How to replace the battery for an electric screwdriver

Repair and replacement of battery components

When carrying out the procedure another, more effective way to restore the battery performance is to replace the failed elements with serviceable ones. However, for this purpose, you will need to buy new cells or take them from another working battery. At the same time, it is extremely important that the dimensions, as well as the electrical characteristics and type of cells to be introduced coincide with the originally installed.

The procedure is performed by cutting out the old elements and soldering the new elements into the chain. It will require the following basic set of necessary consumables and tools:

Replacing the old Ni-Mh battery of an electric screwdriver with Li-Ion cells

“How much will it cost to replace the old nickel batteries with lithium-ion batteries in my electric screwdriver”.This is probably one of the most popular questions you hear from our customers. And indeed, the problem is quite common. Many have an old cordless electric screwdriver (wrench, peorator, jigsaw, grass trimmer, etc.д.) in which regular batteries are out of order, and new ones are impossible to buy either because they can be withdrawn from sale or because one just does not want to spend money on obviously outdated technology, and wants to immediately replace the Ni-Mh batteries with Li-Ion and give, often expensive and high-quality power tools a second life.

The reasons for such a desire are really many:. The first, and the main one, is that Li-Ion batteries have a much higher electrical density than Ni-Mh batteries. Simply put, for the same weight, a Li-Ion battery will have a higher electrical capacity than a Ni-Mh. Accordingly, by installing Li-Ion batteries into an old case we get much longer working time of the tool.

But also stopping factors for doing such an idea is enough:. Owing to technological limitations, Li-Ion batteries cannot be charged more than 4.25-4.35V and discharged less than 2.5-2.7V (which is specified in the technical specification for each particular battery). If these values are exceeded, you can damage the battery and put it out of service. To protect the Li-Ion battery, special charge-discharge controllers are used to keep the voltage on the Li-Ion cell within the permitted limits. Т.e besides the batteries themselves you also need a charge-discharge controller The voltage of Li-Ion batteries is always a multiple of 3.7V (3.6V), while that of Ni-Mh batteries is a multiple of 1.2V. This is due to the nominal voltage (the amount of voltage that holds on a Li-Ion battery for a long enough time in the middle of the volt-ampere characteristic of the discharge curve) on a single cell. For Li-Ion batteries, this voltage is a multiple of 3.7V, for Ni-Mh. 1,2В. Therefore, you will never be able to assemble a 12v battery from a 12v Li-Ion battery pack. In rated, it can be 11.1V (3 in series) or 14.8V (4 in series). over, the voltage of the Li-Ion cell varies during operation from fully charged to 4.25V to fully discharged.2,5В. So the voltage of 3S (3 serial. 3 serial connections) of the battery will vary during operation from 12.6V (4.2×3) to 7.5В (2.5х3). for 4S battery. from 16,8V to 10V Li-Ion battery 18650, and 99 percent of all Li-Ion batteries consist of 18650 cells, has a different overall dimensions from the Ni-Mh cell. The 18650 cell size is 18 mm in diameter and 65 mm high. It is important to “estimate” how many Li-Ion cells you can fit into your battery case. It should be understood that for a 11.1V battery you need a multiple of 3 Li-Ion cells. For a 14.8V battery. four. There must be enough space for the charge-discharge controller and the patch cables The battery charger for Li-Ion batteries is not the same as the charger for Ni-Mh batteries. To be fair, it should be noted that chargers provided with many screwdrivers are universal chargers and can charge both NI-Cd, Ni-Mh and Li-ion batteries. Make sure that your charger has this capability Cost of Li-ion batteries. which, compared to Ni-Mh batteries, can vary by several times.

If the above does not scare you, then consider an example of the process of making a Li-Ion battery to replace our existing Ni-Mh battery from the DeWALT DC840 impact wrench.

This ratchet is equipped with two rechargeable 12V Ni-Mh batteries with a capacity of 2.6Ah.

First we will decide on the voltage rating for our Li-ion battery pack.

