Replacing cadmium batteries with lithium in an electric screwdriver
Hand tools are divided into professional and amateur. The budget option does not involve heavy use. The units are made of plastic, the battery is nickel-cadmium. Lithium batteries are installed in a professional instrument. But the models of the previous years had an “indestructible” complete set, up to 15 cadmium cans were installed in them, which significantly made the structure heavier. If the old battery has already lost its capacity, and the new one will wear out soon, you can replace the battery using lithium cells.
What is the difference between nickel-cadmium batteries and lithium
Since the middle of the last century, the era of nickel-cadmium electrochemical cells has begun. Today, this type of salt battery is still in demand, and is superior to lithium in some respects. Due to their practicality and safety, they are used in hand tools, screwdrivers and drills. Strong points of nickel-cadmium batteries:
- low risk of overheating, since there is an endothermic reaction inside with heat absorption:
- the sealed metal case is durable, the device remains operational even at 40 0 С;
- service life up to 8 years, subject to correct operation;
- affordable cost.
The significant disadvantages of this type of energy sources are the memory effect and a long charging cycle, 12-14 hours. You can charge the battery only after the voltage is set to zero and to the eyeballs. Otherwise, the capacity will decrease.
Lithium-ion batteries belong to a new class of alkaline cells with a high charge density. They do not have a memory effect, they are charged at any residual capacity, but they are demanding to use.
Working conditions of lithium-ion batteries:
- There is a great risk of overheating and short-circuit during overcharging and in the environment at 60 0 C and above. Only lithium-iron-phosphate cells work at sub-zero temperatures.
- The case is robust, has additional protection against overheating, short-circuit and dangerous voltages.
- The capacity of a lithium battery is 2 times that of a cadmium battery, you can recharge at any time.
- The product does not tolerate overcharging, landing below 2.5V.
- Capacity decreases during operation and storage by about 3% per year.
Lithium batteries can be charged quickly in about an hour. A complete two-stage charge cycle is approximately 3 hours. Products are larger in size than cadmium ones, but they need 2.2.5 times less, the tool becomes lightweight, the working capacity is long, you can recharge at any idle.
The general class of lithium batteries includes lithium-ion and lithium-polymer. By the type of active substance used, they are subdivided:
- lithium cobalt;
- lithium manganese;
- lithium iron phosphate;
- lithium titanium.
Each type of lithium battery operates in its own parameters, has a characteristic capacity, charge, resistance. In traction batteries for forklifts, stackers and other battery technology operating in heat, battery capacity, mobility, and efficiency are important. Here, lead-acid batteries are inferior in all respects. Lithium iron phosphate batteries are used. They are not fire hazardous, work with a large minus and are not afraid of deep discharge, but not lower than 2 V.
|Capacity W / Kg
|Number of charge / discharge cycles
|Service life, years
In automotive technology, acid batteries firmly occupy a niche as a starter battery.
Accumulators and batteries
Energy storage information website
Nickel cadmium and lithium batteries for electric screwdriver
Nickel-cadmium batteries are more commonly used in screwdrivers and drills. The tool is provided with the energy of the required parameters, you can work outdoors in winter. Charging is carried out for a full cycle, in order to avoid loss of capacity.
If your hand tool is inexpensive and amateur level, it is better not to make alterations, do not change cadmium batteries to lithium ones. Do-it-yourself upgrade to a lithium battery will cost about 2,000 rubles. What’s the point in reworking if a new drill could be cheaper?
In the drill and the electric screwdriver, there is a nickel-cadmium AA battery, the lithium battery is slightly larger in size. When reworking, it is necessary to put the new elements in the nest so that they lie compactly, without backlash. In addition, you will need to include in the circuit a discharge and overcharge protection board, a balancer, use a modified or special charger.
The new battery will make the electric screwdriver more efficient. In some cases, the power of the drill will increase slightly. But for stable operation, it must be remembered that the best mode for a lithium battery is a narrow operating voltage range.
Thinking of putting a lithium-ion battery on an electric screwdriver? Take a close look at the order of work on the video.
