Lithium Screwdriver Conversion Kit

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 is special. The chemical process is individual, the charge in closed systems is different. If there is a malfunction in one bank, the design does not provide the required voltage. Control system and charge balancing in individual components is not provided.

  1. Each Ni-Cd bank provides 1.2V and Li-ion 18650 3.6V.
  2. Lithium battery capacity is 2 times that of nickel-cadmium battery, similar size.
  3. An overheated li-ion battery threatens an explosion and fire, therefore, the installation of monitoring the uniformity of the charge in the banks is mandatory. The manufacturer is not interested in BMS nickel-cadmium batteries.
  4. Lithium cells have no memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
  5. 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 the input voltage is required for the screwdriver, the rework of the charger is made, taking into account the placement of the lithium battery cells and control elements in the factory container. You can also do with a flashlight by upgrading the socket for a block of 18650 cells.

Lithium Screwdriver Conversion Kit

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 slightly increase, the capacity is solid pluses. But when dismantling, you must leave the terminals and the native thermal sensor.

Conversion of 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-volt, 14-volt, 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 a screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.

Alteration of the Hitachi 12 V screwdriver to lithium batteries 18640

Features of reworking the Hitachi 12 V 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 service 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.

Converting a Makita screwdriver to a lithium battery

There is a Makita screwdriver with a battery with a capacity of 1.3 A / h and a voltage of 9.6 V. To change the power supply to a lithium-ion one, you will need 3 18650 components. 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 4.2V, lower voltage 2.7V. 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 amps, 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 terminals 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.

  1. You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while weighing. Direction of impact downward, butt-joint along the bottom of the body.
  2. Take only contact plates from the old assembly, carefully disconnecting them from the battery. Leave the sensor and breaker.
  3. Solder 3 elements in series using TAGS flux and insulated jumpers. The wire cross section must be greater than 0.75 mm2.
  4. Assemble the circuit with the controller, and connect the power supply to the contact connectors with 1.5 square wires.
  5. 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 required charging is already there. The screwdriver is ready to work.

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 adjusted 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.

  • 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 adhesive 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 leads and. Instead of a thermal 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 lids. Work pointwise.
  • Connect 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.
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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.

Translation of the Hitachi screwdriver to “lithium”

At present, there are a great many different batteries, protection boards, balancing boards, chargers, etc. It was necessary to select the right one and glue it together.

So, it was decided to supply high-current Li-Ion batteries. The current consumption of different screwdrivers can reach 30A and the batteries must be able to deliver such a current. Cheap “fingers” worth 80r apiece do not know how.

It was also decided to abandon the balancing BMS board, since all batteries were selected and were the same. By and large, at the beginning of operation it is not important.

This pair of batteries in a collapsible case was subject to alteration:

It was necessary to collect a battery of 4 batteries. The protection board was used with 4 batteries and 20A current. I do not give the link on purpose, because very soon it will not work. Search for a position by keywords

4S 14.8V / 16.8V 20A peak li-ion BMS PCM battery protection board bms pcm

The set turned out like this:

We assemble the battery with soldering of all contacts with an ordinary soldering iron. Please note: the connection of the assembled battery to the protection board MUST be carried out strictly in the following sequence: B-, B1, B2, B3, B:

It turns out this assembly kit:

Now we are preparing the contact pads:

You need to add a terminal for the charger to the case and you will get this final assembly:

Pay attention to how you fix the contact pad on the top of the battery. The self-tapping screw must be screwed in exactly in this place.

Here it is necessary to clarify. There are also protection boards with one contact group per charge and discharge. Here it is used with separate connectors, so the charging terminal is taken out separately. I recommend to put it in the specified place.

Now with regard to charging such a battery. You can remake a native charger (this is not difficult and will be discussed in another article, perhaps), but I decided to sell my own charger, and use an extra power supply from a laptop with a voltage of 18 volts. At its output, a controller for the end of charging was made of the following type (built into the power supply case):

After charging is complete, the LED will turn off reliably. In this case, the charge current was 1.5A and at the end of the charge before disconnection was about 1A. The full charging time of the battery was about 1.5 hours.

Budget: each set for one block was 1000r and its service life will be unlike a regular nickel-cadmium battery.

Minus one: it is not advisable to use it in cold weather.

It is also necessary to take into account that in a more powerful screwdriver it is necessary to use protection boards with an operating current of 30A, otherwise, under difficult operating conditions, the protection board will go into protection and de-energize the screwdriver. In this screwdriver with this protection board, such a problem has not been noted even once.

7 May 2018

Nikolay (Friday, 07 September 2018 04:10)

Good day. I decided to read the articles on your site. Came across this one. Without going into the details of your alteration, I strongly disagree with your method of charging lithium.
Firstly, balancing cans is needed! Otherwise, after 10 charge cycles, your bank voltages will be different. As a result, undercharging some and overcharging usually one can. Reducing the capacity of the entire battery as a whole. The risk of failure (overheating during charging) of the can that will be recharged. So put a separate balancing pad in the battery case or take out the balancing connector.
The second is your charging method. Forgive me for being straightforward, but this is not how lithium is charged. In this case, the approach, the simpler, the better does not work. Lithium must be charged according to the scheme (constant current, constant voltage) and by the end of the charge the voltage on your battery should be 16.8v. The current at the end of the charge should be no more than 0.1A. And you beat 18V instead of 16.8 and the current at the time of the BMS controller protection is 1.5A. Buy a current limited buck converter board. Set it to 16.8v at the output and limit the current to 2A. There are indicators on this board that will show you that the charge is over. She stands on ALishka 100 rubles. And the balancing fee of the cans also costs a penny.
Well, or if you have Imax on your farm, then charge it.
Just such a barbaric charge without balancing you will very quickly kill your battery, and it costs money!
Here are the links to the boards: Spm = a2g0v.12010615.8148356.21.44125425vlpyyw

RV9CX (Friday, 07 September 2018 07:43)

That’s right, Nicorlai. But let’s pay attention to where the batteries are operated. In a screwdriver! I understand if a device that is in operation around the clock was subjected to alteration, but in this case it is not. Secondly, I am skeptical about balancers. They are certainly needed, but not in such a performance. With a charging current in amperes and balancing of only 66mA, balancing cannot be achieved even with repeated charging. I conducted experiments: different batteries still do not equalize. Well, such a current is not enough for balancing. A few hundred mA at least. Then yes.

As for CC / CV. Same. For a screwdriver, there is no need to be pedantic about its batteries.

I completely agree with you. over, when using only the battery protection boards, they do not have time to gain their capacity, turning off when they reach 4.2V, but it would be necessary to hold them for a while at this voltage.

Thus, when using only the protection board without BMS, the batteries will never overcharge. They won’t get the capacity, yes. But they won’t recharge. The imbalance is not bad either. Protection will operate on low voltage. But once in a certain time it is necessary to check the balance and align the batteries. Yes. For this, there are boards with external connectors. But there is no need to keep the balancer connected at all times, because with it, the charging time increases significantly, and with intensive work with a screwdriver, this is critical. However, for my second shura, I brought a board with a built-in balancer and a 40A operating current. I can’t deliver for six months. Not up to her.

This is the case for high charge-discharge currents. In my other designs, I still put a balancer. For example, in a battery for an echo sounder. There is an article next to it. The batteries there are not 18650, but flat, but this does not change the essence. The charge current is 200mA and you can clearly see how the balancer works. It began to charge 3 times longer, but here I am just nowhere and in no hurry.

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One more case. Also next article. Antenna analyzer. There, too, there is only protection without BMS, the charge current is about 1A. I have been using it for probably 10 years already. At the same time, the batteries were disassembled from a dead laptop block, i.E. Already unhealthy. And it is still in excellent condition. The difference on the banks is 0.1 volts. And do not care! Discharge current is typically 170mA, maximum 250mA when backlit. This is not 40A. Will itch. I will even out the tensions, but now that’s enough for me.

This is me to the fact that you need to take into account the operating conditions of batteries.