The choice is between a 3S Li-Ion battery with a voltage range of 12.6V. 7.5V and a 4S Li-Ion battery with a voltage range of 16.8V. 10В. We will use the second variant, because: a) Battery voltage drops fairly quickly from maximum to nominal, ie.е. from 16.8V to 14.8V, but for an electric motor, which in fact is the wrench, an excess of 2.8V is not critical. b) The minimum voltage of a 3S Li-Ion battery is 7.5V, which is extremely low for a power tool to work properly. And the efficiency of a 4S battery in this case is higher than the efficiency of a 3S Li-Ion battery. c) We can increase the electrical capacity of our battery by installing 4 Li-ion cells.

So, we have solved the first point: we make a 4S (14.8V) Li-Ion battery.

Second. Deciding on the choice of Li-Ion cells.

For this we have to determine the limiting factors. In the case of making a Li-Ion battery for power tools, the main limitation is the maximum load current. Nowadays there are Li-Ion batteries with an allowable nominal (continuous) load current of 20-25A. Impulse (short-term, up to 1-2 seconds) load current values can reach 30-35A. You will not disturb the structure of the battery.

Our case of the old Ni-Mh battery can comfortably accommodate up to 6 Li-Ion 18650 cells. Accordingly, we can not assemble 4S2P (4 series and 2 parallel connections) Li-ion battery, which require 8 cells and have to fit in 4 cells. Of course, in this case, each of the cells must “hold” a single maximum current load over the entire range of the power tool.

Determining the maximum current flowing in the battery during operation of the wrench. In the video below you can see that we connected the impact wrench to a laboratory power supply (PI) with a maximum current of 30A. the maximum current limiter regulator is set to the maximum possible value. Having set voltage of power supply close to nominal voltage of our future accumulator battery we start to press the trigger softly. Current consumption of the impact wrench. rises to 5A.

Now let’s pull the trigger very sharply, which practically shorts out the power supply. The current is pulsed up to 20. 30А. Maybe it would climb higher, but the power of the power supply does not allow you to see that. It should be understood that it will be a momentary load current in case of a very sharp pull on the trigger of the wrench. And any electric screwdriver/whatever has a motor will behave exactly the same way. That’s why it is funny to hear customers saying that your controllers and batteries are no good, because you see, my electric screwdriver consumes only 4A. I measured it. and I bought 2200mAh Samsung 22F batteries (the cheapest with a maximum current of 3A) and 8A controller and nothing works. And unprotected Li-ion batteries and controllers are not exchangeable/refundable. Here, I think everything is clear. Ignorance of the law is no excuse. Now let’s clamp the ratchet head in a fixed vice and see up to what value the current consumption will increase during operation, when the ratchet is triggered. The current rises to 10-12A.

At this point we have determined the value of the load current. In our case, it would be 5A at idle, 30A at quick start, and at maximum load. 12А. Correspondingly. we choose Li-ion cells with nominal load current of 10-20A and pulse current of 25-30A.

We are suited for Li-ion batteries (available at the time of writing): 18650 2000mAh LG INR18650HD2 3,7V 25A. 18650 2500mAh LG ICR18650HE4 3,7V 20A. 18650 2600mAh Sony US18650VTC5 3,6V 30A, 18650 3000mAh LG INR18650HG2 3,7V 20A.

We have opted for 18650 3000mAh LG INR18650HG2 3,7V 20A to ensure maximum capacity.

The choice of controller (overdischarge/overdischarge protection board).

The controller must meet two parameters:

nominal operating voltage (in our case 14,8V) nominal operating current.

The voltage is clear: if the battery is 14.8V, then the controller must be 14.8V, if the battery is 11.1V, then you should choose the controller with a nominal voltage of 11.1V.

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The parameter “rated operating current” determines the “bandwidth” of the protection board. Т.е. the controller at 4A is designed for a current of 4A, and at 8A it will go into overload protection. controller for 16A rated load will “go into protection” at 30±10A. All these parameters are given in the tab “Characteristics” for each specific model of controller.

At the same time, one instance of the controller may have a limiting current of 30A and another instance 50A. And both these controllers will formally work. But we are also limited in size so we have to choose the controller so that it will fit into your old battery case.

Based on the above conditions, we chose a protection board for a 14.8V battery model HCX-D177 with a value of the nominal operating current of 16A and a threshold value of maximum current of 30±10A.

