A power screwdriver is one of the most popular power tools in home and professional activities. It allows not only to twist and twist various types of fasteners, but also to drill holes. By the method of power supply, the devices are divided into network and battery. Models with batteries are practically not inferior in performance to tools operating on a 220 V network. At the same time, they can be used to carry out work operations in offline mode. It is also convenient that the power cord does not restrict movement. But you should properly charge and store the battery of a screwdriver so that it lasts a long time. Many problems with the battery pack can be fixed by yourself, using a multimeter to identify the cause of the malfunction.
Screwdriver battery device
The battery is an energy source for cordless screwdriver models. Due to the occurrence of physicochemical processes (electrolysis), this element accumulates electricity, and then produces a constant voltage of the desired value at its respective outputs. Voltage and capacitance are the main parameters of any drive. The first shows the potential difference between the cathode and the anode of the battery. Voltage is measured in volts. The capacity determines the amount of current issued by the battery for 1 hour, therefore this parameter is measured in ampere-hours.
For different models, the battery pack (battery) looks and is designed in a similar way. It consists of the following structural elements:
- cases with contacts located on it;
- power elements (batteries);
- temperature sensor circuit (thermistor), which performs the function of protecting the unit from overheating (range is from 50 to 600 degrees).
Not all models are equipped with thermistors. The case is usually a two-piece plastic box. He basically has about 10 batteries inside, and sometimes there are more. In this case, the batteries are connected to each other in a chain. The free terminals of the extreme cans are connected to the contacts located on the housing, designed to power the electric motor of the instrument and connect to the charging equipment. Battery output voltage determined by summing this parameter of all batteries connected into a single circuit.
There are 4 contacts on the battery case:
- 2 power ("", "-"), designed for charging and discharging;
- one control top connected to a thermistor;
- one contact used for charging from special stations that are able to equalize the charge value of all the batteries available in the unit.
By type of batteries rechargeable drives are divided into the following types:
- nickel metal hydride (designated NiMh) with an output voltage of 1.2 V;
- nickel-cadmium (labeled NiCd) output also give 1.2 V;
- lithium-ion (denoted by Li-Ion symbols), in which the voltage depends on the number of power elements in the battery and can be in the range of 1.2-3.6 V.
Lithium-ion batteries have a control board. At the same time, a special controller monitors the operation of batteries.
A separate battery consists of the following structural elements:
- positive and negative contacts;
- positive charge electrode;
- external cover of the body;
- negative electrode.
Nickel-cadmium energy storage devices are most widely used due to the affordable price, compact size and large capacity. They can be recharged more than 1 thousand times.
General battery charging rules
In order to properly charge the screwdriver battery, a certain external battery must be provided. temperature condition. The optimal temperature is from 10 to 40 degrees. An undesirable point is a possible overheating of the battery pack during charge accumulation. To avoid possible negative consequences of this phenomenon, it is necessary to disconnect the battery for cooling from the charger.
It is not recommended that after the batteries have reached full capacity, left in a disconnected charger or inserted into a screwdriver, which will then not be used, it is better to put them in a case from under the tool.
Battery packs that are not used for a long period of time are recommended to be recharged once a month.
The recommended battery charging time is from 30 minutes to 7 hours and depends on its type. For a specific model of power tool, it is indicated in the operating instructions. These instructions must be followed exactly so that the product lasts a long time. Most Chargers equipped with indicators, showing at what stage the process is. In such cases, by lighting up LEDs of a certain color, it is not difficult to determine how much batteries need to be charged. After reaching the full capacity level, you must immediately stop the process.
The nuances of charging various types of batteries
Charging various types of battery packs has its own characteristics. They are related to the properties of the materials of which the batteries are made. For regular recharging of battery packs, pulsed or conventional chargers are used. Adapters of the first type are equipped with professional power tools, and the second. models for domestic use. New or discharged drives during storage must be properly charged before use, taking into account their characteristics.
So, nickel cadmium batteries different pronounced "memory effect". The first time it is recommended to charge them three times in a row, each time at the same time completely discharging. Only in this way will the maximum (working) value of the battery capacity of the drive be achieved. After that, you need to conduct a regular connection of the screwdriver to the charger when its power drops to a minimum.
Video: How to Store a Screwdriver Battery Properly
At nickel metal hydride batteries there is also a “memory effect." Before the first use, it is recommended to repeat the full charge / discharge cycle for them 4-5 times. With further use, the charge is replenished as necessary.
If the initial charging of the nickel-cadmium and nickel-metal hydride batteries is not performed correctly, then the capacity of their batteries will gradually decrease.
Lithium battery packs least whimsical. There are no special rules for them, because there is no “memory effect". Lithium-ion nutrients can maintain their initial levels of working capacity for a long time. Each time it is not necessary to bring them to full charge / discharge.
Charging methods without using a special charger
When a standard charger is missing or simply broken, you can do without it. Craftsmen came up with different ways to recharge the battery from different sources. To charge the battery of a screwdriver without a conventional charger, you can use:
- car charging;
- universal type charger;
- external sources of electricity.