Re-flashing the capacity of battery cells
Nickel-cadmium batteries “suffer” from one drawback called the memory effect. During the operation of the tool, the batteries can “remember” the moments of undercharging. Therefore, no matter how much such batteries are charged, they will still remain undercharged.
To remove this phenomenon, the batteries of the screwdrivers are reflashed, restoring their nominal capacity. The essence of the method is that a current is applied to the poles of the battery with a voltage three times higher than the nominal value of 1.2v.
The capacity is restored in the following order:
- The battery is disassembled into separate elements. Spot-welded nickel tape is torn off the battery poles with pliers.
- Each element suspected of having a memory effect is exposed to a powerful charger. You can use the device to charge car batteries.
- The charger is set to impulse with a voltage of 3.6 V.
- The terminals of the wires of the charger are pressed to the poles of the same name of the battery for 3-5 seconds.
- After that, the elements are tested with a multimeter. If the voltage is 1.4 V, then this means that the battery has restored its capacity and got rid of the harmful memory effect.
- The rest of the banks that did not meet the required requirements (less than 1.4 volts) are disposed of.
In the case of low battery values for screwdrivers, they need to be repaired. Proceed as follows:
- The body of the power block is separated into two parts, making the banks accessible. To do this, it is enough to remove the housing screws with a screwdriver;
Attention! Brand manufacturers make battery boxes non-separable. Home craftsmen disassemble them using a knife and screwdriver.
- A block of nickel-cadmium cans, interconnected by nickel strips by means of spot welding, is found under the housing cover;
- The purpose of the repair is to identify inoperative battery circuit elements. For this, the cans are freed from the nickel tape with the help of nippers and pliers;
- Each “keg” is checked by a tester. The voltage should be between 1.2-1.4V;
- With a low index, elements are set aside for further resuscitation;
- Rejected barrels are checked for swelling, body integrity and the absence of electrolyte drips;
- Bloated, cracked items dispose of.
- The rest of the banks can be tried to “bring back to life”.
Installing new cans in the battery box
All cells can be replaced with new batteries. But, if unusable “barrels” have been identified, and some of the elements have shown their efficiency, you can replenish the battery with only a few banks. This will allow you to get out of the situation at the lowest cost.
Additional Information. There should be no doubt what to replace the unusable banks with. They can be exchanged for exactly the same elements. Under no circumstances should nickel-cadmium cells be exchanged for lithium-ion batteries or other sized cans.
Typically, a battery prefabricated structure has two levels. The bottom row usually consists of 10-11 elements. The upper level holds two batteries or one bank. You need to form a new pyramid in the same order as the old configuration.
It is necessary to observe the same position of the poles as before. Can restore connections in two ways:
Replacing batteries in an electric screwdriver
There comes a time when the owner of a cordless screwdriver begins to notice that his tool has begun to work worse. The whole reason is that the battery is out of order. Typically, a power tool is sold with two power boxes. If one unit starts to junk, it is possible that the second battery leaves much to be desired. Replacing two batteries in a screwdriver is a rather expensive operation.
Restoration of battery performance for screwdrivers
Kegs that showed low voltage can not be replaced with new elements, but try to reanimate them. They do it like this:
- Armed with a syringe, distilled water, a screwdriver with a drill ø 0.8-1 mm.
- A hole is drilled in the upper part of the battery case.
- Distilled water is drawn into the syringe and, using a needle, it is slowly introduced into the hole on the body.
Important! If electrolyte flows towards the battery when water is introduced into the battery case, the battery is thrown away. This recovery method is only suitable for dry batteries.
- If after 30 minutes the multimeter shows an increase in the voltage value, then the battery will be able to serve for quite a long time.
- The hole is sealed with epoxy.
- The battery is inserted into the socket of the charger and the voltage is brought to the nominal value.
