Every craftsman faces the problem of tool performance degradation, or complete failure due to the battery. Manufacturers use nickel-cadmium batteries in 12, 14, 18 volt screwdrivers. The series assembly scheme of several elements creates the desired voltage. Replacing nickel-cadmium batteries with lithium batteries increases battery life by lightening the design. The obligatory installation of a BMS board adds reliability. Therefore, the conversion of a screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.
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 desired voltage. The control system and charge balancing in individual components is not provided.
- Each Ni-Cd bank gives 1.2V, and li-ion 18650 - 3.6V.
- The capacity of a lithium battery is 2 times that of a nickel-cadmium battery of similar size.
- An overheated li-ion battery threatens to explode and ignite, so setting charge uniformity control in banks is mandatory. BMS is not installed in nickel-cadmium batteries - the manufacturer is not interested.
- Lithium cells do not have a 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 cans.
There are only two obstacles to converting a screwdriver for lithium batteries - it is impossible to work with it at a minus. The capacity of cans drops, 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 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 elements.
Let's say you need to remake a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 banks, the output voltage is not enough: 3.6 x 3 \u003d 10.8 V. With 4 components, the power of the device will be higher: 3.6 x 4 \u003d 14.4 V. This will make the tool lighter by 182 g , its power will increase slightly, capacity - solid pluses. But when dismantling, it is necessary to leave the terminals and the native temperature sensor.
Converting 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 18650 form factor are more often used. They easily fit into a container or nest, since instead of two or three native ones, they install one lithium one. Alteration of the battery of a screwdriver should be carried out taking into account the features of lithium batteries for 18650.
This type of energy source does not tolerate deep discharge and excessive charge. So, it is necessary to use voltage control boards. Since each battery has its own character, their charge is adjusted by the balancer. The point of reworking a 14.4 V screwdriver is to create a device using lithium batteries to lighten a hand tool and increase its performance. Lithium 18650 batteries are the most suitable for this purpose.
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 need to stock up on a good soldering iron, non-acid flux and thick wires to make jumpers.
Equipment:
- Lithium-ion banks in the amount of 4 pcs.
- Li-ion battery controller for 4 banks, CF-4S30A-A fits well. It has a built-in balancer that controls the charge of each element.
- Hot melt adhesive, flux for soldering TAGS, solder.
- heat-resistant adhesive tape;
- Connecting jumpers or thick wire insulated with a cross section of at least 0.75 square, cut for bridges.
The procedure for converting a screwdriver under 18650:
- Dismantle the case and remove a bundle of 12 Ni-Cd elements from the container.
- Remove the garland, leaving the connector with the conclusions "+" and "-". Instead of a temperature sensor, a thermocouple from the controller will be installed.
- Solder the assembly, taking into account that no acid can be used, only neutral flux and pure solder. During the connection period, do not heat the lids. Work precisely.
- Connect balancing points to the controller according to the diagram. Connectors are provided on the board.
- Connect the assembly to the plus and minus terminals.
- Check the functionality of the circuit. If everything works, the assembled battery, place the controller in the socket, secure with sealant.
If the memory 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 3x18650 3.7 V to lithium batteries is used. In the same way, a screwdriver is remade using a 18650 battery kit in the amount of 2 elements.
Converting a Makita screwdriver to a lithium battery
There is a “Makita” screwdriver with a battery capacity of 1.3 A / h and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. , will add power as the operating voltage rises to 10.8V.
The design will require the use of a BMS, a master controller that keeps the lithium cells operating within operating limits. With this interrupter, the charging of each can will be uniform without exceeding 4.2 V, the lower voltage is 2.7 V. A built-in balancer is used here.
The controller parameters should accompany the operation of the tool when the operating current increases to 10-20 A. The 30 A Sony VTC4 board, designed for a capacity of 2100 A / h, can ensure operation without shutdown. Of the 20 amps, the Sanyo UR18650NSX is suitable, receiving energies of 2600A / h. The board is needed for 3 elements, which is marked in the 3S classification. In this case, the board should have 2 contacts, plus and minus. If the conclusions are marked with the letters "P-", "P +", "C-", they are intended for later models of screwdrivers.
A step-by-step instruction for converting a Makita 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 hanging. The direction of impact is down, in the 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 circuit breaker must be left.
- Solder 3 elements in series using TAGS flux and jumpers with insulation. The cross section of the wire must be greater than 0.75 mm2.
- Assemble the circuit with the controller, and connect the power supply to the connectors with 1.5 square wires.
- Check the operation of the circuit and assemble the case by putting 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 supplies. 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 12V, the charger will flash red and green. But the necessary charging is already there. The screwdriver is ready to go.
Converting a Hitachi 12V screwdriver to 18640 lithium batteries
Features of converting a 12 V Hitachi screwdriver to lithium batteries. The very compact battery cell socket is designed for finger cells. Therefore, you should prepare a place for 18650 elements. It is necessary to cut one side of the partition in order to tightly place 1 element.
You need to get flux, a flat metal connecting tape, hot melt adhesive. It is necessary to install lithium batteries in a screwdriver when reworking 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 in one direction, connected with solder to the leads from thick wires and filled with hot melt adhesive.
Assemble a power source with one of the controllers designed for 3 elements. Assemble a series circuit of 3 Li-ion elements. Connect controller. The conversion of the 12V lithium battery is completed when the structure is installed in the block, secured, and the charging indicator lights up. After fully charged, measurements show 12.17 volts in the external network. But this is enough for trouble-free long-term operation of the device.
Alteration of the Interskol 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 LH "Interskol" on lithium batteries serve much better. The conversion of a screwdriver to 18 volt lithium batteries has been mastered by craftsmen.
You need 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 18650 lithium batteries, you can leave them with factory thermistors by extending the wires. During installation, create a contact pad, insert the assembly, check the operation, and fix it. The assembly features of the wizard's advice are given in detail in the video. Here's the full info on rebuilding the 18V Lithium Screwdriver
For a long time there was no review of the conversion of a screwdriver to lithium :)
The review focuses on the main BMS board, but there will be links to some other little things involved in the transfer of my old screwdriver to 18650 lithium batteries.
In short - you can take this board, after a little finishing, it works quite normally in a screwdriver.
PS: a lot of text, pictures without spoilers.
P.S. The review is almost anniversary on the site - the 58000th, according to the address bar of the browser;)
What is this all for
I have been working for several years, bought cheaply in a construction store, an unnamed two-speed screwdriver for 14.4 volts. More precisely, not completely nameless - it bears the mark of this construction worker, but not some eminent one either. Surprisingly tenacious, still hasn't broken down and does everything I ask of him - drilling, screwing and unwinding, and how the winder works :)
But his native NiMH batteries did not want to work for so long. One of the two complete ones finally died a year ago after 3 years of operation, the second one has recently no longer lived, but existed - a full charge was enough for 15-20 minutes of operation of the screwdriver with interruptions.
At first I wanted to do with small forces and just replace the old cans with the same new ones. Bought these from this seller
They worked perfectly (although a little worse than relatives) for two or three months, after which they died quickly and completely - after a full charge, they were not even enough to tighten a dozen screws. I do not recommend taking batteries from him - although the capacity initially corresponded to the promised one, they did not last long.
And I realized that I still have to be confused.
Well, now about the main thing :)
Having chosen Ali from the offered BMS boards, I settled on the monitored one, in terms of its size and parameters:- Model: 548604
- Voltage overcharge shutdown: 4.28+ 0.05 V (per cell)
- Recovery after overcharge shutdown at voltage: 4.095-4.195V (per cell)
- Over-discharge shutdown at voltage: 2.55±0.08 (per cell)
- Disable overcharge delay: 0.1s
- Temperature range: -30-80
- Short circuit trip delay: 100ms
- Overcurrent trip delay: 500ms
- Cell balancing current: 60mA
- Working current: 30A
- Maximum current (protection operation): 60A
- Short circuit protection operation: self-healing after load disconnection
- Dimensions: 45x56mm
- Main functions: overcharge protection, overdischarge protection, short circuit protection, overcurrent protection, balancing.
All board components are placed on one side: 
The second side is blank and covered with a white mask: 
The part responsible for balancing when charging: 
This part is responsible for protecting cells from overcharging / overdischarging, and it is also responsible for general short circuit protection: 
Mosfets: 
Assembled neatly, there are no frank streaks of flux, the view is quite decent. The kit included a tail with a connector, it was immediately plugged into the board. The length of the wires in this connector is about 20-25 cm. Unfortunately, I did not take a picture of it right away.
