Electric Cordless Screwdriver Restoration. HITACHI DB3DL2 3.6V
Battery types
So what kind of batteries are there? Usually, nickel-cadmium and lithium batteries are used for electric drills. There are also nickel-metal hydride batteries, and they are good in their own way. But for screwdrivers, they began to be used very rarely: these batteries, unfortunately, heat up very quickly both when charging and when the tool is used intensively. In addition, nickel-cadmium batteries, despite the fact that they can rightfully be called “veterans” in a number of chemical current sources, are still superior to nickel-metal hydrides in many characteristics.
Recommendations for using lithium batteries
To extend the life of a lithium battery and improve its performance, you need to follow these simple guidelines:
- avoid complete discharge of the battery, regularly recharge it when the charge level drops to 20%;
- prevent the battery from overheating and exposure to direct sunlight;
- do not use the battery in severe frost, insulate it for winter operation;
- store a lithium-ion battery with a 50% charge level, at a temperature of 0 C;
- protect the battery from shock, damage and strong vibration; when installing on electric vehicles, place a soft layer.
What does the battery capacity say?
Battery capacity is written in numbers from 1.0 to 7.0 and is measured in amperes times hours (Ah). The value is deciphered as follows: the specified number of amperes can be delivered by the drive within an hour. But since no electric screwdriver consumes 1-5 A per hour, its use time stretches from 2 to 8 hours. The higher the capacity, the longer the tool can stay in use.
What characteristics are important when choosing a battery for an electric screwdriver
Considering the advantages and disadvantages of different types of batteries, you can choose the one suitable for specific operating conditions. Now let’s look at two key characteristics that all types of batteries have that affect the choice of an electric screwdriver.
Benefits of nickel-cadmium batteries
People condemn cadmium storage batteries because they are older. However, despite numerous condemnations, these blocks have high rates. For example, they are more capacious, during operation they do not heat up as much as the same nickel metal hydride battery cells.
This is due to the heat-absorbing reactions that occur inside the battery. A heat-absorbing reaction is the absorption of the generated heat inside an element. Such reactions do not release heat outside the working mixture.
There are no heat absorbing reactions in Ni-Mh. Because they get so hot.
If you choose a battery cell for an electric screwdriver, relying on its practicality and productivity, then Ni-Cd is much better than Ni-Mh. At the moment, they are the most common type of battery not only for electric screwdrivers or drills, but also for other household appliances.
- Lower chance of overheating block elements.
- They will not burn out or deteriorate in a short time, in contrast to Ni-Mg.
- Equipped with a robust and reliable metal casing, which provides a good sealing structure.
- Resistant to various unwanted chemical reactions.
- Resistant to negative temperatures. They function even at 35 ° C.
- With correct operation, the batteries work for about 7-11 years.
- Adequate cost. Li-ion storage batteries cost much more.
So that nickel-cadmium storage blocks do not break down before the due date and serve 7-11 years, it is necessary to adhere to some operating rules.
First of all, remember that nickel batteries are not afraid of a full discharge of cells. Therefore, when working, discharge the storage unit to the very end.
After discharging, you can put the battery on charge, because it will not lose its capacity.
It is recommended to store batteries in a discharged state, because the reversible loss of capacity, or the so-called “memory effect”, will be less pronounced.
There is no need to recharge the battery during storage. Reversible capacity loss is not a major threat to the battery. To reduce the damage from the “memory effect”, it is recommended to fully charge and discharge the battery several times. These manipulations will help reduce reversible capacity loss.
Types of storage
Most often, a nickel-cadmium or lithium-ion battery is installed in electric screwdrivers. There is also Ni-Mg drives that have their merits.
However, nickel-metal hydride batteries are rarely installed in screwdrivers, because electrolytes are heated too quickly during charging. This is also very noticeable during continuous work with the tool.
Battery selection based on application
So, having thoroughly examined all the key factors, we will discuss with which battery to choose an electric screwdriver for home and professional activities. This will help you not to overpay and have a reliable tool at hand.
Conversion of the Hitachi electric screwdriver to lithium batteries
Nickel-cadmium batteries are inconvenient because of their “memory effect”, so switching to lithium-ion batteries is expedient and profitable.