For soldering nickel-cadmium batteries, it is best to use an induction soldering station. The soldering iron tip is made of copper coated with a ferromagnetic alloy. Due to the inductive nature of the electrical impulse, the sting of the device does not overheat. This is important because battery banks do not tolerate high temperatures. The electrolyte can boil and the cell can simply explode. The soldering process proceeds as follows:
- For the convenience of soldering, the batteries will need to be fixed in the desired position. You can put a rubber ring on them or wrap them with threads.
- The nickel strip is cut into the required lengths. If one is not at hand, the tape can be cut from a simple tin can.
- Prepare solder, flux and tip cleaner from brass shavings.
- First, the flux is applied with a sting to the back of the nickel strip and the top pad of the battery. Then both sides tinker.
- Press the tape to the jar and heat it from above with a soldering iron tip. After setting, the soldering proceeds to the soldering of the next element.
- It is recommended to press a metal rod (thick hardware or similar material) near the junction during soldering. This will create heat dissipation and prevent the battery from overheating.
- The battery repair block is again enclosed in the battery casing, fastening its parts with screws.
Failure of power units occurs when screwdrivers are often used as a drill. Active overload can cause the electrolyte to boil inside the batteries. This is fraught with swelling of their bodies and leakage of electrolyte.
In order not to recklessly spend on purchasing new batteries, you need to diagnose old batteries. Everything can be done only by repairing the charging elements. The battery is checked in this order:
- The battery is connected to the charger.
- After half an hour, the voltage is measured. The voltage is usually 13 volts. After 2 hours, the voltage at the battery terminals will be 14V. Finally the battery will show 17v.
- If, after 60 minutes after the start of the charging process, the current strength is 1 A or more, then the battery is fully functional.
- Next, check the battery under load. Usually they connect a 40-watt lamp or take a 12-volt light bulb for a 35-watt car headlight.
- If after three minutes the voltage at the box terminals is less than 12.4 V, then one of the cans or several pieces at once requires replacement.
Successful soldering of can joints is available to experienced craftsmen. To avoid setbacks, it is better to use spot welding. Such a device can be assembled by hand or use the services of a workshop.
VOTO 12 Volt Lithium-ion Battery Cordless Screwdriver. Battery Replacement
A feature of resistance welding is that the connection of metal elements occurs on an area of 2-3 mm2 within milliseconds. The metal at the junction melts under the influence of a high-power electric current pulse. The heating zone does not expand beyond the contact.
Welding a nickel strip with a nickel-cadmium battery is as follows:
- Two copper electrodes with a gap of 2 mm between them are pressed against a metal strip laid on the pole of the battery barrel.
- Press the button to turn on the supply of a current pulse.
- During the time of passage of current (40 mlsec), metal parts are welded.
- After that, the next battery covered with a nickel plate is pushed under the electrodes. The welding process is repeated.
- By sequential transition from the negative area of one element to the positive terminal of the next can, the entire battery is welded.
- A block of battery cans is welded to the output terminals of the power housing.
- The parts of the casing are connected with screws using a screwdriver.
The above gives an idea of how it is possible to restore the working capacity of the battery with the help of repair and replacement of batteries, so that the screwdriver can fully function. If it is not possible to do this work at home, then the workshop will always come to the rescue.
Putting together a lithium-ion battery
Here are the new elements of Sanyo UR18650NSX (according to this article they can be found on Aliexpress) with a capacity of 2600 mAh. For comparison, the old battery had a capacity of only 1300 mAh, half the size.
It is necessary to solder the wires to the elements. The wires must be taken with a cross section of at least 0.75 sq. Mm, because we will have considerable currents. A wire with such a cross section normally works with currents of more than 20 A at a voltage of 12 V. You can solder lithium-ion cans, short-term overheating will not harm them in any way, this has been verified. But you need a good fast-acting flux. I use TAGS glycerin flux. Half a second. and you’re done.
We solder the other ends of the wires to the board according to the diagram.
I always put even thicker wires of 1.5 sq. Mm on the battery contacts. because the space allows. Before soldering them to the mating contacts, I put a piece of heat-shrinkable tube on the board. It is necessary for additional isolation of the board from battery cells. Otherwise, the sharp edges of the solder can easily rub or puncture the thin film of the lithium-ion cell and cause a short. It is possible not to use heat shrinkage, but at least something insulating to be laid between the board and the elements is absolutely necessary.