So, we have decided on the components of our Li-ion rechargeable battery. There were no problems with the charger, because it is designed to work with both Ni-Mh and Li-ion batteries.

Plus, provided we put a charge-discharge controller, we are insured against overcharging our battery.

Proceed to the process of disassembly and disassembly.

Open the old battery by unscrewing the 5 screws.

You can see that the contact area, which is meshing with the contact group of the nutrunner, is welded to the plane of the minus contact of one of the Ni-Mh cells.

Cordless screwdriver battery replacement and test (before and after)

Cut off the welding spots with a DREMEL 4000 multi-purpose tool with a mounted cutting stone. As a result, we are left with the contact pad from the battery.

We solder wires with cross section not less than 2mm2 for power leads and 0.2mm2 for thermistor connection to the contacts and glue the contact pad to the battery case with thermo glue.

We choose 4 cells LG INR18650HG2 3000mAh according to the internal resistance on the meter of internal resistance batteries. Its value must be the same for all four batteries in our battery.

LG INR18650HG2 Li-Ion cells are glued with hot melt adhesive in such a way as to provide the most convenient layout in the case.

We weld the cells on the machine for resistance welding with the help of nickel welding tape with a cross section of 2x10mm.

At this point we can already see how much lighter our battery is.

The weight of the old Ni-Mh batteries was 536g. Weight of the new Li-Ion battery is 199gr. Thus, the weight gain is 337 g, which is quite appreciable in the process of operation. In this case, the capacity increases from 31.2Wh (12V 2.6Ah) of the original Ni-Mh battery to 44.4Wh (14.8V 3Ah)

Installing the battery in the case. Fill the voids with soft packing material.

The video shows that when you pull the trigger, the current protection of our protection board is triggered. But in real conditions such a mode most likely will not be used. Unless special efforts are made to trigger protection, the wrench behaves in an absolutely predictable manner. Clamp the tip in the jaws of the vice. As expected, the battery power is more than enough to actuate the ratchet, which limits the torque.

Discharging the Li-ion battery of our impact wrench at the electronic load. We set the discharge current to 5A. The discharge graph is shown in the illustration below.

Inserting the battery into the standard battery charger. The charging current measured was 3A, which is within the allowable charging current for these Li-ion cells (for LG INR18650HG2 maximum charging current is 4A, which is shown in the Specifications tab).

In terms of time, the replacement of Ni-Mh batteries for Li-Ion batteries took about 2 hours (with check of all parameters on the equipment. about 4 hours). Basically it is possible to do it by yourself “by hand”, but contact welding and battery selection can not be done without special equipment.

Let’s see what we have in terms of cost:. the cost of 4x Li-ion batteries 18650 3000mAh LG INR18650HG2 3,7V 20A, at the time of writing is 4 x 550rub = 2200rub. the cost of the charge controller with the balancer HCX-D177 is 1240rub. Welding and assembling costs 800rub

Total, it turns out that the self-made Li-ion battery 14.8V 3Ah costs 4240rub

Let’s find a similar factory-made Li-Ion battery for any other electric screwdriver. The Makita 194065-3 battery has absolutely identical parameters.

At the time of writing such a battery costs from 5500 to 6500

It turns out that the direct savings are 1300 to 2300rub. And, while we should not forget that the battery we made, you can not buy in principle!

PS. Special thanks for the test wrench and moral support 🙂 to Rent4Event company.

Cell replacement in the battery screwdriver with their own hands

Hello! I offer you a review with step by step instructions for replacing the cells in the screwdriver battery. In the review a little text, a little more photo material, as well as the answer to the question: “What is the capacity of Chinese batteries at 2500 mA/h?”.

