Converting a 12v electric screwdriver to lithium 18650 batteries

Components needed for conversion

converting, electric, screwdriver, lithium

Beforehand, it is necessary to pick up components that will help transform the electric screwdriver. The composition is determined by the specifics of the process, namely by soldering, using special cassettes or spot welding. cassettes are not recommended due to their vulnerability to current. The rest of the list includes:

  • Li-ion18650 batteries;
  • Protective circuit board or module that provides a uniform load when charging;
  • contact welding machine. It is preferable to soldering because lithium batteries are sensitive to heat and can fail;
  • Wire gauge 0.75 mm², 1.5 mm², 2.5 mm²;
  • heat shrink;
  • screwdriver;
  • circular knife.

Battery must match the capacity of the old components in the proportion of 1/3. Т.е. Lithium cell is a full-fledged replacement for 3 nickel-cadmium batteries. Usually use 3 pcs. Li-ion instead of 10 Ni-Mh, which will slightly reduce the power of the unit. You can install 4 batteries, but this will reduce the operating life of the electric motor.

The key factor is the current rating on the data sheet of the electric screwdriver. It ranges from 15-40A, respectively selected elements with similar kickback parameters. This applies to both batteries and protection boards. Universal option BMS module for 25A or 30A. It is undesirable to use batteries from an old laptop, because they are not designed for a high load.

How to convert an electric screwdriver to lithium batteries

It is known that the service life of the mechanical part of the power tool is in most cases much longer than that of the batteries. Batteries are nearing the end of their service life, but the electric screwdriver may very well continue to work. You just have to solve the power issue. In some cases it is difficult, expensive or even impossible to buy new batteries of the same type. Therefore, you will have to make a decision. to convert the power tool to work from the mains, losing mobility, or to adapt to work with a battery of another type.

If you have chosen the second option, then it is best to use lithium-ion batteries. they have an increased electrical capacity per unit of geometric volume, they have almost no memory effect (although this type of battery inherent and certain disadvantages).

Pros and cons of modernization

Before how to remake an electric screwdriver to lithium batteries 18650, it is necessary to understand what the master will get as a result. The advantages of these manipulations are as follows:

  • a manifold increase in the operating time of the electric screwdriver;
  • increase the rate of charge of the battery. for a full set of energy for lithium batteries need approximately 1 hour;
  • An increase in charging current capacity to a value of 1-2 C;
  • reduced costs for the regular purchase of new NiCd batteries due to their insufficient service life;
  • complete absence of memory effect in lithium batteries.

Also, before converting the battery with your own hands to a more modern technology, you should be aware of the negative consequences:

  • Requires the mandatory connection of the controller to determine the level of charge, because the device can not be charged more than 4.2 V and discharged less than 2.7 V;
  • Lithium ion batteries for Li-lon series screwdrivers lose their abilities when used in low temperature conditions;
  • When converting an electric screwdriver to lithium battery, there may be difficulties with the adaptation of the battery charger from NiCd, here it is necessary to use a universal device.

Dismantling the battery case

Each user is able to disassemble the two-piece case, which is made up of screws and glue. The screws are unscrewed, the layer of glue is broken with a thin object that is pushed all around the perimeter.

After repairing, the screws are put back in their original place and the glue layer is renewed.

The safest way to join the cans is by spot welding. Its essence is the following: the electrodes are pressed to the welding point. There is a large amount of current flowing through them for a short period of time. During this time, the metal plate has time to melt and weld to the radiator. In this case, the heat does not have time to penetrate the battery and cause damage.

  • on a flat surface set the banks that need to be connected, for convenience, they can be wrapped with electrical tape or duct tape, so they are located the same way as in the finished assembly;
  • On top of the battery we put the connecting tape;
  • press the electrodes to the tape and turn on the current.

Spot-welding machine can be purchased or made by your own hands.

Converting a screwdriver battery to Li-Ion

I will not say anything new in this article, but I just want to share my experience of upgrading batteries of my old Makita screwdriver. Originally this tool was designed for nickel-cadmium batteries (which died a long time ago, as died and bought the same ones to replace them). Disadvantages of Ni-Cd are known: low capacity, short life time, high price. This is why cordless tool manufacturers have long switched to lithium-ion batteries.

Well, what about those who have an old tool? Yes, everything is very simple: throw out the Ni-Cd banks and replace them with Li-Ion of a popular format 18650 (marking indicates a diameter of 18 mm and length of 65 mm).

What board and parts are needed to convert the screwdriver to lithium-ion?