Preparation: selection of the necessary devices, elements
A battery pack that has lost its working qualities must be disassembled. The halves of the case can be fastened with glue and / or screws, clamps. To disconnect the glued seam, it is carefully tapped with a rubber hammer so that the halves of the plastic case separate from each other, but do not crack. The elements collected in a “cassette” are removed from the opened case. The contact pad is carefully separated, it will need to be fixed on new lithium batteries.
The new Li-Ion battery for the Hitachi electric screwdriver requires the purchase of additional accessories, while the following circumstances must be taken into account:
- New batteries must be similar in size and voltage to the old ones.
- It is more advisable to choose batteries that are already equipped with nickel plates so as not to waste time on soldering.
- The lithium-ion battery needs a BMS board (Battery Management System). It evenly distributes energy between the banks, protects the device from sudden power outages, turns it off if the charging time is exceeded, or the batteries are discharged to almost zero. To protect against overheating, a thermal detector is connected to the board.
- To connect the cassette to the contact pad, you need a power insulated wire of suitable thickness.
How to convert a Hitachi electric screwdriver to lithium batteries: process description
If the cans were sold without nickel electrodes, they are soldered. It is important to do this with great care, as overheating can permanently damage the battery, or even provoke an explosion. Before starting the process, it is useful to clean the soldered surfaces so that the likelihood of overheating decreases and the connection is strong.
The batteries are connected in series, the board is connected. The power wire is soldered to the microcircuit and the contact pad. Then, using a multimeter, the voltage readings are checked: for each battery, this figure should be about 1.3 V.
Upon completion of the test, all connections are carefully insulated. The assembled cassette is carefully placed into the case, the wire is laid without kinks and creases. The halves of the case are held together.
First activation after the transition, terms of use
The assembled lithium-ion battery pack must be put into working order. This is done so that new batteries do not wear out prematurely. The unit is fully charged and begins to be used intensively until the charge is depleted to zero and the device turns off. After that, it is recharged to 100% again, and work until it is completely discharged. This cycle can be repeated a third time. After this preparation, the battery module can be used normally.
You need to start charging the battery with lithium-ion banks when it is discharged to 20%, charging should always be done to 100%. It is forbidden to overexpose the device on recharging. as soon as the batteries are full, the charger must be disconnected.
Disassembling the battery case
The body is often assembled on self-tapping screws, other options are assembled with latches or glue. The glued block is the most difficult to disassemble, you have to use a special hammer with a plastic head so as not to damage the parts of the case. Everything is removed from the inside. You can reapply only the contact plates or the entire terminal assembly for connecting to the tool, charger.
Conversion of an electric screwdriver to lithium batteries 18650
The industry has been making screwdrivers for a long time, and many people have older models with nickel-cadmium and nickel-metal hydride batteries. Converting an electric screwdriver to lithium will improve the performance of the device without buying a new tool. Now many companies offer services for altering batteries for an electric screwdriver, but you can do it yourself.
Conversion of an electric screwdriver to lithium batteries
Battery selection
12 V batteries are often used for screwdrivers. Factors to consider when choosing a Li-Ion battery for an electric screwdriver:
- In such instruments, elements with high values of the discharge current are used;
- In many cases, the cell capacity is inversely related to the discharge current, so it cannot be selected based on capacity alone. The main indicator is the current. The value of the operating current of an electric screwdriver can be found in the instrument’s passport. Usually it is from 15 to 30-40 A;
- It is not recommended to use cells with different capacities when replacing the battery of an electric screwdriver with a Li-Ion 18650;
- Sometimes there are tips to use a lithium battery from an old laptop. This is absolutely unacceptable. They are designed for a much lower discharge current and have inappropriate technical characteristics;
- The number of elements is calculated based on the approximate ratio. 1 Li-Ion to 3 Ni-Cd. For a 12-volt battery, you will need to install 3 new ones to replace 10 old cans. The voltage level will be slightly reduced, but if 4 cells are installed, the overvoltage will shorten the life of the motor.
Important! Before assembly, it is necessary to fully charge all elements to equalize.
