Things to consider when purchasing a cordless screwdriver. review of the best models

What batteries can be used for screwdrivers

Power tool manufacturers always indicate in the characteristics of screwdrivers which batteries are recommended for working with them. The battery type is spelled out in several English letters. To know with which battery to choose a screwdriver, you need to understand the decoding of the abbreviation and know the advantages and disadvantages of each type of battery.

Nickel Cadmium (NiCd)

This type of battery appeared in the middle of the twentieth century. Nickel hydroxide supplemented with graphite powder acts as a cathode in it. To create the movement of ions from the cathode, an electrolyte is used - potassium hydroxide. The last key element is the anode, which here is made of cadmium oxide hydrate. The second version is metallic cadmium used in powder form.

Nickel Metal Hydride (NiMh)

This type is most often used in AA batteries. They began to be developed in the late 1970s. The main substances for the accumulation of charge and its return are nickel-lanthanum, which serves as the anode, and nickel oxide, which is the counterpart, the cathode. The transfer of ions is provided by potassium hydroxide.

Lithium Ion (Li-Ion)

One of the new generations of batteries, which first appeared in 1991. Japanese radio engineering companies began to actively use them, and subsequently they managed to increase their power and use them with power tools.

This type is used in mobile phones, laptops and electric vehicles. Their cathode and anode are made of aluminum and copper foil, between which a perforated separator is installed. A valve may be present to vent the internal pressure.

Differences in Sparky models

Models BR2 10.8Li HD, BR2 10.8Li – C HD, BR2 7.2Li refer to cordless drills. The voltage during operation does not exceed 10.8 volts. In terms of charging time, all three models take approximately the same time - half an hour. Such models are comfortable with a handle - it is much more convenient to hold a screwdriver in an upright position than it will resemble a handle in shape. All three tools come with two batteries, which makes their use even more convenient (the main thing is to use the rules for using batteries). The weight of the models is also about the same - about 1 kilogram. Thanks to this, the hand does not get tired and the process does not seem so tedious.

BUR2 18 Li HD (2/4 Ah), in addition to two batteries, also has an additional handle. Considering that this screwdriver has the functions of a drill, they come in handy. The model has a high torque (75 N * m) and 25 steps of its adjustment.

The BAR 12E is a cordless angle drill that allows you to work in the most difficult-to-reach places. For added convenience, the work area is illuminated with built-in LEDs. The voltage of this device is 12 volts, and the battery type is Ni-Cd.

How to choose?

When it comes to choosing a battery for a screwdriver, the task comes down to the selection of the electrical device itself, complete with which there will be a battery of a specific model.

The rating of inexpensive cordless screwdrivers this season looks like this:

• Makita HP331DZ, 10.8 volts, 1.5 A * h, lithium;
• Bosch PSR 1080 LI, 10.8 volts, 1.5 A * h, lithium;
• Bort BAB-12-P, 12 volts, 1.3 A * h, nickel;

• Interskol DA-12ER-01, 12 volts 1.3 A * h, nickel;
• Kolner KCD 12M, 12 volts, 1.3 A * h, nickel.

The best professional models are:

1. Makita DHP481RTE, 18 volts, 5 A * h, lithium;
2. Hitachi DS14DSAL, 14.4 volts, 1.5 A * h, lithium;
3. Metabo BS 18 LTX Impuls 201, 18 volts, 4 A * h, lithium;
4. Bosch GSR 18 V-EC 2016, 18 volts, 4 A * h, lithium;
5. Dewalt DCD780M2, 18 Volt 1.5 A * h, lithium.

The best cordless screwdrivers in terms of reliability:

1. Bosch GSR 1440, 14.4 volts, 1.5 A * h, lithium;
2. Hitachi DS18DFL, 18 volts, 1.5 A * h, lithium;
3. Dewalt DCD790D2, 18 volts, 2 A * h, lithium.

This voltage is considered the industry professional standard for lithium batteries.Since a professional tool is designed for long-term active work, and also implies an additional level of comfort, a significant part of the produced 18-volt screwdriver batteries are fully compatible with each other, and sometimes even interchangeable between tools from different manufacturers.

In addition, the 10.8 volt and 14.4 volt standards are widely used. The first option is found only among the most inexpensive models. The second is traditionally a "middle peasant" and can be found both among professional models of screwdrivers and in models of the middle (intermediate) class.