So, here’s my 9.6V battery with a capacity of 1.3 Ah. At maximum charge, it has a voltage of 10.8 volts. Lithium-ion cells have a nominal voltage of 3.6 volts and a maximum voltage of 4.2 volts. Consequently, to replace the old nickel-cadmium cells for lithium-ion cells, I need 3 cells, their operating voltage will be 10.8 volts, the maximum. 12.6 volts. Exceeding the rated voltage will not damage the motor in any way, it will not burn out and at a greater difference, you do not have to worry.

Lithium-ion cells, as it has long been known, categorically do not like overcharge (voltage above 4.2 V) and excessive discharge (below 2.5 V). If the cell exceeds this operating range, it will degrade very quickly. That is why lithium-ion cells always work together with an electronic card (BMS. Battery Management System) that controls the cell and monitors both the upper and lower voltage limits. This is a protection board that simply disconnects the bank from the circuit when the voltage exceeds the operating range. So in addition to the elements themselves, you will need such a BMS board.

Now two important points, with which I experimented several times unsuccessfully, 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 the operating currents at high load reach 10-20 A. Therefore it is necessary to buy cells capable of supplying high currents. Personally, I successfully use the 30-amp 18650 cells manufactured by Sony VTC4 (2100 mAh) and 20-amp Sanyo UR18650NSX (capacity of 2600 mAh). They work fine in my electric screwdrivers. But, for example, Chinese TrustFire 2500 mAh and Japanese light green Panasonic NCR18650B 3400 mAh are not suitable, they are not designed for such currents. So I don’t need to worry about the cell capacity, even 2100 mAh is more than enough, and the main thing is not to miscalculate the maximum allowable discharge current.

And in the same way, the BMS board must be designed for high operating currents. I’ve seen on YouTube how people build batteries on 5 or 10 amp boards. I don’t know, I’ve personally had boards like that go right into protection when I turn on the screwdriver. I think it’s a waste of money. I will say that Makita themselves put 30 amp boards in their batteries. So I use a 25 amp BMS bought on Aliexpress. They cost about 6-7 dollars, and are searched for by request “BMS 25A”. Since you need a board for a 3-cell assembly, you have to look for one with “3S” in its name.

One more important point: some boards have different pins for charging (marked “C”) and load (marked “P”). For example, the board may have three contacts: “P-“, “P” and “C-“, as on a native Makita lithium-ion board. Such a board will not work for us. Charging and discharging should be done with one contact! That is, on the board must be two working contacts: just “plus” and just “minus. Because our old charger also has only two pins.

In general, as you can guess, I spent a lot of money on the wrong elements and the wrong boards with my experiments, making all the mistakes that could be made. But I gained invaluable experience.

How to Disassemble a Screwdriver Battery

How to Disassemble an Old Battery? There are some batteries where the halves of the case are fixed with screws, but there are also some with glue. My batteries are the latter, and for a long time I thought they couldn’t be disassembled. It is possible if you have a hammer.

In general, with the help of intensive blows to the perimeter of the lip of the bottom of the case (hammer with a nylon head, the battery needs to be held in the hand in the weight) the gluing place is successfully disconnected. The housing is not damaged in any way, I have already taken apart 4 units.

From the old circuit need only contact plates. They are firmly welded to the upper two elements by spot welding. You can open the welding with a screwdriver or pliers, but pick picking should be as carefully as possible not to break the plastic.

Everything is almost ready for further work. By the way I kept the temperature sensor and the circuit breaker, although they are not really needed.

But it is very likely that the presence of these elements is necessary for normal operation of the regular charger. So I strongly recommend to keep them.

Assembling the lithium-ion battery

Here are new cells Sanyo UR18650NSX (you can find them on Aliexpress by this article number) with the capacity of 2600 mAh. Just to compare, the old battery has a capacity of only 1300 mAh, half as much.

We have to solder the wires to the elements. You must use wires with a cross section of at least 0.75 kV.mm, because we will have considerable currents. A wire with such a cross section will normally work with currents of more than 20 A at 12 V. It is possible to solder lithium-ion battery banks, a short overheating won’t do any harm. But you need a good fast flux. I use glycerine flux TAGS. Half a second and it’s done.

Solder the other ends of the wires to the board according to the diagram.

For battery connectors I always use even thicker wires, 1.5 kV.mm, because space allows. Before soldering them to the mating pins, I put a piece of heat shrink tubing on the board. It’s needed for additional isolation of the board from the battery cells. Otherwise, the sharp edges of the solder can easily rub or puncture the thin film of the lithium-ion cell and cause shorting. You can not use the heat shrink, but at least something insulating to put between the board and the cells is absolutely necessary.

The pin can be attached to the battery with a couple of drops of superglue.

It’s good when the hull is screwed, but that’s not my case, so I just glue the halves back together with Mint.

