Conversion of an electric screwdriver to lithium batteries 12v hitachi

How to transfer an electric screwdriver to lithium (li-ion) batteries with their own hands

How to convert an electric screwdriver from old nickel cadmium batteries to lithium ones at home.

Hello to all lovers of making things with their own hands! Today almost everyone has a cordless electric screwdriver, and even more than one. In today’s article I want to show how you can with your own hands transfer an electric screwdriver to lithium batteries.

Most electric screwdrivers have nickel cadmium batteries, but they don’t have a very long life and are very finicky about charging.е. they can not be charged until they run out of power, because they have a memory effect and their capacity will diminish. Just the price of the original batteries is also quite high.

This screwdriver is 4 years old. I won it on this site by entering one of the contests. I would like to take this opportunity to thank the site useful DIY and in particular the administrator Alexander for such a wonderful prize! Good luck and prosperity to this site.

As I said before, this screwdriver is 4 years old and yet its battery is starting to give up. The charge lasts for a very short time, and even with itself from the idle time it sits down. But I think that 4 years is a long time for such batteries.

Peculiarities of choosing lithium batteries

When choosing a Li-ion cell, you should pay attention to the number of available cycles of discharging and charging. The latest models have a capacity of discharging up to 600 times. When choosing, you need to consider that the higher the capacity, the longer the tool will be able to work. If you install a higher capacity battery on a weak model, the electric screwdriver will fail faster. A 12 V battery on a tool that is designed for 18 V will limit its power. That’s why the battery voltage has to be exactly the same as on the electric screwdriver.

Hitachi electric screwdriver conversion to lithium batteries

Nickel-cadmium batteries are uncomfortable because of their “memory effect”, so switching to lithium-ion batteries is advisable and beneficial.

Preparation: selection of the necessary devices, elements

A battery pack that has lost its performance must be disassembled. The halves of the case can be fastened together with glue and/or screws, fixing devices. To separate the glued seam it is carefully tapped with a rubber mallet, so that the halves of the plastic housing are separated from each other, but not cracked. The elements, assembled in a “cassette”, are removed from the opened case. The contact pad is carefully separated, it will need to be attached to the new lithium batteries.

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

• New batteries should be similar to the old ones in size and voltage.
• It is advisable to choose batteries already equipped with nickel plates to avoid time-consuming soldering.
• A Li-ion battery needs a BMS board (Battery Management System). It evenly distributes power between the banks, protects the device from sudden voltage glitches, shuts it down if the charging time is exceeded, or the batteries are discharged to almost zero. Temperature detector is connected to the board for overheat protection.
• A power insulated wire of suitable thickness will be required to connect the cassette to the contact pad.

Instructions for setting up the charger

Everything fits the snaggy description)). Works perfectly. I will use it to charge my converted electric screwdriver. Arrived in Samara in 25 days. For those who can’t figure out how the LEDs work, I found a great description:

The upper one lights up as long as the inverter is able to deliver the set current to the load (in the case of using it as a charger it turns out to be a CC phase indicator, as soon as it goes out. CV phase) the middle LED lights up until the current in the load drops to 0.1 set, extinguished. the charge is finished.

The value is 0.1 is set by default, if you want it can be corrected either more (charging faster, less capacity) or less (charging time increases, the battery is charged more fully) with the middle potentiometer. But the charging continues even after switching off, this is only an indication that the battery is in principle charged and ready for use. Lower LED. just a converter operation indicator.

charge. this LED lights up as long as the current in the output circuit is above the set value. This value is set in relation to the maximum current. at setting a big maximal current (units of ampere) it might not be possible to set the indication of a small current (units and tens of milliampere).

Choice of chemistry type of lithium batteries

The first thing to do is to decide on the type of lithium battery chemistry. There are two options here, either lithium iron phosphate (LiFePO4) or lithium ion (Li-ion). But in any case when working with such a powerful load you need to consider that the battery should be able to give the necessary current without harming your health! Let us briefly outline the special features of these battery types.

