How To Convert A Screwdriver To Lithium Batteries

23rd July 2020

Accumulators and batteries What is the difference between a lithium battery and a nickel-cadmium battery. Calculation of t component schemes of alteration. Operating conditions of the lithium battery. Features of alteration of batteries and chargers from different manufacturers.

Accumulators and batteries

Energy storage information website

The meaning and procedure for converting screwdrivers to lithium batteries

Why do nickel-cadmium batteries fail quickly? In a garland of series-connected cans, each is special. The chemical process is individual, the charge in closed systems is different. In the event of a malfunction in one bank, the design does not provide the required voltage. There is no provision for monitoring and balancing the charge in individual components.

Each Ni-Cd bank provides 1.2v, and the Li-ion 18650 provides 3.6v.
The capacity of a lithium battery is 2 times that of a nickel-cadmium battery of similar size.
An overheated li-ion battery threatens an explosion and fire, therefore, the installation of control of the uniformity of the charge in the banks is mandatory. Bms is not installed in nickel-cadmium batteries. The manufacturer is not interested.
Lithium cells have no memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
The screwdriver becomes much easier after converting the battery to li-ion, using 18650 cells.

There are only two obstacles to converting a screwdriver for lithium batteries. It is impossible to work with it at minus. The capacity of cans decreases, starting from a decrease already from 10 0 C. Lithium batteries are expensive.

Knowing what input voltage is required for the screwdriver, the charger is reworked, taking into account the placement of the lithium battery cells and control elements in the factory container. You can also do with a flashlight by upgrading the socket for a block of 18650 cells.

how to convert a screwdriver to lithium batteries

Let’s say you need to rework a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 cans, the output voltage is not enough: 3.6 x 3 = 10.8 V. With 4 components, the power of the apparatus will be higher: 3.6 x 4 = 14.4 V. This will make the instrument 182 g lighter , its power will slightly increase, its capacity is solid pluses. But when dismantling, it is necessary to leave the terminals and the native thermal sensor.

Conversion of the “Hitachi” 12 V screwdriver to 18640 lithium batteries

Peculiarities of reworking the 12 V Hitachi screwdriver for lithium batteries. The very compact battery compartment is designed for finger cells. Therefore, you should prepare a place for 18650 cells. It is necessary to cut one side of the partition to fit 1 element tightly.

You need to get a flux, flat metal connecting tape, hot glue. It is necessary to install lithium batteries in a screwdriver during rework through a protective controller. It should serve 3 18650 cells, 3.7v, and rated for 20-30 amps.

Remove the old battery from the socket, carefully disconnect the contacts in the assembly with the temperature sensor and the power indicator. Clean up and sign contacts. They should be brought out to one side, connected with solder to the leads from thick wires and filled with hot melt glue over the assembly.

Assemble a power source with one of the 3 cell controllers. Build a serial circuit of 3 Li-ion cells. Connect the controller. The conversion of the 12-volt lithium battery is completed when the structure is installed in the unit, secured, and the charging indicator lights up. After fully charging, the measurements show 12.17 volts in the external network. But this is enough for trouble-free long-term operation of the device.

Preparation: selection of the necessary devices, elements

A battery pack that has lost its working qualities must be disassembled. The halves of the case can be fastened with glue and / or screws, clamps. To separate the glued seam, it is carefully tapped with a rubber mallet so that the halves of the plastic case separate from each other, but do not crack. From the opened case, the elements collected in “cassette”. The pad is carefully separated and will need to be secured to new lithium batteries.

A new Li-Ion battery for a Hitachi screwdriver requires the purchase of additional accessories, while the following circumstances must be taken into account:

New batteries should be similar in size and voltage to the old ones.
It is more advisable to choose batteries already equipped with nickel plates, so as not to waste time on soldering.
The lithium-ion battery needs a BMS board (Battery Management System). It evenly distributes energy between the banks, protects the device from sudden power outages, turns it off if the charging time is exceeded, or the batteries are almost empty. To protect against overheating, a thermal detector is connected to the board.
To connect the cassette to the pad, you need a power insulated wire of suitable thickness.

Conversion of the Hitachi screwdriver to lithium batteries

Nickel-cadmium batteries are inconvenient due to their “memory effect”, therefore, switching to lithium-ion batteries is expedient and beneficial.

How to convert a Hitachi screwdriver to lithium batteries: process description

If the cans were sold without nickel electrodes, they are soldered. It is important to do this with great care as overheating can permanently damage the battery, or even provoke its explosion. Before starting the process, it is useful to clean the soldered surfaces so that the likelihood of overheating is reduced and the connection is strong.