Battery cell connection
The connection of Li-Ion batteries for a screwdriver is performed in several ways:
- The use of special cassettes. The method is fast, but the contacts have a large transition resistance, they can quickly collapse from relatively high currents;
- Soldering. A method suitable for those who know how to solder, since you need to have certain skills. Soldering should be done quickly, because the solder cools quickly, and prolonged heating can damage the battery;
- Spot welding. This is the preferred method. Not everyone has a welding machine, such services can be provided by specialists.
Important! The elements must be connected in series, then the voltage of the batteries is added up, and the capacity does not change.
At the second stage, wires are soldered to the contacts of the assembled battery and to the protective board according to the connection diagram. To the contacts of the battery itself for power circuits, wires with a cross-sectional area of 1.5 mm² are soldered. For other circuits, you can take thinner wires. 0.75 mm²;
A piece of heat shrink tubing is then placed over the battery, but this is not required. You can also put on heat shrinkage on the protective microcircuit to isolate it from contact with the batteries, otherwise sharp soldering projections can damage the cell shell and provoke a short circuit.
Battery assembly
Further battery replacement consists of the following steps:
- The disassembled parts of the case are well cleaned;
- Since the dimensions of the new battery cells will be smaller, they must be securely fixed: glued to the inner wall of the case with Moment glue or sealant;
- The positive and negative wires are soldered to the old terminal block, it is placed in the same place in the case and fixed. The protective board is laid, the parts of the battery pack are connected. If they were previously glued, then “Moment” is used again.
Difficulties in rework
There are objective disadvantages in Li-Ion batteries, such as poor performance at low temperatures. In addition, when converting an electric screwdriver to lithium 18650 batteries, a number of difficulties can be encountered:
- The 18650 standard means that a single cell has a diameter of 18 mm and a length of 65 mm. These dimensions do not match the dimensions of the nickel-cadmium or nickel-metal hydride cells previously installed in an electric screwdriver. Replacing batteries will require placing them in a standard battery case, plus the installation of a protective microcircuit and connecting wires;
- The voltage at the output of the lithium cells is 3.6 V, and on the nickel-cadmium cells. 1.2 V. Let’s say the nominal voltage of the old battery is 12 V. This voltage cannot be ensured when Li-Ion cells are connected in series. The range of voltage fluctuations during the charge-discharge cycles of the ion battery also changes. Accordingly, converted batteries may not be compatible with an electric screwdriver;
- Ionic batteries differ in the specifics of their work. They do not withstand overcharging voltage more than 4.2 V and discharge less than 2.7 V until they fail. Therefore, when a battery is being reworked, a protective board must be installed in an electric screwdriver;
- An existing charger may not be used for an electric screwdriver with a Li-Ion battery. You will also need to redo it or purchase another.
Important! If the drill or electric screwdriver is cheap and not of very high quality, then it is better not to rework. This can cost more than the cost of the tool itself.
Tips for choosing a security chip
The lithium ion battery of the electric screwdriver cannot function normally without the BMS protection board. Instances on sale have different parameters. BMS 3S marking assumes, for example, that the board is designed for 3 elements.
What you need to pay attention to in order to choose a suitable microcircuit:
- The presence of balancing to ensure the uniformity of the charge of the cells. If it is present, the value of the balancing current should be in the description of the technical data;
- The maximum value of the operating current withstood for a long time. On average, you need to focus on 20-30 A. But this depends on the power of the electric screwdriver. Low-power enough 20 A, powerful. from 30 A;
- Voltage, upon reaching which the batteries are disconnected when overcharging (about 4.3 V);
- Voltage at which the electric screwdriver turns off. It is necessary to select this value based on the technical parameters of the battery cell (the minimum voltage is about 2.6 V);
- Overload protection operation current;
- Resistance of transistor elements (minimum value selected).
Important! The magnitude of the overload tripping current is not very important. This value is offset from the workload current. In case of short-term overloads, even if the tool has turned off, you must release the start button, and then you can continue to work.