Operating Temperature

If you intend to use the electric screwdriver in sub-zero temperatures, it is better to choose lithium iron phosphate (LiFePO4) batteries. Temperature range at which they can be discharged.20

65 °С. The capacity of a Li-ion battery drops quickly in freezing temperatures. If you plan to work mainly at temperatures above zero, then both types are suitable. But both types of batteries (except for some LiFePO4 models) must not be charged at negative temperatures. And the upper limit of the temperature when charging at those and other about 60 ° C.

Dimensions and weight

With the same capacity, LiFePO4 batteries are almost one and a half times heavier and more voluminous than Li-ion.

Longevity

Number of full charge/discharge cycles of LiFePO4 batteries is more than 1000, for Li-ion less than 500. But! If not to 0% discharge and not to 100% charge, the number of cycles increases significantly. Storage any lithium batteries do best when half charged at 0 10°C. Read more about storage in this article.

Operating voltage

One cell of Li-ion battery at 100% charge has a voltage of 4.2 V, at full discharge about 3 2.5 V. Average operating voltage of 3.7 V.

One cell of LiFePO4 battery at 100% charge has a voltage of 3,6 V, at full discharge about 2 V. Average working voltage 3.2 V.

On this basis we consider the number of cells connected in series to get the necessary voltage at the battery output. It is customary to denote this by the number of cells in series symbol S (serial serial). Voltages are summed up in this connection.

Li-ion: 1S-4.2V, 2S-8.4V, 3S-12.6V, 4S-16.8V, 5S-21V

LiFePO4: 1S-3.6V, 2S-7.2V, 3S-10.8V, 4S-14.4V, 5S-18V

That is, for example, for a 12 volt electric screwdriver needs a battery Li-ion 3S, or LiFePO4 4S.

Нестандартная переделка Hitachi на литий-ион!

Operating Current

The battery specifications usually indicate the nominal and maximum (peak) discharge current. At rated current it is capable of working for a long time, and at peak current for a few seconds. Therefore, for such a powerful load as an electric screwdriver, you should pay attention to this indicator and choose high-current battery models.

When idling, a 12 volt electric screwdriver of average power consumes a current of 1-2 A, and at maximum load (especially in the braked state), the current can reach 30 A. Therefore, if you intend to use, for example, a GTF HG2 18650 3000 mAh battery with a rated and peak current of 10A and 25A, respectively, you must do a minimum 3S2P assembly so as not to overload the batteries. Parallel connection of two batteries doubles the allowable currents, connection of three triples it, etc.д.

Converting an electric screwdriver to lithium batteries

Over time, the original nickel-cadmium batteries of an electric screwdriver lose their capacity, the charge is enough for a couple of screws, and the charge takes a couple of minutes. If faced with such a problem, the first thing that comes to mind is to buy a new battery or an electric screwdriver. But it is possible to give a second life to a screwdriver and convert it to a lithium battery (of course, if the electric screwdriver is not killed and appropriate). As an example, I will use an electric screwdriver Soyuzmash ASH-14M with a voltage of 12 V.

Necessary details: Electric screwdriver Soyuzmash ASh-14M x 1 pc; Battery LiitoKala HG2, 18650, 3000 mAh x 3 pcs; BMS 3S, 40A, 12.6V with balancing x 1 pc; XL4015 voltage reducing converter x 1 pc; 1.5 mm wire (black, red) 20 cm.

Disassembly of the case:In my case, the battery case is fastened with screws, also there is a variant with latches or glue. The most difficult thing to disassemble with a glued block, for disassembly use a special hammer with a plastic base. All removed from the inside of the battery pack, we need only the contact plates to connect the screwdriver and charging station.

Battery choice: Electric screwdriver ASh-14M is designed to work with 14 V batteries, so I will use three lithium-ion batteries with a total voltage of 12.6 V, of course you can use four batteries and raise the voltage to 16.8, but then you will need to use a separate power supply, as well as high voltage reduce the life of an electric screwdriver. Not all batteries will be suitable for battery conversion, so you need to consider several factors:

It is not recommended to use batteries with different capacities; you should not choose batteries only by capacity, the main parameter is the discharge current. Some recommend using lithium batteries from old laptops, this is not correct, they are designed to work with a lower discharge current.

