What affects the battery capacity of an electric screwdriver

DeWALT DCD791P2

• Chuck type. quick-clamping;
• Maximum torque, (Nm). 70;
• Battery capacity, (Ah). five;
• Battery type. Li-Ion;
• The number of batteries included. 2.

Body and ergonomics. This model is housed in a compact plastic case with a raised rubber grip. It can be worn on a belt, which is convenient when working at height and frequent movements. The handle has a built-in LED flashlight, the brightness of which can be adjusted. Due to the increased power, the tool weighs 1.7 kg.

Engine, gearbox, battery. The electric screwdriver is powered by a brushless electric motor that does not overheat even with intensive use. It has two speeds with smooth acceleration up to 550 and 2000 rpm. To increase the operating time, two lithium-ion batteries with a capacity of 5 Ah are used.

Keyless chuck is made entirely of high quality steel. The maximum torque of 70 Nm allows you to work with self-tapping screws of any running size.

Functional. The electric screwdriver accepts accessories with a shank diameter of up to 13 mm. It is powerful enough to drill 40 mm round holes in wood. Reverse and motor brake option available.

• Powerful and reliable electric motor.
• Full metal gear and chuck.
• Electronic speed control.
• Large battery capacity.
• Adjustable backlight brightness.
• High price.
• Perceptible weight.

The effect of storing the charge level

This phenomenon is called “memory effect”. If the battery on the instrument was not completely discharged and then put on charge, then the residual charge level begins to be perceived by the battery as zero. Having charged to a full stage, it will function until the energy supply reaches a new level, and after that it will report that it is discharged, although the container will not be completely emptied.

In view of this phenomenon, the master has to make sure that the battery is completely discharged, and only then put it on charge. This is not always convenient if there is still a charge at the end of the day, and tomorrow there is a lot of work ahead. All types of nickel batteries have a memory effect. But lithium-ion models can be charged at any time. they will always use up the accumulated energy to the end, without spontaneous decrease in capacity.

Full discharge ratio

This is an important aspect affecting battery life, which can be significantly reduced by improper use. All modern lithium batteries cannot be fully discharged. The optimal storage condition is 40% charge. If you generate all the energy to 0, then this can completely disable the drive.

Therefore, such elements must be put on recharge even if the instrument is still working well. Both types of nickel batteries tolerate full discharge well and can be operated until the electric screwdriver stops turning.

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.

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.

Cordless screwdriver battery replacement and test (before and after)

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 release internal pressure.

Don’t buy cordless electric screwdriver before you see this

Which battery is best for an electric screwdriver

The battery is an essential element of any electric screwdriver. Its technical characteristics affect how powerful the tool will be, how long it can work and how comfortable it is. For this reason, in order for the choice to be really high-quality, it is necessary to understand the design features of the battery, which is what today’s article will be about.

What types of batteries are there

The battery should be chosen based not only on the available amount, but also on the expected frequency of operation with an electric screwdriver. At the moment, the following types of batteries are distinguished with which the tool is completed:

• Nickel-cadmium. this type of battery is obsolete, but this does not prevent them from successfully competing with more modern devices. It is popular for its affordable cost. Compared to metal hydride, nickel-cadmium is almost 2-3 times cheaper. When compared with other types, the difference in cost is even more noticeable. The main negative quality of this type of battery can be called the “memory effect”. If you do not follow the charge / discharge cycle, then the capacity of the battery can be significantly reduced, to the point that it will fail.
• Nickel-Metal Hydride. These batteries also have the disadvantage of a nickel-cadmium sample, but this is largely minimized. The “memory effect” is present here, but it is expressed much less. These batteries are good for their increased capacity and significantly reduced self-discharge. Compared to nickel-cadmium products, this type of battery is more expensive.
• Lithium-ion. there are simply no shortcomings of the previous two types. However, there are still weaknesses. Li-on batteries cannot be completely discharged or, conversely, recharged. They will simply be destroyed (even explode). As a result, the technical requirements for the device itself increase. Advantages: high specific capacity, compactness and light weight, better coefficient of electrical density, no memory effect. Disadvantages: does not tolerate negative temperatures well, the battery cannot be restored, it is expensive, you can only use the factory charger.
• Lithium polymer is a modern development based on li-ion technology. It is worth noting that such batteries are practically not used in electric tools, since they are characterized by high cost. The main distinguishing feature is that the standard electrolyte is replaced by a gel-like polymer. This made it possible not only to increase the capacity, but also to manufacture batteries of any shape. Like other products, this type has its negative qualities: a relatively short service life (about 2 years or 500 charge-discharge cycles) and high requirements for use. As noted, such types are practically not used in power tools, due to the high cost.

Features of choice depending on the scope of use

When choosing a battery, one should make a start not only on its type, but also on the purpose and to what extent the electric screwdriver will be used.

For example, if a tool is selected for production work or is needed by a person who regularly makes repairs, it will require trouble-free operation of the power tool for a long time. It is important that the battery is not afraid of high or low temperatures, different weather conditions. Great if you can charge it quickly.

In such conditions, it is best to choose a nickel-cadmium battery. This is the kind that is usually installed on powerful professional screwdrivers. In order for the tool to work truly offline, many craftsmen purchase additional and spare batteries. Thus, there is no need to stop work to recharge the battery.

In the case of household use of an electric screwdriver and with small loads, you can build on two options. If you want the battery to last about 6 years and during this period did not create any difficulties, professionals recommend the nickel-cadmium type. Li-ion is optimal if the master is able to comply with the charge-discharge conditions. Such batteries are installed in low to medium power tools, and they can be charged regardless of how discharged they are. An additional benefit. lithium-ion products are more compact and lighter, which has a positive effect on work performance.

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Battery capacity. what it affects

If the indicator is higher, then the electric screwdriver can work longer. The number of hours during which the battery will provide the maximum discharge current depends on it. Measurement unit. mA / h.

The lowest capacity indicator is inherent in nickel-cadmium products. The largest indicator is lithium-based batteries. Do not think that the battery charge of the former will not be enough to meet household needs, unless, of course, this is the construction of a house.

You can choose one or another type of battery, taking into account the operating conditions of the instrument. If the priority is low cost and durability, then nickel-cadmium products are chosen. Lithium-based batteries are great because they have more capacity.