The best option for car charging is a device with the ability to control the magnitude of the voltage and current. The main thing in such cases is to avoid overcharging. For this, the charging current is set so that the process goes from 0.5 to 0.1 A h, depending on the size of the total capacity. For example, if it is 1.3 A h, then the current should be from 650 to 130 mA.
When the current values are too large, and the regulator cannot set lower values, additional resistance is used, for example, a car lamp. It is connected in series to the battery pack.
Universal charging convenient in practice. They have many additional settings that allow you to optimally select the appropriate current parameters for recharging batteries from various power tools.
External power sources They are mainly used for worn screwdrivers, for whom it is not economically feasible to purchase new batteries. In such cases, the power tool is upgraded in a certain way, and an appropriate connection diagram is developed. An example is a redesigned USB charge, additionally equipped with a fuse.
Battery Storage Recommendations
It is recommended to store any type of battery by disconnecting it from the screwdriver. Each type of battery also has its own characteristics in this regard:
- Nickel-cadmium batteries must be discharged before storage to such an extent that the screwdriver does not work at its full capacity;
- Nickel-metal hydride batteries are recommended to be kept fully charged, but their small discharge is still allowed;
- Before storing a lithium-ion battery, it also needs to be discharged, but only half.
After a long storage period nickel metal hydride batteries, capable of withstanding 200 to 300 recharge cycles without loss of capacity, it is necessary to recharge within 24 hours. Blocks of this type are distinguished by a significant self-discharge parameter.
As mentioned above, lithium ion power cells deprived of the "memory effect". They have a large capacity and the lowest self-discharge rate. You can recharge their charge at any time, despite the degree of discharge.
Do not completely discharge Li-Ion batteries, because this may cause the built-in electronic protection system to turn off against rising temperatures or voltages.
In order to achieve 50% of the charge required for proper storage, lithium-ion batteries need to be charged from almost zero level for a period of about 65% of the time it takes to reach full capacity.
Compliance with the simplest recommendations on the storage and charging of various types of battery packs will make it possible to develop the entire resource of batteries inherent in them by manufacturers.
Checking the battery status with a multimeter
Not always, when the battery runs out quickly or does not function at all, you need to buy a new one or carry the unit to the service center specialists. In many cases even an inexperienced electrician will be able to find the cause of the malfunction independently, having familiarized himself with the search algorithm. To do this, you will need to use a multimeter or instruments similar to it in measuring capabilities. In addition to this device, you will also need the following tools:
- soldering iron with a set for soldering;
In order to accurately determine the cause of the battery malfunction, it is necessary to find out the performance of each individual power supply. But first recommended check charger. With a multimeter, this is done in this way:
- turn on the device;
- set the switch of the measured values of the multimeter to a constant voltage;
- install the probes in the corresponding sockets of the multimeter and touch them to the contacts ("" and "-") of the charger;
- compare the value displayed on the instrument panel with the output voltage of the charger specified in the operating instructions or on the case;
- if the values do not match, then repair the adapter or buy a new one.
Whenever possible, the measurement range that is closest to the output voltage indicated on the charger is selected on the device used.
To check screwdriver battery multimeter, perform the following steps:
- fully charge the battery pack;
- check the output voltage of the battery with a multimeter by setting the device switch to its constant value, and touch the plus and minus with the probes;
- if the discrepancy of the measured parameter to the value specified in the operating instructions is established, then the battery pack is disassembled and all batteries are removed;
- when there are no damaged banks (leaked or swollen), then check the voltage at the terminals of each battery with a multimeter, first using a soldering iron to solder the circuit;
- the load is connected to the batteries in turn for the same time (for example, a lamp of the corresponding voltage);
- on which battery the greatest drawdown occurred, it is damaged.
For testing, nickel-metal hydride and nickel-cadmium energy storage devices are completely discharged. this is done in order to avoid the "memory effect".
When checking batteries, it should be noted that for nickel-cadmium and nickel-metal hydride types of batteries, the output voltage should be in the range from 1.2 to 1.4 V, and for lithium ones from 3.6 to 3.8 V.
If you find a defective battery, you can replace it with a new one or try to temporarily restore it by adding distilled water or exposure to high voltage. You can also use a multimeter measure current: if it grows and in the first hour exceeds 1 A, then the battery is considered operational.
If there is no voltage at the output of the battery, then there is a high probability of breaking the integrity of the circuit inside the unit. At the same time, they also disassemble the block and first search visually, and then with the help of a multimeter, the place of the cliff.
Before using the new cordless screwdriver, you must carefully study the instructions for use of this product supplied by the manufacturer. The features of the type of batteries installed on the power tool should be taken into account in order to properly charge them and also to store them for a long time. Compliance with simple recommendations will extend the battery life to a complete exhaustion of the resource. When there is no branded charger, then the alternative charging methods mentioned above will temporarily help.
If the battery capacity drops, the operating time on a single charge decreases, you can repair them with your own hands. To do this, it is enough to set the output current or voltage with a multimeter and compare their compliance with the standard values of these parameters.