How to solder batteries for an electric screwdriver

What is the problem with Ni─Cd batteries??

When you use Ni─Cd batteries the voltage and the discharge capacity gradually decrease. The following are the main factors causing these processes:

  • decrease of working surface of positive and negative electrodes;
  • loss of active mass, as well as its redistribution over the electrodes;
  • occurrence of current leakage due to formation of dendrites of metallic Cd;
  • Processes that result in irreversible consumption of water and oxygen;
  • changing the composition and volume of the electrolyte.

Similar processes occur when operating Ni-MH batteries. The only difference is in the electrode materials used.

All these changes of the nickel-oxide electrode are caused by permanent overcharging in which oxygen is released in the space of the positive electrode. The more batteries go through charge-discharge cycles, the more crystals of the active mass of the positive electrode become enlarged. Therefore, the working surface decreases, and therefore the capacity of the battery.

solder, batteries, electric, screwdriver

At the cadmium electrode the degradation process is determined mainly by the migration of the active mass. As a result, there is some loss of electrolyte. In addition, the active mass clogs the pores in the surface layer of the negative electrode. This makes it difficult for the electrolyte to reach the deeper layers. The result of the active mass migration is the growth of dendritic bridges through the separator to the positive electrode. These lead to numerous microcircuits and increase the self-discharge. At the cadmium electrode during operation there also occurs growth of crystals and increase of volume of active mass.

In addition to the processes described above, in Ni─Cd batteries there are oxidation processes of various additives that are present in the battery. The metal ceramics of the positive electrode gradually oxidizes with the consumption of water. And another unpleasant process that leads to the loss of performance of the Ni─Cd battery is the withdrawal of electrolyte from the separator. This is due to changes in the porous structure of the electrodes and leads to increased internal resistance of the nickel-cadmium battery. The composition of the electrolyte also changes during operation. In particular, the volume of carbonates grows. The conductivity of the electrolyte decreases and all parameters of a Ni─Cd battery on discharge. The picture becomes especially noticeable at low temperatures. What to do in such cases?

How to change the banks in the battery of an electric screwdriver

As you know, any battery sooner or later will wear out its life and needs either a partial replacement of batteries, or it should be changed completely. If we are talking about an electric screwdriver, for some people it is much easier to buy a new one than to replace the batteries in it, because it requires both time and a certain skill. However, with skill and skill, replacing the batteries in an electric screwdriver can be a good alternative to buying a new one. In many cases it is less expensive.

As batteries in screwdrivers are usually used nickel-cadmium or lithium-ion cells. Nickel cadmium batteries are more rugged and if you do a partial replacement of the cells in such a unit, it will work for a long time. Lithium batteries can also be partially replaced, but it is a bit more difficult. It should be borne in mind that not only the cells themselves, but also the balancing board will have to be soldered. Also in recent years, electronics enthusiasts often change the batteries of an electric screwdriver with their own hands, from nicd batteries to lithium batteries. This is a good option if the screwdriver is used frequently and intensively. The capacity of lithium ion batteries is much higher and the number of cycles is greater.

Types of batteries used in screwdrivers, and their differences

As you know, the battery of any electric screwdriver includes several batteries, which are connected in one chain in a certain sequence. A distinction is made between Ni-Cd, Ni-MH and lithium cells.

Nickel-cadmium batteries, in this case, are the most popular and frequently used. The voltage of each individual cell is 1.2 volts, and the capacity is 12,000 mAh, if we have a 12-volt tool. It is worth noting right away that, unlike lithium batteries, they are recoverable because they have a so-called “memory effect” in the form of reversible loss of capacity.

As for the lithium batteries, you will hardly ever be able to recharge them with the popular Imax B6 battery charger, because lithium tends to decompose over time.

Restoring an electric screwdriver battery in a similar way can also fail for cadmium batteries. Such a battery is distinguished by the fact that the electrolyte in them sometimes completely boils out. However, in the case of cadmium batteries, the chances of “reanimating” them are much greater. But it is important not to rush and not to use in a hurry common methods of “quick recovery” Ni Cd batteries. Read more about which battery is best for an electric screwdriver →

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Tools

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

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Electric screwdriver battery: construction and types

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

If we take it apart, we can see that it is assembled from small elements that are assembled in series. And we know from high school physics that cells connected in series add up to their potential.

Note. The sum of each cell gives us the total voltage at the battery terminals.

The set pieces or cans are usually of standard size and voltage, differing only in capacity. Battery capacity is measured in A/h and is indicated on the cell (pictured below).