Nikolay (Friday, 07 September 2018 10:13)

Regarding charging, not CC \ CV. I disagree. Well, why risk overcharging and turn off charging when the protection board is triggered when 100 r. And all the cases. And control of current and LED indication! Beauty! Overcharging is quite possible. One of my acquaintances had it. And the picture is exactly like yours. Makita screwdriver, BMS without palancier, charging from the native block with a current of 2.5A. As a result, the banks were unbalanced and one bank gained charge earlier than others. Shorter by the 1st 4.1 by the 2nd 4.1 by the 3rd 4.0 and by the 4th 4.6 BMS disconnected charging when the total voltage was 14.8. Result 1 can almost puffed, the temperature safety valve worked. The battery is parsing, replacing the can, installing it inside the balancer board. Now more than a year has passed. All perfectly. Now about the work of the balancer. You are wrong that it balances the banks only at the moment of charging. It works by itself and evens out the stress on the cans by burning off the surplus of the more charged cans. So by the time of charging, your banks are all even and start charging more or less evenly. You can take the balancing jack outside and sometimes connect a balancer to it. I have several converted shura and one of the most successful I consider the one in which I did not put the bms board at all. She stupidly did not fit in there. But I redid my own charger for CC \ CV and put a balancer in it. So I plug in the battery and it charges and balances. And when I use it, there are no problems with the protection activation. And in my opinion, only a fool can overdose the battery in a screwdriver. You feel that you started to twist weakly, changed the battery and this one for charging. It starts to twist weakly when the voltage on the battery is 10.10.5v.

RV9CX (Friday, 07 September 2018 19:57)

Some kind of wrong protection board. In theory, it should stop charging after reaching the limit voltage on at least one element! By the way, in the photo in the article, one of the two such boards was dead and cut off the voltage already when 4.5 volts was on the bank! Then they sent a new one, but the new batteries were already overheated, okay I saw ((

What you need to estimate before starting work?

Also, more lithium cells will give more capacity. This means longer operating time of the screwdriver.

Lithium battery cells 18650

The nominal voltage of lithium cells is 3.6-3.7 volts, and the capacity in most cases is 2000-3000 mAh. If the battery case allows, you can take not 4, but 8 cells. Connect them two by two into 4 parallel assemblies, and then connect them in series. As a result, you will be able to increase the battery capacity. But not every case will be able to pack 8 cans of 18650.

And the last preparatory stage is choosing a controller. According to its characteristics, it must correspond to the rated voltage and discharge current. That is, if you decide to assemble a 14.4 volt battery, then choose a controller with this voltage. The working discharge current is usually chosen half of the maximum permissible current.

Charge-Discharge Controller Board

All pros and cons of converting a screwdriver battery to lithium cells

First you need to think about whether I need this alteration? After all, it will be a frank self-propeller and in some cases can lead to failure of both the battery and the screwdriver itself. Therefore, let’s consider all the pros and cons of this procedure. It is possible that after that some of you will decide to abandon the conversion of the Ni─Cd battery for a screwdriver to lithium cells.

Arguments for

Let’s start with the benefits:

  • The energy density of lithium-ion cells is much higher than that of nickel-cadmium, which are used by default in screwdrivers. That is, the battery on lithium cans will have less weight than on cadmium with the same capacity and output voltage;
  • Lithium battery cells are charged significantly faster than Ni-Cd. It will take about an hour to charge them safely;
  • Lithium ion batteries have no memory effect. This means that they do not need to be fully discharged before charging..

Now about the disadvantages and complexities of lithium batteries.

Converting a screwdriver battery to lithium cells

Many screwdriver owners want to convert their batteries to lithium battery cells. Many articles have been written on this topic and in this material I would like to summarize information on this issue. First of all, we will consider the arguments in favor of converting a screwdriver to lithium batteries and against it. And also consider some moments of the process of replacing batteries.

Replacing batteries in a screwdriver with lithium

The arguments against

  • Lithium battery cells cannot be charged above 4.2 volts and discharged below 2.7 volts. In real conditions, this interval is even narrower. If you go beyond these limits, the battery can be damaged. Therefore, in addition to the lithium cans themselves, you will need to connect and install a charge-discharge controller in the screwdriver;
  • The voltage of one Li─Ion cell is 3.6─3.7 volts, and for Ni─Cd and Ni─MH this value is 1.2 volts. That is, there are problems with assembling a battery for screwdrivers with a voltage rating of 12 volts. From three lithium cans connected in series, you can assemble a battery with a nominal value of 11.1 volts. Out of four ─ 14.8, out of five ─ 18.5 volts, and so on. Naturally, the voltage limits during charge-discharge will also be different. That is, there may be problems with the compatibility of the converted battery with a screwdriver;
  • In most cases, 18650 standard cans are used in the role of lithium cells for conversion. They differ in size from Ni─Cd and Ni─MH cans. In addition, you will need space for the charge-discharge controller and wires. All this will need to fit in a standard battery case of a screwdriver. Otherwise, it will be extremely inconvenient for them to work;
  • The cadmium battery charger may not be suitable for recharging the battery after a redesign. You may need to improve the charger or use universal chargers;
  • Lithium batteries lose their performance at low temperatures. This is critical for those who use a screwdriver outdoors;
  • The price of lithium batteries is higher than cadmium.