What else I ordered specifically for this alteration:
Batteries -
Nickel strips for soldering batteries: (yes, I know that you can solder with wires, but the strips will take up less space and turn out to be more aesthetically pleasing :)) Yes, and initially I even wanted to assemble contact welding (not only for this alteration, of course), and therefore I ordered strips, but laziness won and I had to solder.
Having chosen a free day (more precisely, brazenly sending all other cases away), I took up the alteration. To begin with, I dismantled the battery with dead Chinese batteries, threw out the batteries and carefully measured the space inside. Then I sat down to draw a battery holder and boards in a 3D editor. The board also had to be drawn (without details) in order to try on everything assembled. It turned out something like this: 
As planned, the board is attached from above, with one side into the grooves, the second side is clamped with an overlay, the board itself lies in the middle on a protruding plane so that when it is pressed, it does not bend. The holder itself is made of such a size that it sits tightly inside the battery case and does not hang out there.
At first I thought about making spring contacts for batteries, but abandoned this idea. For high currents, this is not the best option, so I left cutouts for nickel strips in the holder, with which the batteries will be soldered. I also left vertical cutouts for wires that should go from the inter-jar connections outside the lid.
I set it to be printed on an ABS 3D printer and after a few hours everything was ready :) 
I decided not to trust the screws when screwing everything attached and fused these M2.5 nuts into the body: 
Take it here -
Great product for this kind of use! Melted slowly with a soldering iron. To prevent the plastic from stuffing inside when fused into blind holes, I screwed a bolt of a suitable length into this nut and heated its cap with a soldering iron tip with a large drop of tin for better heat transfer. The holes in the plastic for these nuts are left slightly smaller (by 0.1-0.2 mm) than the diameter of the outer smooth (middle) part of the nut. They hold very tightly, you can screw in and unscrew the bolts as much as you like and not be particularly shy with the tightening force.
In order to be able to control per jar and, if necessary, charge with external balancing, a 5-pin connector will stick out in the back wall of the battery, for which I quickly threw on a scarf and made it on the machine: 
The holder provides a platform for this scarf.
As I already wrote, I soldered the batteries with nickel strips. Alas, this method is not without drawbacks, and one of the batteries was so indignant at such treatment that it left only 0.2 volts on its contacts. I had to solder it and solder another one, since I took them with a margin. Otherwise, there were no difficulties. With the help of acid, we tin the battery contacts and nickel strips cut to the desired length, then carefully wipe everything tinned and around it with cotton wool and alcohol (but you can also use water), and solder. The soldering iron must be powerful and either be able to react very briskly to the cooling of the tip, or simply have a massive tip that will not cool down instantly upon contact with a massive piece of iron.
Very important: during soldering and during all subsequent operations with a soldered battery pack, you must be very careful not to close any battery contacts! Also, as pointed out in the comments ybxtuj, it is very desirable to solder them discharged, and I absolutely agree with him, so the consequences will be easier if something still closes. A short circuit of such a battery, even a discharged one, can lead to big troubles.
I soldered wires to the three intermediate connections between the batteries - they will go to the BMS board connector for controlling banks and to the external connector. Looking ahead, I want to say that I did a little extra work with these wires - they can not be led to the board connector, but soldered to the corresponding pins B1, B2 and B3. These pins on the board itself are connected to the connector pins. 
By the way, I used silicone-insulated wires everywhere - they do not react to heat at all and are very flexible. I bought several sections on Ebee, but I don’t remember the exact link ... I like them very much, but there is a minus - the silicone insulation is not very strong mechanically and is easily damaged by sharp objects.
I tried on the batteries and the board in the holder - everything is excellent: 
I tried on a scarf with a connector, cut a hole for the connector in the battery case with a dremel ... and missed the height, took the size from the wrong plane. It turned out a decent gap like this: 
Now it remains to solder everything together.
I soldered the tail that came with the kit to my scarf, cutting it to the desired length: 
I also soldered the wires from the interbank connections there. Although, as I already wrote, it was possible to solder them to the corresponding contacts of the BMS board, but there is also an inconvenience - in order to pull out the batteries, you will need to solder not only the plus and minus from the BMS, but also three more wires, and now you can just pull out the connector.
