How to Measure a Screwdriver Torque
Battery pack malfunctions, this is the most common problem with owners of hand-held power tools. The mechanics break less often. As a result of rush and negligence when using the tool, the battery charge and discharge mode is violated. The result is a two to three times reduction in battery life. I have to buy a new one. But before buying, it is worth checking the condition of the battery to make sure that the malfunction is indeed in it.
Battery design and types of cans
The battery for screwdrivers is designed as a small block, mating with the tool from the back, usually from the bottom of the handle. This is done for an optimal center of gravity and comfortable grip in the hand. The block is easily removed and fixed in its slot. Everything is made for convenient and quick work.
The unit itself is a plastic case with batteries inside. Since existing chemical current sources do not provide a typical power supply voltage for a screwdriver (12-18 V), they are dialed into a serial battery. The findings of the elements are connected by a metal flat bus, which is welded to them by contact welding. This method least of all heats the elements during assembly.
Thus, the battery is not repairable. In developed countries, they are disposed of without repair. Elements, or as they are simply called, “banks”, are also made non-separable, in addition, sometimes they contain harmful substances. The shape of the elements are cylindrical or rectangular.
Types of batteries
For cylindrical cells, usually Ni-Cd or Ni-MH, the electrodes, together with the active mass and the separator, are rolled up, while for rectangular cells, they are stacked, or sometimes they are also rolled. The goal of any of the methods is to maximize the area of the electrodes, which gives a maximum of the selected current with a minimum of heating. This provides a high power density of the element.
Lithium-ion cells are produced both in cylindrical and flat cases, and lithium-polymer cells with ribbon or wire leads. in flat ones.
In general, the design is similar to oil capacitors, only there the electrodes are called plates, and they are separated by a non-conductive dielectric. oil. In the case of batteries, on the contrary, the filler conducts current, it is an electrolyte solution.
Video: How to Measure a Screwdriver Torque
Battery operation is associated with corrosion of electrodes, and other irreversible chemical processes. Gradually, it loses its effectiveness and becomes unusable. An incorrect charge-discharge mode accelerates these events.
REMEMBER: Nickel-cadmium batteries need to be discharged to a minimum voltage, and only then put on charge. But lithium-ion. on the contrary, recharge more often. This extends their life.
Corrosion disrupts the shape of the electrodes, leads to ruptures and punctures of the separator and further closure of the cathode and anode. This increases self-discharge. The formation of sparingly soluble compounds in large quantities leads to an irreversible increase in internal resistance. Such compounds are obtained in the course of adverse chemical reactions, which are inevitable and limit the service life.
Guide to action
Before declaring the battery unusable, you need to check it for proper operation.
To check the battery, you will need to have a voltmeter, ammeter, connecting wires and devices for capturing contacts: clips such as crocodiles or clamps. Sometimes the design of the contacts of the battery pack does not allow connecting devices without disassembling the case. It is very possible that you have to deal with soldering. Here is the list of necessary:
- Charger (original or compatible);
- Multimeter (or better two);
- Resistance 4.7 10 Ohms for a power of 5 W or more;
- Automobile lamps for 12 V, several pieces;
- Installation wires, section 0.5 mm.kv, 1.5-2 m;
- Sharp knife;
- Soldering iron with solder and flux.
Instead of a native charger, a laboratory power supply would be very suitable, with a voltmeter and an ammeter for a current of several amperes and a voltage of several volts higher than the rated battery. For example, switchgear from a car, if it has good built-in instruments for measuring current and voltage.
A multimeter is most often used to check the battery of a screwdriver, it is also suitable for measuring battery capacity.
In addition to everything else, you need to prepare a convenient workplace with good lighting, remove flammable liquids and objects away.
You will need to set the type of battery first. It is written on its body. Nominal voltage and capacitance should be indicated there in ampere-hours or sometimes watt-hours. The voltages used can be from a number: 9.6, 10.8, 12, 14.4, 18, 24, 36 V. The type of batteries and the voltage rating make it possible to determine the number of cans inside the unit: