How To Replace The Battery For A 12 Volt Screwdriver

Batteries for a household screwdriver 18 volt:

What are, what advantages and disadvantages they have, how they differ from each other.

Nickel metal hydride

The development of this battery was carried out in order to solve the main problems that arise when using nickel-cadmium batteries in a screwdriver. These more advanced products offer the following benefits:

Less weight and compact size;
Low toxicity;
The presence of a mild memory effect;
The presence of a higher indicator of specific capacity;
The presence of such products of high resistance to mechanical damage.

Lithium polymer

This state-of-the-art power tool battery uses lithium-ion technology. Them the cost is quite high, therefore, they are extremely rare in household power tools. Their main difference from lithium-ion batteries is that they use a gel polymer instead of a traditional electrolyte. Its use allowed the manufacturers of these products to increase the battery capacity, as well as get rid of the restrictions regarding the shape of the product body. In addition, such batteries are less explosive.

18 volt batteries for household screwdriver

The main element of this type of power tool is the battery. It provides its work for several hours, and then requires recharging. To work effectively with the cordless screwdriver, when choosing a tool pay special attention to the battery, which it will be equipped with. How to choose the right battery for a cordless screwdriver will be discussed in this article.

Disadvantages

Any type of battery has disadvantages. If we talk in relation to these, then they have the following:

Large dimensions and substantial weight;
The presence of a pronounced memory effect.

Nickel-cadmium batteries have another problem. The thing is that there is a high probability that the popularity of these products will soon come to naught. The main reason for this is that cadmium is a toxic material. In addition, such batteries must be disposed of in a special manner. The procedure itself is quite expensive. As for everything else, such batteries simply do not have any competitors.

By using a nickel-cadmium battery for your tool, you can ensure efficient operation in the following situations:

Reliable operation of the device is required;
The user wishes to purchase a battery with a long service life, which is able to withstand more than one thousand charge and discharge cycles;
It is necessary that the storage period of the battery is long;
Performing work requires the use of large charging currents;
The work will have to be carried out in difficult operating conditions;
Often there is a need to perform work in low temperature conditions;
Requires a battery that is able to maintain the voltage at a stable level throughout its life.

Thus, similar batteries are an excellent choice for not only screwdrivers, but also for any power tool.

Li-ion

Many manufacturers are actively promoting lithium-ion batteries. Such products have both advantages and certain disadvantages.

Nickel-cadmium

These batteries appeared over a century ago. However, despite their long history, they surpass modern types of storage batteries in a number of performance characteristics.

Motorcycle

They differ in weight within 24 kilograms. Voltage 6 and 12 volts.

Automotive

The question often arises whether it is possible to connect a screwdriver to a car battery. Indeed, you can use a battery that has worked out its resource, the capacity of which is already small for a car, but sufficient for a hand tool. The standard voltage of car batteries is 12 volts.

In view of the mass of 14 kilograms, it is advisable to use such source in a stationary workplace, scaffolding or mobile platforms. Wire length 23 meters. Charging will have to be done with a third-party device due to the high charging current.

How to replace the battery for a screwdriver

It should be noted right away that the handicraft modifications will reduce the screwdriver‘s mobility due to the additional wire from the new power source and its weight. On the other hand, the battery life will increase up to 1220 hours, versus 23 with the native battery. This will be very useful in remote sites without power supply.

For convenience and safety, double-insulated flexible wire such as PVA and ShVVP should be used. Section 0.75 mm 2 and more. You can connect it in two places:

To the screwdriver handle;

To the body of the old battery.

The cast body is cracked with a sharp blow to the screwdriver, or is separated by a hacksaw blade at the soldering point. Then the old lead battery is removed, and power is connected to the free wires, observing the polarity, from a new source.

Gel (batteries for UPS)

Their advantage is in a sealed body and a pasty electrolyte, which allow the instrument to be used in any spatial position. It is possible to use a charger from a screwdriver. Here you can not be afraid of acid burns or spoiled clothes. You can attach the battery directly to a screwdriver or carry it in your bag or pockets.

Battery selection

The main parameter that needs to be taken into account is the supply voltage indicated in the passport or on the case. The motors used in screwdrivers also operate at reduced voltage, losing somewhat in speed and torque. The most affordable of the batteries will be acid batteries for cars, motorcycles, and also for uninterruptible power supplies.

How to power a screwdriver from a third-party battery

The service life of the screwdriver is 57 years, and the battery life is at best 2 years. This means that by replacing the power source, it will be possible to extend the life of the beloved instrument by at least 2 years. Of course, it is best to find an original battery, but the problem is availability and cost.