Interested, please come in I have such an inexpensive screwdriver Roteri RCD-14.4, which has served for several years, but over time, the battery charge became less and less enough. Searching for a suitable battery in stores led to nothing. That’s why it was decided to order rechargeable batteries and replace them myself. Disassembled the battery presented a review of the following:

replace, battery, electric, screwdriver

The battery consists of 12 SC Ni-Cd cells. It was decided, ordered, received: To test the performance of all cells, as well as to check the capacity, was used La Crosse RS-700 charger, a review of which I have done here. Due to the size of these batteries can not be installed in the charger normally, so to ensure contact with the device AA batteries with electrical tape on one end were used, and to the reviewed battery cells were soldered wires: The charger itself was switched to TEST mode, and so 3 times, that’s what came out of it: So, out of 12 batteries 3 were defective (real capacity about 100 mA/h), the rest had a capacity in the range of 900mAh to 1500 mAh, not 2500 mAh. This is an answer to the question asked in the “topic. I had to write a complaint to the seller, in response the seller offered to send me 4 similar batteries free of charge. I agreed. The package arrived. This time all 4 batteries were functional with similar capacity to the others. We proceed to the replacement of the cells: For tinning paddles used flux LTI-120, regular rosin is not tinned. It is better to solder on the “minus” side of the battery, i.e.к. the body of the battery is the “minus” and if there is a break in the insulation at the soldering point, it will not lead to anything. At the end the whole battery was tightly secured with duct tape and installed in the case: Checking the screwdriver showed that the 600 had not been wasted!

Hereby I bid farewell, and yes, please don’t be stingy in clicking on “liked the review”, i.e.к. this is an incentive for writing new reviews 🙂

Repair: 12v cordless drill battery replacement

Disassembly of the battery

Before disassembling the battery should be charged as far as possible. This is for later diagnosis. If you can not do it, it will be necessary to charge the elements separately. This will need an adjustable power supply.

Next, you need to disassemble the battery. The process depends on the design. somewhere you will need to unscrew the screws, somewhere to unfasten the latches. If the case is connected with glue, the process will be more laborious, but the result is still achievable.

As a result you should take out the battery cells connected in series. There is no need to disconnect them unnecessarily.

How to easily increase the battery capacity of a screwdriver

It was bought for household purposes, I did not want to take a cheap one, and in the more expensive and branded did not see much sense. Actually, we had a choice. To buy a 1500 mAh Favourite or a 2000 mAh Favourite. The price difference is 500. Well, the photo shows that I chose. No complaints about the work of the tool, for my money is the usual tool. But out of boredom today I decided to estimate how many cells there are, how they are arranged, and whether the inscription on the case is correct.

A simple calculation (14.4 : 3.6 = 4) showed that there are four batteries of 2000 mAh. Three cylinders shaped like standard batteries shine through the vent:

So. Three. it’s not four. All right, in two layers arranged. But then it should be six. Figured out how to connect six batteries to get the above specifications, but never got around to it, not my specialty. But my hands itched, so I decided to unscrew it:

Four batteries. Not surprised at all, the standard cell, with which you can dial in a battery of 18 volts. And this is what is written on the batteries:

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1500 mAh. I wonder what is written on the batteries of the screwdriver, as in this picture?

Actually, here’s the answer to the headline. Just put a piece of paper with the required capacity. The seller is useless to show, of course, and I do not want to. I could not find a manufacturer’s website, only suppliers who have a mess of and labels on their own website. Moral. Open the tool right in the store. Joke. There is no morality, it’s just hurtful. Maybe it is my fault, but I am not an expert in such cases, I do not know other ways to make sure, except as described

Let me tell you a secret. Just no one! Even the 1500 you see isn’t necessarily 1500.

Ask someone you know if they have something like an Imax B6. Test the actual capacity.

I’m just saying.! Write 16000 with a marker and work from fence to fence!

A good manufacturer usually gives you a capacity reserve. I mean, a new battery labeled 2Ah actually has a capacity of 2.2-2.3 Ah. But this is clearly not the case.

You can open the battery at the cash register and make a big deal out of it.

How many and what kind of batteries to buy

In most cases you can convert any electric screwdriver to lithium batteries with a 18650. This number refers to the linear dimensions:

These batteries belong to the category of finger batteries. have a cylindrical shape with positive and negative pole leads on opposite sides. The voltage of one cell when fully charged is 3.6 volts. For each electric screwdriver, it is necessary to dial in the necessary voltage. You can find it on the case of an old battery.