I had to tinker a little with the battery contacts: in the native version, the plastic part (holding the contacts) inside the battery leg is pressed by one battery standing right under it, and now I had to think about how to fix this part, so as not to be tight. Here is that detail: 
In the end, he took a piece of silicone (left over from pouring some form), cut off an approximately suitable piece from it and inserted it into the leg, pressing that part. At the same time, the same piece of silicone presses the holder with the board, nothing will hang out.
Just in case, I laid Kapton electrical tape over the contacts, grabbed the wires with several snots and drops of hot-melt adhesive so that they would not get between the halves of the case during its assembly. 
Charging and balancing
I left the charge from my screwdriver, it just gives out about 17 volts at idle. True, charging is stupid and there is no stabilization of current or voltage in it, there is only a timer that turns it off about an hour after the start of charging. The current gives out about 1.7A, which, although a bit much, is acceptable for these batteries. But this is until I finish it to normal, with current and voltage stabilization. Because now the board refuses to balance one of the cells, which initially had a charge of 0.2 volts more. The BMS turns off the charge when the voltage on this cell reaches 4.3 volts, respectively, on the rest it remains within 4.1 volts.I read somewhere the statement that this BMS normally balances only with CV / CC charging, when the current gradually decreases at the end of the charge. Perhaps this is the case, so ahead of me is the modernization of charging :)
I did not try to discharge to the end, but I am sure that the discharge protection will work. There are videos on YouTube with tests of this board, everything works as expected.
And now about the rake
All banks are charged to 3.6 volts, everything is ready to run. I insert the battery into the screwdriver, pull the trigger and ... I'm sure that more than one person familiar with this rake now thought, "Damn, your screwdriver started" :) Absolutely, the screwdriver twitched slightly and that's it. I release the trigger, press again - the same thing. I press it smoothly - it starts and accelerates, but if I start it a little sharper - it's a failure."That's it..." I thought. The Chinese probably indicated Chinese amps in the specification. Well, okay, I have an excellent thick nichrome wire, now I will solder a piece of it over shunt resistors (there are two of 0.004 Ohm in parallel) and if not happiness, then at least some improvement in the situation will come to me. There has been no improvement. Even when I completely excluded the shunt from work, simply soldering the minus of the battery after it. That is, not that there were no improvements, but no changes at all.
And then I got into the Internet and found that the copyright for this rake does not shine for me - they have long been trodden by others. But somehow the solution was not visible, except for the cardinal one - to buy a board that is suitable specifically for screwdrivers.
And I decided to try to get to the root of the problem.
I dismissed the assumptions that overload protection is triggered at inrush currents, since even without a shunt nothing changed.
But still I looked with an oscilloscope on a homemade 0.077 ohm shunt between the batteries and the board - yes, PWM is visible, sharp consumption peaks with a frequency of about 4 kHz, 10-15 ms after the start of the peaks, the board cuts off the load. But these peaks showed less than 15 amps (based on the resistance of the shunt), so it's definitely not a current overload (as it turned out later, this is not entirely true). Yes, and a ceramic resistance of 1 ohm did not cause a shutdown, but the current is also under 15 amperes.
There was another option for a short-term drawdown on the banks at startup, from which the overdischarge protection is triggered, and I climbed to see what was happening on the banks. Well, yes, horror is happening there - a peak drawdown of up to 2.3 volts on all banks, but it is very short - less than a millisecond, while the board promises to wait a hundred milliseconds before turning on the overdischarge protection. “The Chinese indicated Chinese milliseconds,” I thought, and climbed to look at the voltage control circuit of the cans. It turned out that it has RC filters that smooth out sharp changes (R=100 Om, C=3.3 uF). After these filters - already at the input of the microcircuits that control the banks, the drawdown was smaller - only up to 2.8 volts. By the way, here is the datasheet for the can control microcircuits on this DW01B board -
According to the datasheet, the response time to overdischarge is also considerable - from 40 to 100 ms, which does not fit into the picture. But okay, there’s nothing more to suggest, so I’ll change the resistances in the RC filters from 100 Ohm to 1 kOhm. This radically improved the picture at the input of microcircuits, there were no more drawdowns of less than 3.2 volts. But the behavior of the screwdriver did not change at all - a slightly sharper start - and plugging.