But the designations of 220 volts in the characteristics of the best models cannot be seen, since this indicates that the screwdriver is connected with a wire to a household power outlet.

Advantages and disadvantages

• The main advantage of lithium batteries is their high electrical capacity. This allows you to create a lightweight and compact hand tool. On the other hand, if the user is ready to work with a heavier device, he will receive a very powerful battery that allows the screwdriver to work for a long time.
• Another advantage is the ability to fill lithium batteries with energy relatively quickly. A typical full charge time is approximately two hours, and some batteries can be charged in half an hour with a special charger! This advantage can be an exceptional reason for equipping a screwdriver with a lithium battery.

Lithium batteries also have some specific disadvantages.

• The most noticeable is the significant drop in practical capacity when operating in cold weather. At subzero temperatures, tools equipped with lithium batteries have to be warmed up from time to time, and the electrical capacity is fully restored.
• The second noticeable drawback is not too long service life. Despite the assurances of the manufacturers, the best samples, with the most careful use, withstand no more than three to five years. Within a year after the purchase, a lithium battery of any common brand, with the most careful use, can lose up to a third of its capacity. After two years, hardly half of the original capacity will remain. The average period of normal operation is two to three years.
• And another notable drawback: the price of lithium batteries is much higher than the cost of nickel-cadmium batteries, which are still widely used in handheld power tools.

What difficulties can you face during modernization?

Before starting work, it is necessary to determine the feasibility of revision. It is wiser not to remodel a poor-quality or long-used tool - it is unprofitable.

The cost of the necessary materials and the effort expended will be 2/3 of the cost of the equipment itself.

• Lithium 18650 batteries (only they will work as a replacement) are 6.5 cm long and 1.8 cm in diameter. The Ni-CD receptacle will not work with Li-ion. The batteries will have to be placed in the battery case. In this case, you will need to independently perform the installation of wires and a protective microcircuit.
• The Li-ion output voltage is 3.6 V. This parameter for Ni-CD is 1.2 V. New batteries may simply be incompatible with the equipment.
• Lithium-ion batteries will not withstand a recharge voltage of more than 4.2 V and a discharge voltage of up to 2.7 V. Working in this mode will very quickly destroy the battery cells, so the installation of a protective board is mandatory.
• The native charger (supplied with Ni-CD equipment) cannot be used for Li-ion in 8 out of 10 cases. You will need to buy a new one. If there is no purchase in the plans, then it is also necessary to remake the charger of the screwdriver to work from lithium batteries, which can also have its own difficulties.

All the inconveniences cannot be ruled out by reworking the instrument.

The new one shows poor performance when used at low temperatures.

Pros and cons of modernizing a screwdriver

The replacement is carried out for other reasons:

• The capacity of lithium-ion batteries is 2 times that of nickel-cadmium batteries of the same parameters;
• There is no "memory effect" charge. Charging can be carried out at any discharge of the cell, at any time.
• The 18650 standard will lighten the weight of the structure. It will be easier and easier to work with.

Do not forget about the need to install a protective board (overheating, the Li-ion cell explodes, can provoke a fire) during work.

Choosing a screwdriver

For high-quality and easy use, the screwdriver should be light in weight, have a reverse motion (reverse) to release a stuck screw, it is desirable that the "blow" function is available, as well as several speed modes. Another important aspect is torque. Usually, for wood, devices with a minimum torque of no more than 15 rpm are used. To the maximum, it is more efficient to purchase a screwdriver with the highest torque, for example, professional ones reach more than 1,000 revolutions.

Modern screwdrivers are rechargeable, that is, they do not have a mains wire, but are only charged from the mains. Therefore, the choice of a battery is an important task for further operation. After all, if your instrument is constantly "on charge", there will be little sense from it. There are several types of batteries for these devices.

• Ni-Cd or nickel-cadmium is the very first and most popular type of battery among screwdrivers. It is believed that such a battery is designed for 1,000 charges and is most suitable for home use.
• Ni-MH or Nickel-Metal Hydride is slightly worse, as its battery capacity decreases over time due to frequent charges. This model is usually rated for 500 charges.
• Li-Ion or lithium ion is considered the most environmentally friendly, with no harmful cadmium. The only drawback is that it does not tolerate negative temperatures well. Therefore, it must be stored carefully, preferably at room temperature. According to the characteristics, the storage temperature is stated not lower than -10 and not higher than +60 degrees.