Standard battery voltage, V Number of lithium-ion cellsTotal voltage, V
10,8 3 10,8
12 3-4 10,8 or 14,4
14 4 14,4
18 5 18

Obviously, from 3.6-volt cells it is not always possible to dial in a voltage strictly equal to the nominal. So, for 18 V everything turns out perfect, and for 12 V you have to be happy with either a little less or a little more voltage. It should be understood that in the first variant the torque will fall a little, and in the second it will increase, but you should be ready to reduce the service life of the mechanical part. In addition there is the possibility that the high voltage can damage the electronic control circuit. Although the reviews on the web say that it works fine in this regard.

ways of connecting batteries

In addition to soldering, there are other ways to connect the cans into rechargeable batteries:

  • spot welding;
  • Through holders (holders);
  • Pressing the strips to the terminals with neodymium magnets;
  • using conductive glue.

All of these methods, with the exception of welding, do not give a reliable contact, so in circuits with high currents it is better not to use them.

Converting an electric screwdriver to 12v lithium batteries

What we have: an old electric screwdriver Interskol DA-12ER-02 quite cheerfully working, but with dead batteries.

Our goal: to replace old Ni-Cd batteries with new li-ion ones

To remake according to my variant we will need:

  • electric screwdriver Interskol Da-12ER-02 )))
  • – soldering iron from 60W t.к. less powerful can not solder
  • – multimeter (tester)
  • – “solder acid.”. There are many variations, take them with a brush

a battery:

  • 18650 lithium batteries, for example take batteries already with tails. We need high amperage batteries.
  • protection board with balancer 3S 40A 12.6V 40A lithium battery protection board
  • wires short but thick cross section from 1,5
  • double sided tape
  • Thick wide relatively soft gasket 1.5. 2cm

Battery charger (you don’t have to rebuild it):

  • – DC-DC converter (XL4015). Article about these converters read
  • – A breadboard for example. We need a thick board.
  • – 4 diodes from 100v 3A or a ready made diode bridge, I used a. Either that will take from the original charger board.
  • – Capacitor from 470μF 35V. Or it can be taken from the original charger board.
  • – Two LED’s of different color 5mm.
  • – Thermal glue
  • – wires of different lengths and cross sections.
  • – 2mm drill bits

Precautions:

  • – When working with batteries it is necessary to be extremely careful not to allow their short circuit, at the moment of short circuit at the point of contact huge currents occur, which can lead to burns, eye injuries, explosions and fires. As well as the failure of all components.
  • – when working with acid be very careful because.к. It can get in your eyes, on your skin, etc.д. the consequences can be very unfortunate.
  • – work only on the equipment switched off from 220v power supply. It is also necessary to take into account that power circuits use capacitors, which accumulate charge and when you unplug the device from the mains, it does not mean that the board is de-energized.

Let’s go:

If you don’t have something from the list above it’s better not to get to work t.к. You’ll get more work done than you can handle.

Preface

You can also use 6 pcs. 18650, which will double our battery capacity, but will require a higher charging current, which will require abandoning the native power supply without modifications, and our charging will last oooooooooooooo long.

I want to draw your attention, and this is very important, the batteries in the photo are not suitable for our problem, it’s my fault, I bought it without thinking. Use only high amperage batteries. But t.к. I didn’t have any options, I did with them.

Why do we need high amperage batteries. Lithium batteries are designed to be used under certain conditions of charge-discharge, the ones in the photo allow them to cut currents of 2C.е. in this case it is about 6A.an electric screwdriver at start consumes from 15A to 25A and at a constant load about 10A. As we see we have exceeded the manufacturer’s requirements. High-amperage batteries are designed for higher discharge currents from 10A, which guarantees us a longer life, and fewer surprises in the future from improper operation. Read about these batteries

The protection and balancing board will allow us to operate the lithium batteries within the limits that the manufacturers recommend. It will protect our batteries from deep discharge and overcharge, which for lithium batteries is very critical, and violations of this point will lead to a very rapid degradation of the battery t.е. loss of capacity. Also this board has a balancing circuit that is supposed to equalize the charge of each battery cell. Our batteries are connected in series, which during operation will cause them to charge unevenly read.п.1, but this board will eliminate that effect. Presented board, upgraded at the request of the workers and self-restoring when the protection is triggered.