In this article I use LiitoKala HG2 batteries, type 18650 size, 3000 mAh capacity and a discharge current of 30A, come already with soldered tails and without, in my case without, for convenience I advise to buy with tails

Choice of BMS board: You can not use a lithium ion battery without a BMS board. There are different numbers on the market with different parameters. The BMS 3S marking indicates that the board is designed for three batteries. The BMS 3S designation suggests, for example, that the board is designed for 3 cells. What you need to pay attention to:

The balancing ensures that the batteries are charged evenly. Maximum long-term operating current.

In this article I use a BMS 3S, 40A, 12.6V with balancing, it is well-proven.

Battery modification (assembling): I use batteries without soldered tails so I will solder the wires directly to the contacts. I use a 60W soldering iron or a big one to avoid overheating the battery.

Attention! Do not overheat the battery in any case.

Take acid, solder and tin both sides of the battery terminals and solder the wires, instead of wires you can use the lithium nickel strip that you can buy or take from an old battery. In my case I use a wire 1 square meter thick, because the place will not allow to place the battery evenly and the tape will not reach. After all the wires are soldered, we take all the batteries and solder them together with duct tape. Various battery holders are now available.

Now according to the circuit, solder each battery output in series from 0 to 12.6, so at first we solder to 0, then 4,2, then 8,4, then 12,6 to the BMS 3S board

Then we solder the wires with the cross section of not less than 1,5 square meters to the contact plates and fix them in the battery case with hot melt adhesive. Some people leave two old batteries to keep the contact strip in place.

Solder the wires from the contact plates to the board BMS observing polarity and in reverse order of assembling the battery case and everything is ready.

Adaptation of the charger: The electric screwdriver Soyuzmash ASh-14M, comes with a charger, but it is designed to charge the nickel-cadmium batteries to charge the lithium-ion battery needs to finalize it. Of course, some people use the chargers without modification, but it’s not right.

Revision is that you need to add a board to reduce the voltage and limit current, well proven board on the chip XL4015.

I don’t see the point in describing the modification because for each charger is different, but the essence is that you need to cut a couple of tracks on the charger board and the output circuit transformer soldered to the input with XL4015. Next, you need to set the voltage 12.6 V, in my case 3S or 16.8 V for 4S and set the current to 1A, if the current is higher, charging will go faster, but the batteries will fail quickly, if less charging will take longer.

Who does not want to deal with the remaking, you can buy a ready-made charger with a charging indicator.

Optional: optional indicator can be added, to display the battery charging level. Of course I could convert my electric screwdriver to 16.8V (4S), but I had to stay within budget.

Buy on Aliexpress Battery LiitoKala HG2, 18650, 3000 mAh BMS 3S, 40A, 12.6V with balancing XL4015 step-down voltage converter

Buy in Samara and the region Battery LiitoKala HG2, 18650, 3000 mAh BMS 3S, 40A, 12.6V with balancing XL4015 voltage reducing converter

The first version of the battery.

I started by buying this BMS 4S 40a on ali, with a balancer. Cost about 140r. At that time I had Sanyo batteries, bought new, but they were half-charged and stored in the fridge for about 2 years (I just bought them as flashlights, and then suddenly got some batteries from laptops). Residual capacity was 2Ah. (new 2.4). I put the batteries in a holder with good contacts, wired everything with a thick wire 1,5 mm and in this condition began to use.

Then I also made a battery charge indicator on a board like this. The board is very handy! It’s thin so it fits nicely into the battery compartment. To make the diodes shine through the red plastic better, I soldered the diodes on the board and put the red body ones to spread them wider (it was like one big spot of light).

At the bottom of the battery compartment made a flat button, which is not pressed accidentally, but very comfortable to feel with your finger. That’s what turns on the display board.

In this form, I worked with the screwdriver about six months. The protection circuit board tripped and shut down the motor when overloaded. But after a while I got fed up with it. Batteries had to be kept constantly charged, or when half-charged, overload alarms simply prevented normal operation. So I decided to redo the whole thing.

Converting EB1414S battery of DS14DVF3 electric screwdriver to Li-Ion and decreasing current in Hitachi UC18YG battery charger

Мodifying the EB1414S battery of the Hitachi DS14DVF3 electric screwdriver into Li-Ion lithium batteries and, respectively, transforming it into Li-Ion one and decreasing the current in the Hitachi UC18YG charger.

We remove the Ni-Cd batteries from EB-1414S box and solder the rechargeable 18650 Li-Ion batteries (5 pcs x 4.2V = 21V).

Why 21V and not like Ni-Cd 12pcs x 1.44V=17.28V and need to put about 4pcs Li-Ion x 4.2V = 16.8V max? Because the quality of the circuit and the screwdriver motor is high, and it keeps perfectly well the voltage raised by 21%, and power respectively by 47%, moreover, the starting current is limited by the circuit and the regulator turns (the button when lightly pressing it gives a slow speed, and with a strong high).

and change the regulator ZD2 for BZX55C20 (for 20V), and change variable resistor VR1 (there is one with yellow “cross” knob) for constant 300 kOhm, as a result the charger will charge the battery with 400mA current, showing charge up to 21V by red LED (up to 21V it to charge battery with low current, like Li-Ion needs).

After the conversion check the voltage at the terminals of the battery charger without the battery, it is 20.6 21.0 V (jumps once per second). If the voltage is higher than 21V it is better to pick up the ZD2 regulator for a little lower voltage. When installing a dead battery, check charging current on R15 resistor 0.1 Ohm (measuring for current), with a charging current of 0.4A the voltage on it will be 40 millivolts (0.04V).

• Li-Ion battery is twice as light as Ni-Cd and more powerful spinning, at 47%.
• Capacity. If you usually have Ni-Cd 1500mAh work one day, then with the same Li-Ion 2200mAh will work a day and a half.
• The result of charging with a small current of 0.4A Li-Ion battery life will be 4-5 years, which is twice as long as it was on the former native 2.6A accelerated charge Ni-Cd (2-3 years) overheat cutoff! of the battery every time you charge it.
• The red indicator at the end of the charge does not go out, and the charger itself is warm enough from the bottom, even without a battery (in standby mode, it is better not to leave it on, so that it does not eat electricity).
• Longer charging time of 2200mAh Li-Ion battery, current 0.4A for about 6 hours.
• Of course, Li-Ion batteries lose their ability to work much faster and harder than Ni-Cd batteries, but the cost of new Ni-Cd 1500mAh batteries is higher than the price of rewiring.
• The battery circuit does not have a balancer for lithium batteries so that there is no overcharge above 4.2V, so you have to put the same capacity batteries in the ac.

Not recommended: Even a little overdischarge Li-Ion batteries (that is, at a loss of electric screwdriver power (discharge) is strictly prohibited to kill the converted Li-Ion battery in the trash (finish the job to the end), but in reality because of his laziness or race to drain the battery to zero. If you are pressed for time, it is more important to charge the battery at least a little and finish the construction issue without killing the battery. After all, Li-Ion batteries are more prone to loss of capacity upon heavy discharges (Below 3.6V per ac, and here x 5pcs = 18V).

It is important to sign everything remade bright marker, 21V Li-Ion, for example, 2200mAh, it is also strictly forbidden to SAVE IN HOLE, so as not to stick in other chargers and did not burn anything.

It is also important to take the principle: work with a screwdriver, and be sure to put the battery on the charger.

Where to get 5 pcs of Li-Ion batteries 4.2V ?

• A dead neighbor’s battery from an old broken laptop.
• You can go to any laptop shop and ask the master dead laptop batteries: (there are usually even 6 pcs 18650, new ones are about 2200mAh, and for 5 years, usually a couple of 18650 die, and 4 pcs of them do not lose capacity below 1300 mAh). You can test the batteries with the BT-C3100 V2.2 by capacity and internal resistance, the higher the capacity and the lower the resistance, the better the batteries. In the screwdriver battery it is more important to find the same capacity lithium batteries. If the internal resistance of the Li-Ion battery is above 500 milliOhms, and the 5 piece is above 2500 milliOhms (2.5 ohms), they will not pull the screwdriver.
• Buy from china on aliexpress (but not the Chinese trash 4200mAh-6000mAh, actually 800mAh).) you can real branded Panasonic NCR18650B 3400mAh with cashback on the program http://epngo.bz/cashback_index/uzlpel. They really will pull more than twice as long as the original EB1414S. 1500 mAh.