For the layout of screwdriver batteries, the following types of cells are used:

  • Nickel cadmium (Ni Cd) batteries, with a nominal voltage of 1.2V per bank;
  • Nickel-metal hydride (Ni-MH), cell voltage 1,2V;
  • Lithium-ion (Li-Ion), with a voltage of 3.6V.

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

  • The most common type due to low cost;
  • Not affected by low temperatures, such as Li-Ion batteries;
  • Stored in a discharged state, yet retains its characteristics.
  • Manufactured only in third world countries, due to toxicity in production
  • Memory effect;
  • Self-discharge;
  • Small capacity;
  • Fewer charge/discharge cycles, so do not live long with heavy use.
  • Environmentally friendly production, it is possible to buy a high-quality branded battery;
  • Low memory effect;
  • Low self-discharge;
  • High capacity compared to Ni Cd;
  • Higher number of charge/discharge cycles.
  • No memory effect;
  • Almost no self-discharge;
  • High capacity battery;
  • The number of charge/discharge cycles is many times greater than with previous types of batteries;
  • To set the necessary voltage it is necessary to have fewer cells, which significantly reduces the weight and size of the battery.

With the elements we have got acquainted, let’s move on to the other elements of the battery pack of an electric screwdriver. Disassembling the unit, for example, to repair the battery of an electric Hitachi screwdriver (shown below), is very simple, unscrew the screws on the perimeter and disconnect the housing.

  • Two power and charge/discharge terminals;
  • the upper control, it is included through the temperature sensor (thermistor). Thermistor is needed to protect the batteries, it switches off or limits the charging current when the temperature of the cells exceeds a certain point (usually in the range of 50 600C). Heating occurs because of the high currents during forced charging, so called fast charging;
  • The so-called service contact, which is included through a resistance of 9Kohm. It is used for complex charging stations, which equalize the charge on all cells of the battery. In the home such stations are useless because of their high cost.

This is actually the whole construction of the battery. Here is a video on how to disassemble the block.

Troubleshooting

With the purpose of the elements of the battery design figured out, now let’s consider how to determine the malfunction, it is h.2 electric screwdriver battery repair. It is necessary to notice at once that all elements cannot fail at once, and as the circuit we have is serial, at failure of one element all circuit does not work. So, our task is to determine where we have the weakest link in the circuit.

For this we will need a multimeter, and for the second way to find the fault a 12 volt lamp, if your battery on the electric screwdriver is also 12 volt. The procedure is as follows:

Note. A difference of 0.5 to 0.7V between the cells in a battery pack is considered to be significant, this means that the cell becomes unusable.

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

If your electric screwdriver works with 12V or 13V you can search with simpler method. Fully charged battery disassemble and to the contacts and. plug in a 12 volt bulb. The lamp will be a load, and will discharge the battery. Next, measure the battery cells, where the biggest drop in voltage, there is the weak link.

There are other ways, instead of the lamp you can pick up resistance, but this requires the basics of electrical engineering, and it is doubtful that the resistor with the required resistance was at hand.

The other faults are very rare. For example loss of contact in the soldering points of batteries or power contacts of the block, failure of thermistor. That’s more of a problem with counterfeits. Due to rarity, we will not focus our attention on the battery elements.

The problematic elements are solved, it is necessary to repair. How to Repair an Electric Screwdriver Battery? In general, 2 ways are available for repair, if I may say so. This is the restoration and replacement of elements that have fallen into disrepair.

Can the cells be reanimated and how can they be reanimated??

Let’s proceed to h.3 electric screwdriver battery repair and immediately stipulate that the concept of reanimation for lithium ion batteries is not applicable. They have no memory effect, the lithium has most likely decomposed, and there is nothing you can do about it. In such batteries, it is necessary to find out what is the cause of the malfunction: the cell itself or the control circuit. Here are two options:

  • change the control circuit from another, but similar to our battery, if it helped find a replacement and change it;
  • supply 4V to the cell with a current of about 200mA, this requires an adjustable charger. If the cell voltage rises up to 3,6V the cell is intact, the problem is in other cells or in the control circuit.

Electric screwdriver battery reanimation repair is available mainly for Ni Cd batteries, but they are usually the most common in household screwdrivers.

So, how to resuscitate the battery of an electric screwdriver? There are two types of reanimation for these types of batteries:

  • Seal or compression method (it will work in cases where the electrolyte is still present but has lost volume);
  • Flashing with voltage and current greater than the nominal. This method eliminates the memory effect, and although not completely, restores the lost capacity.
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Note. As a rule, the main cause of capacity loss in nickel cadmium batteries is electrolyte boiling off, and if it is critically low, no amount of firmware will help.

