the electric screwdriver does not charge what to do. The battery on an electric screwdriver dies quickly
Why the battery of an electric screwdriver does not hold a charge or does not charge at all?
A cordless electric screwdriver, can always be useful at home, but over time, its power source suddenly refuses to work. It is expensive to buy a new electric screwdriver. Its price consists of about 70% of the cost of the battery. And as models change frequently, it is quite difficult to find a new battery for this particular tool. So the question arises. what to do next? Buy an electric screwdriver or look for a similar battery? But this problem can be solved by repairing the battery by your own forces, prolonging its life for a few more years.
To ensure the autonomous work of power tools are usually used three main types of batteries, about which it is necessary to tell in detail.
Ni-Cd or nickel-cadmium power sources
Used for a very long time and quite deservedly considered the oldest batteries installed in a variety of modern equipment. Their main advantages are:
- the lowest self-discharge, thanks to which the batteries can gather dust in a closet somewhere for a long time, and then work quietly without recharging;
- Not a bad capacity in a very compact size, which provides a long autonomous operation of the screwdrivers;
- resistance to low temperatures, because of which Ni-Cd cells are often used in all-weather machinery;
- low price.
The disadvantages include the need to constantly go through a full charge-discharge cycle of batteries. If they are not charged fully, the so-called memory effect is triggered. The battery is getting worse and worse, after which it shuts down altogether.
Ni-Mh or nickel-metal hydride power supplies
Considered to be an improved analogue of Ni-Cd batteries, but their advantages include only more environmentally friendly production and a slightly reduced memory effect. In general, this kind of batteries is inferior to the nickel-cadmium. The thing is that they have a very high percentage of self-discharge. To use the battery effectively, you need to constantly recharge it, which completely loses its autonomy.
Li-ion, or lithium-ion batteries
It is these batteries that are installed on almost any equipment, including power tools Makita, Interskol, Bosch, as well as numerous gadgets. The list of advantages is as follows:
- extremely high capacity;
- practically no memory effect;
- The possibility of equipping special controllers that monitor the level of charge and count the charge-discharge cycles;
- low self-discharge percentage;
- high load resistance, possibility of use in high-power machinery.
The disadvantages of lithium-ion batteries are unstable operation in cold weather, as well as high cost in comparison with the above described analogues.
What kind of batteries are used in screwdrivers
In order to understand why a battery quickly runs out of power, or does not charge at all, it is necessary to know what kinds of batteries exist in general, and what characteristics each of them has. This will help you understand the specifics of this or that electric screwdriver battery and learn how to properly use the resource of this or that type of battery.
There are three main types of batteries commonly used in screwdrivers:
Each of these battery packs has its own specific purpose. It depends on the planned load of the power tool in the first place, because different jobs require different performance and capacity of the batteries.
Those who know screwdrivers well and deal with them all the time know that any of them comes standardly with two batteries. If one is discharged, the other can always be used. However, even this can not always save the situation. Self-discharge can occur at the most inopportune time. Especially when the battery has not been used for a long time.
The “oldest” of the representatives of autonomous power cells are nickel-cadmium batteries. Despite the fact that at the European level, representatives of animal protection and the environment are constantly talking about the “toxicity and danger” of their production, they are still actively used in our country. And no owner of an electric screwdriver has suffered from them.
Their main advantage is the low self-discharge and the battery can be stored without being used for a long time. Nickel-cadmium batteries are compact in size, and their capacity, despite criticism from amateurs of more expensive counterparts, is quite decent. And the price is the most affordable.
Of course, self-discharge of such batteries is also present. But at the same time they like “pumping” with a standard charger: they charge effectively, passing more than 1,000 charge-discharge cycles.
In principle any craftsman can be quite satisfied with the use of these “budget” cells if he is aware of their one essential disadvantage, such as the “memory effect”. If such batteries are subjected to constant “recharging” without a full cycle, they tend to “accumulate” inside themselves the information of incomplete charge. Then they begin to work inefficiently, without using their real resources. This is when you get the impression that the battery is “dead”.
How to properly charge nickel-cadmium batteries? The answer is simple: if you want to keep their optimum performance as long as possible, it is important that from time to time they are fully discharged. and then followed by 2-3 cycles of “pumping” with the charger.
It’s simple and straightforward, and no trouble at all for the craftsman. Any batteries can be completely discharged after a few hours of continuous use. And then you can simply put the battery to charge normally, using a spare battery pack. The “memory effect” can only be removed in this way. temporarily, of course, but effectively.
The second group of cells most commonly used in screwdrivers are nickel-metal hydride batteries. They have replaced the nickel cadmium batteries as the more advanced counterparts.
Whether they are really more advanced than Ni-Cd batteries is still debatable. Their production technology is cleaner, so if you follow European standards, the ecosystem will not be harmed. Nickel-metal hydride batteries do have a memory effect, but it is much less pronounced.
But their self-discharge rate is very high. and they need to be constantly recharged to ensure that their capacity is not lost forever. Nickel-cadmium batteries, on the contrary, tolerate storage without recharging.
And finally, the most advanced and “powerful” lithium ion batteries. They can be found not only in more expensive screwdrivers, but also in all household appliances, all gadgets: cell phones, laptops and tablets.
The first lithium-ion batteries were very dangerous and they often exploded. But nowadays the technology of their production has reached a certain perfection. They all have safety and charge level controllers.
Li-ion batteries have a very high capacity. This is not the case with nickel cadmium or nickel metal hydride cells. They have practically no memory effect. and they last a long time and are usually used in high-power tools.
The disadvantage of these batteries is their high cost and the fact that they may perform worse at low temperatures. Otherwise, lithium-ion cells are very good.
Recently, it has become popular among electronics enthusiasts to replace the battery of an electric screwdriver from nickel-cadmium to lithium cells. If you need to perform intensive work all the time, this is an excellent way out. You can not buy an expensive tool with a ready-made lithium battery, but rather do a rearrangement of some batteries for others.
Replacing the batteries completely or partially
If the screwdriver’s battery can’t be restored “by accident,” you’ll have to change the batteries. Any battery in a screwdriver is a chain of battery cells connected in series. With this type of connection, if one cell “sags”, the whole battery has a reduced charge and discharges quickly. And the characteristics deteriorate to the extent that the most faulty bank has “sagged”.
How to repair the battery of an electric screwdriver: full or partial replacement of the batteries
So you can restore the battery in two ways. The first option is to find the “weakened” elements and replace them. The second is to change “all together”. The second variant is more expensive, but more “long-lasting”. In the first variant the rest, while serviceable banks, too will soon be sagging. It will be necessary to repair the battery again. So it is advisable to choose the second method.
How to find exactly what is broken
Before being engaged in repair of a charger or a battery for an electric screwdriver, it is necessary to measure the indicators of circuit voltage. A multimeter designed to measure current and voltage, as well as resistance and capacitance of capacitors will help. Then check that the battery charger is to blame. To do this, it is connected to the mains and attention is drawn to the LEDs. If the light does not go on, you can move on and look for the damage directly in the circuit elements.
Warning! Before disassembling the charger body, disconnect it from the mains. Connect it to the socket only when you make measurements with a multimeter to see if each of the elements is working.
How to find the defective fuse
Functionality of the fuse of the power supply can be determined with the help of a tester, it is necessary to prepare in advance. The following list of actions will help to find the breakdown:
- Remove the screws that fix the back cover of the charger. Their number varies from 3 to 6, depending on the model of the PSU and the electric screwdriver itself.
- Inspect the case from the inside. You can find traces of soot on one of the elements, which will immediately tell you what is causing the failure. In this case, do not hurry, because other parts of the circuit could also be damaged.
- Get hold of the tester and switch it to “continuity test” mode.
- Touch the fuse outputs with the feeler gauges.
If the tester begins to beep, then the fuse is not broken.
How to determine the faulty capacitor
Next it is necessary to check the serviceability of the capacitor. For this purpose an external inspection of the element is carried out. If traces of bloat are found, the capacitor is replaced with a serviceable, similar part.
Before you start to unsolder it, make sure that it does not work. This requires:
If the screen shows “0”, then the patient is dead. It should be carefully unsoldered and replaced with a serviceable element.
How to find a blown diode bridge
It is possible for all 4 diodes in the charger to fail, or just 1. They should be checked after the capacitor, t.к. the rectifier breaks down less often and most often afterwards. Step by step instruction on how to find out if the diode bridge is burned out:
- Visually inspect the part. Traces of soot on diodes may be obvious.
- Take a multimeter and set it to constant voltage measurement mode.
- Touch the output of each of the diodes with the probes in turn. Parts that carry current should show corresponding values on the tester screen.
- Reverse polarity and probe all diodes in the other direction with the multimeter. If the current flows in both directions then the rectifier is defective.
Diodes leaking voltage in the opposite direction are unsoldered and replaced with functional elements.
How to Identify a Faulty Resistor
If all parts inspected up to this point are serviceable, then the last point of inspection of the electric screwdriver power supply is the resistor. To check if a battery charger choke is working, you need to
The choke is considered to be serviceable if the device shows the declared resistance of the current and beeps (depending on the chosen mode of the multimeter). A faulty resistor will not show signs of life and must be replaced.
If all of the above parts after examination and repair work properly, but the charger still does not work, then the reason may lie in the smallest and most atypical places. An electric screwdriver charger can break down because of:
- Breakage and burnout of the power cable;
- transformer short circuit;
- oxidation of the toggle switch contacts and the output contacts of the device;
- any damage to the wires.
This is a small part of the list of things that can cause the charger to malfunction. But most often the search ends at the diode bridge.
How to check the battery capacity of an electric screwdriver with a multimeter
The main property of a battery is capacity. This value indicates the stored energy, that is, the amperage in 1 hour. Measured in A/h.
How to Check a Battery Capacity with a Multimeter?
- Disconnect the battery from the electric screwdriver.
- Charge the battery to 100%.
- Using a multimeter, a resistor and a light bulb, measure the time it takes the light to go out, the voltage at the battery’s output.
- Calculate the capacity according to the formula/
- Compare the results with the information in the instruction manual of the electric screwdriver.
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Let’s assume the battery voltage reaches 18V. With a 10W incandescent bulb, the battery discharge time should reach at least 2.3 hours.
If the connected light bulb goes out after 30 minutes, then the calculated capacity of the battery is:
This value is much lower than the capacity of e.g. a nickel cadmium battery in an electric screwdriver.3 Ah.
How to charge properly
After the purchase and before the first use, it is necessary to check the level of charge, then proceed depending on the type.
If this model has no “memory effect”, you can immediately charge it and get to work, otherwise you will need preparation:
- Ni-Cd: discharge twice or three times and then fully charge to reach full capacity, then use the standard charging procedure;
- Ni-Mh: also can be “pumped” like the previous option;
- Li-Ion: does not require a full discharge at all (it is even harmful), so you can charge at once.
- Recommended temperature is 10-40 Celsius (or according to the manual);
- Ni-Mh can overheat, for this reason it is necessary to control the charging (others can also overheat, so in the heat or in a warm room it is worth to arrange cooling for the battery, if necessary);
- the charged battery must be disconnected from the charger.
- if the tool is not used, it is better to disconnect it from the charger
- If stored for a long period of time it is necessary to charge periodically;
- note the specific characteristics of each type (Li-Ion and Ni-Mh batteries should not be discharged and Ni-Cd batteries, on the contrary, can be stored discharged).
- first of all. according to the instructions of the device, additionally paying attention to the indication on the charger;
- If you need to quickly recharge. at least half an hour (again, if not contrary to the instructions);
- A full charge can take up to 7-8 hours, more exact time is shown in the documentation of the device.
It is worth paying attention to the type of charger. In the amateur segment, a simplified circuit is used, while professional models can be equipped with pulse variants. They are more “smart” and powerful, so the full charge time may be about an hour.
What to do after diagnosis
Once you have established reliably which equipment is faulty, you need to choose the way to solve the problem. The easiest action is to replace the faulty unit. This way is not always the best for economic reasons. batteries and chargers are expensive, and it is not rational to throw them away because of a penny breakage. And it is not always possible to buy accessories, especially for older models.
In many cases, electrical equipment can be restored to working order. If there are any oxidized or rusty pins on the charger they need to be scraped with a fine emery cloth. Better yet, replace the contact plates by taking them from a faulty donor charger.
For this you will need a soldering iron, solder and flux on the basis of rosin (acid-free). The same applies to damaged contacts of the battery pack.
If there is no AC voltage on the charger board then the power cord needs to be replaced. It can be taken from any other device or you can make it yourself by buying a plug and a piece of wire.
If everything is normal and the battery charger doesn’t blink or give out any voltage, then the control board is defective. You may try to repair it. For this you need some qualification and equipment (at least a multimeter and an oscilloscope). You can find the schematic diagram of the charger on the internet.
If you have an idea to use the charger of another electric screwdriver, even of the same manufacturer, you must be extremely cautious. The charger must be designed for the same voltage, deliver sufficient current, and most importantly, be designed for the same type of battery. The data on the charger and the battery should match.
The failed cells or cells with zero voltage should be unsoldered and set aside separately. If the voltage is zero, it may be assumed that the electrolyte has dried out. In this case it is necessary to drill a hole in the body of the battery and try to gradually inject about 1 milliliter of distilled water inside with a syringe. If the water is not absorbed, the cell can not be recovered.
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If it is possible to fill the internal cavity with water, then you must try to charge each defective cell (including the lagging jars) with a pulse current up to 1.2 volts. The point of the method is to charge with a current 10 times the capacity, in 2-4 second pulses. If the operation is successful, it is necessary to seal the hole in the cell body and let it sit for a few days. Then the battery has to be re-soldered and reassembled in a plastic case.
Nickel-metal hydride cells can be tried to be restored by training. Experience has shown that for batteries that have not been deeply discharged, the chances of success are high. To do this, the lagging cells must be individually discharged to 1 volt by loading them with a light bulb or resistor. Then charge to nominal again, and repeat this cycle several times.
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It is impossible to restore the capacity of a Li-ion battery, but the battery may become unusable if one or several cells are deeply discharged. In this case, the control circuit assumes that the cells are faulty, and blocks their charge. You can try to “tighten” the batteries to their rating so that the balancer does not cut them off when charging. To do this, the discharged cell (you can find it by measuring the voltage on each battery), you have to take out and assemble a simple circuit.
The voltage must be raised from zero until the current reaches about 0.2 of the battery capacity. In this mode you should charge the cell to 3,7 volt and then disconnect it and check the battery voltage for a few days. If it decreases due to self-discharge, the cell is to be discarded. If not, you can do a test charge-discharge cycle. Please remember that even if the capacity is restored, this effect is only temporary. The cell will soon be out of order, so be prepared to completely replace the battery.
Advice to charge a deeply discharged cell with high currents from a constant voltage source through a resistor looks doubtful. In this case the chance to lose the battery is higher than to recover the cell. Even more questionable is the advice to freeze the battery before charging.
If it turns out that the electric screwdriver does not charge, this problem can be solved in many cases. But the approach must be conscious, otherwise the situation will only worsen and lead to financial losses.
There are three types of batteries for the tool:
- Nickel-cadmium (NI-Cd). The older generation, which is still being used in household screwdrivers. Reasonable price, good size/capacitance ratio (quite compact), holds a charge for a long time when not working. Disadvantage. memory effect. If recharged without a full discharge, the “information” of incomplete capacity is accumulated, it prevents the charge to exhaust the real resource.
- Nickel-metal hydride (Ni-Mh). Improved analogue of the nickel-cadmium batteries with purer production technology. Memory effect, although present, is weaker. The main drawback. quickly discharged during storage.
- Li-ion. The most advanced type, which gradually replaces the other types in the professional/semi-professional electric hand tools segment. High capacity, almost no “memory”, long life, low self-discharge in storage mode. The only drawback. high cost compared to other analogs.
Important! The price of a “can” of nickel-cadmium type with the capacity of 2 Ah is about twice as much as “cans” of lithium-ion type.
As a bonus, pick up a few valuable tips, perhaps they will help you with your energy problems:
Causes of absence or weak charge level, as well as ways to fix the problem are different:
Important! The most difficult moment of the can replacement is soldering the cans into the battery. The factory uses spot welding, and when repairing “with your own hands” more often a soldering iron. During work, it is important not to overheat the battery, you must work quickly.
There is another reason for the lack of charge, but it is typical only for nickel-cadmium batteries. the memory effect is triggered, and the battery is not charged, although its resource is not exhausted yet. To avoid this, it is important to charge properly.
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