DIY lithium-ion battery repair

Lithium batteries are increasingly used in everyday life. Nowadays, they are increasingly found as replacement batteries for screwdrivers and other power tools. Despite their merits, lithium batteries also have their drawbacks.

So, after 1.5 years of operation, the batteries from the DeWalt screwdriver began to discharge quickly, it became impossible to work. The batteries were charged up to a maximum of 14.4 volts, although a standard DCB-107 charger was used for this. In addition, charging took place very quickly, instead of the prescribed 60 minutes, at most 15 minutes.

Before talking about how we managed to solve this problem, I would like to acquaint the reader with the device of a lithium battery from a screwdriver.

This is how the standard DeWalt DCB-145 battery looks like.

To open such a battery, you need a TORX hex screwdriver. The rechargeable battery consists of 4 lithium (Li-ion) "cans" SAMSUNG SDI INR18650-13B with a capacity of 1300 mA / h each. All four "cans" are installed in a plastic box and connected in series using current-carrying plates. The plates are spot welded to the battery contacts. It can be seen that this is a high-quality factory assembly.

I do not advise separating the "cans" of a composite battery by cutting off the connecting current-carrying plates. I did so and regretted it. Next, I'll tell you why you shouldn't.

Batteries SAMSUNG SDI INR18650-13B do not have a built-in charge / discharge controller. Unfortunately, to find documentation for batteries of this particular model (with the index 13B) I did not succeed. But, judging by the parameters of the batteries of this line, the maximum continuous discharge current (Max Continuous Discharge Current) can be from 18 (INR18650-13L) to 23 (INR18650-13M) ampere! Not surprisingly, they don't have a built-in controller.

Also in the battery case is a 5-pin connector and a small printed circuit board.

The multi-pin connector is necessary so that when charging, it is possible to control the charge of each of the four INR18650-13B batteries separately. As you know, the voltage is more than 4.1

4.2V for lithium batteries is dangerous and may cause damage or even fire. Therefore, the charger equalizes (balances) the current through each "cell" of the composite battery so that the voltage on each of them does not exceed 4.1V.

Also on the printed circuit board is a temperature sensor, which is adjacent to one of the lithium "cans".

Thanks to the sensor, the standard charging DeWalt DCB-107 measures the temperature of the battery and turns off the charging mode if the battery is overheated or has a temperature below +4 0 C. In addition to the temperature sensor, some kind of circuit is mounted on the board, but it is filled with sealant.

This battery assembly is called “Pack for Power Tool“, That is,“ Package ”or battery assembly for the power tool. This is how it looks.

Large companies like Samsung supply these assemblies for custom-made power tool manufacturers. Perhaps that is why I could not find the exact specifications for INR18650-13B batteries.

We got acquainted with the device of the Li-ion battery for the power tool. Let's go back to our "dead" batteries.

Before the batteries "died" they were very badly discharged. We used a screwdriver until the battery was discharged, and then, after taking a break, we worked with it for a while. After that, the batteries began to charge poorly and did not hold the capacity.

After measuring the voltage on each "bank" of the battery, it turned out that 3 "banks" out of 4 were not fully charged - up to 3.5 volts. Only one was charged to the required 4.1 volts (for Li-ion).

If we add up the voltage of all the cans, we get exactly the same 14.4V.Let me remind you that the standard charger very quickly charged the battery and turned off.

The first thing that came to mind was to replace those lithium "cans" that were not fully charged. But, search for original INR18650-13B returned no results. Perhaps due to the fact that such assemblies are supplied only on order and are not available at retail. And the cost of four new batteries, for example, INR18650-22R practically equal to the price of one DeWalt DCB-145 battery. Therefore, I decided to refuse to replace the batteries at that time.

And, then a sensible idea came to my mind, but it, as always, is late. What if the standard charging failed to properly balance the composite lithium battery after a deep discharge? That is, the standard DeVolt's charger charged one “can” to the required 4.1V and turned off. In this case, the remaining 3 lithium "banks" were not fully charged, but only up to 3.5V.

It was decided to check the standard DCB-107 charger for any malfunction, but it turned out to be in good order. And the new batteries were charged perfectly.

Thus, I came to the conclusion that the stock charger failed to properly balance the composite lithium battery after deep discharge.

It was decided to discharge / charge each 18650 lithium cell separately using a third party charger. For this, a charger was used. Turnigy Accucell 6 (analogue of IMAX B6), which I already talked about.

