Battery warms up when charging an electric screwdriver
One of the most universal power tools nowadays is an electric screwdriver. Variety of nozzles, adapters and accessories makes it indispensable for any repair.
But the main advantage of an electric screwdriver is its mobility. Using a rechargeable battery for an electric screwdriver allows you to work quickly and not think about extension cords and outlets. At field sites or just outdoors. But rechargeable batteries have a limited lifetime. In order to prolong the life of the battery, it must be properly charged.
Battery charger types
The popularity of a screwdriver is due to the fact that it simplifies the process of screwing or unscrewing various fasteners. Characterized by mobility and small size, it is indispensable for assembling furniture, dismantling equipment, roofing and other construction works. The tool owes its mobility to the rechargeable batteries it contains.
The advantage of using rechargeable batteries is that they can be used repeatedly. Batteries, while giving the accumulated energy to the device, periodically need to recharge themselves. Chargers are used to restore the value of their capacity.
There are two ways to charge a screwdriver battery: with a built-in charger or with an external charger. Built-in charger allows you to charge the battery without removing it from the screwdriver. The capacity recovery circuit is located right next to the battery. Whereas remote charging involves removing them and placing them in a separate fixture for recharging. A distinction is made between chargers based on the type of batteries that can be regenerated. The batteries used can be:
the final cost of a screwdriver, not least of all, depends on the type of batteries used and the charger capabilities. Chargers are available for 12 volts, 14.4 volts and 18 volts. In addition, chargers are differentiated by their capabilities and can have:
The most used battery chargers use a slow charge due to the low current. They have no operating display and do not turn off automatically. This is more true for built-in capacity recovery devices. Chargers based on pulse circuits provide the possibility of rapid charging. They switch off automatically when the required voltage is reached or in the event of an emergency.
The types of batteries used
Nickel-cadmium batteries have no problems with rapid charging. Such batteries have a high loading capacity, low price and can safely operate at minus temperatures. The disadvantages include: memory effect, toxicity, high self-discharge rate. Therefore, before recharging this type of battery, it must be completely discharged. The battery has a high degree of self-discharge and discharges quickly, even if not used. Currently hardly available due to its toxicity. Of all types have the lowest capacity.
Nickel-metal hydride batteries are superior to NiCd in every respect. They have a lower self-discharge value, less memory effect. They have a higher capacity for the same dimensions. They do not contain any toxic material, cadmium. In the price category this type ranks in the middle, so it is the most common type of capacitive cell in the screwdriver.
Lithium-ion ones are characterized by high capacity and low self-discharge value. These batteries do not tolerate overheating and deep discharging. In the first case, they can explode, and in the second case, they can no longer restore their capacity. They are also able to operate at negative temperatures and have no memory effect. The use of microcontroller-controlled charging stations has made it possible to protect the battery from overcharging, thus making this type the most attractive for use. They are more expensive than the first two types.
In addition, the main characteristic of batteries is their capacity. the higher the value, the longer the screwdriver will work. Capacity unit is milliampere per hour (mA/h). The battery is designed so that the cells are connected in series and placed in a common case. For Li-Ion the voltage per cell is 3.3 volts, for NiCd and NiMH. 1.2 volts.
To what voltage the battery can be discharged
There is a concept of battery fully discharged in order to perform further operations and discharged to zero, which requires resuscitation. How much battery discharge depends on the type of model and the number of batteries in the battery. Cells are connected in series, the voltage at the output terminals is added together. Therefore, the discharge limit is different for acid, alkaline and lithium batteries.
Whether a new battery needs to be completely discharged? Yes, if it is the nickel-ion or nickel-metal hydride type. These batteries have a memory effect. Before you start working they need to be fully discharged 3-5 times, then recharged. Any further charging of this type of battery must be done after it has been fully discharged. Only leave the battery fully discharged for storage. How much can I discharge a nickel battery?? The cell is brought up to 0.9 for training.1,0 В. Knowing the number of cells, you can calculate for yourself, how many volts to discharge the battery.
People often ask if a new lithium-ion battery needs to be discharged. There is no memory effect in this type of cell. The device operates steadily at a medium level of charge. Therefore, you can charge the battery at any convenient moment with a special charger. Can a lithium-ion battery be fully discharged?? It is possible, but after the discharge of less than 3.2 V special charging methods must be used, at 2.0 V the cell can not be restored. A typical deep discharge is 2.5 volts per cell.
To how many volts can you discharge the banks of lead-acid battery? With a cell output voltage decrease of 1.70V the total voltage of a 6 cell battery will be 10.3V. A fully discharged battery will leave a minimum reserve of survivability. Whether an acid battery needs to be completely discharged? An unmaintained calcium car battery can be destroyed even after a single deep discharge. All acid batteries are bound to lose some capacity after a deep discharge due to plate sulfation.
Different battery types require a varied approach to maintenance. Therefore, whether it is necessary to fully discharge the battery, new or in the process of calibration and testing, is written in the instruction manual of the device.
There are situations in which an electric screwdriver charger is not available. For example, it can fail, which may cause the work stoppage. In addition, the charger can be lost. The third cause is elementary burnout and wear and tear of the charger, as well as unbent terminals in the battery itself, due to which the contact comes off. To eliminate the problem, you have to look for the right options for charging that are compatible with your electric screwdriver model. In this case, it is preferable to buy the right charger, which will promote safe operation and fully charge the battery of the tool.