"Let's go with a simple logical move" ©. Only these DW01B microcircuits, which control all discharge parameters, can cut off the load. And I looked at the control outputs of all four microcircuits with an oscilloscope. All four microcircuits do not make any attempts to turn off the load when starting the screwdriver. And from the gates of the mosfets, the control voltage disappears. Either the mystic or the Chinese screwed up something in a simple circuit, which should be between microcircuits and mosfets.
And I started reverse engineering this part of the board. With obscenities and running from the microscope to the computer. 
Here is what emerged as a result: 
In the green rectangle are the batteries themselves. In blue - the keys from the outputs of the protection microcircuits, also nothing interesting, in a normal situation, their outputs to R2, R10 simply “hang in the air”. The most interesting part is in the red square, that's where, as it turned out, the dog rummaged. I drew mosfets one at a time for simplicity, the left one is responsible for the discharge into the load, the right one for the charge.
As far as I understand, the reason for the shutdown is in the resistor R6. Through it, an “iron” protection against current overload is organized due to the voltage drop on the mosfet itself. Moreover, this protection works as a trigger - as soon as the voltage at the base of VT1 starts to rise, it starts to reduce the voltage at the gate of VT4, from which it begins to reduce conductivity, the voltage drop on it increases, which leads to an even greater increase in the voltage at the base of VT1 and went avalanche a process leading to the full opening of VT1 and, accordingly, the closure of VT4. Why this happens when starting the screwdriver, when the current peaks do not reach even 15A, while a constant load of 15A works - I do not know. Perhaps the capacitance of the circuit elements or the load inductance plays a role here.
To test, I first made a simulation of this part of the circuit: 
And this is what I got as a result of her work: 
On the X axis - time in milliseconds, on the Y - voltage in volts.
On the lower graph - the load is turned on (you can not look at the numbers along Y, they are conditional, just up - the load is on, down - off). The load is a resistance of 1 ohm.
On the upper graph, red is the load current, blue is the voltage at the mosfet gate. As you can see, the gate voltage (blue) decreases with each load current pulse and eventually drops to zero, which means the load is turned off. And it does not recover even when the load stops trying to consume something (after 2 milliseconds). And although other mosfets with different parameters are used here, the picture is the same as in the BMS board - an attempt to start and turn off in a matter of milliseconds.
Well, let's take this as a working hypothesis and, armed with new knowledge, let's try to crack this piece of Chinese science :)
There are two options here:
1. Put a small capacitor in parallel with resistor R1, this is: 
Capacitor 0.1 microfarad, according to the simulation it is possible and less, up to 1 nf.
The simulation result is as follows: 
2. Remove resistor R6 altogether: 
Simulation result of this option: 
I tried both options - both work. In the second option, the screwdriver does not turn off under any circumstances - start, rotation lock - twists (or tries hard). But somehow it’s not quite easy to live with disabled protection, although there is still protection against short circuits on microcircuits.
With the first option, the screwdriver starts confidently with any pressure. I was able to achieve a shutdown only when I started it at second speed (high for drilling) with a locked chuck. But even then it pulls quite strongly before shutting down. At the first speed, I could not get it off. I left this option to myself, it completely suits me.
There are even empty places for components on the board, and one of them seems to be specially designed for this capacitor. It is calculated for the size of SMD 0603, here I soldered 0.1 microfarads (circled it in red): 
TOTAL
The board fully lived up to expectations, although it brought a surprise :)I don’t see the point in describing the pros and cons, it’s all in its parameters, I’ll point out only one advantage: a completely minor revision turns this board into a fully functional one with screwdrivers :)
PS: damn it, I redid the screwdriver in less time than I wrote this review :)
ZZY: perhaps my comrades, more experienced in power and analog circuitry, will correct me in something, I myself am a digital and analog perceive a deck through a stump :)
For several decades, screwdrivers have been used in various jobs. These devices are powered by nickel or cadmium batteries. But progress does not stand still, scientists have found a replacement for such outdated batteries. They were replaced by lithium counterparts. To use such a battery, you need to remake the screwdriver. The lithium battery will increase the performance of the old tool. Moreover, it is possible to perform such an alteration on your own, without resorting to the services of special firms.