I discharged each 18650 cell to 3V with a current of 0.3A. Then he charged up to 4.1V with a current of 0.5A. Then he again discharged in order to determine how much current is poured into each specific "jar". This is necessary in order to assess their capacity. As it turned out, the batteries are in good order and each of them was filled with 1164 before 1186 mA... Which is not so far from the declared capacity of 1300 mA / h. Thus, I made sure that the batteries are in good working order and should not be replaced.

After the test (charge-discharge) of each battery, we measure the voltage on each lithium "bank". It should be within 3.1

3.3V each. Thus, the composite accumulator will discharged up to 12.4

Then I collected all the "cans" in a box, soldered the board with a connector and installed it in the case. Set completely discharged the DeWalt DCB-145 battery is already in the standard DeVolt's charging and has registered the time of the beginning of the charging process. As I expected, after 1 hour (60 minutes, as indicated in the instructions), the charging was completed.

As a "test shot" I measured the voltage at the terminals B + and B-... It amounted to 16.4Vas it should be for a fully charged battery.

Thus, it was possible to restore two DeWalt DCB-145 batteries and avoid wasting money on the purchase of new batteries, the total cost of which is almost equal to the cost of an inexpensive screwdriver.

Now I'll tell you about the "rake" that I stepped on.

Attention! The assembly must be done very carefully and not to allow a short circuit between the terminals of the "cans" and those conclusions that go to the balancing connector. If you close something with pliers or tweezers, then fireworks from sparks are provided! I was convinced of this in practice. The currents are such that a wire with a cross section of 0.5 mm. melt like it's the thinnest fuse wire.

I also strongly advise against separating lithium cans by cutting or biting the connecting conductive plates that are welded.

First, there is no need for this. You can charge each "can" simply by connecting the leads of the charger to the poles of the required battery. The only thing that may be required is to unsolder the balancing connector leads and temporarily remove the connector itself from the assembly.

Secondly, you can damage the insulation of lithium batteries and, because of this, short-circuit them.

Third, after the lithium "banks" are tested, the question of connecting them together will arise. And even if the plates can be soldered together, then putting such an assembly back into the case will be a very time-consuming task. The battery case is very tightly fitted to the dimensions of the assembly.

Hey! Today we will repair the screwdriver battery.Did you know that the history of the creation of a screwdriver goes back to the deep Middle Ages - already in the 15th century, when the knights put on armor before the battle, and the squires helped them twist parts of the armor, guess what? A screwdriver!

This went on for a long time, until in 1907 the Canadian inventor Peter Robertson patented the Robertson screw with a standard square hole, into which a screwdriver tip was inserted. Since that time, screws began to be produced on an industrial scale and used in households. Later, in 1934, inventor Henry Phillips redesigned the head of the screw and a Phillips screw was introduced into which the corresponding screwdriver was inserted. By that time, the engine had already been invented and the idea of ​​creating a "screw and screw rotator" was in the air. However, there were big problems with the batteries - their weight and dimensions. The problem was solved only in the 1980s, when the first nickel-cadmium Ni-Cd and lithium-ion Li-Ion rechargeable batteries appeared.

The USA and Japan were the first to master the production of household and professional cordless drills and screwdrivers. All this happened thanks to the emergence of new energy-intensive batteries of electricity. We will urgently change them inside the Interskol DA-10 / 10.8 ER cordless drill-screwdriver that fell into my hands. The malfunction was like this - when the button was pressed, the engine simply did not spin, but the LED lit up, though the light was weak.

Let's start repairing the screwdriver battery. We remove the battery from the handle of the screwdriver and unscrew the three self-tapping screws that are located under the sticker at the bottom.

After unscrewing the screws, carefully push back the hooks of the latches, as in the photo. And remove the bottom of the plastic battery case.

Inside we see lithium-ion cans Chinese company HighStar model ISR18650-1300 Li-Ion. This means that the batteries have never been changed. Because it is known that Interskol purchases batteries from this company and inserts them into almost all of its cordless tools.

The photo below shows the insides of the screwdriver battery in all its glory with three cans, which were produced already in 2011. These batteries lasted five years during active use at a construction site. So the result is very decent. Usually they die earlier, probably in cold weather they were not exploited.

To replace the battery cells, you need to disassemble it even more. I advise you to remember the location of the plus, minus and charging contacts so as not to confuse the wires when reassembling.

Pay attention to the voltage control board on the batteries - especially often stabilizers and protective diodes fail on it. It is imperative to ring suspicious radioelements on this board with a multimeter.