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How to charge a new battery properly?
For nickel cadmium and nickel metal hydride batteries, initial charging cycles that will allow them to use their full capacity are important. Batteries of the first type must be completely discharged and then charged three times to reach their maximum capacity. Then they are charged only fully, the end of this process will be indicated by indicators or the warming of the case. Type II batteries require four to five cycles of full discharge and recharge. Then they are charged as necessary without waiting for complete discharge. However, the discharge-discharge cycles are regularly repeated 4-5 times to restore the capacity.
Differences of types of batteries in a screwdriver
The rechargeable battery is a chemical power source. It consists of several cells of a certain type. Budget electric screwdrivers use nickel-cadmium cells, sometimes nickel-metal hydride cells, more expensive ones use lithium-ion cells or lithium-polymer cells. They are called, respectively, Ni-Cd, Ni-MH, Li-ion, Li-Po. The cells in the battery are connected in series. Each cell, when charged, produces a fixed potential difference. Connected in series, these cells provide the operating voltage of the battery. Each one connected in series gives a potential difference with the neighboring one, and the two outermost ones give a total working voltage value. You can read more about batteries on Wikipedia:
When a battery is charged, electrons sequentially penetrate the batteries, and restore the chemical solution. During operation, as well as storage, oxidation of the substance occurs, and the electrons go back to a neutral state, in passing, doing useful work. This is called a charge-discharge cycle. It is not fully discharged and there is still some amount of potential difference. This is called residual voltage. The battery is based on electrolytic dissociation processes.
How long does it take to charge the battery and what does this time depend on?
It will take at least 2-3 hours, in which case the charge is enough to start the engine of the car. It is possible to charge the battery fully, but it will take 8-14 hours. When fully discharged, it takes at least 15 hours to fully charge it. If a low voltage charger is used, it will take longer to charge. To get more accurate numbers you need to consider the battery capacity.
It should take approximately 2 hours for the battery to regain its starting capacitance. you can check if the charge level has changed by measuring the voltage. Compare the reading on the multimeter screen with the discharged state. If it was about 16 V and became 1-2 volts more, then everything works fine.
After that, the charge level is checked again. This is done by plugging in the power plug, or simply connecting the battery to the onboard power supply. If the starter turns, it means the operation was successful.
How an electric screwdriver battery works
Voltage and capacity are the main parameters of any storage device. The voltage indicates what the potential difference is between the cathode and anode of the battery. It is measured in volts. Capacity determines the amount of current the battery produces in one hour. This parameter is measured in ampere hours.
Models can be different. And yet the battery packs are similar to each other by their design. The battery necessarily consists of such structural elements:
IMPORTANT! The body is usually a plastic box made of two parts. It generally has about 10 batteries inside. In some cases there are more. The batteries are connected to each other and form a chain.
The free terminals of the outermost battery terminals are connected to terminals located on the battery case. The contacts are designed to power the electric motor of the tool and connect it to the charging equipment. To determine the output voltage of a battery, you must sum up this parameter of the batteries, which are connected in a single chain.
How long does it take to fully charge
How long does it take to charge a screwdriver battery?? It should be clarified for what purpose it is being charged. Manufacturers are looking to speed up charging times, to reduce interruptions and increase competitiveness. For this reason the maximum permissible charging currents are established. Often sacrifice a 10-20% capacity charge at the end of the charging cycle.
This can be seen in the lithium battery charging graph. Where during the first hour of charging 70% of the capacity is reached, during the second hour 20% more, which makes 90%, and the last 10% takes 1 hour more, i.e. 3 hours. And the regular “Bosch” charger from China charges a lithium battery in only 30 minutes. With these subtleties in mind, you can now answer the question you asked.
It is enough to charge the battery once to operate the tool. If necessary, you can not wait for the end of charging time, and in half the time of standard charging start to work. Undercharging the batteries in isolated cases does not have any negative consequences.
Maximum charging of the battery is required for training cycles and even more so to restore the battery capacity. How do you do this with the standard battery charger if it automatically shuts off? After the voltage has stabilized, after 20-30 minutes you can continue charging the battery on the standard charger again. It will take even more energy. The charge cycle should be up to three times. So the battery will be charged to almost 100%. it is important that in the subsequent training cycle the full volume of the electrolyte is used.
New Ni-Cd and Ni-MH cells are charged with the standard battery charger for 1 to 8 hours, according to different manufacturer’s data sheets. This variation in time is caused by different settings of the charging current, depending on the manufacturer’s position on this issue. over, even chargers from the same manufacturer may have a range of up to 2 hours due to inaccuracies in the settings because in the final phase of charging current decreases extremely slowly. And the minimum current will always be.
Specialist in repair, maintenance of electrical and industrial electronics.
Tip! During long-term use of the screwdriver the actual capacity decreases. It is helpful to measure the charge time of new batteries after practice cycles and write it down on the case. Comparing with the subsequent charge time in a year, two years, you can understand how much capacity the battery has lost.
New lithium (Li) batteries charge from 30 minutes to 120. It also depends on the charger settings of each manufacturer.