How to remake and assemble?

Often, the master already has an old cordless screwdriver that suits him completely. But the device is equipped with outdated nickel-cadmium batteries. Since the battery will still have to be changed, there is a desire to replace the old battery with something newer. This will not only provide more comfortable work, but also eliminate the need to look for batteries of an outdated model on the market.

The simplest thing that comes to mind is to assemble a power supply from an electronic transformer in an old battery case. Now you can use the screwdriver by connecting it to the household power supply.

14.4 volt models can be connected to car batteries. Having assembled an extension adapter with terminals or a cigarette lighter plug from the body of an old battery, you get an indispensable device for a garage or work "in the field".

If we convert an old battery pack to lithium, we can take into account that 18650 lithium cells are extremely widespread in the market.This way, we can make screwdriver batteries based on readily available parts.

Moreover, the prevalence of the 18650 standard allows you to choose batteries from any manufacturer.

Opening the case of the old battery and removing the old filling from it will not be difficult

It is important not to forget to mark the contact on the case to which the "plus" of the old battery assembly was previously connected.

Depending on the voltage for which the old battery was designed, it is necessary to select the number of lithium cells connected in series.The standard voltage of a lithium cell is exactly three times that of a nickel cell (3.6 V instead of 1.2 V). Thus, each lithium replaces three nickels connected in series.

By providing for the design of the battery, in which three lithium cells are connected one after the other, it is possible to obtain a battery with a voltage of 10.8 volts. Among nickel batteries, these are found, but not often. When four lithium cells are connected to a garland, we already get 14.4 volts. This will replace both 12 volt and 14.4 volt nickel batteries - these are very common standards for nickel cadmium and nickel metal hydride batteries. It all depends on the specific model of the screwdriver.

After it was possible to determine the number of successive stages, it will probably turn out that there is still free space in the old building. This will allow two cells to be connected in each stage in parallel, which will double the battery capacity. To connect lithium batteries to each other in production, a nickel strip is used. Sections of the tape are connected to each other and to lithium elements by resistance welding. But in everyday life, soldering is quite acceptable.

Soldering lithium cells should be done with great care. The joint must be thoroughly cleaned beforehand and a good flux must be applied. Tinning is done very quickly, with a well-heated soldering iron of sufficiently high power.

The soldering itself is done by quickly and confidently warming up the place where the wire is connected to the lithium cell. To avoid dangerous overheating of the element, the soldering time should not exceed three to five seconds.

It is good that now there are ready-made electronic control and balancing modules on sale at fairly low prices. It is enough to choose a solution that suits your particular case. Basically, such controllers differ in the number of series-connected "steps", the voltage between which is subject to equalization (balancing). In addition, they differ in their permissible load current and temperature control method.

In any case, it is no longer possible to charge a homemade lithium battery with an old nickel battery charger. They have fundamentally different charging algorithms and control voltages. You will need a dedicated charger.

Battery types

Screwdriver batteries are classified into three types:

1. lithium-ion - the most advanced type of battery. Compact, lightweight battery. Developed by the SONY concern (Japan). Due to the lack of memory effect, the battery can be charged with any amount of consumed energy and removed from the charge when not fully charged. Withstands up to 700 recharges. Suitable for professional use. This leads to a higher price in comparison with other batteries. Does not function in the cold.
2. Nickel-metal hydride is more modern, lightweight, environmentally friendly, keeps charging for a long time. You can store it even with an unused battery. There is a low memory effect. Wear resistant. Works poorly in the cold. Convenient for indoor work. The battery, if used correctly, can be charged up to 500 times. The battery must be fully charged.
3. Nickel-cadmium is a time-tested battery. Heavy and bulky enough. At the same time, it is the longest-playing one, withstands up to 1000 recharges. It has a high memory effect, therefore, it is impossible to put on recharge until the entire previous charge has not been fully used. Otherwise, the battery will lose power. Weighs more than other batteries. Store such a battery completely discharged to zero so as not to fail. The plus is that it can work at low temperatures.

In the future, the battery gives only the amount of energy that was before setting for recharging.