» Electronics »Converting a 12V screwdriver with Ni-Cd to Li-ion batteries

Alteration of a 12V screwdriver with Ni-Cd to Li-ion batteries


The cordless tool is more mobile and easier to use compared to its network counterparts. But do not forget about the significant drawback of the cordless tool, this is how you yourself understand the fragility of the batteries. Buying new batteries separately is comparable in price to acquiring a new tool.

After four years of service, my first screwdriver, or rather, the batteries began to lose capacity. To begin with, I assembled one of two batteries by choosing working “banks”, but this modernization did not last long. Remade his screwdriver on a network one - it turned out to be very inconvenient. I had to buy the same, but the new 12-volt Interskol DA-12ER. The batteries in the new screwdriver lasted even less. As a result, two serviceable screwdrivers and not one working battery.

On the Internet, they write a lot how to solve this problem. It is proposed to remake outdated Ni-Cd batteries to 18650 Li-ion batteries. At first glance, there is nothing complicated about this. You remove the old Ni-Cd batteries from the case and install new Li-ion. But it was not so simple. The following describes what to look for when upgrading a cordless tool.



For alteration you will need:




Flexible wire 2.5 sq. mm
Soldering iron
Old battery (housing)


I'll start with 18650 lithium-ion batteries. Purchased on.



The rated voltage of the elements is 18650 - 3.7 V. According to the seller, the capacity is 2600mAh, marking ICR18650 26F, dimensions 18 by 65 mm.

The advantages of Li-ion batteries over Ni-Cd are its smaller size and weight, with a larger capacity, as well as the absence of the so-called "memory effect". But lithium-ion batteries have serious flaws, namely:

1. Negative temperatures sharply reduce capacity, which is not the case with nickel-cadmium batteries. Hence the conclusion - if the instrument is often used at low temperatures, then replacing it with Li-ion will not solve the problem.

2. A discharge below 2.9 - 2.5V and a recharge above 4.2V can be critical, a complete failure is possible. Therefore, we need a BMS board to control the charge and discharge, if it is not installed, then the new batteries will quickly fail.

On the Internet, they mainly describe how to remake a 14 volt screwdriver - it is ideal for modernization. With a series connection of four 18650 cells and a nominal voltage of 3.7V. we get 14.8V.- just what you need, even when fully charged, plus another 2V, this is not a problem for the electric motor. And what about a 12V tool. There are two options: install 3 or 4 elements of the 18650, if three is not enough, especially with partial discharge, and if four is too much. I chose four and in my opinion made the right choice.

And now about the BMS board, it is also with AliExpress.




This is the so-called charge control board, battery discharge, specifically in my case CF-4S30A-A. As can be seen from the marking, it is designed for a battery of four "cans" of 18650 and a discharge current of up to 30A. The so-called "balancer" is also built into it, which controls the charge of each element separately and eliminates uneven charging. For the board to work properly, the batteries for assembly are taken from the same capacity and preferably from one batch.

In general, there are a great variety of BMS boards with different characteristics on sale. I don’t advise taking a current below 30A - the board will constantly go into protection and to restore operation, some boards need to be supplied with charging current for a short time, and for this you need to remove the battery and connect it to the charger. There is no such drawback on the board that we are considering, you just release the trigger of the screwdriver and, in the absence of short circuit currents, the board will turn on itself.



To charge the converted battery, the native universal charger perfectly fit. In recent years, Interskol began to equip its tool with universal memory.



The photo shows to what voltage the BMS board charges my battery together with a standard charger. The voltage on the battery after charging 14.95V is slightly higher than that required for a 12-volt screwdriver, but this is probably even better. My old screwdriver became faster and more powerful, and the fears that it would burn out, after four months of use, gradually disappeared. That seems to be all the basic nuances, you can proceed with the alteration.



We disassemble the old battery.



We evaporate the old cans and leave the terminals together with the temperature sensor. If you remove the sensor, then when using the standard memory, it will not turn on.

Alteration of a 12V screwdriver with Ni-Cd to Li-ion batteries


According to the scheme in the photo, we solder 18650 elements into one battery. Jumpers between the "banks" must be made with a thick wire of at least 2.5 kV. mm, since the currents during operation of the screwdriver are large, and with a small cross section the power of the tool will drop sharply. The network writes that it is impossible to solder Li-ion batteries since they are afraid of overheating, and recommend connecting using spot welding. You can only solder you need a soldering iron with a power of at least 60 watts. The most important thing is to solder quickly, so as not to overheat the element itself.



It should turn out approximately so that it fits into the battery case.



From the board to the terminal, the wires should be flexible, as short as possible and a cross section of at least 2.5 square meters. mm



We carefully place the entire circuit in the case and fix it with any gasket to prevent damage to the parts.