We check the voltage at the output of the battery - it turned out 4.4 volts, and it should be 3.7 x 3 = 11.1 volts in the norm and 10.8 volts with the minimum charge of the batteries. In general, the banks are dead - they need to be changed unambiguously.

This can be done in several ways - you can unsolder the wires that go to the board.

You can also simply remove the contacts from the top battery cover. The photo shows the shape of the curved contacts, so you can easily remove them yourself.

Under the plastic cover, we see how the batteries are connected to each other. Their spot welded... This solution is used in almost any battery of another tool. This is a safe and gentle battery connection. At the same time, the destructive heating of the lithium batteries themselves is minimal.

Gently tear off or bite off the metal tape with pliers to disconnect the cans from each other. From the side of the board, they were also connected with a tape and glued to a cardboard gasket. This is done so as not to short-circuit anything on the board. Remember to put it back in place when reassembling the battery.

Due to the lack of a spot welding device, new lithium-ion batteries will be soldered very quickly with a well-heated powerful soldering iron. We remember that heating lithium-ion batteries reduces their service life and is generally explosive.

Pay particular attention to the condition of the wires inside the battery. They can be broken or frayed. They need to be qualitatively isolated or replaced with fresh ones. Since I was repairing a screwdriver battery on the road in the field, I had to apply a brilliant invention of the engineering mind. He took out a blue radio-technical electrical tape.

When disassembling the battery of the Interskol DA-10 / 10.8 ER screwdriver, I was pleasantly surprised - a thermal sensor was installed in the budget screwdriver to control the temperature of the batteries. It turns out that when the lithium cans overheat, the protection circuit turns off the power until the temperature returns to normal. True, the owner never managed to drive him into such a regime. We carefully tear off this thermal sensor so as not to break it - then we will place it in the same place on new cans.

can be done in different ways, for example with thick wires. I decided to solder a torn-off metal strip taken from old cans. First, I tinned the tapes in the places of future contacts on both sides. Later I tinned the battery contacts with a well-heated soldering iron with a drop of solder. But so that they do not get too hot - let them cool down. Then he pressed the tape to the contacts of the cans and soldered the tape again without severe overheating of the battery cans.

The minus leads are the hardest to solder, but with a good flux, things go very quickly. True, then it is better to wash the flux afterwards to clean the insides of the battery.

Now comes the most important thing. What batteries were used when repairing the battery of the Interskol DA-10 / 10.8 ER screwdriver, you ask? Well, I won't hide. These were the most Chinese of the cheap cans that the owner of the device honestly bought in the store. Batteries of standard size 18650 firm Bailong with a fictitious capacity of 8800 mAh. This is of course a laugh and God forbid that they have a 2200 mAh battery. Judging by how long the screwdriver worked after repair on a full charge. I would reduce this figure by a factor of two. But nevertheless, the screwdriver was urgently repaired and it pleases the owner.

When assembling, do not forget to replace the cardboard gasket between the banks and the board. This is so that the fresh soldering does not short-circuit anything on the board.

This completes the repair and restoration of the lithium-ion battery of the Interskol DA-10 / 10.8 ER screwdriver. Almost all batteries are repaired in much the same way. popular manufacturers of screwdrivers: Bosch, Makita, DeWALT, Metabo, Hitachi, Elitech, Skil and my favorite Bison. This concludes my story about repairing a screwdriver battery. Ask questions in the comments. Better yet, in the appropriate thread on our forum or write to the Solder Master personally by mail.

Best regards, Solder Master. Happy repairs!

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To begin with, there are a lot of videos on the Internet on recovering batteries from screwdrivers, and they are all the same as a mirror, a brief description of the recovery process that these people offer is that we take the battery, push it with a power supply or another battery, then charge and we use it, and it’s strange that someone doesn’t look, but what kind of stress will be on him when he lies down for a week or two. I propose a completely different way to restore

Which does not just charge and use until the battery dies again. And the one that you did and use as a new battery until the need arises.This method was filmed in draft about a month ago, but I never dared to post it on the site, I just didn't want to reshoot it for a more correct explanation. And frankly speaking, I have very little free time lately.

But now the time has passed which has shown that the recovery option that many people on the network offer to use are not destined to live for more than a certain period of time. And my version, even after 2-1 month of inactivity, as if nothing had happened quietly works and charges, I still tried to shoot a new video clip, where I will try to tell everything.

In fact, everything turned out to be very simple, and in this I was helped by the NI-CAD 1.2V battery I disassembled, which showed me that even with all the zeros on the outside of the device, the patient inside is rather alive than dead and feels very good.

An attempt to regenerate the bus relative to the collector plate was done using distilled water, and the process was quite successful, as a result of which I came up with the easiest way to restore them even without disassembling the batteries!

It is enough to drill a hole in the accumulator in the place behind the rollers +, and pour 20-40 ml of distilled water into it. after a couple of cycles, the hole is slightly covered with silicone.

Before repeating, I recommend watching the video, where I tried to describe the process in more detail.

If you are not sure or afraid of ruining a damaged battery, for example, you can do this with one battery.

If your batteries have voltage and are within the operating range, then you may have a problem with the following:

- faulty charger

- the thermal protection of the battery pack has worked

- there is one battery in the battery pack that has dropped to 0 Volts.

Also, if you notice that the drill began to work somehow sluggishly and at the same time it works as long in time after charging, then you most likely have a problem in one or more batteries that are at zero!

A very interesting effect on the battery capacity, it was equal to or slightly more than the indicated battery capacity after restoration by this method.

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The cost of a new screwdriver is approximately 70% of the cost of the battery for it. Therefore, it is not surprising when, faced with a battery failure, we ask ourselves the question - what's next? Buy a new battery or screwdriver, or maybe it is possible to repair the screwdriver battery with your own hands and continue working with an already familiar tool?

In this article, which we conditionally divide into three parts, we will consider: the types of batteries that are used in screwdrivers (part 1), their possible causes of failure (part 2) and available repair methods (part 3).

It should be noted that regardless of the brand of the screwdriver and the country of the manufacturer, the batteries have an identical structure. The assembled battery pack looks like this.

If we disassemble it, we will see that it is assembled from small elements that are assembled sequentially. And from the school physics course, we know that elements that have a serial connection harmonize their potentials.

Note. The sum of each battery gives us the total voltage at the contacts of the battery.

Typesetting parts or "cans", as a rule, have a standard size and voltage, they differ only in capacity. Battery capacity is measured in Ah and is indicated on the cell (shown below).

For the arrangement of screwdriver batteries, the following types of elements are used:

• nickel - cadmium (Ni - Cd) batteries, with a nominal voltage on the "banks" of 1.2V;
• nickel-metal hydride (Ni-MH), voltage across elements - 1.2V;
• lithium-ion (Li-Ion), with a voltage of 3.6V.

Let's consider in more detail the advantages and disadvantages of each type.

• The most common type due to its low cost;
• Low temperatures, such as Li-Ion batteries, are not scary;
• It is stored in a discharged state, while retaining its characteristics.

• Produced only in third world countries, due to toxicity during production;
• Memory effect;
• Self-discharge;
• Small capacity;
• A small number of charge / discharge cycles, which means that they do not "live" for a long time with intensive use.

• Environmentally friendly production, there is an opportunity to purchase a high-quality branded battery;
• Low memory effect;
• Low self-discharge;
• High capacity compared to Ni - Cd;
• More charge / discharge cycles.

• Price;
• Loses some of its characteristics during long-term storage in a discharged state;
• It does not "live" for a long time at low temperatures.

• No memory effect;
• Self-discharge is almost absent;
• High battery capacity;
• The number of charge / discharge cycles is several times greater than that of previous types of batteries;
• To set the required voltage, a smaller number of "cans" are required, which significantly reduces the weight and dimensions of the battery.

• High price, almost 3 times in comparison with nickel - cadmium;
• After three years, there is a significant loss of capacity, because Li decomposes.

We got acquainted with the elements, let's move on to the rest of the elements of the screwdriver's battery pack. Disassembling the unit, for example, for repairing the battery of a Hitachi screwdriver (pictured below), is very simple - we unscrew the screws around the perimeter and disconnect the case.

The housing has four contacts:

• Two power ones, "+" and "-", for charge / discharge;
• Upper control, it is switched on through a thermal sensor (thermistor). A thermistor is necessary to protect batteries, it cuts off or limits the charge current when a certain temperature of the cells is exceeded (usually in the range of 50 - 600C). Heating occurs due to high currents during forced charging, the so-called "fast" charging;
• The so-called "service" contact, which is connected through a 9K ohm resistance. It is used for complex charging stations that equalize the charge on all battery cells. In everyday life, such stations are useless, due to their high cost.

That's actually the whole design of the battery. Below is a video on how to disassemble a block.