The contact part can be fixed in the battery case with a couple of droplets of super glue.
USB & Li-ion Upgrading dead Black & Decker Screwdriver. 892
It’s good when the case is on screws, but this is not my case, so I just glue the halves again with “Moment”.
The battery is charged with a standard charger. True, the algorithm of work is changing.
I have two chargers, DC9710 and DC1414 T. And they work differently now, so I’ll tell you exactly how.
Replacing the battery in an electric screwdriver with lithium batteries
The inevitable has come. the batteries in my old Hitachi DS 12DVF3 are completely dead. They have become disgusting to hold a charge for a very long time, but the available capacity was enough for small household needs, so I never thought about solving this problem. Until the moment when I needed to drill a hole in a stainless steel kitchen sink, which took me forty minutes! One hole! One battery could not be swung at all, while the other did not work, twists for twenty seconds, charges for about ten minutes. It was then that I realized that it was time to give a new life to my favorite instrument. It is clear that first it was necessary to familiarize myself with the theory a little in order to understand what in general I have to do. Of course, this topic is not at all new and everyone who is not lazy is engaged in the translation of screwdrivers into lithium. But each does it in his own way, depending on his education, the amount of laziness and the concept of beauty. I needed everything to be done absolutely correctly from the technical point of view, so that it did not look scary from the outside and that the batteries could be conveniently used. After re-reading and reviewing a huge amount of material, I took a project from AlexGyver as a basis.
Here you need to carefully break off the upper contact pad, it will be needed later. You will also need nickel jumpers to solder the second unit to the batteries, so I move this stuff aside for now. Next, I try on new components in order to understand the front of the upcoming work.
Makita DC9710 charger and lithium-ion battery
Previously, the battery was controlled by the device itself. When the full level was reached, it stopped the process and signaled the completion of charging with a green indicator. But now the BMS circuit we have installed is engaged in level control and power off. Therefore, when charging is complete, the red LED on the charger will simply turn off.
If you have such an old device, you are in luck. Because everything is simple with him. The diode is on. charging is in progress. Off. charging completed, battery fully charged.
Wiring diagram for converting an electric screwdriver for Li-Ion batteries
Before replacing batteries in an electric screwdriver, it is recommended to prepare the correct assembly diagram. To exclude the failure of any components, it is necessary to accurately observe the polarity of the connection.
Important! When drawing up a diagram, it is recommended to mark the positive polarity on it in red, and negative polarity in blue.
Power supply for charging
For lithium-ion batteries, the chargers are selected based on the number of batteries connected in series in the battery. The more there are, the more the output voltage should be.
How does the battery voltage affect the operating time of an electric screwdriver
The question of how the battery voltage affects the duration of the product is of interest to many. To understand what power the product has, you need to multiply the voltage by the battery capacity.
For reference! For example, an electric screwdriver with a 14.4 V battery and 1.5 A / h will have a power of 21.6 W.
How to change batteries in an electric screwdriver with your own hands
an electric screwdriver is one of those tools that every man needs. The device can operate both from the mains and from special chargers. Therefore, it is recommended that every owner of such a product know how the batteries are replaced in an electric screwdriver. The process is simple, but some models may have certain features.
For each product, the number of cans in the battery may be different
Lithium battery capacity indicator
Indicators are LED and digital. The latter are cheaper, but not convenient to use. Better to choose LED options based on the number of batteries connected in series.
The technology of replacing Ni-Cd with Li-ion in an electric screwdriver
Lithium cells are durable, so many screwdriver owners think about replacing nickel-cadmium products with them.
The replacement technology includes several steps that must be followed.
How can you replace the “native” battery in an electric screwdriver
If the batteries in your electric screwdriver are worn out, they can be easily replaced. There is such a thing as battery interchangeability. For example, under the PowerPlant brand, batteries are produced that are compatible with most popular brands of power tools. They cost much less than the “native” batteries and are quite efficient.