Assembly:

We use the batteries with the tails already welded on. First of all we remove the shielding from the ends and then we need to tin the ends. You can not tin without using acid (carefully) so take the acid, soldering iron and solder and tin. We tin the two ends. Apply a thin layer of acid, that’s enough otherwise you will get splashing in different directions.

If you bought acid without a brush, you can pour it into a tube of nail polish or you can use a disposable syringe, where you squeeze the drop and immediately pulled it back, leaving a thin film. We need to tin the pluses of the first two batteries, in these places we will be connecting the batteries together.

Once you’ve tinned everything, we solder the batteries in series.Figure. The tab on one of the batteries is reversed. Soldering also is made by powerful soldering iron, simply having put a tongue and having pressed by a sting of soldering iron. This is what we should have.

Now we fix everything with the duct tape or we can do it before soldering. Glue double sided adhesive tape to fix the board.

Take apart the original battery. Remove old batteries (Careful).

Bite off the black thing and solder it. We need thick wires t.к. We will have currents up to 25A and more. which with thin wires can cause them to catch fire, and we will also have a loss in power. We carefully put the batteries aside.

Now we need to find a thick, wide and relatively soft gasket 1.5. 2cm. I ripped it off the packaging of some gadget. We cut it according to the size of the case and put it on the bottom, put double sided tape and glue the batteries. Fix the black thing, the protruding end should be long enough to fit into our batteries to close the case with some tension. Don’t mix up the polarities!

In this case, my brown wire is minus and my black wire is plus. The brown one is a lot thicker than the black one.

We cut the wires as short as possible, so as not to lose current on losses, but we must take into account that we need to solder the board. Solder and assemble the case, the battery is ready.

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You can use the finished battery with the existing charger, but:

  • – There are complaints that the case will be very warm, which many people are afraid of. But in the construction of the charger a transformer is used and heating is a normal phenomenon for it. In my experiments with 1A it got up to 60C. The design does not include a current limiting system so that the current in the system can be many times higher and the heat higher. At the same time now we need more time to charge the batteries.
  • – the charger is designed with a system of time limitation of charge time and is one hour. Т.е. we have to jumper the battery to fully charge it.
  • – It will be hard to use the native charger if we decide to use 6 18650 cells t.к. The maximum current deliverable according to the manufacturer should be 1.8А. Т.е. prolonged use at currents higher than this may have unknown consequences. For 3 cells with 3000mAh and a recommended charging current of 0,5C.1С (1.5A. 3A) we are within the parameters of the charger. For 6 cells we need twice the charging current. And yes, as I said before, there is no circuit to limit the charging current in the charger t.е. at some interval we will be charging our batteries at the limits of the charger’s capability, which is tolerable for 3 cells, but not for 6 cells.

Basically it is the main nuances of using of native charger.

About the native charger.

At idle speed charger gives us 19-20V and short circuit current not measured. The manufacturer claims the operating current of 1.8A.

SD-C804S charger schematic diagram, found on the Internet.

USB & Li-ion Upgrading dead Black & Decker Screwdriver. 892

The circuit has, in my opinion, a number of incorrect notations, but not the point. There are no nodes in the circuit that would monitor and limit the charging current. But there is a circuit for tracking the voltage performance on the chip U1 (not a fact, to confirm the performance of this node did not work), as well as a node to limit the time the charge is made on the chip U2.

What bothers us: what bothers us is the charging time limitation circuit, but it can simply be switched off, otherwise it’s kind of fine. But, I was not able to make charger show the end of charge. Turning on the native battery to charge, the charge indicator light came on, but breaking the circuit on the battery t.е. we got the output supply voltage, the LED never went out, and had to, if the end of the charge is regulated by the battery voltage (I’m not a specialist in electronics and to understand how it works completely can not). And for us this is a critical point because.к. The protection circuit board for our molded batteries just breaks the circuit at the end of the charge.

There were a lot of thoughts on how to make a charge. from upgrading the current circuit, with automatic selection of which battery is inserted the old or new one on simple elements, to front-end all on Arduino with control of everything and everything. But all this takes a lot of time and effort It was decided not to re-invent the wheel and go the way of all.

As charge control was selected DC-DC converter with charge current control on XL4015 chip read

Rebuild of the original charger (horrible kolhoz):

We will remake with the expectation of being able to charge the old type of batteries.