The lithium battery of a screwdriver has a number of advantages that were absent in cadmium counterparts.
The energy density of the Li ion screwdriver battery is much higher. The battery with lithium banks is lightweight, and the voltage of 12 volts, as well as the capacity of the battery, remains unchanged. Lithium batteries charge faster than ion batteries. Safe charging takes about 60 minutes.
Lithium-ion batteries do not have a "memory effect". In other words, they do not need to be completely discharged in order to be charged. Among the positive qualities of a lithium battery, there are a number of disadvantages that must be considered:
- Charging lithium batteries should not be higher than 4.2 volts, and discharging higher than 2.7 volts. But this is theoretical data. In real life, the interval gets even worse. If the set values are not met, the battery will simply stop functioning. To avoid this situation, after converting the screwdriver to lithium, you need to install a special discharge controller in the screwdriver, as well as its charging.
- One Li ion has a voltage of 3.63.7 V. For a nickel battery, it is no more than 1.2 volts. In other words, converting a screwdriver to li ion material causes problems associated with the assembly process of a battery whose nominal voltage is 12 volts. Three lithium banks connected in series give a voltage of 11.1 volts, four 14.8 V. The charge voltage limits will change. In other words, altering the battery for a screwdriver is connected with solving the problem of compatibility of the new battery with the tool.
- To rework the cadmium battery of a screwdriver, craftsmen use 18650 lithium cans. Their dimensions differ from nickel cans. Alteration of the battery for a screwdriver also requires the installation of a controller, which will require additional space.
- After the alteration, the nickel battery charger will have to be finalized, or use a universal charger.
- Minus temperatures adversely affect the operation of ion batteries. Therefore, such a converted screwdriver is not always possible to work outdoors.
- The cost of lithium batteries is much higher than cadmium counterparts.
Algorithm for converting a battery to a lithium-ion battery
How to remake a screwdriver to get the highest performance? This requires strictly following a certain technological sequence.
Choosing the right battery
The connection of the batteries is made in series, therefore the voltage rating of each element is added to the next one. That is, to get 14.4 volts, you need four cells with a voltage of 3.3 V.
To remake a cordless screwdriver, you need to buy miniature batteries from only a well-known manufacturer. For example, LiFePO4 batteries manufactured by Sistem A123. The cell capacity reaches 2,300 mAh. This value is sufficient for the efficient operation of an electric tool. Cheap batteries made in China won't do much. They will wear out quickly.
When choosing a battery for rework, you need to have copper strips on the terminals. Soldering such elements is much easier.
Selection of tools and materials
Soldering technology is different in its specificity. The temperature of the soldering iron tip is constantly high. If the battery is kept under such thermal exposure for a long time, it will quickly deteriorate. Therefore, the heating of the soldering iron should be minimal.
For this to happen, it is necessary to replace ordinary rosin with soldering acid. It can be purchased at a radio parts store. For such a process, you will also have to purchase a soldering iron with enough power to melt the solder in the shortest possible time. The most suitable would be a household soldering iron with a power of 65 watts. At 100 watts, the battery will overheat all the time.
Soldering work requires a lot of experience. For example, a 40-watt soldering iron will heat up for a long time, you can just “overdo it”. To start converting ion batteries, you need to purchase the following parts:
- 18650 battery.
- BMS board CF-4S30A-A/
- Wires with a cross section of 2.5 square meters. mm.
- Soldering iron.
- The case of the old battery.
A few words about BMS board
It is designed to control the charge or discharge of the battery. The CF-4S30A-A is designed for four banks of 18650 batteries, giving a discharge current of 30A. The board is equipped with a special "balancer". It performs the functions of controlling the charge of each element separately. This completely eliminates the possibility of uneven charging. For the board to function correctly, the batteries for the assembly must have the same capacity. It is desirable that they be taken from the same block.
The industry produces a large number of BMS boards that differ in their technological characteristics. For reworking a screwdriver battery, a board that runs on a current less than 30A is not very suitable. It will always turn on protection mode.