This method, if its result is positive, will not solve the problem of failure of the cells. Rather, it will only delay the replacement of defective batteries and later will still need repair of the battery of an electric screwdriver Makita or any other.

Repair and replacement of electric screwdriver battery cells

A more effective way to repair electric screwdriver batteries is to replace the cells that we have identified as faulty.

To make the repair we need either a battery. a donor, in which some of the elements are in good condition, or new cans. To buy them will not be difficult, even on the Internet you can easily find a dozen stores that are willing to send these elements by mail.

Note. When buying a new cell, make sure that its capacity and dimensions coincide with the native elements.

Also we need a soldering iron, low-corrosive flux (preferably alcohol flux on rosin) and tin. We don’t talk about spot welding, because for a single battery repair there is hardly a need to buy or assemble it

In the replacement itself there is nothing complicated, especially if at least some. you have experience in soldering. The pictures show everything in detail, cut off the faulty element and solder a new one instead.

  • When soldering with soldering iron, try to solder quickly so that the battery does not heat up, i.e.к. You run the risk of damaging it;
  • If possible implement the connection with the native plates, or use copper plates of the same size, it is important because charging currents are large and with the wrong cross section of the connecting wires, they will be warm, respectively will trigger the protection of the thermistor;
  • Under no circumstances mix up the plus of the battery with the minus of the connection serial, which means that the minus of the previous bank goes to the plus of the new bank, and the minus of the new. on the plus side of the next.

After soldering the new elements, it is necessary to equalize the potentials on the banks, because they are different. Charge/discharge cycle: let it charge all night, let it cool down for a day and measure the voltage of the cells. If we have done everything correctly the multimeter reading on all the cells is the same, about 1,3 volt.

Next, we proceed to discharge the battery, insert the battery in the electric screwdriver and load it to its full capacity. The main thing is to spare the electric screwdriver, otherwise you will have to repair it as well. Bringing it to a complete discharge. repeat this procedure twice more, i.e.е. Charge and fully discharge.

It should be noted that the procedure of erasing the memory effect should be carried out once every three months. Conducted by analogy to the above training.

Such a not very tricky procedure will prolong the work of your electric screwdriver, at least until it itself will not have to be replaced with a new one

Repairing the battery of an electric screwdriver with the replacement of the batteries with your own hands

Hi! Today we will conduct the repair of the battery of an electric screwdriver. Did you know that the history of the electric screwdriver goes back to the deep Middle Ages. as far back as the 15th century, when knights were dressed in armor before the battle, and the squires helped them twist the armor parts with guess what? Screwdriver!

This went on for a long time, until in 1907, Canadian inventor Peter Robertson patented the “Robertson” screw with a standard square hole into which the screwdriver’s stinger was inserted. Since then, screwdrivers have been produced on an industrial scale and used in households. Later in 1934 inventor Henry Phillips perfected the head of the screw and a crosshatched screw was invented to fit the screwdriver. By this time, the motor had already been invented, and the idea of the “screwdriver” was in the air. But there were big problems with the batteries, their weight and dimensions. The problem was not solved until the 1980s, when the first nickel-cadmium Ni-Cd and lithium-ion Li-Ion rechargeable batteries appeared.

The USA and Japan were the first to produce cordless drills and screwdrivers for domestic and professional use. All this has happened due to the emergence of new energy-consuming batteries of electricity. Just them and we will urgently change in the hands of a cordless drill, an electric screwdriver Interskol DA-10/10.8 EP. The problem was the following. when you press the button the engine does not spin, but the LED did light up, but the light was weak.

Repair of electric screwdriver battery with your own hands

Why does the battery have a bad charge capacity?? How to work if the electric screwdriver does not work more than 10 minutes after charging? Such questions arise from users whose cordless tool has been in use for more than a year. There are several ways to solve this problem. You can, for example, contact a service center. There, you are likely to be offered to buy a new battery, as experts do not officially repair failed elements. And what if such models are no longer manufactured and to pick up a suitable analogue is not possible? Do I have to part with my favorite tool and buy a new one with a new battery and charger?? With today’s not everyone can afford it. Therefore, many craftsmen undertake the repair of the electric screwdriver battery with their own hands. By the way, not all of them are chasing economy. For some, it is an occasion for creativity an opportunity to breathe new life into an old tool. After all, you can not make things worse, but it is worth trying!