The battery is charged with the regular charger. But the algorithm changes.

I have two battery chargers, a DC9710 and a DC1414 T. And they work differently now, so I will tell you how.

The Makita DC9710 charger and the lithium-ion battery

Earlier the battery charge was controlled by the device itself. It used to stop the process when it reached full and signaled when it was done charging with a green light. But now the BMS circuit that we installed is doing the level control and turning off the power. So when charging is complete, the red LED on the charger will simply turn off.

If you have such an old device. you are lucky. Because it’s so simple. LED on, charging. Off. charging completed, battery fully charged.

Makita DC1414 T battery charger and lithium-ion battery

There is a little nuance 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 volts. The charger is charging as usual with the red LED on:

And when the battery (which in the case of NiMH-cells should have a maximum voltage of 10.8 volts) will reach 12 volts (we have Li-Ion cells, which may have the maximum total voltage of 12.6 volts), the charger will go crazy. Because he does not understand what kind of battery he is charging: whether it is a 9.6 volt or 14.4 volt. At that point, the Makita DC1414 will go into error mode, alternately flashing red and green LEDs.

That’s fine! Your new battery will still recharge. but not completely. The voltage will be approximately 12 volts.

That is, some of the capacity you will miss with this charger, but I think this can be survived.

Total battery upgrade cost about 1000. A new Makita Makita PA09 costs twice as much. And we ended up with twice the capacity, and further repair (in the case of an early failure) will consist only of replacing the lithium-ion cells.

How to place the cells

Unlike Ni-Cd or Ni-MH cells, lithium batteries have a higher capacity and voltage, so there will be less in the battery. The dimensions of the 18650 cell are as follows: 65mm high and 18mm diameter. Initially check how many of these will fit in the empty case and determine the layout, if necessary cut away the interfering ribs.

If the battery pack has a protruding top, it will accommodate a couple of cells. Another one conveniently placed on its side directly underneath the two vertical ones. You can put 5 to 7 more batteries in the remaining space. If the battery has a slide connector for charging, stack the cells across the case in two stacks.

The voltage of a Li-ion battery pack is 3.7 V, but under load there is a drawdown of about 1012%. That means you’ll need at least 4 batteries for a 12-volt screwdriver and at least 5 for an 18-volt., But it is better to use 6, because it is not too few. Don’t worry about the motor getting spooked by the high voltage and giving up its life. When sagging under load, the excess voltage will be minimal and well within operating limits. With the number of batteries you need to know before you cut the balancer connector into the housing, because there should be one more contact in it than there are cells in a series connection.

Now for the capacity. Lithium cell capacity ranges from 2.5 to 3 A / h, which in itself is not bad. To double the capacity you need to double the number of batteries, but it is definitely worth it. The only thing that can stop you in this venture is the size of the battery pack. In any case remember that the number of elements must be a strict multiple of 4, 5 or 6, depending on the voltage.

When you put the batteries in the right order, fasten them to each other with electrical tape and make sure that the cells are completely immobile inside the case, filling the remaining space with pieces of Styrofoam or polyurethane foam. There is no need to leave any space for the wires, at the very least you will need to make a couple of extra cuts during final assembly.

Reverting your screwdriver to lithium 18650 batteries

In this article, you will learn how to economically convert your screwdriver battery from nickel-cadmium batteries to lithium-ion 18650 batteries, thereby improving your screwdriver battery, making it more powerful and increasing battery life. All steps of the modification are described in detail, so there should be no problems, all necessary components are specified and available.

Components needed for the remodel

To replace the batteries in my screwdriver (12V) were used batteries 18650 with a capacity of 2500 mAh. These batteries already have soldered solder wires for soldering, which is very convenient and also you can save a lot on battery compartments.

You’ll also need two 12.6V 40A BMS boards for the modification, I bought them here:

Battery Conversion

The first step is to carefully disassemble the battery compartment and discard the old, discharged nickel-cadmium batteries.

Then you need to disconnect the power terminal of the battery.

Two wires should be soldered, preferably with a large cross section. In this case we used 4 mm² and a length of about 100 mm. In the photo above you can see the red wire, it is left to avoid reversing polarity, it is desirable to solder the red wire to this wire, so that there is no trouble and you will know exactly what it is

Solder the negative wire to the shiny contact:

Then you must insert the terminal with soldered wires into the case in its place, always respecting the polarity!

To fix the terminal you can pour hot glue inside the glass, I couldn’t find a better fixing option, especially since it holds very well!

You can now proceed to solder the batteries. Remove the heat shrink tubing from the batteries and bend them so that they can be welded one by one.