Let’s take our Chinese board and connect it to the lab PSU and set the voltage at 19v, or let’s take apart the battery charger and connect the diodes to the outputs.

We turn the voltage trimmer and set the output voltage of 15 volt.к. native Ni-Cd batteries have a full charge voltage of 1.4v-1.5v, and we have 10. For the new battery assembly this parameter is indifferent, the main thing is more than 12.6в.

UPD: protection board with balancer disconnects the battery itself when the battery voltage exceeds 12.6V, so 15V is not important for us. This is important for charging the old batteries i.e.к. There is no protection board.

Switch the multimeter to the current measurement mode. unscrew current trimmer resistor counterclockwise (like this way) to the end t.е. Set the minimum output current. We connect the ends of the multimeter to the output, close the circuit, set the current of 1A. The higher the current, the faster our battery will be charged, but it will also warm up more. Do not put more than 1.5A to be on the safe side. The board tuning is now done.

Let’s take apart our charger. To introduce the new board we will need to unsolder the original board, remove everything but the two LEDs, diode bridge, and the smoothing capacitor, as well as the connector for the battery. This is done because we won’t be able to stick a new board t.к. The board is in the way. I decided to keep the original board intact and make a kolhoz.

We take the breadboard, diode bridge, capacitor, two LEDs or solder out the original board. We are also soldering out the connectors.

Next, we need to assemble on a breadboard. Figure. (as I was able to) what is circled with a black line.

And solder our LEDs as shown in the picture. We use brown as a minus, and orange as a plus (what kind of wires we have). To keep the wires from breaking off at the soldering point, we put hot melt glue on them. We solder everything according to the schematic. Do not reverse the polarity of the capacitor and all connections. LEDs in the case mounted on hot melt.

As a result we have such a kolhoz.

Now we test it, assemble it and use it. I have a protection with this board does not work by pressing, but my hand, perhaps, make it work. The charge lamp will turn off when the charge current is less than 10% of the set t.е. less than 0.1А

Addendum from 15.09.20:

I don’t use the screwdriver often and after modifying it I worked three times. So today I put the battery pack on charge and after a couple of hours I heard a pop. When I opened the case I found leakage of one of the battery banks, all batteries were depleted to zero and when you try to charge them with an external source, they do not take the charge. BMC board has no external damage or short circuits in the main points.

What happened I do not understand and I do not have the desire to find out. I ordered myself a new Interskol DA-10/14.4Л3, 1.5Ah [383.0.2.00]

As a variant, I think, in the future BMC boards take not from obscure Chinese, but take clones of BMC boards from real machines.

What is an electric screwdriver battery and what are the batteries

The electric screwdriver’s portability is ensured by the use of an independent power supply. As such source is a rechargeable battery, the principle of operation of which is similar to the usual battery for a clock or remote control. Only a power tool battery has a voltage several dozen times greater than that of an ordinary thumbtack battery.

The battery powers the electric screwdriver motor. As the electric motor armature rotates, torque is transmitted to the gearbox. The gearbox increases or decreases the rotation speed (depending on the mode set) of the chuck where the bits are fixed. The independent power supply as a battery on an electric screwdriver is a key element without which the work of the device is simply impossible.

Often owners of inexpensive screwdrivers are faced with a situation such as a rapid discharge of the battery. The reason for this is the material of manufacture of the independent power source. There are three main types of batteries for an electric screwdriver:

  • Nickel-cadmium ones are the simplest, inexpensive and short-lived. Another disadvantage of this material is a small charge reserve
  • Nickel-metal hydride is an improved version of cadmium batteries, which have higher resistance to frequent charges and discharges (but they discharge quickly). Exposure to low temperatures negatively affects the life of the power supply
  • Lithium ion batteries are a new age battery that not only holds a long charge (slow drain due to high capacity) but can also last for at least 10 years

Often owners only realize after buying an electric screwdriver that comes with a nickel-cadmium battery that they should have chosen a power tool with a lithium battery. The reason for buying a power tool with a nickel-cadmium source is also easy to explain, because with such a battery the device costs several times cheaper. If you don’t believe me, you can compare the price of chainsaws in the online store Cylinder.

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