To fix the terminal, I simply put it in place and wedged it with wooden wedges. It remains only to assemble the body.



The weight of a standard Ni-Cd battery is apparently 558 grams.



The weight of the converted battery is 376 grams, therefore, the tool has become lighter by 182 grams. In conclusion, I want to say that this rework is worth it. The screwdriver has become more powerful and the charge lasts much longer than with a native battery. Redo, you will not regret!
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72 commentary
Stason
And where is the temperature sensor on the circuit?
And I have the same opinion ... And also passed ...
I bought a few lithium shuriks ... And I sorted out the old ones - they will come in handy for homemade products.)))) There are cartridges, engines and planetars ...
Greg6204
NiCa are good with regular use.And if you have the urge to wrap a dozen self-tapping screws every six months, the shurik will surely be discharged. A short type charge in 20 minutes, if only to work out, it will only kill the batteries. Lithium is always ready for work and is not afraid of charging at any moment of the working cycle. Personally, it was because of this that I switched to lithium. And I do not regret ...
Author
the battery noticeably lost capacity - the BMS board is working
Broostr
Once again about connecting the BMS board:
We connect the finished (assembled) battery, starting from the minus and then on the increase in voltage. Otherwise, the board will not work and will kill the batteries ...
Broostr
I want to clarify a little ...
You need to connect the BMS board to the batteries in the strict sequence that is described on the purchase page, otherwise the board will fail.
Lithium batteries such a characteristic as "discharge current", and from the laptop to put on the shurik is not desirable. I personally ordered batteries with the HG2 marking, according to the description up to 20 amperes, only today they came, I’ll pick up, check and unsubscribe.
As for the charger, I have not decided yet, but I think a current stabilizer is needed, I will try on lm338. Let's see further.
Author
Guest Vitaliy, if you have connected everything correctly and the screwdriver does not work with the board, as an option the board is faulty, the batteries are not charged or the batteries are bad, in which the board goes into defense. It is not recommended to turn on these batteries without a charge - they are sensitive to overcharging, as well as to a discharge below the permissible limit.
Guest Vitaliy
I did it one-on-one as the author, and the screwdriver is the same, but the screwdriver works without a board and after a few seconds the voltage drops to 10-11 V and the screwdriver rises ... then the voltmeter shows 10 volts from the board, and directly from the batteries 14, 2 volts and easily works. What is the reason ?? is the board bad (on the small black and red wiring of the board is 14.2 volts, and on the terminals of the board is only 10 volts)?
can I directly connect the min P and B so that the screwdriver works and will it be charged?
Author
my charger behaves the same, but when the battery is charged and pressed sharply and under a decent load, it does not turn off (currents and voltage drops do not exceed the maximum allowable. The more powerful the tool, the more currents), but when the battery is partially discharged it happens that the BMC is in protection leaves, then charging will be required soon!
and now - progress has spoiled us !!!
Recently, I also “changed” my powerful “Makita”, with a sharp press of a key, the protection of the BMS-ki is triggered, with a smooth - normal. Native charging at the end of the charge indicates a battery malfunction - this BMS disables the charge! But while everything works!
Author
I completely agree, in ancient times, thanks to manual labor, people were healthier, and now progress has spoiled us !!!
I use it constantly while everything works!
In the distant times of my youth, the power tool was not available to us, I used a hand drill, everything worked! smile
Author
Hello everybody! If anyone is interested, more than two years of operation have passed - the "flight is normal", I use it constantly while everything works!
But if the starting memory does not fail me, the current at which the battery rotates the engine reaches 300 amperes (it is not for nothing that a wire with a finger is thick on the starter).

Modern, which are designed to sharply twist the frozen three-liter diesel engine in the cold, are designed for 1000 amperes. Only for 10-15 seconds.
I myself spent several times in childhood
I remember I didn’t go to school yet, but I put the scissors in the socket! Apparently, the "bugs" were made of nails, I managed to admire the fireworks! Well then, my mother retreated with my belt! smile
Some use lead car batteries as a welder
Do you know how the load fork works? Measures voltage sag under load! smile
As a child, I myself often spent several times standing in the garage battery
It's good that my father did not see! smile
lithium plate and fabric coated with carbon powder in an electrolyte
The plate is definitely not made of lithium, in appearance it seems to be copper! In my school years, lithium was stored in a jar of kerosene! smile
small r is the resistance of the current source (battery) than it is less than the greater the current strength in the circuit
The current strength in the circuit is determined by E / R, the contribution of r is negligible, with a normally charged battery! smile
Quote: Valery
But what drawdown is there? ... More precisely, the drawdown will be - to zero! ))) So you can measure the current (if it’s not labs) only once! .. Next - the battery to discharge, and the next to test!))))

