Cordless angle grinder

The cordless angle grinder is a portable angle grinder designed to perform straight, cross and angle cuts, or roughing and polishing tasks on various materials such as metal, stone, ceramics and concrete. Unlike corded grinders, this type of angle grinder operates using rechargeable batteries, providing greater freedom of movement and versatility, making it ideal for construction work, light carpentry and DIY.^[1]

Metabo cordless angle grinder

Their ergonomic design makes them easy to operate with one hand. Cordless angle grinders have gained popularity due to their portability and ease of use. They are characterized by their mobility, lightness, and versatility, especially in places without access to the electrical grid. They use lithium-ion batteries, usually 12 V, 18 V, or 20 V.^[2]

History

The angle grinder was invented in 1954 by the German company Ackermann + Schmitt (FLEX-Elektrowerkzeuge GmbH) in Steinheim an der Murr ^[3]

Characteristics

From a technical point of view, the radial grinder incorporates a circular abrasive disc that rotates at high speed, with diameters usually between 115 mm and 150 mm. This system allows cutting, sanding or polishing with great precision, depending on the type of disc mounted. The drive is supported by variable power motors, generally between 1200 and 2000 W, and some models incorporate brushless technology, which increases efficiency, reduces eight, wear and improves range, allowing it to be operated comfortably with one hand, and its lightweight and compact structure has contributed to its popularity. The batteries used usually have voltages of 12 V, 18 V or 20 V, although there are more powerful models that work with 36 V packs, aimed at professional or industrial use.

Advantages and disadvantages

Advantages

This cordless tool has a number of clear advantages over wired versions. The freedom of movement it offers allows you to work easily in open or inaccessible spaces. In addition, its lower weight and dimensions make it more comfortable for quick cuts or short interventions. However, it also has certain limitations: its autonomy depends directly on the state of charge of the battery, and its power, although increasing, is still lower than that of the models connected to the grid. For this reason, for prolonged work it is recommended to have additional batteries or fast charging stations.

Limitations

However, it also has certain limitations: its autonomy depends directly on the state of charge of the battery, and its power, although increasing, is still lower than that of the models connected to the grid. For this reason, for prolonged work it is recommended to have additional batteries or fast charging stations.

Battery types

Cordless radial grinders, like cordless hand drills, are divided by the voltage of the pack, which directly influences the type of application they are intended for and their power and runtime.. The 10 to 12 volt models, such as the Bosch GWS 12V-76 or the Makita CP100DZ, are focused on light cutting work, precision repairs or tasks in very small spaces.

In the 14.4-volt range, although currently less common, there are still intermediate grinders such as the Makita DGA452Z, which supports 14.4 V and 18 V batteries. These models offer moderate power and good versatility.

The 18 to 21 volt models represent the professional range. In this segment we find tools such as the Bosch GWS 18V-10, the Makita DGA513Z, the DeWalt DCG405N, the Einhell TE-AG 18 Li or the Worx WX800, all designed for demanding cuts, on-site work and continuous roughing of hard surfaces. They frequently incorporate brushless motors, electronic brake, and reverse control.

Finally, there are industrial versions of 28 to 36 volts, more powerful and designed for larger diameter discs (up to 230 mm). Models such as the Milwaukee M28 CAG125X and Makita DGA900Z offer similar features to their wired counterparts, but with the freedom of wireless use.

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Comparison between market models

Source:^[4]

They started with small, low-power radials, but today they cover a very wide range. ^[5]

Brand	Model	Voltage	Motor	Max RPM	Disc diameter	Electronic brake	Kickback	Approx. weight.	Observations
Bosch	GWS 18V-LI	18 V	4 poles	11,000	115 mm	No	No	2.3 kg	Equivalent to 800 W wired
Bosch	GWS 12V-76	12 V	Brushless	19,500	76 mm	No	No	0.5 kg	Ultra compact
Bosch	GWX 18V-15 PSC	18 V	BITURBO	11,000	125 mm	Yeah	Yeah	2.7 kg	X-LOCK, speed control
Makita	DGA452	18 V	With brushes	11,000	115 mm	No	No	2.3 kg	Classic LXT model
Makita	DGA513Z	18 V	Brushless	8,500	125 mm	Yeah	Yeah	2.5 kg	Cruise control, AVT
Makita	DGA900Z	36 V	Brushless	7,800	230 mm	Yeah	Yeah	5.4 kg	Double battery, industrial use
DeWalt	DCG405N	18 V	Brushless	9,000	125 mm	Yeah	Yeah	1.74 kg	XR, compact and powerful
DeWalt	DCG418	54 V	Brushless	9,000	125 mm	Yeah	Yeah	2.2 kg	FLEXVOLT, high performance
Einhell	TE-AG 18/115 Li	18 V	With brushes	8,500	115 mm	No	No	1.2 kg	Light, economical
Einhell	AXXIO 18/125	18 V	Brushless	8,500	125 mm	No	Yeah	1.4 kg	Professional, PurePower engine
Worx	WX800	20 V	Brushless	8,600	115 mm	Yeah	Yeah	1.9 kg	Compact, PowerShare
Worx	WX812L	20 V	Brushless	8,500	115 mm	Yeah	Yeah	1.8 kg	Nitro, anti-kickback

Brand	Model	Voltage	Disc diameter	Max cut at 90°
Makita	HS301DSAE	12 V	85 mm	25 mm
Bosch	GKS 18V-57	18 V	165 mm	57 mm
DeWalt	DCS570N	18 V	184 mm	64 mm
Metabo	KS 18 LTX 66 BL	18 V	165 mm	66 mm

Technical notes

• Max RPM : No-load speed. The higher the speed, the more efficient it is at fine cutting.
• Electronic brake : Stops the disc when the trigger is released, improving safety.
• Kickback control : Detects blockages and shuts off the tool to prevent kickback.
• BITURBO / FLEXVOLT / XGT : Technologies that increase performance in high-end models.

