How to convert a screwdriver to lithium batteries
Converting a screwdriver to lithium batteries 18650
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 required 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 a screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.
The meaning and procedure for converting screwdrivers to lithium batteries
Why do nickel cadmium batteries fail quickly? In a garland of series-connected cans, each one is special. The chemical process is individual, the charge in closed systems is different. In the event of a malfunction in one bank, the design does not provide the required voltage. The control system and charge balancing in individual components is not provided.
- Each Ni-Cd bank provides 1.2V and Li-ion 18650 3.6V.
- The capacity of a lithium battery is 2 times that of a nickel-cadmium battery, similar in size.
- An overheated li-ion battery threatens an explosion and fire, therefore, the installation of control of the uniformity of the charge in the banks is mandatory. BMS is not installed in nickel-cadmium batteries. the manufacturer is not interested.
- Lithium cells have no memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
- The screwdriver becomes much easier after converting the battery to li-ion, using 18650 cells.
There are only two obstacles to converting a screwdriver for lithium batteries. it is impossible to work with it at minus. The capacity of cans decreases, starting from a decrease already from 10 0 C. Lithium batteries are expensive.
Knowing what input voltage is required for the screwdriver, the charger is reworked, taking into account the placement of the lithium battery cans and control elements in the factory container. You can also do with a flashlight by upgrading the socket for a block of 18650 cells.
Let’s say you need to rework a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 cans, the output voltage is not enough: 3.6 x 3 = 10.8 V. With 4 components, the power of the apparatus will be higher: 3.6 x 4 = 14.4 V. This will make the instrument 182 g lighter. its power will increase slightly, capacity. solid pluses. But when dismantling, it is necessary to leave the terminals and the native thermal sensor.
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Alteration of the “Hitachi” 12 V screwdriver for lithium batteries 18640
Features of reworking the 12 V Hitachi screwdriver for lithium batteries. The very compact battery compartment is designed for finger cells. Therefore, you should prepare a place for 18650 cells. It is necessary to cut one side of the partition in order to tightly place 1 element.
You need to get a gumboil, a flat metal connecting tape, hot glue. It is necessary to install lithium batteries in a screwdriver during rework through a protective controller. It should serve 3 18650 cells, 3.7V, and rated for 20-30 amps.
Remove the old battery from the socket, carefully disconnect the contacts in the assembly with the temperature sensor and the power indicator. Clean up and sign contacts. They should be brought out to one side, connected with solder to the leads from thick wires and filled with hot melt glue on the assembly.
Assemble a power source with one of the 3 cell controllers. Build a serial circuit of 3 Li-ion cells. Connect the controller. The conversion of the 12-volt lithium battery is completed when the structure is installed in the unit, secured, and the charging indicator lights up. After fully charging, the measurements show 12.17 volts in the external network. But this is enough for trouble-free long-term operation of the device.
Conversion of the Makita screwdriver to the lithium battery
There is a “Makita” 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. The alteration will give the old tool new possibilities: it will increase the operating time on a single charge. will add power as the operating voltage rises to 10.8V.
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 4.2V, the lower voltage is 2.7V. 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 screwdriver to lithium batteries looks like this.
- It is possible to disassemble the battery with glue if you tap the junction with a soft-headed hammer on the weight. Direction of impact downward, butt-joint along the lower part of the body.
- Take only the contact plates from the old assembly, carefully disconnecting them from the battery. The sensor and the breaker must be left.
- 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 a screwdriver with an old DC9710 charger, after charging the 18650 lithium battery, 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. The screwdriver is ready to work.
Accu Screwdriver Upgrade to Li-Ion Battery with USB Charger
Conversion of a 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 screwdriver battery should be carried out taking into account the peculiarities of lithium 18650 batteries.
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 a screwdriver with a voltage of 14.4 V lies in creating 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 screwdriver is high, you must select the appropriate BMS for the required number of cans and at least 30 A. To convert the charging of the screwdriver to a lithium battery, you must stock up on a good soldering iron, non-acidic flux and thick wires to make 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 a 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 circuit for connecting 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.
Alteration of the Interskol screwdriver for 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 DSh “Interskol” on lithium batteries serve much better. Alteration of a 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 operability, 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 screwdriver
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 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 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 almost empty. 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.
Conversion of the Hitachi screwdriver to lithium batteries
Nickel-cadmium batteries are inconvenient because of their “memory effect”, so switching to lithium-ion batteries is expedient and profitable.
How to convert a Hitachi screwdriver to lithium batteries: a description of the process
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 surfaces to be soldered 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 in the case, the wire is laid without kinks and creases. The halves of the case are held together.
The assembled lithium-ion battery pack must be put into working order. This is to ensure 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 charged again to 100%, and they 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%. Do not overexpose the device on recharging. as soon as the batteries are full, the charger must be disconnected.
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. 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-shrink 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.
Change Old Dead BOSCH Battery/ NI-MH Ni-Cd To Li ion With Test
Now everything is insulated as it should.
The contact part can be fixed in the battery case with a couple of droplets of super glue.
Battery ready for assembly.
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 will tell you exactly how.
Converting the battery of the screwdriver to Li-Ion
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.
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 ones, 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 will be 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 30-amp 18650 cells made by Sony VTC4 (2100 mAh capacity) and 20-amp Sanyo UR18650NSX (2600 mAh capacity). They work fine in my 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 assemble 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.
Makita DC9710 charger and lithium-ion battery
Previously, the battery was controlled by the device itself. When the full level was reached, it stopped the process and signaled the completion of charging with a green indicator. But now the BMS circuit we have installed is engaged in level control and power off. Therefore, when charging is complete, the red LED on the charger will simply turn off.
If you have such an old device, you are in luck. Because everything is simple with him. The diode is on. charging is in progress. Off. charging completed, battery fully charged.
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 disconnected. At the same time, the case is not damaged in any way, I have already disassembled 4 pieces this way.
The part of interest to us.
From the old circuit, only contact plates are needed. They are permanently spot welded to the top 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.
Makita DC1414 T charger and lithium-ion battery
There is a small nuance here that you need to know. This charger is newer and is designed to charge a wider range of batteries from 7.2 to 14.4 V. The charging process on it proceeds as usual, the red LED is on:
But when the battery (which in the case of NiMH cells is supposed to have a maximum voltage of 10.8 V) reaches 12 volts (we have Li-Ion cells with a maximum total voltage of 12.6 V), the charger will blow the roof. Because he will not understand what kind of battery he is charging: either 9.6-volt, or 14.4-volt. And at this moment Makita DC1414 will enter error mode, alternately blinking red and green LED.
This is normal! Your new battery will still charge. though not completely. The voltage will be approximately 12 volts.
That is, you will miss some part of the capacity with this charger, but it seems to me that you can survive.
In total, the upgrade of the oBosch battery cost about 1000 rubles. Makitovsky’s new Makita PA09 costs twice as much. over, we ended up with twice the capacity, and further repairs (in the event of a slight failure) will consist only in replacing lithium-ion cells.
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