The batteries are connected in series, the board is connected. The power wire is soldered to the microcircuit and the contact pad. Then, using a multimeter, the voltage readings are checked: for each battery, this figure should be about 1.3 V.

Upon completion of the test, all connections are carefully insulated. The assembled cassette is carefully placed in the case, the wire is laid without kinks and creases. The halves of the case are held together.

Transferring the Hitachi screwdriver to “lithium”

At present, there are a great many different batteries, protection boards, balancing boards, chargers, etc. It was necessary to select the right one and glue it together.

So, it was decided to supply high-current Li-Ion batteries. The consumption current of different screwdrivers can reach 30A and the batteries must be able to deliver such a current. Cheap “fingers” worth 80r apiece they do not know how.

It was also decided to abandon the balancing BMS board, since all batteries were selected and were the same. By and large, at the beginning of operation it is not important.

The following pair of batteries in a collapsible case was subject to alteration:

It was necessary to collect a battery of 4 batteries. The protection board was used on the basis of 4 batteries and 20A current. I do not specifically give the link, because very soon it will be inoperative. Search for a position by keywords

All pros and cons of converting a screwdriver battery to lithium cells

First you should think about whether I need this alteration? After all, it will be an outright “self-propeller” and in some cases can lead to failure of both the battery and the screwdriver itself. Therefore, let’s consider all the pros and cons of this procedure. It is possible that after that some of you will decide to abandon the conversion of the Ni─Cd battery for a screwdriver to lithium cells.

What do you need to estimate before starting work?

Also, more lithium cells will give more capacity. This means more operating time of the screwdriver.

Lithium battery cells 18650

The nominal voltage of lithium cells is 3.6-3.7 volts, and the capacity in most cases is 2000-3000 mAh. If the battery case allows, you can take not 4, but 8 cells. Connect them two by two in 4 parallel assemblies, and then connect them in series. As a result, you will be able to increase the battery capacity. But not every case will be able to pack 8 cans of 18650.

And the last preparatory step is choosing a controller. According to its characteristics, it must correspond to the rated voltage and discharge current. That is, if you decide to assemble a 14.4 volt battery, then choose a controller with this voltage. The working discharge current is usually chosen to be two times less than the maximum permissible current.

Charge-Discharge Controller Board

The cons

Lithium battery cells cannot be charged above 4.2 volts and discharged below 2.7 volts. In real conditions, this interval is even narrower. If you go beyond these limits, the battery can be damaged. Therefore, in addition to the lithium cans themselves, you will need to connect and install a charge-discharge controller in the screwdriver;
The voltage of one Li─Ion cell is 3.6─3.7 volts, and for Ni─Cd and Ni─MH this value is 1.2 volts. That is, there are problems with assembling a battery for screwdrivers with a voltage rating of 12 volts. From three lithium cans connected in series, you can assemble a battery with a nominal value of 11.1 volts. Out of four ─ 14.8, out of five ─ 18.5 volts, and so on. Naturally, the voltage limits during charge-discharge will also be different. That is, there may be problems with the compatibility of the converted battery with a screwdriver;
In most cases, 18650 standard cans are used in the role of lithium cells for conversion. They differ in size from Ni─Cd and Ni─MH cans. In addition, you will need space for a charge-discharge controller and wires. All this will need to fit in a standard battery case of a screwdriver. Otherwise, it will be extremely inconvenient for them to work;
A cadmium battery charger may not be suitable for recharging a battery after a redesign. You may need to revise the charger or use universal chargers;
Lithium batteries lose their performance at low temperatures. This is critical for those who use a screwdriver outdoors;
The price of lithium batteries is higher than cadmium batteries.

Converting a Li-ion screwdriver for home

How to convert a battery from a screwdriver from nickel-cadmium to lithium batteries at home.

I got myself two used screwdrivers. One had a battery, the other didn’t, just the wires were brought out. I cleaned it and decided to complete it with normal batteries. I will convert it to lithium-ion.

High-current elements are needed here, they will not work from a laptop. I have used elements, with a residual capacity of a little more than 1 ampere / hour.

Battery conversion process

We disassemble the old battery and remove some of the batteries, leaving only two with a contact group.

We solder the wires to the positive and negative terminals. I soldered directly to the poles, since the contact plates did not get tinned.

We connect 18650 batteries in parallel and solder old elements with a contact group to them.