Leave Комментарии и мнения владельцев on who got what.

A guide for converting a screwdriver and charging to Li-Ion. Easy current reduction in the MT3608 to charge converted Ni-Cd to Li-Ion batteries for a screwdriver

If you have (or even know) an old screwdriver for Ni-Cd and all batteries are dead, and even the charger is broken (burned out), order at ali board MT3608 for 40 rubles, look for an old charger from a cell phone (all in bulk) and old batteries from a laptop (they need batteries Li-Ion 18650).

Today we will change the old screwdriver from nickel-cadmium batteries to lithium-ion, and accordingly modify its charger.

All can be easily remodeled. Let’s start with the batteries.

If you have a 12 volt screwdriver, we need 4 18650 batteries (16.8V max), if at 14.4V 5 pcs (21V max), if it was 18V then 6 pcs (25.2V max). The safety margin of the electric motor and other mechanisms in a screwdriver is large, and we can not prevent a power increase.

First you test the batteries 18650 Li-Ion, if there is a choice, they are chosen with the same capacity. Expensive and accurate can be done with the BT-C3100 V2.2 or similar. Factory capacity 18650 batteries from laptops 2000-2200 mAh, written on them, if not, you can divide by 2 the capacity written on the nameplate of the battery. The performance will be better if you give 3 charge/discharge cycles. If the measured capacity is 5-10% lower than the written capacity, it is acceptable, but if the capacity is much lower then the batteries have lost capacity. Also measure the internal resistance of the batteries in the device and it should also be the same.

Without precision instruments, it is sufficient to charge the Li-Ion 18650 batteries to 4.2V in any suitable voltage-limited charger, give them the same load and after the same time, measure the voltage on them. If dropped to the same values, then fine. For example, we load a fully charged 18650 with a load of 3-5 ohms (current from 1.5 to 0.8 A), and after the same amount of time (for example, three minutes), measure the remaining capacity of 4 ohms.2V with and without load. If the final voltage under load and without load is the same, the batteries are suitable. This indicates the same load capacity and the same internal resistance.

We throw out the old dead/short-circuited Ni-Cd batteries and solder instead the Li-Ion ones for the voltage we need. The Li-Ion batteries themselves are better to leave the flat connectors from the laptop, but if you still solder to the Li-Ion wires, the soldering point should be cooled with air, solder quickly with flux or acid to reduce the heating time of the battery surfaces, in order to avoid failure. Take soldering wire from an old computer power supply, or thicker.

It will be better if you solder the batteries through the battery balancer board: a 4S or 6S balance protection board, it will not let the batteries overcharge above 4.2V. Also through such a board will be better charged multi-capacitor batteries, but in the case of different batteries will degrade much faster less capacitive batteries, because they will be discharged below the minimum voltage 2.8V, while higher-capacity ones still have a voltage reserve. The screwdriver is still spinning, but the weaker batteries are already degrading.

Then we check how the screwdriver twists on Li-Ion ac, usually it is an increase in power by 20-40% and reduce the weight of the replacement battery.

Now move on to redesigning the battery charger, especially if it’s burned out or missing. They are different from company to company, Bosch, Shturm, Hitachi, all different. From the charger case you can take out all the stuffing, except the terminal block. Basically we just need a terminal block to connect the removable battery. Of course, everything will be better in the case. I had too much current from the heavy transformer and it was heavy, so I found a better use for it (in a lab PSU).

Solder cell phone charger output to MT3608 board on VIn pins, plus, minus. We turn it on and adjust the resistor to the desired output voltage, this is 16.8, 21 or 25.2V accordingly, what kind of battery you have Li-Ion.

