How to Reanimate a Home Screwdriver Battery
Cordless screwdriver. a convenient mechanism that allows you to quickly cope with the repair. Instead of a heavy drill on the wire, it is better to take a lightweight screwdriver that copes with the same tasks without being tied to one place.
They have one problem. the batteries fail. There are many reasons for this:
- Long downtime. Modern lithium-ion batteries require periodic charging and discharging. They dramatically lose capacity if they are idle for a long time.
- Temperature differences. Li-Ion does not tolerate high temperatures. Therefore, there are recommendations for storing these batteries in the refrigerator. But they cannot work in such conditions.
- Overdischarge. The protection system can cause the batteries to discharge to zero and to restore them you need to apply a large current to the input.
The most common cause of failure is the failure of only one element. They are connected in series, which means that even a drop in capacity on one battery will lead to a complete malfunction of the entire battery. In this case, we need:
- Screwdriver. Typically, the case is connected to the cross screws. In some models, there is protection "from the fool" and there may be stars with an anti-vandal system, triangles or even spanners.
- Multimeter. Any model is enough, even the cheapest DT-830. Since measurements are carried out in millivolts, Soviet switch voltmeters will not work.
Next, follow the instructions:
- The battery is disconnected from the screwdriver. It must be fully charged.
- The case is disassembled.
- Now you need to remove all the cans. In Ni-Cd there are more of them, since the rated voltage of one section is less.
- Each bank measures voltage. For nickel-cadmium. nominal is 1.2 volts. In lithium. the normal voltage is in the range of 3.6-3.8 volts.
- After measuring, you need to look at which banks the voltage is reduced. For example, if the voltage on two lithium batteries is 3.8, and on one 3.5, it means that it is defective.
- The battery is assembled and installed in the tool. Now it needs to be set to zero.
- The battery is disassembled and the voltage is measured again. If the voltage on the proposed element is much lower than on the others, then it goes under replacement or repair.
General repair recommendations
How to restore a screwdriver battery? You need to have basic ideas about electrical engineering. The battery circuit is simple. Normal serial circuit (plus connects to minus).
When repairing Ni-Cd, the following recommendations should be considered:
- They have a memory effect. The classic commissioning scheme for the operation of such batteries is 3 full charges and 3 discharges to zero. A new element must go through the same buildup.
- Similar item. So that he does not get out of the chain and does not break the battery at all, the new element must fully correspond to the previous rating.
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The lithium screwdriver battery can be repaired at home, given the following:
- They can not be soldered. Intolerance to high temperatures will lead to an irreparable condition. To do this, use contact welding (it heats the electrode for a short time without harming the battery). If there is no access to the COP, soldering with a very powerful soldering iron of 100 watts is allowed. Movement must be fast and accurate.
- Same models. Now there are several major manufacturers of lithium batteries, which are used in popular foreign models of screwdrivers, such as Hitachi, Makita and domestic: Interskol, Bison.
Replacing the cans in the battery
How to repair a battery for a screwdriver? The easiest way to revive the battery is to replace one of the cans.
Need to find a defective element with a low voltage. To do this, use the tester.
Instructions on how to check the battery of a screwdriver with a multimeter:
- A conventional multimeter has two probes. red and black. From the opposite ends of the can there are two contacts (plus and minus).
- The tester selection lever is set to “constant voltage” mode. If the multimeter has automatic selection of values - this is enough. If not, you need to put the lever in position "20".
- The probes are applied to the pads and the voltage is measured. The screen shows the real voltage. If there is a “-” sign in front of the numbers, then the probes need to be exchanged with each other.
- Each jar is checked by this algorithm.
When a broken element was found, it simply solders and changes. You need to use a powerful soldering iron so as not to overheat the jar.
Topping up with distilled water
Restoring the screwdriver battery with topping up should take place with a fully discharged battery. Ni-Cd batteries are covered with paper. If there was evaporation, then there will be noticeable traces on the surface.
After measuring the voltage, you need to completely discharge all the banks using a 12 volt light bulb. After that, the voltage is measured again. Those elements where it fell to 0.7 are faulty.
To fill with distilled water, you need to make a hole in the side of the can. A very thin drill (0.5-0.7 mm) is a groove. It is necessary to ensure that it does not go inside and does not damage the plate.
A small amount of water is poured into the syringe with a thin needle. After that, the breakdown must be closed with epoxy resin or sealant.
Now the battery can be shaken. Each block must be discharged once again to zero by attaching 1.5 volt bulbs to them. When the procedure is over, the battery is collected and it is necessary to conduct 5 cycles of charging and discharging.
Repair and replacement of battery cells
Do it yourself repairing a screwdriver battery can be more overwhelming. For example, the conversion of Ni-Cd to lithium. To do this, you need to purchase several Li-Ion batteries and a charging board. The number of batteries should correspond to the original voltage rating.
As practice shows, most screwdrivers can easily be converted from one type of battery to another, without any problems. Thanks to the increased endurance, resistance to constant use and larger capacity, the old screwdriver will work much longer.