Instruments

The cost of a new screwdriver is approximately 70% of the cost of the battery for it. Therefore, it is not surprising when, faced with a battery failure, we ask ourselves what next? To buy a new battery or screwdriver, or maybe it is possible to repair the screwdriver battery with your own hands and continue working with an already familiar tool?

In this article, which we will conventionally divide into three parts, we will consider: the types of batteries that are used in screwdrivers (part 1), their possible causes of failure (part 2) and available repair methods (part 3).

Is it possible to reanimate the elements and how?

Let’s proceed to part 3 of repairing a screwdriver battery and immediately make a reservation that the concept of resuscitation for lithium-ion batteries is not applicable. There is no memory effect in them, most likely, lithium decomposition has occurred, and nothing can be done about it. In such batteries, it is necessary to find out what the cause of the malfunction is: the element itself or the control circuit. There are two options here:

We change the control scheme from another, but similar to ours, battery, if it helped, we find a replacement and change;
Apply 4V to a cell with a current of about 200mA, this requires an adjustable charger. If the voltage on the element rises to 3.6V, the element is good, the problem is in other elements, or in the control circuit.

Screwdriver battery refurbishment is available primarily for Ni-Cd batteries, but these are generally the most common in household screwdrivers.

So how do you reanimate a screwdriver battery? There are two types of resuscitation for these types of batteries:

Compaction or compression method (it will work in cases where the electrolyte is still present, but the volume is lost);
Firmware with voltage and current greater than nominal. This method allows you to eliminate the memory effect, and although not completely, but to restore the lost capacity.

This method is shown below on.

This method, if its result is positive, will not solve the problem of element failure. Rather, it will only delay the replacement of those that have become unusable and in the future you will still need to repair the battery of the Makita screwdriver or any other.

Screwdriver battery: design and types

It should be noted that regardless of the brand of the screwdriver and the country of manufacture, the batteries have an identical structure. The assembled battery pack looks like this.

How To Replace The Battery For A 12 Volt Screwdriver

If we disassemble it, we will see that it is assembled from small elements that are assembled sequentially. And from the school physics course, we know that elements that have a serial connection harmonize their potentials.

Typesetting parts or cans, as a rule, have a standard size and voltage, they differ only in capacity. Battery capacity is measured in Ah and is indicated on the cell (pictured below).

For the arrangement of screwdriver batteries, the following types of elements are used:

Nickel cadmium (Ni Cd) batteries, with a nominal voltage of 1.2V on the banks;
Nickel-metal hydride (Ni-MH), voltage across elements 1.2V;
Lithium-ion (Li-Ion), with a voltage of 3.6V.

Let’s consider in more detail the advantages and disadvantages of each type.

The most common type due to its low cost;
Low temperatures, such as Li-Ion batteries, are not scary;
It is stored in a discharged state, while maintaining its characteristics.

Produced only in third world countries, due to toxicity during production;
Memory effect;
Self-discharge;
Small capacity;
A small number of charge / discharge cycles, which means they do not last long with intensive use.

Environmentally friendly production, it is possible to purchase a high-quality branded battery;
Low memory effect;
Low self-discharge;
High capacity compared to Ni Cd;
Charge / discharge cycles.
Loses some of its characteristics during long-term storage in a discharged state;
Does not live long at low temperatures.
No memory effect;
Self-discharge is almost absent;
High battery capacity;
The number of charge / discharge cycles is several times greater than that of previous types of batteries;
To set the required voltage, fewer cans are required, which significantly reduces the weight and dimensions of the battery.
High price, almost 3 times in comparison with nickel-cadmium;
After three years, there is a significant loss of capacity, because Li decomposes.

We got acquainted with the elements, let’s move on to the rest of the elements of the screwdriver battery pack. Disassembling the unit, for example, to repair the battery of a Hitachi screwdriver (shown below), is very simple, we unscrew the screws around the perimeter and disconnect the case.

The housing has four contacts:

Two power, and. , for charge / discharge;
Upper control, it is switched on through a thermal sensor (thermistor). A thermistor is necessary to protect batteries, it cuts off or limits the charging current when a certain temperature of the cells is exceeded (usually in the range of 50-60C). Heating occurs due to high currents during forced charging, the so-called fast charging;
The so-called service contact, which is connected through a 9K ohm resistance. It is used for complex charging stations that equalize the charge on all battery cells. In everyday life, such stations are useless, due to their high cost.

That’s actually the whole design of the battery. Below is how to parse a block.

Screwdriver battery: design and types
Fault definition
Is it possible to reanimate the elements and how?
Repair and replacement of screwdriver battery cells

Fault definition

We figured out the purpose of the battery structure elements, now we will consider how to determine the malfunction, this is part 2 of the screwdriver battery repair. We note right away that all the elements cannot fail at once, and since our circuit is sequential, when one element fails, the whole circuit does not work. So, our task is to determine where we have the weakest link in the chain.

