeWalt media event in Baltimore, MD we were finally given access to what DeWalt had been touting for weeks as “the world’s first”. It’s a big claim, but from what I saw, the company delivered. While there were several “world’s first” on display at the event, the most notable was its FlexVolt battery system.
Last year David Frane reported on the year in power tool batteries, which offers an overview of where the cordless power tool industry was headed by the end of 2015. This year, things are changing rapidly and it’s safe to say that competition around battery technology is getting even more intense. The teams are growing, their players are bigger and stronger than ever, and their playbooks are the most sophisticated we’ve seen in a long time. If corded tools are like the desktops of old, cordless tools are becoming more akin to laptops and tablets in how they’re changing the way we work.
So what’s the big deal about DeWalt’s FlexVolt? As an overview, it’s a battery pack that offers 60V Max OR 20V Max, depending upon which tools it’s powering. Yes, you read that correctly. The new batteries offer 60V Max in a new line of tools that DeWalt will begin launching in October 2016 – cordless tools that include a 7 ¼-in. circular saw (DCS575), 4 ½-6-in. grinder (DCG414), reciprocating saw (DCS388), ½-in. VSR stud and joist Drill (DCD460), and 8 ¼-in. table saw (DCS7485), as well as 120V Max FlexVolt 12-in. fixed head compound miter saw (DHS716) and 12-in. sliding compound miter saw (DHS790). Aside from the new higher voltage, these packs also convert automatically to 20V Max when mounted to any 20V Max tools.
All high-capacity battery packs are made of 3.6V cells. Now, you’ll notice on the images below that the cells are labeled 4V Max – that’s because technically when not under load the cells produce 4Vs. However, the moment you put the cell to work, voltage drops to 3.6. That’s the difference between 18V and 20V Max tools. It’s a marketing thing, basically – but on the surface, both battery platforms are using the same 3.6V cells so a 20V Max battery is essentially giving you 18V. It gets technical and complicated quickly – and some tool manufacturers will argue why their 18V is more powerful than competitors (often due to efficiencies in the motor). We’ll cover this topic in greater detail at a later date. For now, let’s look at the basics of FlexVolt and how it alternates between two voltage outputs.
You can do one of two things with battery cells: connect them in a parallel circuit or in a series. Speaking in generalities for simplicity sake, when you connect them in a parallel circuit, you get more run time and when you connect them in a series you get more power with less run time. A couple of images help illustrate how this works.
DeWalt’s 20V Max batteries run on a parallel circuit. Each row consists of 5 cells provides 2 Ah; 5 cells x 4VMax = 20V Max @ 2 Ah per row. Add a row, also in parallel circuit, and you add another 2 Ah to the battery’s capacity. In the FlexVolt platform there are 3 rows, for a total of 6 Ah when connected this way. The battery automatically knows that it’s in a 20V Max tool.
The FlexVolt also connects cells in a series when mounted to 60V Max and 120V Max tools. 15 individual cells, just as above, except this time they are all connected. 15 cells x 4V Max = 60V Max. In this configuration you’re not adding the Ah capacity of each row so you’re left with 2 Ah total. Remember, Amp Hour (Ah) is the amount of fuel in a cell. As David Franes year in power tool batteries article points out, battery manufacturers can modify the chemistry to some extent in order to get more Ah, but the standard is 2 Ah.
Stay tuned for more in-depth coverage of battery technology, and reviews of DeWalt’s FlexVolt tools.