But if this option does not suit you, then the batteries themselves in the unit can be replaced with new ones. To do this, you will have to disassemble the battery pack and remove the elements that make up it.
Which battery for an electric screwdriver is better to choose
The cordless electric screwdriver is a rather convenient and demanded tool. The independence of the power supply makes this device mobile and allows you to work in hard-to-reach places. But despite all the advantages, the rechargeable battery (AKB) is the weak link in an electric screwdriver. Therefore, when choosing a power tool, you first need to understand what types of batteries exist, what is their difference, the pros and cons of different types of batteries.
Nickel metal hydride batteries
NiMH batteries have been designed to overcome the disadvantages of nickel-cadmium batteries. The positive characteristics of NiMH batteries are as follows:
- have smaller dimensions and weight;
- have low toxicity;
- The “memory effect” is poorly expressed;
- have high capacitive characteristics;
- resistant to mechanical damage;
- increased number of charge-discharge cycles (up to 1500).
However, NiMH batteries have their drawbacks:
- it is forbidden to use them at negative ambient temperatures;
- The battery tends to discharge quickly;
- shorter battery life when compared to nickel-cadmium batteries;
- high price;
- takes a long time to charge;
- The battery does not “tolerate” deep discharge.
Thus, although NiMH batteries were designed to compete with nickel-cadmium batteries, they are significantly inferior in performance to the latter.
This type of battery is the most common, although it is over 100 years old. NiCd batteries have good capacity and low cost.
Nickel-cadmium batteries have the following advantages.
- Durability. With proper operation, the battery can last 8-10 years.
- Ability to work at low temperatures. The battery power is practically not reduced, which allows using the tool in the winter outdoors.
- High degree of reliability and unpretentiousness to working conditions.
- The battery can withstand a thousand charge-discharge cycles.
- The battery can be stored for a long time in a discharged state.
Since NiCd batteries are not “afraid” of full discharge, you can work with the tool until it stops completely, that is, until the battery is deeply discharged. Only then can you put it on charge, without fear that the battery capacity will decrease.
However, nickel-cadmium batteries are not without their drawbacks. Toxicity of internal battery filling causes disposal problems.
In some European countries, the operation of nickel-cadmium batteries is prohibited in order to preserve the environment.
Batteries of this type are quite heavy when compared to other types of batteries. In addition, they have a “memory effect”. This phenomenon occurs in a nickel-cadmium battery when it is prevented from fully discharging. If you turn on such a battery for recharging, then it will “remember” this value and during further work it will be discharged exactly to this mark. This will lose a significant portion of the battery’s capacity. The figure below clearly demonstrates how the “memory effect” appears.
Varieties of batteries for an electric screwdriver
There are 3 types of rechargeable batteries on the power tool market:
- (NiCd) nickel-cadmium;
- (NiMH) nickel metal hydride;
- (Li-Ion) lithium-ion.
Li-Ion batteries significantly outperform other types of batteries. The advantages of lithium-ion batteries include the following:
- almost complete absence of the “memory effect”;
- You can recharge the lithium-ion battery at any stage of discharge, without fear of loss of capacity;
- no power loss at low battery charge;
- the effective service life is 5-8 years;
- low self-discharge;
- takes little time to charge;
- there are no toxic elements;
- high power with small dimensions.
- sensitivity to impacts (may explode with strong impacts);
- the battery does not tolerate full discharge and overcharge. this causes the battery to fail;
- discharges quickly at low temperatures;
- high price;
- service life is lower than that of nickel-cadmium batteries.
It is difficult to say unequivocally which battery is better. Basically, you must decide for what purpose you are going to purchase an electric screwdriver. If for home use, which implies infrequent switching on with long interruptions in work, then you need to choose a tool with a nickel-cadmium battery.
This can be explained by the fact that during long-term storage without recharging the NiCd battery does not lose its properties, provided that it has been completely discharged.
Lithium-ion batteries are the professional choice. They are designed for continuous, long-term and uninterrupted operation. The recharge time of the battery is also important for a professional tool. But it’s worth remembering one rule: a lithium battery cannot be brought to full discharge.