Cordless Drill Lithium Battery Conversion using 18650 Cells

Next, apply hot glue to the resulting side of the battery where the contacts protrude upward, and glue the BMS board as shown in the photo below. Note that the plus and minus sides of the board and the batteries are facing each other.

Then we bend the battery contacts over the contacts of the board and solder them, starting with the minus!

We solder a short wire to the B1 board contact, and solder its other end to the battery connection point!

In the same way we solder a short wire to the contact B2, with the other end soldered to the battery junction from the opposite side!

Well and finally weld the last positive contact.

Now it remains to connect the housing terminals to the resulting battery, to do this solder the red wire to the terminal “P” and the blue, negative wire to the terminal “P-“.

If someone gets confused, here is the connection diagram of BMS, depending on the number of batteries (power supply voltage screwdriver).

I would also like to point out that it is worth paying attention to the charging. For this you can either buy a ready made charger or buy a current and voltage stabilization module (also known as DC-DC) and use it to convert your own charge for the voltage and current we need.

This completes the battery conversion! It remains to repair the made battery and put the second part of the case back. After the tests the electric screwdriver worked no worse than the factory battery and I would say much better in power and the charge lasts longer. I recommend everyone to redo their old and tired batteries!))

Buy ready to use 12V 2A battery charger

That’s all, I hope this article was useful, and if you liked it, thumbs up, write Комментарии и мнения владельцев, don’t forget to share it on social networks at the links below.

Converting an electric screwdriver to lithium 18650 batteries

In this article you will learn how to inexpensively remake the battery of an electric screwdriver from Ni Cd to Li-ion batteries 18650, thereby upgrading the battery of an electric screwdriver, making it more powerful and increasing battery life. All steps of this recharge are described in details, so you should have no problems, all components are listed and available.

Necessary components for converting

For the conversion were used high-current batteries 18650 with a capacity of 2500 mA/h. These batteries have already welded terminals for soldering, which is very convenient and on top of that you can significantly save on battery compartments. They can be ordered online, they come in batches of 4 or 6. You can buy these at the links below:

You will also need two BMS 12 boards.6V 40A, bought it here:

The charger also needs to be rewired and you need a voltage and current regulator.

You can buy a voltage regulator at the link below:

At the time of conversion, all components (for two batteries) cost only 1100, this is much cheaper than buying a new battery for an electric screwdriver, which will stand all the same Ni Cd batteries. Looking at the on the internet, I found that one battery costs from 1200, but for the conversion of TWO batteries, I spent only 1100! All the links to the components can also be found at the end of the article!

Battery modification

The first thing you need to carefully dismantle the battery and throw out the old Ni Cd batteries.

Then it is necessary to disconnect the power terminal of the battery.

To it you need to solder two wires, preferably with a large cross section, in this modification we used wires with a cross section of 4 mm² and a length of about 100 mm. In the photo above you can see the red wire, it was left in order not to mix up the polarity, it is advisable to solder a red wire to this wire too, to avoid trouble and you will know exactly what it is

To the shiny contact you need to solder the minus wire:

Then you need to put the soldered wire terminal back in the case in its place, making sure that the polarity is correct!

For fixation of the terminal you can pour thermo glue inside the jar, it is the best way to fix the terminal, it holds very well!

Now you can start soldering the accumulators. Remove the heat shrink tubing from the batteries and bend them so that you can solder them in series.

Next, we apply hot melt to the side of the resulting battery, where the contacts stick out to the top and glue the BMS board as shown in the photo below. Please note that the plus and minus pins of the board and the battery are facing each other.

Then we bend the battery contacts onto the board contacts and solder them starting from the minus side!

To the contact of the B1 board solder a short wire, the other end of which we solder to the place where the batteries are connected!

To the contact B2 as well solder a short wire, the other end of which, solder to the point of battery connection on the opposite side!

Finally, we solder the last plus-solder contact.

Now we need to connect the case terminals with the battery, to do this we solder the red wire to terminal P, and the blue, negative wire, to terminal P-.

At this point the modification of the battery is complete! Now we need to fix the battery and put the second part of the case back. It took no more than an hour of time and, as mentioned above, 1,100 bucks to rebuild two batteries. After the tests, the screwdriver does not work worse than with the factory battery and I would say much better, in terms of power and the charge lasts longer. I advise everyone to convert their old batteries! ))

Buy BMS 12 board.6V 40A Buy Samsung 18650 Batteries 2500 mah 6 pcs.Buy Samsung Batteries 18650 2500 mah 4pcs.Buy Voltage and Current Stabilization Module Buy 3 S 25A Li-Ion 18650 BMS Boards Buy Socket for Charger Connection Buy Soldering iron

For those who have no desire to remake the charger, the link below, you can buy ready-made.