What kind of battery are you talking about? Some use lead car batteries as a welder. As a child, I myself repeatedly spent a short while standing in the garage battery. It is clear that such currents did not add health to them. But if the starting memory does not fail me, the current at which the battery rotates the engine reaches 300 amperes (it is not for nothing that a wire with a finger is thick on the starter).
Lithium ion i
Quote: Valery
Sorry, but either you wrote off on the labs, or it was a very long time ago ...)))))) (just kidding).
Because, as Pokhmelyov once said, "horses mixed up in a heap, people")))
according to Ohm's law for a complete circuit, Current is the voltage divided by the resistance.

And what then do you think, Ohm's law for a section of the chain? ))))
You see ... You’re talking about the full, you are formulating for the site, but you are applying the law to the site full!))) ... Brrr ... Head around ...))
What difference does it make to you, what currents will flow inside the battery? (If they do not exceed, of course, the maximum allowable))). The current in the screwdriver is important to you! But does it depend on what ??? (at U = const) ... That's right ... From the resistance of the shurik motor.))) And, it seems, it has not changed ...))) .. So, connect this shurik to any-oh a source with a suitable spring, and the current flows in it the same !!! (If the battery is able to give it)))
Uh ... And what are the plates in the lithium battery?

small r is the resistance of the current source (battery) than it is less than the greater the current strength in the circuit.
Uh ... And what are the plates in the lithium battery?
There is one plate in a lithium battery, since a galvanic pair of lithium - carbon immediately gives us 3.7 volts. Most often, it is a lithium plate rolled into a scroll and a fabric coated with carbon powder in an electrolyte.
if we consider the same ordinary battery, then you measure it with a voltmeter and there is voltage, but the hour hand does not pull
This is the whole trick, as the discharge rises, the internal resistance of the battery rises and the current drops! smile
Quote: Korolev
you need to short-circuit the current source and measure the current strength
And do you take into account the voltage drop? Or take the open circuit voltage (EMF)? The ratio of the load resistances and the source wondered? As a rule, the load resistance is several times greater and the internal resistance of the voltage source is neglected.

I no longer remember exactly how we carried out these laboratory works (since it was a long time ago). Perhaps along with the measurement of current in the circuit, a voltmeter was connected in parallel.
As a rule, the load resistance is several times greater and the internal resistance of the voltage source
This is true for appliances plugged in. And if we consider the same ordinary battery, then you measure it with a voltmeter and there is voltage, but the hour hand does not pull. Then the same batteries of cell phones, they can’t be short-circuited because they have a protection board, but it is precisely because of the current drop, and not the voltage that they do not change, that the phones begin to reboot and stupid after two years.
20 years ago it was. I don’t know for a long time or not.
It is necessary to short-circuit the investigated current source as a rule - it is a battery or accumulator. We did not short circuit the current source connected to the electric network (at least on purpose).
or you wrote off on labs, or it was already a very long time
need to short-circuit current source
Laboratory The current source must be protected.
But what drawdown is there? ... More precisely, the drawdown will be - to zero! ))) So you can measure the current (if it’s not labs) only once! .. Next - the battery to discharge, and the next to test!))))
Sorry, but either you wrote off on the labs, or it was a very long time ago ...)))))) (just kidding).
Because, as Pokhmelyov once said, "horses mixed up in a heap, people")))
according to Ohm's law for a complete circuit, Current is the voltage divided by the resistance.