Replacement with lithium batteries
Replacing NiCd cells with Li-Ion is also not difficult. It is known from the school course that if the batteries are connected in series, then their voltage ratings will be summed up. For example, your electric screwdriver runs on a battery with a voltage of 14.4 V, which means that it can be replaced with four 3.3 V finger batteries. This voltage will be enough, because the lithium batteries do not “sag” too much when starting the device.
It is recommended to buy batteries from well-known manufacturers, for example, Sistem A123. The LiFePO4 battery of this company has a capacity of 2400 mAh, sufficient for the normal functioning of an electric screwdriver. If you buy batteries via the Internet, then they will cost you less. around 900 rubles for 3 pieces.
When buying batteries, pay attention to whether there are copper strips on their contacts. If they are, then the soldering process is much easier.
You will also need to purchase soldering acid instead of alcohol flux. In this case, overheating of the batteries will be minimized. The soldering iron must have a power within 65W.
You can learn more about how batteries are replaced with lithium batteries by watching this video.
Replacing batteries with similar ones
On some units, you can see the mounting screws that need to be removed. But on most battery packs there are no self-tapping screws, since the body is glued together. To open such a block, you will need to carefully insert a screwdriver into the gluing place (shown by an arrow in the photo) and press lightly so that the walls of the case are detached. The same actions need to be done around the entire perimeter.
After opening the block, you will see the batteries in it.
- You need to solder quickly, not allowing the battery to heat up, as it may become unusable.
- For connections, you need to use the “native” plates, desoldering them from the old batteries (they have the desired cross-section and resistance).
- It is important to correctly connect the plus and minus of the battery. The elements must be connected in series: the minus of the previous battery must be connected to the plus of the new one, and the minus of the new battery to the plus contact of the next battery.
After connecting all the elements, it is necessary to equalize the potentials on all batteries, since they are different. Carry out one charge-discharge cycle: connect the charger to the battery overnight, then let it cool down for a day and measure the output voltage in turn on all the cells. If everything went well, then on all batteries the indicator will be the same. within 1.3 V.
Now the battery needs to be discharged by inserting it into an electric screwdriver and loading the latter to the maximum. The main thing is not to overheat the engine of the tool. Give him a little rest. Bring the battery to full discharge. Repeat this procedure 2 more times (full charge and full discharge).
Difficulties in rework
There are objective disadvantages in Li-Ion batteries, such as poor performance at low temperatures. In addition, when converting an electric screwdriver to lithium 18650 batteries, a number of difficulties can be encountered:
- The 18650 standard means that a single cell has a diameter of 18 mm and a length of 65 mm. These dimensions do not match the dimensions of the nickel-cadmium or nickel-metal hydride cells previously installed in an electric screwdriver. Replacing batteries will require placing them in a standard battery case, plus the installation of a protective microcircuit and connecting wires;
- The voltage at the output of the lithium cells is 3.6 V, and on the nickel-cadmium cells. 1.2 V. Let’s say the nominal voltage of the old battery is 12 V. This voltage cannot be ensured when Li-Ion cells are connected in series. The range of voltage fluctuations during the charge-discharge cycles of the ion battery also changes. Accordingly, converted batteries may not be compatible with an electric screwdriver;
- Ionic batteries differ in the specifics of their work. They do not withstand overcharging voltage more than 4.2 V and discharge less than 2.7 V until they fail. Therefore, when a battery is being reworked, a protective board must be installed in an electric screwdriver;
- An existing charger may not be used for an electric screwdriver with a Li-Ion battery. You will also need to redo it or purchase another.
Important! If the drill or electric screwdriver is cheap and not of very high quality, then it is better not to rework. This can cost more than the cost of the tool itself.
Tips for choosing a security chip
The lithium ion battery of the electric screwdriver cannot function normally without the BMS protection board. Instances on sale have different parameters. BMS 3S marking assumes, for example, that the board is designed for 3 elements.