Some boards require a brief charge current to restore operation. To do this, you will have to remove the battery from the case, reconnect the charger to it. The CF-4S30A-A board does not have such a disadvantage. It is enough to release the trigger for turning on the screwdriver, if there is no current causing a short circuit, the board will turn on automatically.
The converted battery on this board can be charged with a universal charger. The latest models, the Interskol company, completes with multifunctional chargers.
Mounting the lithium-ion battery
Of course, any installation requires preliminary preparation. It includes several very important points. Before you start soldering the parts, you need to determine how the battery mounting compartment will be arranged. All the necessary elements should easily fit in it.
Then the new lithium batteries are sealed with tape. Since the contacts oxidize over time, they are cleaned with a fine-grained sandpaper before soldering.
The nuances of the soldering process
First, the contact part of the battery is thoroughly degreased. Then tinning is carried out by heating the applied solder. Solder POS-40 is most suitable for tinning.
The contact of the soldering iron with the battery contact should not exceed 2 seconds. The process of soldering the battery plus requires special attention. Jumpers made of copper wires with a cross section of more than 2.5 mm are considered the most suitable. sq. Cambric is put on all wires, which plays the role of a good insulator.
The connection of mini-batteries must be carried out with special jumpers according to the developed scheme. Jumpers can be metal strips or thin wires.
At the final stage, the wires are connected to the conclusions made in the compartment intended for the battery. If the installation of the prefabricated block is difficult, it is necessary to remove the stiffeners. Since they are made of plastic, they are easy to bite with ordinary side cutters.
Pinout diagram
To connect to the memory, you need to select the connectors that correspond to a specific model. Soldering of connecting cables is carried out according to the electrical diagram:
Connectors for connecting to the charger are selected depending on its model. Both connecting cables are soldered according to the scheme.
- "+" - 5 and 9.
- "-" - 1 and 6.
- Balancing contacts (ascending) - 2, 7, 3, 8 and 4.
Of course, the installation of lithium-ion batteries has a large number of positive qualities:
- Lack of "memory".
- Minimum self-load.
- You can operate the tool at sub-zero temperatures.
- Long service life (8 years).
However, these batteries are highly sensitive to the charging process. The voltage should always be at the minimum values, otherwise the Li-ion battery will quickly become unusable. To fulfill such conditions, you need another memory, the cost of which is an order of magnitude higher. The screwdriver's native charger will not be able to charge a lithium-ion battery.
It is impossible to say unequivocally which battery for a screwdriver is better. Their service life depends on careful handling, on exact observance of the instructions supplied by the manufacturer.
Popular Models
Today, batteries are produced by many manufacturers. Among such a large range of lithium-ion systems, the most popular are: "Bosh" 10.8, with technical characteristics:
- Capacity - 1.3 A / hour.
- Voltage - 10.8 V.
- Dimensions -110 x 54 x 52mm.
- Warranty -1 year.
- Power is average.
If we talk about nickel-cadmium batteries, the following brands remain the most popular:
- "Bort".
- Hitachi.
Russian batteries are designed for low voltage, they differ from imported models only in price. They are much cheaper, but at the same time they are not inferior to their technical indicators. The most famous models are:
- "Kraton".
- "ZAKB".
Conclusion
Lithium batteries have always been considered the most technologically advanced devices. But a tool with such batteries is much more expensive. You can, of course, remake your device and get rid of cadmium batteries. However, this will cause other problems. Therefore, the decision to convert a screwdriver to lithium is made by everyone himself, depending on the circumstances.
Interesting videos about altering the battery of a screwdriver
Many craftsmen in the service have a cordless screwdriver. Over time, the battery degrades and holds a charge less and less. Battery wear has a huge impact on battery life. Constant recharging does not help. In this situation, “repacking” the battery with the same elements helps. The most commonly used elements in screwdriver batteries are the "SC" size type. But the most valuable thing for a master is a do-it-yourself repair.
Let's remake a screwdriver with a 14.4 volt battery. Screwdrivers often use a motor for a wide range of supply voltages. So in this case, only three Li-ion cells of the 18650 format can be used. I will not use control boards. The discharge of elements will be visible in the work. As soon as the self-tapping screw does not twist, for example, it's time to put it on charge.
