The Festool 577108 Energy Set SYS 18V 2x4.0/TCL6DUO is a battery and charger set built for users who want to keep Festool cordless tools running without piecing together batteries, chargers, and storage separately. This is a battery and charger set designed for powering and charging Festool 18V cordless tools in the shop or on the jobsite. Model Number: 577108. If you bought a Festool Basic tool with no batteries included, or you need more ready-to-go power during the day, this set solves that problem in one shot.

What makes this set useful is the balance between runtime, size, and charging speed. You get two 18V 4.0 Ah Li-HighPower Compact battery packs plus the TCL 6 DUO rapid charger, which can charge both packs at the same time at 2 x 6.0 A. That matters in real use because it keeps your rotation moving without tying up extra outlets or spreading chargers all over the bench. Festool built this around the reality of how cordless systems get used: one pack in the tool, one cooling or charging, and no wasted motion when the day gets busy.

The battery choice here is also deliberate. Festool says these Li-HighPower Compact packs are 20% lighter and 50% more compact than a 5.2 Ah standard battery pack. For drilling, driving, trim work, installation, punch-list tasks, and general cordless tool use, that smaller size can make a real difference in comfort and control, especially on overhead or repetitive work. If your main priority is compact handling rather than maximum runtime, these are the packs a lot of users will prefer.

There is also some smart system thinking built in. The included battery packs support Bluetooth functionality that can automatically start a connected Festool mobile dust extractor equipped with a Bluetooth receiver when the tool is switched on. That is the kind of feature that sounds small until you use it every day. It cuts one extra step out of the workflow and helps keep the work area cleaner when you are moving between cuts, sanding, or cleanup-sensitive work.

Storage is a big part of the value here too. Festool packs the set in a SYS3 M 187 Systainer with heavy duty foam so the batteries and charger are protected, organized, and easy to carry. There is enough space for a total of four battery packs plus the DUO rapid charger, which makes this a practical grab-and-go power station for your van, trailer, or bench. Because it is a Systainer3, it is also compatible with previous Systainer generations, Festool mobile dust extractors, and other system accessories, so it drops into the broader Festool setup instead of becoming one more odd-shaped case.

Compatibility is strong, but it is not universal across every cordless product Festool has ever made. Festool positions this set for most 18V cordless products and all applications where compact design matters, while noting exceptions. It is suitable for most Festool 18V cordless tools except cordless sanders, and the DUO charger works with 10.8V, 14.4V, and 18V battery packs except BP-XS for CXS/TXS 10.8V tools. That is important if you are buying into the system and want a charger that can cover more than one battery class.

Who should buy it? This set makes the most sense for existing Festool cordless users, especially anyone buying bare tools, building out a second battery rotation, or wanting a cleaner charging setup in the shop. It is also a strong fit for remodelers, finish carpenters, installers, cabinet crews, and service pros who move tool to tool and need compact batteries more than maximum pack size. If you run long, heavy-draw applications all day, Festool itself points you toward its 5.2 Ah BP 18 energy sets instead. For most everyday cordless work, though, this kit is the practical middle ground.

A Smart Buy for Festool Users Running Bare Tools

The Festool 577108 Energy Set SYS 18V 2x4.0/TCL6DUO is the kind of package that makes a cordless system easier to live with every single day.

• Who it's for: Festool users adding batteries to Basic tools, building a cleaner charging setup, or wanting compact 18V packs for everyday work.
• Why it stands out: You get two compact 4.0 Ah batteries, true dual-slot rapid charging, and a Systainer that keeps the whole setup organized instead of scattered around the shop.
• Worth knowing: This set is aimed at compact design and general 18V use, not maximum runtime for the heaviest continuous-draw applications. Festool points heavy-demand users toward 5.2 Ah BP 18 options.

• What kind of product is this? It is an Energy Set that includes two Festool 18V 4.0 Ah battery packs, one TCL 6 DUO rapid charger, and one SYS3 M 187 Systainer.
• Can the charger charge both batteries at the same time? Yes. The TCL 6 DUO rapid charger is built to charge two battery packs simultaneously.
• Are these batteries for all Festool 18V tools? Festool states the battery packs are compatible with most Festool 18V cordless products, with cordless sanders called out as an exception.
• Does this set work only with 18V batteries? No. Festool states the TCL 6 DUO charger works with 10.8V, 14.4V, and 18V battery packs, except BP-XS for CXS/TXS 10.8V tools.