So that the contacts with the elements do not fall through, I made a support from a wooden block.

Now you need to install a connector for charging each element, a balancing connector. I used the connectors from the motherboard and the computer’s power supply.

We solder everything in order. Plus with the first contact. The second contact to the plus of the second element, and so on.

Cut a hole for the connector and fix the connector with epoxy glue. The glue is dry and we close the battery. We put it aside.

Since I will be charging the battery with a smart charger, I need to do the wiring for it. One part from the power supply, the second from the flop. We modify the connector from the flop, cutting off all the guides and keys. After removing all the keys, it fits my Turnigy just fine, it fits Imax too.

We put on the charger with a balance (3S). After the end of the charge cycle, we use it. I am working on the second battery using this technology, and everything works fine. The first screwdriver with a converted battery proved to be excellent.

Battery preparation and assembly

There are often cases when a high-quality screwdriver stops performing its functions due to a weak battery. Throwing out such a tool ЖAL-KO, it is better to perform alteration of the screwdriver battery. Nickel batteries are commonly found in low-cost equipment because of their poor performance.

Advantages of injection molded batteries:

Good current efficiency;
The power of the screwdriver does not decrease when the battery is discharged;
The product is slowly discharging;
Charging time is 1-1.5 hours;
The battery can be recharged without damage to the volume.

Injection-molded batteries have a convenient “can” shape with a diameter of 18 mm and a length of 65 mm. To screwdriver translate for a high-quality battery, high-current banks should be purchased.

For alterations of the screwdriver battery it is required to connect the molded batteries. A special battery compartment is prepared for this. You can also try soldering the devices, but this will require a weak soldering iron, since such products do not tolerate overheating. Experienced craftsmen to connect do-it-yourself molding batteries use precise welding.

It is important that all banks have the same capacity, otherwise the battery with lower rates will fail faster. To secure the system, it is recommended that injection battery circuit enable payment protection.

Conversion of a screwdriver to lithium batteries

Alteration sequence

To screwdriver translate on a molded battery, you need to disassemble the battery. It is recommended to leave the terminals from nickel devices. Any excess plastic inside the case should be removed. If there is not enough space, then the special compartment will have to be abandoned, and injection battery circuit connect by soldering. The board is glued to the top of the batteries using double-sided tape.

A thick power cable can be used as the power wire to connect the terminal block. Then a hole is made in the case to install a charging socket. The terminal block is connected in parallel to do it yourself molding battery output from the protection module. The wires are soldered vertically to the protection board.

It is important to fix the block with terminals to prevent it from slipping (you can insert a regular bamboo skewer). Then the structure is assembled, the bolts are screwed in.

It remains to check the correctness alterations of a screwdriver for injection-molded batteries on practice. For this, the battery is connected to the tool and several screws are screwed.

Then the battery is fixed to the screwdriver. If there is only one battery, then it can be safely bolted. When it is possible to change the device, then you can use ordinary chamber rubber bands.

Spare battery transportation

Spare batteries can cause a fire if not transported properly.

All types of spare batteries (such as Lithium, Nickel-Cadmium (Ni-Cad) and Alkaline) can be carried freely in your carry-on baggage provided they are properly protected against short circuits. You can prepare them for shipment as follows:

The ability to transport a lithium battery by air depends on its configuration and capacity (watts / hour) (for rechargeable lithium-ion / polymer batteries) or lithium content (for non-rechargeable lithium metal batteries). Since we only fly to airports where security checks are carried out, your belongings can be confiscated if they do not meet the requirements.

For your safety, as well as the safety of other passengers, please observe our requirements and read the detailed instructions on the carriage of lithium batteries.

For more information on portable medical devices, see the Medical Devices section.

From January 1, 2018 Smart bags with built-in lithium batteries for charging external devices or powering wheels Non-removable lithium battery bags may not be carried in carry-on baggage or checked baggage.

Smart bags of this type are not considered portable electronic devices (PEDs) and their batteries are subject to the regulations for power storage or spare lithium batteries.

When carrying a Smart Bag, you must be able to remove the battery in case the bag has to be checked in at any stage of the journey.
The removed lithium battery must be carried in your carry-on baggage in accordance with applicable regulations for carrying spare lithium batteries.

If you wish to carry a smart bag in your carry-on bag, it must have a removable battery inside the bag.
If it is impossible to remove the battery, such a bag may not be carried in carry-on baggage or checked baggage.

We recommend that passengers check the rules for carriage of batteries and smart bags with carriers operating connecting flights.