What you need to pay attention to in order to choose a suitable microcircuit:
- The presence of balancing to ensure the uniformity of the charge of the cells. If it is present, the value of the balancing current should be in the description of the technical data;
- The maximum value of the operating current withstood for a long time. On average, you need to focus on 20-30 A. But this depends on the power of the electric screwdriver. Low-power enough 20 A, powerful. from 30 A;
- Voltage, upon reaching which the batteries are disconnected when overcharging (about 4.3 V);
- Voltage at which the electric screwdriver turns off. It is necessary to select this value based on the technical parameters of the battery cell (the minimum voltage is about 2.6 V);
- Overload protection operation current;
- Resistance of transistor elements (minimum value selected).
Important! The magnitude of the overload tripping current is not very important. This value is offset from the workload current. In case of short-term overloads, even if the tool has turned off, you must release the start button, and then you can continue to work.
Connection diagram of elements with a protective board
Whether the controller has an autorun function can be determined by the presence of an “Automatic recovery” entry in the technical data. If there is no such function, then in order to restart the electric screwdriver after the protection is triggered, it will be necessary to remove the battery and connect it to the charger.
The advantages of lithium-ion batteries
Nickel-cadmium batteries have a low price, withstand many charging cycles, and are not afraid of low temperatures. But the capacity of the battery will decrease if you put it on charge without waiting for a full discharge (memory effect).
Lithium-ion batteries offer the following benefits:
- high capacity, which will provide a longer operating time for the electric screwdriver;
- smaller size and weight;
- keeps charge well when inoperative.
But a lithium battery for an electric screwdriver does not withstand a full discharge, so factory tools on such batteries are equipped with additional boards that protect the battery from overheating, short-circuit, overcharge in order to avoid an explosion, a complete discharge. When the microcircuit is inserted directly into the battery, the circuit is opened if the unused battery is separated from the tool.
12 V batteries are often used for screwdrivers. Factors to consider when choosing a Li-Ion battery for an electric screwdriver:
- In such instruments, elements with high values of the discharge current are used;
- In many cases, the cell capacity is inversely related to the discharge current, so it cannot be selected based on capacity alone. The main indicator is the current. The value of the operating current of an electric screwdriver can be found in the instrument’s passport. Usually it is from 15 to 30-40 A;
- It is not recommended to use cells with different capacities when replacing the battery of an electric screwdriver with a Li-Ion 18650;
- Sometimes there are tips to use a lithium battery from an old laptop. This is absolutely unacceptable. They are designed for a much lower discharge current and have inappropriate technical characteristics;
- The number of elements is calculated based on the approximate ratio. 1 Li-Ion to 3 Ni-Cd. For a 12-volt battery, you will need to install 3 new ones to replace 10 old cans. The voltage level will be slightly reduced, but if 4 cells are installed, the overvoltage will shorten the life of the motor.
Important! Before assembly, it is necessary to fully charge all elements to equalize.
Disassembling the battery case
The body is often assembled on self-tapping screws, other options are assembled with latches or glue. The glued block is the most difficult to disassemble, you have to use a special hammer with a plastic head so as not to damage the parts of the case. Everything is removed from the inside. You can reapply only the contact plates or the entire terminal assembly for connecting to the tool, charger.
Conversion of an electric screwdriver to lithium batteries 18650
The industry has been making screwdrivers for a long time, and many people have older models with nickel-cadmium and nickel-metal hydride batteries. Converting an electric screwdriver to lithium will improve the performance of the device without buying a new tool. Now many companies offer services for altering batteries for an electric screwdriver, but you can do it yourself.
Conversion of an electric screwdriver to lithium batteries
Further battery replacement consists of the following steps:
- The disassembled parts of the case are well cleaned;
- Since the dimensions of the new battery cells will be smaller, they must be securely fixed: glued to the inner wall of the case with Moment glue or sealant;
- The positive and negative wires are soldered to the old terminal block, it is placed in the same place in the case and fixed. The protective board is laid, the parts of the battery pack are connected. If they were previously glued, then “Moment” is used again.