Cordless drill

A **cordless drill**  or **battery drill** is a portable power tool that operates on rechargeable batteries, usually **lithium-ion** technology. Its cordless design allows great freedom of movement, making it ideal for DIY, carpentry, assembly and professional use on construction sites. 

## Features 
* It works without a cable, powered by a rechargeable battery.
* Allows drilling, screwing and has percussion in some models
* Includes automatic or manual chuck.
* It has multiple torque positions.
* They usually incorporate an LED light, charge indicator and carrying case.

## Type according voltage 
Cordless drills are classified by battery voltage, which determines their power and autonomy.

### 10–12V 
Compact, lightweight models suitable for household or precision tasks.

* **Bosch PS31 10-12V **
* **Bosch GSR 12V-15**
* **Makita DF331DSAE**
* **Black+Decker BDCHD12S1**

### 14.4V 
Balance between power and size. Still present in mid-ranges.

* **Bosch GSR 1440-LI**
* **Makita HP347D**
* **Makita DF347DWE**
* **Makita BL1430B** (compatible battery)

### 18–21 V 
Professional range. High power for demanding jobs.

* **Bosch GSR 1800-LI**
* **Bosch GSB 18V-21**
* **Makita DHP453RFE**
* **DeWalt DCD776C3-QW**
* **Einhell TE-CD 18 Li-i**
* **Worx WX375 20V**

### 28V 
Less common models aimed at industrial or high-performance tasks.

* Some Milwaukee and DeWalt models in industrial ranges.

## Technical comparison between models  
They started out as low-power electric screwdrivers, but today they fill a very wide range. 

## 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.  The battery regulator is typically a device built into the battery pack that performs battery balancing.  Most modern cordless drills use lithium-ion batteries that offer: 

* Greater energy density.
* Less weight.
* Absence of memory defect.
* Fast charging and extended battery life.

## Internal architecture of battery packs 
The nominal voltage of a battery pack is determined by the number of 3.7V cell subgroups connected in series. Each subgroup can consist of one or more cells in parallel, which increases the capacity (Ah) of the pack 

The presence of intermediate taps in the pack connection allows the BMS (internal or located in the charger) to monitor and balance the state of charge of each group of cells. This balance is essential in series configurations, since the cells do not automatically balance as they do in parallel. Some low-cost designs use diodes to limit the imbalance between cells, although this technique offers limited protection and can reduce the useful life of the set. 

== Power packs => % charge vs. Volts ==

## Applications 
* Furniture assembly.
* Installation of shelves, curtains, supports.
* Drilling in wood, metal, plastic and masonry (models with percussion).

## Security 
* Ergonomic and non-slip handle.
* Overload and overheating protection.
* Electronic brake on some models.
* LED light for dark areas.

## References 
## Bibliography 
* Bell, Brian. Farm Machinery. Old Pond Books, 2010-02-12. . 
* Peterson, Chris. Black & Decker Readymade Home Furniture: Easy Building Projects Made from Off-the-Shelf Items. Cool Springs Press, 2018-12-25. . 

## Other websites 
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