Connection diagram of elements with a protective board
Whether the controller has an autorun function can be determined by the presence of an “Automatic recovery” entry in the technical data. If there is no such function, then in order to restart the electric screwdriver after the protection is triggered, it will be necessary to remove the battery and connect it to the charger.
The advantages of lithium-ion batteries
Nickel-cadmium batteries have a low price, withstand many charging cycles, and are not afraid of low temperatures. But the capacity of the battery will decrease if you put it on charge without waiting for a full discharge (memory effect).
Lithium-ion batteries offer the following benefits:
- high capacity, which will provide a longer operating time for the electric screwdriver;
- smaller size and weight;
- keeps charge well when inoperative.
But a lithium battery for an electric screwdriver does not withstand a full discharge, so factory tools on such batteries are equipped with additional boards that protect the battery from overheating, short-circuit, overcharge in order to avoid an explosion, a complete discharge. When the microcircuit is inserted directly into the battery, the circuit is opened if the unused battery is separated from the tool.
electric screwdriver Hitachi convert to lithium-ion
Energy storage information website
Every craftsman is faced with the problem of reduced tool performance, or complete failure due to the battery. Manufacturers use nickel-cadmium batteries in 12, 14, 18 volt screwdrivers. The sequential assembly of several elements creates the desired voltage. Replacing nickel-cadmium batteries with lithium batteries extends battery life by making the design lighter. Mandatory BMS board installation adds reliability. Therefore, the conversion of an electric screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.
Hitachi electric screwdriver DB3DL2
Conversion of the Makita electric screwdriver to a lithium battery
There is a “Makita” electric screwdriver with a 1.3 A / h battery and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. charge, will add power as the operating voltage rises to 10.8 V.
The design will require the use of a BMS, a control controller that maintains the lithium cell operating mode within operating limits. With this breaker, each cell will be charged evenly without exceeding 4.2 V, the lower voltage is 2.7 V. The built-in balancer is used here.
The parameters of the controller should accompany the operation of the instrument when the operating current rises to 10-20 A. The Sony VTC4 30 A board, designed for a capacity of 2100 A / h, can ensure operation without shutdown. Of the 20 amperes, the Sanyo UR18650NSX accepting 2600A / h energies is suitable. The board is needed for 3 elements, which is marked in the 3S classification. In this case, the board must have 2 contacts, plus and minus. If the conclusions are designated with the letters “P-“, “P”, “C-“, they are intended for later models of screwdrivers.
Step-by-step instructions for converting a Makita electric screwdriver to lithium batteries looks like this.
- You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while weighing. Direction of impact downwards, butt-joint along the lower part of the body.
- Take only the contact plates from the old assembly, carefully disconnecting them from the battery. Leave the sensor and breaker.
- Solder 3 elements in series using TAGS flux and insulated jumpers. The wire cross-section must be greater than 0.75 mm2.
- Assemble the circuit with the controller, and connect the power supply to the contact connectors with 1.5 square wires.
- Check the functionality of the circuit and reassemble the case by placing it on the glue again.
In an electric screwdriver with an old DC9710 charger, once the 18650 lithium battery has finished charging, the red LED on the panel will turn off. The built-in controller monitors the charge level.
The Makita DC1414 T charger is used to charge 7.2-14.4 V power sources. While charging, the red light is on. But when charging a lithium battery, its voltage does not fit into the standards of salt products, and after 12 V, the charger will flash red and green. But the necessary charging is already there. electric screwdriver ready to work.
How to disassemble a screwdriver battery
How to disassemble an old battery? There are batteries where the halves of the case are fastened with screws, but there are also glue ones. My batteries are one of the last ones, and I generally believed for a long time that they could not be disassembled. It turned out that it is possible if you have a hammer.
In general, with the help of intense blows to the perimeter of the edge of the lower part of the case (a hammer with a nylon head, the battery must be held in the hand by weight), the gluing site is successfully separated. In this case, the case is not damaged in any way, I have already disassembled 4 pieces this way.
From the old circuit, only contact plates are needed. They are permanently spot welded to the upper two elements. You can pick out the welding with a screwdriver or pliers, but you need to pick it as carefully as possible so as not to break the plastic.
Everything is almost ready for further work. By the way, I left the standard thermal sensor and disconnector, although they are no longer particularly relevant.