Converting a screwdriver to Li-ion without a BMS board
First, let's disassemble our battery. Inside it are 12 elements. 10 pieces in one row and 2 in the second row. A contact group is welded to the second row of elements. We leave a couple of elements with a contact group, we recycle the rest.
Now you need to solder the wires for further work. The contacts turned out to be from a material that cannot be tinned, so we solder the wires to the elements. Minus to the body of the element, and plus directly to the plus patch. Old elements play the role of a support and are not involved in the work.
I will use lithium-ion batteries of the 18650 format. Elements bu. High-current elements are needed for refinement. I “changed” my elements into thermal shrinkage from Sanyo, the old one was pretty shabby. Checked the residual capacity Imax.
We connect the batteries in series and solder the elements of the head. The battery is almost ready.
Now we will provide comfortable charging. You need to install a four-pin connector. I used the connector from the old motherboard for the number of pins I needed. I took the mate from an old computer power supply.
Cut out a hole for the connector. We fill the connector with epoxy glue or super glue with soda. We also solder the wires.
Solder the wires to the elements. Wire from the first contact of the connector to the plus of the battery. The wire from the second contact of the connector to the plus of the second element, it is also the minus of the first element, and so on. Since I will be charging with a “smart” charger, I need to make a balancing wire.
As a connector for connecting to the charger, I will use the wire from the computer's power supply. The wire through which the floppy drive was powered. We cut off all the keys from the connector and it fits perfectly under the charger. It dissolves simply. Red wire to the first contact of the battery connector. Black wire to battery connector pin 2, etc.
A friend has a BOSCH GSR 12-2 Professional screwdriver, it has been working for a long time, but it rarely works, and the batteries began to die intensively, back in the fall, let's tell it to me, I'll revive it over the winter, time and options, the sea, restore old cans, bay in them distilled water and having trained them, replace the dead cans, if there are few of them, convert them to lithium. But no, I say they don’t work enough for me, the capacity is enough, as a result, both batteries died at zero volts by spring, I launched the battery with a charger, but there’s still no capacity, buying new ones is like buying a new screwdriver, changing nickel-cadmium cans too not cheap and not for a long time, as a result I get the go-ahead for conversion to lithium. The owner is a pensioner, so we try to save money, and he uses it from time to time. I order on ALI BMS 4S 15A, which would later be converted into 3S according to the scheme.
Strangely enough, 4S is cheaper than 3S, vision is certainly not the same, but still redone, and 100-150 rubles. saved. I also ordered high-current folk batteries 6 pcs. Samsung inr1865025rm 20a is just for two battery packs. They came, checked the capacity at 1A current.
It seems to be good, and the reviews from the seller are not bad.
There is a lot of information on the network about alterations, but the boards for three and four batteries are slightly different, if the board is for 4 batteries, then you need to put 4 or redo it according to the scheme for 3 batteries. I have done according to this scheme, because the screwdriver itself is 12 volts.
The capacity of each assembly is like two new Ni-Ca (old ones in theory 1.3 Ah), fixed the old and new batteries with hot glue, soldered the battery, not welded it, I know that it’s not Feng Shui but didn’t overheat, it will go like that;) and I didn’t redo the charging ( works in the normal mode, all indications correctly show both charging and the end of the charge), it turns like new and better, I didn’t put a balancer on the battery, it’s at least 300 rubles, it’s better to take it apart in a year or two and balance it manually. This is how they opened a "second wind" to a screwdriver.
GVGVLG, Volgograd, Russia
https://www.drive2.com/users/gvgvlg/
Video selection. The best videos about altering screwdrivers.
1. Converting a screwdriver to a Li-Ion battery.
Converting a screwdriver to a Lithium-ion battery
How to transfer a screwdriver to lithium batteries (welding batteries to a battery)
How to convert a nickel-cadmium battery to a lithium-ion battery yourself in a screwdriver
Converting a screwdriver to lithium-ion batteries of the 18650 standard
Converting a screwdriver to lithium 18650
2. Converting a screwdriver to a network one.
Converting a screwdriver to a network one. Test of different power sources
Converting a screwdriver to a network
When the batteries do not hold a charge and have exhausted their resource, and the screwdriver is still in good condition, it can be connected to a 220V network through a power supply with sufficient power.