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In preparing this article, we have studied many examples of electric screwdriver battery repair with their own hands. Some users restore only the cells, while others create a completely new battery on the basis of cheap Chinese batteries. But such approaches are not always good. For example, the cells of lithium-ion batteries can not be restored. When restoring nickel-cadmium ones, sometimes you need to flash the cells, which means a special device. Repair of a battery with the replacement of individual cells is considered to be a universal way. This is what our article will tell you about.

Changing the battery cells

Sergei’s battery uses 1.2v nickel cadmium batteries. They are not interchangeable, so it is better to pick up something similar to the original in size and as high capacity as possible of those available. Sergei’s battery cells are similar to type D batteries. That’s why we order them. You can find about 2400 mAh in the same size.

I have written before about how I changed the battery cells of an Interskol electric screwdriver. It had a 3.7V lithium-ion battery of the lowest budget class, and even discharged. Then I replaced them with slightly better batteries. Now I would use branded Liitokala batteries at 2200 mAh or Panasonic batteries at 3400 mAh of 18650.

One inconvenient thing is that you have to solder the overheat-sensitive batteries. Such a repair or restoration of the battery can have the opposite effect. Exit such a powerful soldering iron hold 0.5 1 sec. or use a spot-welding machine. The second option is more reliable.

This means to burn through a nickel-cadmium battery by applying short pulses of high current for a few seconds. We can say that this is a kind of emergency resuscitation of batteries. Immediately it should be noted that this option is quite risky, and not every battery is able to withstand such “shock therapy” of high current. The high current can only be used if the electric screwdriver has nickel-cadmium batteries. Other batteries (nickel-metal hydride, lithium-ion) must not be subjected to this treatment.

The essence of purging is to destroy high current crystals that form inside nickel cadmium batteries. These crystals are called dendrites, and their growth gradually reduces the capacity of the battery. “High currents quickly destroy the formed crystals and sharply reduce the self-discharge of the battery.

It is claimed that zapazaping can be effective for any NiCd, even if they are completely drained or have been sitting idle for 10 or 20 years. The question is always the likelihood of successful repair in such “severe” cases. when batteries are “repaired” in this way, it will either succeed or not. But it does not hurt to try to revive them. Of course, while exercising the utmost caution.

To carry out zapadping you will need:

  • any high current charger ;
  • A multimeter to monitor the voltage ;
  • welding machine ;
  • A crocodile-type clamp ;
  • zapping electrode ;
  • protective equipment.

It is not necessary to use an ordinary power supply as a charger. Even if the current capacity of such chargers is 10-15A. they will not withstand high voltages. The double-sided clamp on one terminal ensures a tight contact and the other terminal will hold the electrode itself. It’s impossible to hold it with fingers: during burning it gets red-hot. The zapping electrode is a piece of wire coiled in a tight bundle (no insulation). It has a maximum cross section of 1.5 millimeters. and it’s six or seven centimeters long.

Instead of a higher quality welder, especially brave electronics enthusiasts repair batteries using an ordinary soldering iron. But a spot soldering tool would be preferable for repairs. Protective equipment (gown, glasses, special non-flammable mat) is necessary because sparks always appear during high current purging.

How to proceed

It is better to blow each battery separately, the algorithm is as follows:

  • Attach the electrode with the “minus” sign to its minus pole. Do not reverse polarity, an important point.
  • “Blow” the positive electrode with short pokes, their frequency. 2-3 times per second. Typically for a bank with an output voltage of 1.2 V, blowing must be done for 3-4 seconds at a rate of 2-3 small pokes per second;
  • Measure the voltage reading after the first step. It should be raised to a maximum of 1.3 V. If the voltage is higher, the poke time or the number of pokes should be reduced.

It is necessary to poke very quickly and accurately, avoiding that the electrode even for a short time is welded to the battery Ni Cd pole of an electric screwdriver, to avoid complete burning of the battery. It is recommended to put a protective intermediate electrode on the positive electrode, or hook the “crocodile” to protect the surface of the battery pole.

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The procedure should be repeated up to 25 times until the capacity of the battery is restored. During the entire process, the battery temperature must be monitored at all times. The time between each pulse should be at least 15 minutes. Only then will the reanimated battery have a chance to prolong its lifetime.

Design, construction and repair of Ni─Cd batteries for screwdriver

Today you can find many models of screwdrivers on sale, both from famous global brands, and from unknown companies. There are simple models, as well as functional with rich equipment. They all have one thing in common. they all have batteries for standalone operation. And often the cost of these batteries is more than half the price of the screwdriver itself. Most often these batteries use nickel-metal hydride or nickel-cadmium batteries as their cells. In some cases they can be restored and the screwdriver battery can be repaired. In this material, we will examine how this is done.

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