But it is very likely that the presence of these elements is necessary for the normal operation of a standard charger. Therefore, I highly recommend saving them.
Putting together a lithium-ion battery
Here are the new elements of Sanyo UR18650NSX (according to this article they can be found on Aliexpress) with a capacity of 2600 mAh. For comparison, the old battery had a capacity of only 1300 mAh, half the size.
It is necessary to solder the wires to the elements. The wires must be taken with a cross section of at least 0.75 sq. Mm, because we will have considerable currents. A wire with such a cross section normally works with currents of more than 20 A at a voltage of 12 V. You can solder lithium-ion cans, short-term overheating will not harm them in any way, this has been verified. But you need a good fast-acting flux. I use TAGS glycerin flux. Half a second. and you’re done.
We solder the other ends of the wires to the board according to the diagram.
I always put even thicker wires of 1.5 sq. Mm on the battery contacts. because the space allows. Before soldering them to the mating contacts, I put a piece of heat-shrinkable tube on the board. It is necessary for additional isolation of the board from battery cells. Otherwise, the sharp edges of the solder can easily rub or puncture the thin film of the lithium-ion cell and cause a short. It is possible not to use heat shrinkage, but at least something insulating to be laid between the board and the elements is absolutely necessary.
The contact part can be fixed in the battery case with a couple of droplets of super glue.
It’s good when the case is on screws, but this is not my case, so I just glue the halves again with “Moment”.
The battery is charged with a standard charger. True, the algorithm of work is changing.
I have two chargers, DC9710 and DC1414 T. And they work differently now, so I’ll tell you exactly how.
Conversion of the Interskol electric screwdriver to lithium batteries 18650
Sooner or later, the nickel-cadmium assembly of 15 cans fails. One or two elements are lazy, and it is no longer possible to get the output voltage. Modern DS “Interskol” with lithium batteries serve much better. Alteration of an electric screwdriver for 18 volt lithium batteries mastered by craftsmen.
It is necessary to purchase a protection board for 5S, 3.7 V and 40-50 A. You will need a balancing board and the energy sources themselves. 5 lithium 18650 batteries, you can leave them with factory thermistors by extending the wires. During installation, create a contact pad, insert the assembly, check the functionality, secure. The assembly features of the wizard’s advice are given in detail in the video. See here for full details on reworking an 18 volt lithium electric screwdriver
I won’t say anything new in this article, but I just want to share my experience of upgrading the batteries of my old Makita screwdriver. Initially, this tool was designed for nickel-cadmium batteries (which have long since died, just as those bought for replacement have died). The disadvantages of Ni-Cd are well known: low capacity, short lifespan, high price. Therefore, cordless tool manufacturers have long since switched to lithium-ion batteries.
Hikoki DB3DL2 electric screwdriver unboxing and impression
Well, what about those who have an old instrument? Yes, everything is very simple: throw away the Ni-Cd cans and replace them with Li-Ion of the popular 18650 format (marking indicates a diameter of 18 mm and a length of 65 mm).
What board is needed and what elements are needed to convert a screwdriver to lithium-ion
So, here is my 9.6 V 1.3 Ah battery. At the maximum charge level, it has a voltage of 10.8 volts. Lithium-ion cells have a nominal voltage of 3.6 volts, with a maximum voltage of 4.2. Therefore, to replace the old nickel-cadmium cells with lithium-ion cells, I need 3 cells, their operating voltage will be 10.8 volts, the maximum is 12.6 volts. Exceeding the rated voltage will not damage the motor in any way, it will not burn out, and with a larger difference, there is no need to worry.
Lithium-ion cells, as everyone has known for a long time, categorically do not like overcharging (voltage above 4.2 V) and excessive discharge (below 2.5 V). When the operating range is exceeded, the element degrades very quickly. Therefore, lithium-ion cells always work in tandem with an electronic board (BMS. Battery Management System), which controls the cell and monitors both the upper and lower voltage limits. This is a protection board that simply disconnects the can from the electrical circuit when the voltage goes out of the operating range. Therefore, in addition to the elements themselves, such a BMS board is required.
