Electric screwdriver battery charge indicator with their own hands

How to do the “charge-discharge” of the battery of an electric screwdriver? How Often? How to erase “memory effect”?

There is a concept of a fully discharged battery in order to carry out further operations and discharged to zero, which requires resuscitation. How much battery voltage to discharge depends on the type of model and the number of banks in the battery. Cells are connected in series, the voltage across the output terminals is added together. That’s why the limit of discharge is different for acid, alkaline, and lithium batteries.

Do I have to fully discharge a new battery?? Yes, if it is Ni-ion or Ni-MH type. These batteries have a memory effect. They need to be fully discharged 3-5 times before they can be used, then recharged. Any further charging of this type of battery should be done after it has been fully discharged. The battery is stored only completely discharged. How far can you discharge a nickel battery?? Cells are brought up to 0.9 for training.1,0 В. Knowing the number of cells, you can calculate for yourself, how many volts to discharge the battery.

People often ask if a new lithium-ion battery has to be discharged. This type of galvanic cells has no memory effect. The device operates steadily at a medium level of charge. So you can charge the battery at any convenient moment with a special charger. Can a lithium-ion battery be completely discharged? It is possible, but after a discharge below 3.2V special charging methods must be used, at 2.0V the cell cannot be restored. A typical deep discharge is 2.5 volts per cell.

How many volts can I discharge a lead-acid battery pack?? With a cell output voltage drop of 1.70V, the total voltage of a 6 cell battery is 10.3V. A fully discharged battery will have a minimum reserve of survivability. Do I have to fully discharge an acid battery?? A maintenance-free calcium carbureted automobile battery can be destroyed even after a single deep discharge. All acid batteries inevitably lose capacity after a deep discharge through plate sulfation.

Different battery types require different maintenance approaches. Therefore, whether it is necessary to fully discharge the battery, new or in the process of calibration and testing, is written in the instruction manual of the device.

Removing and Replacing

Here you have to work with the soldering iron. Also, you will need rosin-based alcohol flux and tin.

You cut off the unwanted element, then solder a new one in its place. Solder quickly so as not to damage the battery, as it may overheat. Be sure to check that you connected the plus and minus sides correctly. It is best to use the plates you already have in the unit when soldering.

To even out all the potentials on the banks, charge overnight, let cool for a day, and then measure the voltage. It must be the same on all banks (up to 1.3V). Work the electric screwdriver until it is completely discharged and recharged. Repeat this two more times.

Voltage Indicator for Lithium Battery Assemblies 1-7S

Sometimes I order small meters for my battery boxes and I decided to test them and write a micro review at the same time.Inspection, a little bit of tests and conclusions, I hope that will be useful.

Unfortunately the delivery in the store paid, so I ordered a few at a time to make up for it.At the time of ordering the seller seemed to have only four versions, 1S, 2S, 3S, 4S, but now appeared 6S and 7S, while it is strange that the 5S version is not on sale, I suspect that soon will appear.

Gave most of the meters to a comrade, but kept one piece for myself as well.Each meter is packed in separate package, the only difference is label with the marking in Chinese and the indication of the range of the measured voltage.1S. 3.3-4.3 Volt2S. 6.6-8.4 Volt3S. 11.1-12.6 Volt4S. 13.2-16.8 Volt

electric, screwdriver, battery, charge

There is also a color marking of the glow (presumably), but the seller has only one version.

If you buy several different versions, it is better to mark them at once, because they are neither marked nor differ from each other externally.

On one side of the board is a place for a button, most likely to turn on the indicator, but neither the button, nor associated components on the board is not.

When I received the indicators, I was a bit surprised by the size, for some reason I expect them to be smaller, especially knowing how Chinese stores like to take photos.Dimensions of indicator itself. 31.5х20 mm, general dimensions. 43.5х20х9.5 mm, distance between fixing holes. 36mm.

To not get confused where each indicator is, I had to make a marker on each of them.

The overall quality is a three, there are traces of flux, soldering is poor, the indicator on some boards are crooked relative to the boards themselves.

The circuitry is pretty simple, there is no regulator for supply voltage, so the brightness depends on the supply voltage. There is a reference voltage source based on a regulated TL431 regulator, as well as protection against improper power supply.What kind of chip is engaged in the measurement, I could not determine, first I thought it was a four-channel comparator LM339, but its outputs are derived 1, 2, 13 and 14 pins, and the chip reviewed the board at 1, 7, 8, 14 terminals.

Below in the photo two boards, 1S and 4S, to understand the difference between them.1. Resistors through which the indicator segments are powered (R1-R5).2. Resistor R9.

All other parts are the same on all boards. But the TL431 power supply resistor is the same for all boards and because of this, the current consumption will depend on the input voltage.

The indicator is five segment, the one common as a battery symbol and four segments for charging level indication (actually that’s why I thought it used LM339).Not only that, but there are also many color choices.

The size of the indicator of the board in the review and the one shown above are very similar, 30.8х17.8mm vs.5x20mm on the reviewed board.

Now some tests.The indicator of the reviewed board has two colors of light, the battery symbol. Red, segments. blue. The battery symbol consists of six LEDs connected in parallel.

The brightness is ok, but the lowest voltage version is very dependent on the supply voltage, but this is quite predictable, the others are much more stable.There is also a small difficulty, because of the colors of the glow blue and red, it is better to use a neutral light filter.To give you an example, here are four possibilities. 1. Without light filter2. Green filter, all segments are visible, but the brightness drops down a lot and the LEDs of the battery symbol become more visible.3. Red filter. Only battery symbol is visible4. Blue filter, the segments are perfectly visible, but the battery symbol is almost invisible.

Measurements, to begin with the current consumption.Below is a picture of the measurement results for four of the five modes. only the battery symbol, one segment, two segments and four segments, I have not put up the photo with three segments, but I think you can take the average between the third and fourth picture.In all pictures where the segments are included the current is measured immediately after turning it on.1-4, 1S5-8, 2S9-12, 3S13-16, 4S

You can see that the current is constantly growing, although the ratings of the resistors, through which the LEDs of the segments are fed, are different. This is because the TL431 power resistor is the same on all boards. If it is necessary to decrease the current consumption, you can increase the value of this resistor (R14) proportionally, for example, for a 2S board put 2kOhm.

And now the voltage to turn on the segments. I want to digress right away, there is either no hysteresis or it is very small, so in the lowest voltage version is “flickering” brightness, although in the test I was raising the voltage in increments of 10mV.

Also I made a recalculation of the dependence of the display voltage to one battery, depending on the version of the meter and I got:1S. 2S. 3S. 4S3.35. 3.36. 3.43. 3.373.57. 3.53. 3.64. 3.573.72. 3.70. 3.81. 3.763.92. 3.90. 4.03. 3.97

electric, screwdriver, battery, charge

Varieties of batteries

How much time there is a screwdriver, it is never used in the same conditions. in one case the battery is enough for the entire work, in another. it is necessary to constantly recharge it. Therefore, all modern models are divided by initial battery capacity, and therefore cost, into household and professional batteries.

Screwdrivers are equipped with 3 varieties of batteries:

  • Nickel-cadmium. The most common type of battery. Characterized by small size, high capacity and reasonable cost. Number of charge cycles in good operating conditions can exceed 1000. The main disadvantages are the memory effect, which reduces the capacity and the harmful production, for which reason many manufacturers no longer produce it.
  • Nickel metal hydride. The newest generation of batteries. Characterized by a smaller memory effect and harmlessness of production, but require constant maintenance of the charge, otherwise full recharging is required. They also have a high self-discharge current.
  • Li-ion. Batteries, which exclude the memory effect completely. They are characterized by rapid charging and maximum capacity. However, they are also not without their disadvantages. inability to work at low temperatures and quite high cost.

Important! Do not allow lithium-ion batteries to be completely discharged, as this would disable the protection system. As a result, the device will overheat while charging and can simply burn out.

Charging time

It is not an idle question, how long does it take to charge the battery of an electric screwdriver? Since this parameter is sometimes the deciding factor when choosing a particular model for a particular application. For example, there are situations in which the user cannot afford to wait many hours for a full charge before continuing with installation work.

electric, screwdriver, battery, charge

Charging time of the battery depends not only on its capacity, but also on the characteristics of the charger. The latter are divided into two types:

  • Standard. Used on household power tools. It takes a long time of 3 to 7 hours to regenerate the capacity.
  • Impulse. Used for professional screwdrivers. Charging time is significantly reduced, averaging no more than 1 hour.

Recommendation! Only brand-name chargers or similar with the same voltage rating should be used. Otherwise you may simply burn the battery. with all the consequences that accompany it.

Battery charging cycle

Charging a battery is a complex electrochemical process. The simplest charger models charge the battery in series. This means that the electrons pass through all the cells one by one. At the same time in the extreme batteries the dissociation process will be more complete, while in the middle batteries it will not go all the way through. It also takes much longer to charge. advanced chargers charge each cell in the battery separately. Charging is several times faster, and all cells in the battery are charged to approximately the same degree, the process of dissociation in them is almost complete.

There is a definite disadvantage in the first method of charging. The cells in the middle of the circuit are not fully charged, and over time begin to lose their properties. You may need to replace the battery. Therefore, if you have the possibility, leave such a battery on to charge overnight, but no more than that. Overnight all the cells will be charged.

For all battery types there is such a thing as a memory effect.

That is why it is recommended to discharge the batteries to the end

How to discharge the battery of an electric screwdriver

An electric screwdriver battery uses cylindrical cells of nickel-cadmium, lithium-ion batteries. They are different in maintenance. A new nickel cadmium cell battery needs a dispenser. To discharge the battery, you have to use a 12-volt light bulb, which serves as a load. The battery is considered discharged when the incandescent light goes out.

Lithium-ion batteries do not need to be recharged. May require calibration, for controller to work correctly. In such a case, you need to use a smart device with a discharge function.

How long does it take to get a full charge?

Many users want to know how long to charge the battery of an electric screwdriver. In such cases, there are instructions for the tool or indicators on the charger. Sometimes there is neither.

Average amount of time it takes to charge is 7 hours.

Domestic Interskol, Vihr, Ermak, Zubr screwdrivers require less time. Interskol is considered a versatile electric screwdriver. it can be used as a drill. Top brands like Bosch, DeWALT, Makita, Metabo or Dekker charge faster.

If the power source just needs recharging, it will suffice for half an hour. But don’t do this to nickel-cadmium batteries. With their memory effect they will fail quickly.

There are different versions of battery chargers. Normal, unadulterated batteries are included with most household screwdrivers. Charging time for them. from 3.5 to 6.5 hours. And how much an electric screwdriver is charged with the pulse charger also depends on the model of the tool.

Impulse charger can charge a battery in half an hour. This is a plus and minus at the same time. Minus in the high cost of such tools. The same recommendations are valid for some car batteries.

Much depends on the power of batteries. The voltage of household tools can be 12 and 14.4 в. Professional models reach 18v and higher.

How to properly charge a new battery?

For nickel cadmium and nickel metal hydride batteries, initial charging cycles are important so that they can use their full capacity. Batteries of the first type must be completely discharged and then charged three times to reach their maximum capacity. Next they are only fully charged, the end of this process will be indicated by the indicators or the warming of the case. Type 2 batteries require 4-5 cycles of full discharge and charging. Charge them further as needed without waiting for complete discharge. However, the discharge-discharge cycles are repeated 4 to 5 times at regular intervals to restore the capacity.

Lithium-ion batteries have no memory effect, so there are no recommendations on how to properly charge a new li-ion battery for an electric screwdriver.

How to charge a new battery properly?

For nickel cadmium and nickel metal hydride batteries, initial charging cycles are important to allow them to use their full capacity. Batteries of the first type must be fully discharged and then charged three times to achieve the maximum value of their capacity. Then they are charged only fully, the end of this process will inform the indicators or the warming of the case. Batteries of the second type require 4-5 cycles of full discharge and charging. Then they are recharged as needed without waiting for complete discharge. Nevertheless, the discharge-discharge cycles are regularly repeated 4-5 times to restore the capacity.

Lithium-ion batteries have no memory effect, so there are no recommendations on how to properly charge a new li-ion battery for an electric screwdriver.

What to charge batteries with

Li-ion batteries have gained a lot of popularity also not since there are a decent number of options than there is an option to charge them.

The most logical wrong way to charge a lithium-ion battery is with a regular charger. Thanks to a special device, the battery will receive the maximum charge in the shortest time. It is also completely safe for the battery.

Those who do not know how to charge a lithium-ion battery if there is no regular charger, we inform that it is certainly do not use a computer or a USB cord. But here the current will only reach 0.5 amps.

Also you can charge a Li-ion battery through the cigarette lighter in the car. Now in different stores they sell special USB adapters which give out different amperage. How to charge lithium-ion batteries is much better to know in the documentation that comes with your phone, laptop, or other device. Most batteries are charged at 3.7 to 19 volts. However, there are models of batteries that need more than just what they call a lower voltage. In any case you should not take the risk, but it is better to look in the instruction manual.

If none of the previous methods of charging is not suitable, use an old, yet relevant not at the moment device, which is called in simple terms “frog. These devices are designed more for cell phone batteries. The design of the “frog” is quite simple: there is one dock, where the lithium-ion battery is installed, in addition the contacts, adjustable in width. So this charger will fit almost any battery of this type.

As we now understand, there are enough ways to charge the battery. However, before you charge the lithium-ion battery, you should make sure that even though there is no possibility of using a regular charger. The other methods are used if necessary. They do not harm the battery, in any case, the original charger will take priority over the others.

If a person does not know how to charge the lithium-ion battery of an electric screwdriver, then we inform you that it should be done only with a specialized charger that comes with the device. It is worth noting that if the charger burns out, and to buy a new one is not possible, for example, than there is an option to connect multiple batteries type 18650 not inserted into the box with the original charger. How much battery type 18650 is needed, it is impossible to say, it all depends on the voltage of the electric screwdriver.

What can break in a battery charger from an electric screwdriver

What breaks down in the charge of an electric screwdriver is known to experts who face the problem of the tool not working every day. It is not rational to buy a new battery charger for an electric screwdriver, so if the battery of the power tool does not get a charge, it is necessary to begin repair with finding the cause of failure.

The following parts and mechanisms are the reasons battery chargers fail to work:

  • The fuse. all electric devices, which are not assembled “in the basement”, have protective elements, and one of such elements is the fuse. It protects the battery charger circuit board from overvoltages, stray currents, short circuits, etc.п. For this circuit design applies a fuse designed for the appropriate current rating, the value of which depends on the voltage of the battery. It is usually rated at 5 A and is located right after the transformer and before the rectifier bridge. The fuse has a cylindrical construction of clear glass with steel contacts on each side. Inside is a “hairpin” that is designed to carry up to 5A of current (different models may have different current ratings)
  • Rectifier or diode bridge. if the fuse is good, and how to check it is described below, then let’s move on to consider the diode bridge. These are four diodes which are designed to rectify the current from AC coming from the mains to DC required to charge the battery. To fix the rectifier, you need to unsolder the faulty diode or all the diodes, and replace them
  • Capacitor is a large cylindrical barrel, which is very often the cause of instrument failure. The capacitor blows, which causes the fuse to blow, and often causes the diode bridge to burn out as well
  • The high-voltage transistor of the inverter, which very often fails on the charging blocks of screwdrivers, designed for 220 V

Whatever element is out of order, but first you need to make sure that the breakage is in the power pack itself. After all, they often blame the power supply, when in fact it is high time to replace the battery. If you are going to repair the charging of an electric screwdriver, then you should start by checking the device for malfunction. Above described instructions on how to check the unit itself, so now let’s find the faulty element, which is the reason for the inoperability of the charger.

Methods of restoration of rechargeable batteries

In some cases (when ordering from Aliexpress, for example) you have to wait for new banks for weeks. And it needs to work. In this case, you can try to temporarily improve the characteristics of the “sagging” batteries.

Short-term characteristics can be renewed

Nickel-cadmium batteries

Ni-Cd batteries dry out when heated while in use. There are several options to restore the density/quantity of electrolyte.

Pour distilled water into the electrolyte. They are carefully removed from the block without damaging the plates. The next steps are as follows:

  • In the case. closer to the bottom or top. you carefully make a hole. Diameter. no more than 1 mm. It should only be in a sheath. Make sure that the drill does not go further.
  • Place the battery on its side, with the hole up.

One way to restore the capacity of a rechargeable battery

A severely discharged battery may not accept a charge. In order to “turn off” it a powerful impulse must be applied for a short time. Connect a capacitor with a capacity of 7000 to 7500 uF, charged to 10 to 20 V to the bank. Check the residual charge on the bank, it should not be higher than 0,6. 0,8 V. Let’s check if the cell accepts a charge.

How to Repair a Lithium Ion Battery

Overheating can make lithium-ion batteries swell. The increased pressure inside will bend the contact plate. You can see these batteries, it’s easy to spot. To be sure, you can check their charge. It’s usually very low or zero. It is rare to be able to repair a bloated lithium-ion battery, but you can try. Excess gas must be vented. Remove the battery from the case without tearing off the contact plate. The manipulation is as follows:

  • Bend back the plate on the positive contact, but do not tear it off.
  • Insert an awl under the plate. Slowly push the point of the contact inside the battery until the gas starts to come out.
  • When the gas comes out, the hole is sealed with glue, silicone, any other method.
  • Solder the plate in place.

It can not be said that the described methods of battery recovery always work. They are all risky. Electrolyte in batteries is a gel-like caustic substance, which, in contact with skin, causes chemical burns. That is why all work must be done very carefully. However, sometimes a remanufactured battery can last several months without problems, allowing you to wait out the required time.


Package is lost, so I’ll start with the original packaging On the front of the?) there are 4 small blue LEDs, an activator button and a name/revision. Notice in the upper right hand corner there are pins for auxiliary power, which can provide continuous indication. On the back side there are “brains” with tying LM339 is used, but it is not clear what series.

The indication is activated by a manual button. After 5 seconds the board smoothly dims the lights. In standby mode it consumes about 0.1 mA, on the gif the module did not have time to “sleep”.

Check the voltage range at each level of charge.

25-0%: 18.2-16В (2.2В). The indicator light is lit at half power, at 15.9V stops responding.

I should probably mention that you can order any version and, if necessary, remake it to the required assembly. Simply solder resistor R1

1S: 510 (51Ω) 2S: 201 (200Ω) 3S: 511 (510Ω) 4S: 102 (1kΩ) 5S: 202 (2kΩ)


I was planning to implement the sabot in this electric screwdriver: It’s a funny-looking thing for its price, but it has only one battery, so a battery level would be very handy.

Weighs 1.1kg Holds well in hand Lights up First speed: 0-380 rpm

Just enough guts to rip the heads off screws, but it doesn’t take much effort.

The gearbox is metal. Took it apart for lubrication but didn’t need it

I hope I will not be accused of hidden advertising, if necessary. remove the spoiler.)

It was decided that the most logical thing to do would be to pick the battery, but then there was the problem of space The elements are located very tightly, the board indicator 3.The vise is 5mm wide, that doesn’t allow you to cut plastic for it. It fits well only in the back between two parts of the case, you just need to saw the slots.

That’s it. As for me, the module is quite interesting, and due to its size, it can be built almost anywhere. As always, constructive criticism is welcome in the Комментарии и мнения владельцев. Good morning, everyone =)