Disc table for cordless grinders (76–125 mm)

Diameter (mm)	Usual compatibility	Available disc types	Common applications
76 mm	Compact mini grinders	Fine cut, multi-material, metal	Light repairs, automotive
85 mm	Bosch GWS 12V, Makita 12V	Cutting metal, ceramic, diamond	Electrical installations, plumbing
100 mm	Some 12–14.4 V	Cutting, roughing, turbo diamond	Ceramic cutting, DIY
115 mm	Standard in 18 V	All types: cutting, roughing, diamond, flap	Construction, renovations, carpentry
125 mm	Standard in 18–21 V	All types + special discs (brush, polishing)	Professional work, metallurgy, masonry

Battery pack technology

Battery packs require battery balancing, which is a technique that maximizes a battery's ability to have all of its energy available for use and increases battery longevity. ^[6] Typically, a battery regulator is a device built into the battery pack that performs battery balancing. ^[7] Most modern cordless drills use lithium-ion batteries which offer: ^[8]

• Higher energy density.
• Less weight.
• Absence of memory effect.
• Fast charging and long life.

Manufacturer	Model	Voltage	Capacity (Ah)	BMS type	Observations
Bosch	PBA 12V 2.5Ah	12V	2.5	External	Home use, Power for All system
Bosch	GBA 18V 5.0Ah	18V	5.0	Internal	Professional, CoolPack technology
Bosch	ProCORE 18V 8.0Ah	18V	8.0	Internal	High energy density, smart BMS
Makita	BL1021B	12V	2.0	External	CXT Series, Compact
Makita	BL1850B	18V	5.0	Internal	LXT Series, with charge indicator
Makita	BL4040	40V	4.0	Internal	XGT Series, Battery-Machine Digital Communication
DeWalt	DCB124	12V	3.0	External	XR Compact, light professional use
DeWalt	DCB184	18V	5.0	Internal	XR Li-Ion, compatible with the entire 18V range
DeWalt	DCB546	18V / 54V	6.0	Internal	FLEXVOLT, dual voltage, smart BMS

Internal architecture of battery packs

The nominal voltage of a battery pack is determined by the number of 3.7 V cell subgroups connected in series. Each subgroup can be made up of one or more cells in parallel, which increases the capacity (Ah) of the pack. ^[9]

Structural typology according to voltage

Nominal voltage	Number of 3.7V subgroups in series	Example of models	BMS	Comment
3.7 V	1	USB Power Banks	Not required	The cells are in parallel; a 3.7 V → 5 V DC-DC converter is used.
10.8–12 V	3	Black&Decker BL1510, Makita BL1013, Bosch BAT411 (PS31)	External	2 intermediate sockets for BMS on the charger
14,4–16 V	4	Makita BL1415G	External	3 intermediate sockets; BMS normally in the charger
18–21 V	5	Makita BL1850B, Bosch SM31 (GSR 1800-LI)	Internal	4 intermediate sockets; with integrated BMS

The presence of intermediate taps in the pack's wiring allows the BMS (internal or located in the charger) to monitor and balance the state of charge of each group of cells. This balancing is essential in series configurations, since the cells do not balance themselves automatically as they do in parallel. Some low-cost designs use diodes to limit cell imbalance, although this technique offers limited protection and may reduce the battery's lifespan. ^[10]

Power packs => % Charge vs. Volt

% load	3.7 V pack	10.1 V pack	14.8 V pack	18 V pack	21 V pack
100%	4.2 V	12.6 V	16.8 V	21.0 V	25.2 V
75%	3.9 V	11.7 V	15.6 V	19.5 V	23.1 V
50%	3.7 V	10.8 V	14.4 V	18.0 V	21.0 V
25%	3.5 V	10.0 V	13.2 V	16.5 V	18.9 V

Applications

As for its practical applications, it is frequently used in the assembly of metal structures or furniture, the installation of elements such as shelves, curtains or supports, and the preparation of surfaces by roughing. Some models also allow drilling holes in materials such as wood, plastic or masonry, as long as suitable discs and accessories are used.

Security

Safety in use is a priority aspect in its design. Many cordless radial grinders are equipped with ergonomic handles coated with non-slip material, electronic overload and overheat protection systems, and an electronic brake that stops the rotation of the disc when the trigger is released. The inclusion of LED light in certain models also allows for precise work in poorly lit areas.

See also

• Cordless hand drill
• Angle grinder