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. POS-40 solder is most suitable for tinning.

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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. The most suitable jumpers are considered to be copper wires with a cross section of more than 2.5 mm. Sq. All wires are covered with cambric, which plays the role of a good insulator.

The connection of mini-batteries should be carried out with special jumpers according to the developed scheme. Metal strips or thin wires can become jumpers.

The final step is to connect the wires to the battery terminals made in the compartment. If the assembly of the prefabricated block is difficult, the stiffeners must be removed. Since they are made of plastic, it is easy to snack on them with ordinary side cutters.

Pin wiring diagram

To connect to the charger, you need to select the connectors that correspond to a specific model. Soldering of connecting cables is carried out according to the electrical diagram:

The connectors for connecting to the charger are selected depending on its model. Both connecting cables are soldered according to the diagram.

  • 5 and 9.
  • 1 and 6.
  • Balancing contacts (ascending) 2, 7, 3, 8 and 4.

A few words about the BMS board

It is designed to control the charge or discharge of the battery. CF-4S30A-A is designed for four banks of 18650 rechargeable 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 properly, the batteries for 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 operating on a current value of less than 30A is not very suitable. It will constantly turn on the protection mode.

Some boards require a short supply of charging current to recover. To do this, you will have to remove the battery from the case, reconnect the charger to it. The CF-4S30A-A board has no such drawback. It is enough to release the trigger of the screwdriver, if there is no current causing a short circuit, the board will turn on automatically.

The redesigned battery on this board can be charged with a universal charger. Latest models, Interskol company completes with multifunctional chargers.

DIY li-ion lithium screwdriver conversion

For several decades, screwdrivers have been used for 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 rework the screwdriver. A lithium battery will enhance the performance of your old instrument. over, it is possible to carry out such an alteration independently, without resorting to the services of special firms.

Finding the right battery

The connection of the batteries is made in series, therefore, the voltage rating of each cell is summed up with the subsequent one. That is, to get 14.4 volts, you need four 3.3 V cells.

To convert a cordless screwdriver, you only need to buy miniature batteries from 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 the electric tool. Cheap batteries made in China won’t do much. They will fail quickly.

When choosing a battery for rework, copper strips need to be located on the terminals. Soldering such elements is much easier.

Algorithm for converting a battery to a lithium-ion battery

How to redesign a screwdriver to get the best performance? This requires strictly follow a certain technological sequence.

Converting a Li-ion screwdriver for home

How to convert a battery from a screwdriver from nickel-cadmium to lithium batteries at home.

I got myself two used screwdrivers. One had a battery, the other didn’t, just the wires were brought out. I cleaned it and decided to complete it with normal batteries. I will convert to lithium-ion.

High-current elements are needed here, they will not work from a laptop. I have used elements, with a residual capacity of a little more than 1 ampere / hour.

Battery conversion process

We disassemble the old battery and remove some of the batteries, leaving only two with a contact group.

We solder the wires to the positive and negative terminals. I soldered directly to the poles, since the contact plates were not tinned.

We connect 18650 batteries in parallel and solder old elements with a contact group to them.

So that the contacts with the elements do not fall through, I made a support from a wooden block.

Now you need to install a connector for charging each element, a balancing connector. I used the connectors from the motherboard and the computer’s power supply.

We solder everything in order. Plus with the first contact. The second contact to the plus of the second element and so on.

Cut out a hole for the connector and fix the connector with epoxy glue. The glue is dry and we close the battery. Putting aside.

Since I will be charging the battery with a smart charger, I need to do the wiring for it. One part from the power supply, the second from the flop. We modify the connector from the flop, cutting off all the guides and keys. After deleting all the keys, it fits my Turnigy fine, it fits Imax too.

We put on the charger with a balance (3S). After the end of the charge cycle, we use it. I am working on the second battery using this technology, and everything works fine. The first screwdriver with a converted battery proved to be excellent.