Now there are two important points that I experimented with unsuccessfully several times until I came to the right choice. This is the maximum permissible operating current of the Li-Ion cells themselves and the maximum operating current of the BMS board.
In a screwdriver, operating currents at high load reach 10-20 A. Therefore, you need to buy elements that are capable of delivering high currents. Personally, I have successfully used Sony VTC4 30-amp 18650 cells (2100 mAh capacity) and 20-amp Sanyo UR18650NSX (2600 mAh capacity). They work fine in my electric screwdrivers. But, for example, Chinese TrustFire 2500 mAh and Japanese light green Panasonic NCR18650B 3400 mAh are not suitable, they are not designed for such currents. Therefore, there is no need to chase the capacity of the elements. even 2100 mAh is more than enough; the main thing when choosing is not to miscalculate with the maximum permissible discharge current.
Likewise, the BMS board must be rated for high operating currents. I saw on YouTube how people collect batteries on 5 or 10-ampere boards. I don’t know, personally, when I turned on the screwdriver, such boards immediately went into defense. In my opinion, this is a waste of money. I will say that the Makita company itself puts 30-ampere boards in its batteries. Therefore, I use 25 Amp BMS bought from Aliexpress. They cost about 6-7 and are searched for “BMS 25A”. Since you need a board for an assembly of 3 elements, you need to look for such a board, in the name of which there will be “3S”.
Another important point: some boards have different contacts for charging (designation “C”) and load (designation “P”). For example, the board can have three pins: “P-“, “P” and “C-“, as on the native Makitov lithium-ion board. Such a fee will not work for us. Charging and discharging (charge / discharge) must be done through one contact! That is, there should be 2 working contacts on the board: just “plus” and just “minus”. Because our old charger also only has two pins.
In general, as you might have guessed, with my experiments I threw out a lot of money both on the wrong elements and on the wrong boards, having made all the mistakes that could be made. But I got invaluable experience.
Conversion of an electric screwdriver to lithium batteries 18650 14 V
When converting screwdrivers of different power and flashlights from Ni-Cd to Li-ion, batteries of the form factor 18650 are more often used. They easily fit into a container or a nest, since instead of two or three relatives, one lithium is installed. Alteration of the battery of an electric screwdriver should be carried out taking into account the characteristics of lithium batteries for 18650.
This type of energy source does not tolerate deep discharge and excessive charge. Hence, it is necessary to use voltage control boards. Since each battery has its own character, their charge is corrected by a balancer. The point of reworking an electric screwdriver with a voltage of 14.4 V lies in the creation of a device using lithium batteries to facilitate a hand tool and increase its performance. Lithium 18650 batteries are most suitable for these purposes.
When selecting components, it should be taken into account that the starting current of the electric screwdriver is high, you must select the appropriate BMS for the required number of cans and at least 30 A. jumpers.
- Lithium-ion cans in the amount of 4 pcs.
- 4-cell li-ion battery controller, CF-4S30A-A works well. It has a built-in balancer that controls the charge of each element.
- Hot melt glue, flux for soldering TAGS, solder.
- Heat-resistant tape;
- Connecting jumpers or thick insulated wire with a cross section of at least 0.75 squares, cut for bridges.
The procedure for converting an electric screwdriver for 18650:
- Disassemble the case and remove a bundle of 12 Ni-Cd cells from the container.
- Remove the garland, leaving the connector with the “” and “-” pins. Instead of a temperature sensor, a thermocouple from the controller will be installed.
- Solder the assembly, considering that you cannot use acid, only neutral flux and pure solder. During the connection period, do not warm up the covers. Work pointwise.
- Connect the balancing points to the controller according to the diagram. The board has connectors.
- Connect assembly with plus and minus pins.
- Check the functionality of the circuit. If everything works, assembled the battery, place the controller in the socket, secure with a sealant.
If the charger is not universal, additional alteration will be required. Screwdrivers for 12 V with a universal charger are assembled in the same way, but a protective connection circuit 3×18650 3.7 V for lithium batteries is used. In the same way, a screwdriver is reworked using a set of 18650 batteries in the amount of 2 elements.