MT3608 is a Step Up (step up) voltage converter with pulse width modulation, on typical boards, the output capacitor must be soldered to a large pin of the output VOut and respectively stripped the ground next to it for soldering capacitor. This is a flaw of the Chinese, the board is poorly working from the factory.

We need a 5-15 ohm resistor and the smallest, simplest diode to limit the charging current. We solder the wire of VOut plus directly to the terminal block on top of the battery. And VOut- through the resistor in the minus wire. From the measuring point of the resistor we solder the diode (anode) (cathode with a strip) to the FB signal of the chip, this is the 3rd pin of the MT3608, shallow, but it is tested on the potentiometer on the other side of the board, which is easier to solder.

We connect the battery to the charger and check the charging current, it will be from 50 mA (15 ohms) to 200 mA (5 ohms). Respectively, the current from the cellular charger would be, for example, 50mA(21V/5V/KPD) =300mA, and for 200mA(21V/5V/KPD)=1200mA (may be too large, not every cellular charger will pull it). Check the charger if it gets warm or if the voltage drops from 5V to 2V.5V, then the current should be reduced to avoid overheating.

You may ask why such a small charging current, because it will take a long time to charge. The first point, at high charging currents, close to 1.0C (C-capacity Li-Ion battery), charging time is about an hour, the battery is sure to die after 1-2 years of such atrocities. Secondly even old Li-Ion batteries tend to recover at low currents (unless the chemistry is lost or blown of course), and low current charging will prolong battery life. See https://www.YouTube.com/watch?v=ep8o8DVPz_0 to study the question.

Pros: higher capacity Li-Ion batteries, higher screwdriver power, lighter weight, longer battery life. Minimal rework, parts readily available. If the transformer in the charger works, that’s a bonus (for a lab PSU).

Cons: long time to fully charge (10-20 hours). It is extremely undesirable to put Li-Ion batteries below 3V per cell, i.e. to do full discharge (when the screwdriver twists much weaker), Li-Ion batteries much earlier lose capacity in the cold, already at 0 degrees the screwdriver will work little (You can put a glove or scarf or only on the battery screwdriver for short-term work in the cold, or to heat only the battery indoors at the heating battery).

I strongly advise against buying cheap bright Chinese batteries in stores, their capacity is much less than stated! Better to take a ali NCR18650B Li-Ion 3400 mAh Panasonic (4 pieces 1100r), they are real.

Instead of charging from a cell phone you can take a 5V or 12V from a computer PSU or a PSU from a router/modem.

Somehow I got a very weak Chinese cell phone charger. It says 5V, 450mA. Even at 21V 50mA, the MT3608 would overload the charger, the output voltage would drop to 2V and the charger would boil. What I had to redo:

First I limited the starting voltage of the MT3608 to avoid the converter to turn the charger power supply to 2V 2A when it gets very hot and burns out). You can replace R2 resistor in the circuit with 1-10-100 kOhm (optimally 10K and R1 10K then). This allowed the StepUp converter to turn on only from the higher input voltage, the maximum current for the Chinese charger was at voltage 4.3V, if I raise it a little with a fine trimmer, the converter stops working and the voltage jumps to 5V.

Also I wanted to raise the charging current, 21V 80mA was not enough.

The higher is the secondary voltage of high-frequency converter transformer PSU charging, the more power you can get at the same current (and the maximum current depends on the cross section of the wire), but you can get to oversaturation or overheating of the transformer, and the circuit can PSU goes into protection or burn out.

The output of the charger PSU has a feedback optocoupler and a 3-4V regulator or resistors to stabilize the 5.2В. I was lucky enough to get a charger with a protective 7V.5V, which I soldered in place of the measuring regulator and I got 9V at the output of the charger. It’s better not to boost charger for cell phones above 10V, usually on 11-12 volt there is a failure of stabilization.

I ended up turning the input voltage draw limit to 8.2 volts, got the converter output 21V 140mA, as a result, 13 hours of charging for my 2000mAh 18650 batteries is normal.

Tags: from improvised parts, can be found everywhere, easy to find, easy to remake, simplicity, it’s easier when there is nothing.

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