To do this, we will need a multimeter, and for the second method of troubleshooting a 12V lamp, if your battery for a screwdriver is also 12 volt. The procedure is as follows:

Thus, we have found candidates for resuscitation or amputation and replacement with new elements.

If your screwdriver operates on a voltage of 12 or 13V, you can search with an easier method. We disassemble a fully charged battery to the contacts and. We connect a 12 volt lamp. The lamp will be a load and will drain the battery. Next, we take measurements on the battery cells, where the voltage drop is strongest, there is also a weak link.

There are other ways, instead of a lamp, you can choose a resistance, but for this you already need the basics of electrical engineering, and it is doubtful that a resistor with the necessary resistance would be at hand.

Other faults are very rare. For example, loss of contact at the soldering points of the batteries or the power contacts of the unit, failure of the thermistor. This problem is more inherent in fakes. In view of the rarity, we will not focus on the battery elements.

We figured out the problematic elements, they need to be repaired. How to repair a screwdriver battery? In general, there are 2 methods available for repair, so to speak. This is the restoration and replacement of elements that have become unusable.

Repair and replacement of screwdriver battery cells

A more effective way to repair batteries for a screwdriver is to replace elements that we have identified as faulty.

We also need a soldering iron, a low-corrosion flux (preferably an alcohol flux for rosin) and tin. We do not talk about spot welding, since for a one-time battery repair there is hardly a need to purchase or assemble it

There is nothing complicated in the replacement itself, especially if at least some. Then there is experience in soldering. On the graphs, everything is shown in sufficient detail, we cut off the faulty element, instead of it we solder a new one.

Several nuances should be noted:

When soldering with a soldering iron, try to solder quickly, so that the battery does not heat up, because risk ruining it;
If possible, implement the connection using native plates, or use the same copper plates, this is important because the charging currents are large and if the section of the connecting wires is incorrect, they will heat up, respectively, the thermistor protection will work;
In no case do not confuse the plus of the battery with the minus of the serial connection, which means that the minus of the previous can goes to the plus of the new can, and the minus of the new one. Plus the next one.

After the new elements have been soldered, it is necessary to equalize the potentials on the banks, since they are different. We carry out a charge / discharge cycle: we set it to charge overnight, give it a day to cool and measure the voltage on the elements. If we did everything correctly, the picture will be something like this: on all elements the same indicator of the multimeter, within 1.3V.

Next, we proceed to discharge the battery, insert the battery into the screwdriver and load it in full. The main thing is to spare the screwdriver itself, otherwise you will have to repair it too. We bring it to full discharge. We repeat this procedure two more times, i.E. Charge and discharge completely.

It should be noted that the procedure for erasing the memory effect should be carried out every three months. It is carried out by analogy with the above-described training.

Such a not very tricky procedure will prolong the work of your screwdriver, at least until you have to replace it with a new one.

Battery selection

Motorcycle

They differ in weight within 24 kilograms. Voltage 6 and 12 volts.

Automotive

How can you replace the battery

Gel (batteries for UPS)

Removing the old battery

We take out the tool we need and once again make sure that all consumers are turned off. You should also know that when the system is de-energized, unpleasant things will not happen, because there are times when, after replacing the battery, the settings of the central computer are reset and the engine speed starts to float, the radio tape recorder or completely the car electronics can be blocked. To unlock the car or radio, you need a secret code, which is usually entered through the head unit. If you are not sure that nothing like this will happen, then it is better to connect an additional source in parallel. You can use a 12V battery from a home PC UPS.

And so, remove the protective caps. It happens that both terminals are closed, but more often only a plus. First of all, I unscrew the minus. Why minus you ask. Yes, because the minus is attached to the body iron, and the body is the mass. By unscrewing the minus, you can touch any bolt, metal fastener, and so on with the key and nothing will happen. And if you first unscrew the plus and touch any metal part, a short circuit will occur. This cannot be allowed. We unscrewed the wires, bent them so that nothing would interfere and the next thing we do is fastening. Fasteners are more often found of two types, this is a bar on top of the battery on two studs and the second option is fastening to the body with a bar for the lower protrusion of the battery. Unscrewed, pulled out, put on the ground. Next, you need to prepare the place, get a rubber mat, shake out the dust, dirt, wash it if possible. If there are traces of oxidation, treat with a soda solution, wipe dry.

Now we clean the terminals with sandpaper from the inside and where there are contacts, if necessary (we look at the state). It is better to do all these actions right away when replacing the battery, than you will do it in winter in the cold. Gigantic currents pass through these contacts, the contacts can burn and deform from heating, all this can lead to difficulty in starting the engine and self-discharge.

Sources: