How to repair Ni-Cd, Ni-MH, Li-ion batteries of an electric screwdriver
Hi there! Today we are going to touch upon the topic of construction and summer dacha activities. I will tell you how to repair or restore the battery of an electric screwdriver with your own hands. It must be said that an electric screwdriver is a very handy thing. Charge the battery and you run around without wires, twisting here and there. Only with time such a twist knob turns less and less. This is due to the loss of capacity of the batteries. And that is what we are going to talk about.
The structural elements of an electric screwdriver
The electric screwdriver is justly considered an indispensable universal tool. The modern screwdriver market is represented by a large number of models equipped with batteries. Despite the variety of brands and modifications, all batteries have the same structure and differ only slightly from each other.
Each of them consists of separate elements connected in series with each other. All of them are made in standard sizes and have the same voltage level. Certain types of elements differ only in capacity, measured in A / h and indicated in the marking.
The tool has 4 contacts in the body that perform various functions. Including the two are power, designed for charging and discharging. In addition, there is a control contact on the top, which is included in the circuit along with a special temperature sensor. It protects the battery, cuts off the charging current and limits the charging current to a preset value by changing the temperature regime.
A fourth contact is located separately, connected together with a resistance. It is necessary when using charging stations of increased complexity, capable of equalizing the charges of all the battery cells. Such stations are rarely used in homes because of their high cost. An ordinary 12 volt electric screwdriver does not require such stations.
One of the causes of failure of an electric screwdriver is a malfunction of the battery, that is, its individual cell. In such cases, when connected in series, the entire circuit fails. Therefore, it is very important to accurately identify the faulty place. This usually occurs after the prescribed period of operation. This problem can be solved in two ways: purchase of a new battery or repair and restoration of the old battery.
Why the electric screwdriver battery does not charge. causes and remedy
There are different reasons for the lack or weakness of the charge, as well as ways to fix the problem:
- No contact between the terminals of the charger and the battery. It is a consequence of the battery plates being bent. Carefully unbend the plates, returning them to working condition.
- Oxidation of terminals or sticking of dirt on them. Contacts are cleaned and wiped with alcohol.
- One of the “cans” is out of order. Take apart the battery case by removing the cover (unscrew the screws or remove the catches). “Call each bank with a tester for voltage or discharge current. Voltage is easier. it’s either there or it’s not, but this method doesn’t always work. Discharge current is measured on the load resistor. the defective battery is an order of magnitude lower than the good-performing one. After diagnostics the defective battery is separated from the defective one and a new battery of the same type is installed in its place with the same orientation of polarity towards the rest of the cells.
Important! The most difficult moment of the can replacement is soldering the cans into the battery. In the factory they use 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 characteristic 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 the battery correctly.
How to charge the battery properly
If you buy a new tool with a nickel-cadmium or nickel-metal hydride battery, fully discharge and charge the battery three times before use (pumping). When using an electric screwdriver, do not put the battery on charge until it is completely discharged. Then pumping is repeated periodically as a preventive measure.
Important! You must have a spare battery to avoid downtime.
When Ni-Mh and Ni-Cd batteries are fully charged, they are disconnected from the mains (in the case of lithium-ion batteries, this is done by the controller). If you do not use the electric screwdriver for an extended period of time, remove the battery and store it separately from the electric screwdriver.
With careful handling, following the manufacturer’s instructions, the battery will last a long time and will not require early replacement. And minor repairs can be done with your own hands.
The battery is not charging
Electric screwdriver after prolonged use, sometimes fails. Its working element can stop charging, which will lead to inability to perform the functional abilities of the tool, the tool, roughly speaking, “dies”.
In order to prolong the life of the instrument so that it does not have to be taken out of sight, you can try three methods alternately. Each successive one is considered more complicated and costly. They are:
- restoration and increase of capacity after reversible capacity loss (memory effect);
- adding distilled water to the electrolyte;
- replacing some or all of the battery packs.
General recommendations for repair
How to repair the battery of an electric screwdriver? You should have a basic understanding of electrical engineering. The battery circuit is simple. The usual series circuit (plus is connected to the minus).
When repairing Ni-cd it is necessary to take into account the following recommendations:
- They have a memory effect. The classical scheme of input of such battery operation is 3 full charging and 3 discharging to zero. The new cell must go through the same swing.
- Similar element. To keep it from being knocked out of the circuit and breaking the battery in the first place, the new cell must be the same as the previous rating.
The lithium battery of an electric screwdriver can be repaired at home if you consider the following:
- They cannot be soldered. Intolerance to high temperatures will result in an unrepairable condition. You must use contact welding (it heats the electrode for a short time, without harming the battery). If you don’t have access to CS: GO, you can solder with a very powerful soldering iron from 100 watts. The movement must be fast and accurate.
- Identical models. Now there are several major manufacturers of lithium batteries, which are used in popular foreign models of screwdrivers, such as Hitachi, Makita and domestic: Interskol, Zubr.
General recommendations for repair
How to Repair an Electric Screwdriver Battery? You need a basic understanding of electrical engineering. Battery circuitry is simple. A normal series circuit (plus is connected to the minus).
When repairing the NiKd, the following recommendations should be taken into account:
- They have a memory effect. The classic input pattern for these batteries is 3 full charges and 3 discharges to zero. New element must undergo the same rocking.
- Same cell. To prevent it from being knocked out of circuit and breaking the battery altogether, the new cell must fully match the previous rating.
The lithium battery of an electric screwdriver can be repaired at home by considering the following:
- They cannot be soldered. Intolerance to high temperatures will result in an unrepairable condition. To do this, use contact welding (it heats the electrode for a short time without harming the battery). If you do not have access to CS: GO, soldering with a very powerful soldering iron from 100 watts is allowed. The movement must be quick and precise.
- Identical models. Now there are several major manufacturers of lithium batteries, which are used in popular foreign models of screwdrivers like Hitachi, Makita and domestic ones: Interskol, Zubr.
What you need to know before you start rebuilding a screwdriver battery?
Most batteries in power tools have the same design features (series connection of compact cells). 2. Pay attention to the type of battery (Ni-Cd, Ni-MH and Li-Ion) and capacity (in mAh). 3. When disassembling the battery pack, you need to monitor the polarity (/-) of the connections. 4. The “banks” are protected from overheating by a thermistor with a soldered resistor. 5. It is impossible to restore the battery of Li-Ion type (see below for how to determine its serviceability).
How to Repair an Electric Screwdriver Battery? The easiest way to recharge a battery is to replace one of the jars.
Find the defective cell with the low voltage. Use a tester for this.
Instructions on how to check the battery of an electric screwdriver with a multimeter:
- A typical multimeter has two probes, a red and a black one. There are two contacts (plus and minus) on opposite ends of the jar.
- The tester selection lever is set to “constant voltage” mode. If the multimeter has automatic meter reading, that’s good enough. If it is absent, it is necessary to put the lever in position “20”.
- The styli are placed on the contact pads and the voltage is measured. On the screen you can see the real voltage. If there is “-” sign before the figures, then the probes should be switched with each other.
- Each bank is checked by this algorithm.
When a broken cell is found, it is simply unsoldered and replaced. It is necessary to use a powerful soldering iron not to overheat the bank.
What you need to know before you start rebuilding a screwdriver battery?
Most of the batteries in the power tool have the same design features (series connection of the compact cells). 2. You must pay attention to the type of battery (Ni-Cd, Ni-MH and Li-Ion) and its capacity (in mAh). 3. When disassembling the battery pack, you need to keep track of the polarity (/-) connections. 4. The “banks” are protected from overheating by a thermistor with a soldered resistor. 5. It is impossible to repair a Li-Ion battery (see below for how to determine if it is working properly).
How to repair a battery for an electric screwdriver? The easiest way to revive the battery is to replace one of the jars.
Need to find the defective cell with low voltage. For this you need to use a tester.
Instructions on how to test the battery of an electric screwdriver with a multimeter:
- An ordinary multimeter has two probes. red and black. There are two contacts (plus and minus) on opposite ends of the can.
- The tester selection lever is set to “constant voltage” mode. If the multimeter has automatic selection of values. this is enough. If it is not there, you need to put the lever in the “20” position.
- The probes are applied to the contact pads and the voltage is measured. Actual voltage is shown on the screen. If there is a “-” sign in front of the numbers, then the probes need to be swapped with each other.
- Each bank is checked using this algorithm.
When a broken cell has been found, it is simply unsoldered and replaced. It is necessary to use a powerful soldering iron not to overheat the battery.
Methods for determining the faulty battery of an electric screwdriver
If you disassemble the battery case of an electric screwdriver, you can find the power cells connected in series inside. In most situations, the operating voltage of the electric motor is 18 volts, which adds up to 15 can batteries in the battery case. As a rule, no external signs of failure are found. Therefore, the master faces the task of correctly identifying the link in the existing circuit, which has lost its power capacity.
the efficiency of the entire battery will be lost even if there is even one cell in the system that has lost its capacity. However, all of the power cells can not fail. Consequently, by correctly identifying ineffective cells, they can either be replaced or used batteries can be restored to function. In other words, there are methods to revive batteries.
As a rule, two basic methods are used to unmistakably determine if a battery is faulty:
- Identifying faulty units using a tester (multimeter);
- Identification of faulty power cells in the system using a load
Let’s see how these methods work in practice.
How else can you revive battery cells
If for any reason the battery cannot be restored by replacing the defective cells, an attempt can be made to reanimate them. Only note that this is impossible with lithium-ion batteries. Only batteries with nickel-cadmium cells can be reanimated.
There are two ways to perform resuscitation:
- Use a vice, pliers or a hammer to compress the cans with the detected defect;
- make flashing of defective cans under high voltage.
What is the optimal amount of time for charging?
The recharging period is usually specified in the instruction manual of the device. In most cases the device has a special indicator that helps to understand how long you need to charge. Once charging is complete, turn it off so as not to damage the batteries. The average charging time for an electric screwdriver will be 30 minutes to seven hours. The longest period for Ni-Cd with a voltage of 1.2 V, the charging current of 250 mA is approximately seven hours.
There are also two types of battery chargers: regular and pulsed. Standard charging most often equipped with non-professional tools, the charge lasts about 3-7 hours. The pulse device is designed for professional models and can charge a battery in one hour at the most.
Tip: The electric screwdriver “Interskol” is notable for its versatility, in addition to its main function, it can also be used as a drill.
How to charge properly
After purchase and before first use, check the charge level, then proceed depending on the type.
If this model has no “memory effect”, you can charge immediately 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: can also 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 instructions);
- Ni-Mh can overheat, for this reason it is necessary to control the charging (others may also unnecessarily heat, so in the heat or in a warm room is necessary to arrange for cooling the battery);
- A charged battery must be disconnected from the charger.
- if the tool is not used, it is also better to disconnect the battery from the tool
- If the battery has been stored for a long period of time, it should be periodically recharged;
- Pay attention to the specificity of each type (Li-Ion and Ni-Mh batteries should not be discharged, whereas Ni-Cd batteries should 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 recharge quickly. at least half an hour (again, if not contrary to the instructions);
- a full charge can take up to 7-8 hours, a more precise time is indicated 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 in the order of an hour.
What to do when the battery does not charge
If the battery does not hold a charge (quickly sits down) or does not pick up the reserve of energy at all, you need to start with the identification of the cause, also based on the type of battery.
The fault may lie in the battery itself, in the charging block, as well as at the point of contact. In addition it is worth checking whether the charger is suitable for the battery.
Not enough charging time
For Ni-Cd (and to a lesser extent Ni-Mh) the capacity may drop due to the “memory effect.
To fix this, the device should be fully discharged and then fully recharged. This cycle should be repeated 2 or better all 3 times. This is usually sufficient to “jump start” the battery to almost the same values as before.
It is not charging
If the charger lamp is illuminated but the battery is either not charging or rapidly terminates, check the contacts. If there is dust or traces of oxidation they must be cleaned and wiped with alcohol.
In addition, you need to make sure that the outputs are not bent. this is a trivial, but not uncommon reason why the device does not work. If they do not reach the connector of the battery, you need to carefully bend them back (you may need to disassemble the charger).
You can also use a multimeter to check what’s coming out of the battery charger. To do this in constant voltage mode, connect the red and black probes to the outputs “” and “-” respectively. Next, you need to check the readings of the device with the values indicated on the block. If they are out of range it means that the charger needs to be repaired.
Faulty battery modules and their replacement
Separate case. failure of part of the battery. The thing is that usually the battery is assembled from the standard blocks (“cans”). And if a few lose capacity, the whole battery is degraded. For example, if the Interskol electric screwdriver battery is not charging to full capacity, it is likely that this is the cause. This method requires dexterity and skill with the soldering iron, since soldering is used to connect the elements, and too much heat can damage or explode/ignite the battery.
- Remove the cover (latches or screws);
- Use a tester to check the voltage of each cell. Usually about 1.2 V per “bank” is normal, if lower or missing, you need to restore. A more complicated option is to check the discharge current with a burden resistor. It is much lower in the faulty fragment;
- if the voltage of each block is sufficient, it is necessary to check the internal resistance level (divide the voltage by the current, subtract the load resistance), then compare the obtained value with the normal parameters of the block;
- supply a new module. it is possible to take a working one from a similar battery or use a suitable one according to the characteristics. It is important to solder it in the same orientation so that the tool can work.
An alternative option is to convert to using another type of module with similar voltage/resistance characteristics. For example, you can replace Ni-Cd with Li-Ion.
Important! Overheating a battery is dangerous. Work the soldering iron quickly and accurately.
Check connections at the same time and replace or repair wiring if necessary. The control board should also be isolated from the blocks with a cardboard gasket. To check the operation it is necessary to trace the growth of voltage as charging. Normal for an 18 battery might be 13-13.5-14 through 0.5-1-2 hours, respectively, with output at 17 volts or more by the end.
Defective electronic components
Also possible failure of some parts of the charger electronics. You can repair them only if you are confident in the soldering iron and the availability of spare parts:
- Fuse (usually 5 volts). replacement with analog, if the tester does not beep when testing;
- Capacitor. bloated (or with a resistance of 0 in constant voltage mode) blocks are replaced with similar in parameters;
- Rectifier. replace diodes (faulty diodes leak voltage in both directions);
- Choke/resistor. faulty does not beep when testing.
If the microcontroller or thermistor (refers to the primary winding of the transformer) is broken, repair is usually impractical, it is better to replace the entire device.
How to charge properly
After purchase and before first use, it is necessary to check the charge level, then proceed depending on the type of.
If this model has no “memory effect”, you can immediately charge and start working, otherwise preparation will be required:
- Ni-Cd: discharge twice or three times and then fully charge to reach full capacity, then use the standard charging procedure;
- Ni-Mh: can also be “pumped” like the previous version;
- 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 manual);
- Ni-Mh can overheat, for this reason you need to control the charging (others can also overheat, so in the heat or in a warm room it is worthwhile to arrange cooling for the battery, if necessary);
- the charged battery must be disconnected from the charger.
- if the tool is not being used, it is also better to disconnect the battery from the tool
- in case of long storage it is necessary to charge the battery periodically;
- Consider the characteristics of each type (Li-Ion and Ni-Mh must not be discharged, while Ni-Cd, 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 recharge quickly. 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 specified in the documentation of the device.
It is worth paying attention to the type of charger. In the amateur segment a simplified scheme is used, while professional models can be equipped with pulse variants. They are more “smart” and powerful, so a full charge time can be in the order of an hour.
What to do when the battery does not charge
If the battery does not hold a charge (quickly goes dead) or does not gain power reserve at all, you should start with identifying the cause, also based on the type of battery.
The problem may lie in the battery, in the charging unit, as well as in their contact. Additionally it is worth checking whether the charger is suitable for the battery.
Not enough time
For Ni-Cd (to a lesser extent also for Ni-Mh) the capacity may drop due to the “memory effect.
To fix it you need to fully discharge the device, and then conduct a full charge. This cycle should be repeated 2 or better all 3 times. As a rule, it is enough to “swing” the battery to almost the same values.
Not charging
If the LED on the charger lights up but the battery either does not charge or stops quickly the contacts should be checked. If there is dust or traces of oxidation they must be cleaned and rubbed with alcohol.
In addition, you need to make sure that the outputs are not bent. this is a trivial but not uncommon reason why the device does not work. If they do not reach the battery connector, you need to bend them back carefully (you may need to disassemble the battery charger).
Also with a multimeter you can check the output of the battery charger. To do this in constant voltage mode, connect the red and black probes to the outputs “” and “-” respectively. Then you need to check the readings of the device with the values indicated on the block. If they are out of range it means that the battery needs to be repaired.
Faulty battery modules and their replacement
A separate case is the failure of part of the battery. The thing is that usually the battery is assembled from the standard blocks (“cans”). And if a few lose capacity, the whole battery is degraded. For example, if the Interskol electric screwdriver battery is not charging to full capacity, it is likely that this is the cause. This method will require dexterity and skill with the soldering iron, since soldering is used to connect the cells, and too much heat can damage or explode/fire the battery.
- remove the cover (latches or screws);
- Use a tester to check the voltage at each element. Usually about 1.2 V per “bank” is normal, if lower or missing, you must rebuild. A more complicated option is to check the discharge current with a load resistor. In a faulty fragment it is much lower;
- if the voltage of each block is sufficient, you must check the internal resistance level (divide the voltage by the current, subtract the load resistance), then compare the obtained value with the normal parameters of the block;
- to supply a new module. you can take a working one from a similar battery or use a suitable one with similar characteristics. It is important to solder it in the same orientation so that the tool can work.
An alternative option is to convert to the use of another type of module with similar voltage/resistance characteristics. For example, you could replace Ni-Cd with Li-Ion.
It is important to! Overheating the battery is dangerous. Work the soldering iron quickly and accurately.
On the way you need to check the quality of connections. if necessary replace or restore the insulation. The control board should also be isolated from the blocks with a cardboard gasket. To check the operation of the battery, trace the increase in voltage as it is being charged. The normal value for a battery of 18 may be 13-13.5-14 through 0.5-1-2 hours respectively, going to 17 volts or more by the end.
Faulty electronic components
Also parts of the battery charger electronics may be out of order. These can only be repaired if you are sure you have a soldering iron and parts are available:
- fuse (usually 5v). replacement with analog, if the tester when testing does not beep;
- capacitor. bloated (or with a resistance of 0 in constant voltage mode) blocks are replaced by similar in parameters;
- Rectifier. replace diodes (faulty diodes leak voltage in both directions);
- Throttle/resistor. faulty when testing does not beep.
If the microcontroller or thermistor (refers to the primary winding of the transformer) is broken, repair is usually impractical, it is better to replace the entire device.