And what then do you think, Ohm's law for a section of the chain? ))))
You see ... You’re talking about the full, you are formulating for the site, but you are applying the law to the site full!))) ... Brrr ... Head around ...))
What difference does it make to you, what currents will flow inside the battery? (If they do not exceed, of course, the maximum allowable))). The current in the screwdriver is important to you! But does it depend on what ??? (at U = const) ... That's right ... From the resistance of the shurik motor.))) And, it seems, it has not changed ...))) .. So, connect this shurik to any-oh a source with a suitable spring, and the current flows in it the same !!! (If the battery is able to give it)))
Uh ... And what are the plates in the lithium battery?
you need to short-circuit the current source and measure the current strength
And do you take into account the voltage drop? Or take the open circuit voltage (EMF)? The ratio of the load resistances and the source wondered? As a rule, the load resistance is several times greater and the internal resistance of the voltage source is neglected.
The current at the current source (in this case, the battery) depends on the internal resistance. To measure it, you need to short-circuit the current source and measure the current strength. We did such work on the labs at the institute, for this we need an ammeter with a shunt. The shunt in this case is a conductor with a known resistance. In a conventional tester, its role is played by a small plate. What will happen to her is not difficult to find out if you just close the plus and minus of the battery. As far as I saw on the car battery, the open end wrench melts as if from welding. And this is not surprising because the number of electrons capable of moving from one pole to another depends on the area of ​​the plates and the viscosity of the electrolyte. It is not difficult to guess how much less the plate is in the car battery, in mine and in the lithium battery. In this case, lithium batteries, I measured the current there is not more than 3-4 amperes. Therefore, I can confidently say that my lead battery has less resistance, and therefore a higher short-circuit current than cadmium and lithium batteries without even taking measurements, just by spark.
As for the "burn engine", then according to Ohm's law for a complete circuit. Current is the voltage divided by the resistance. However, the resistance is not only the load, but also the current source. Therefore, replacing the battery, we do not take into account that we change the resistance in the circuit in my case, it decreases, and therefore the current is lost. From time to time, the resistance of batteries has been increasing.
Well, that means THIS current was high ... Because
lead current is more than cadmium, as if not to burn the engine,

this is not only a fallacy, but also ... as it were, so to speak ... operating with completely incorrect properties ...
starter (starter) lead-acid batteries really have the ability to produce high currents !!! (They are made for this). And, for example, of the same size (or even more) and with the same capacity, traction batteries for large currents are not designed !!! (Precisely because they are traction! "
And these differences are caused not by their type (lead-acid and one or the other), but by the design of the plates !!!
I’m talking about misconceptions ... And now about the concept of electricity and terms ...
The current is what flows !!! That is, the current source may be ABLE, or NOT ABLE to give a large current, but the current itself depends on LOAD !!!
In other words, when you say that the battery has a large current and the motor can burn, then it’s about how to say that “there is too much water in the river, if you try to pump it with a hose, the hose will burst !!!”))) Not will burst! Because not all the water from the river will flow through it at once, but only that which he is able to let through ...)))
Sorry for the on-finger explanation ...
You won’t believe it. I connected the motor from the vacuum cleaner to these batteries (to 6 and 12 volts) and despite the fact that it is designed for 220 volts and for AC voltage - the motor worked.
At first I was afraid to connect 12 volts, knowing that the lead current is higher than the cadmium current, so as not to burn the engine, but it worked perfectly at 6 volts. Screws twisted and drilled, only slower, which is sometimes even more convenient. And at 12 he twists faster than at home. Here is a paradox.
Not dry, 6 volt battery
To feed 12V shurik from 6V? And why not from 3V "pills"? smile
It does not dry out, a 6-volt battery that I originally set weighed as much as my own. And this is 12 volts gives more power.
And what are the maximum currents of a gel lead battery? Automotive give up to 500 amperes. I’m afraid to measure my own with a tester because I’m sure that there are more than 20 amperes and it’s a pity to throw out the tester because of such experiments.
He twists it no worse than on his own battery, I calmly drill metal and screw 110 screws into a tree, while with a screwdriver I can’t twist it there just with a ratchet from auto dial.
It will not dry up ... Considering the maximum currents in the battery from the uninterruptible power supply, this will not be a screwdriver, but pampering.)))
... Although ... How can I use an electric screwdriver ... To at least somehow use it, since I did ...
need a battery from the uninterruptible
The hand will dry for a long time to work! smile
Well, I really don’t understand why all this haemorrhoids with boards, expensive batteries and soldering. My version is 100 times simpler, done in 5 minutes and costs from 500 rubles to 0. You just need a battery from an uninterruptible power supply (which can be found in the scrap or under your desk) or buy in a car battery store (there are usually sold small 6 and 12 volts) A piece of wire with terminals or twisted and elastic (in my case this is a car camera)

here I am describing homemade https://enm.imdmyself.com/9821-akkumulyator-dlya-shurupoverta.html
Author
Hello everybody! About a year has passed by using the converted screwdriver - no matter how much I regretted, the battery works without changes; everything is OK! I will continue to use it.
.Batteries in the photo, Chinese shit, I bought these four years ago on Ali, the capacity is three times less than declared.

I bought the same "Chinese shit." Capacity - A little ABOVE declared. They have been working in external charging for three years already ... I have not yet seen a decrease in capacity.
Last spring, reworked, Samsung picked up 6 batteries from two laptop faulty batteries. Bmsk with Ali for 55 rubles. Connected in series-parallel, in pairs. Soldering station, solder and phosphoric acid. Shurik still works fine. The batteries in the photo, Chinese shit, bought these four years ago on Ali, the capacity is three times less than declared.
But protection, it is protection in Africa too. Protective valve, it is protection))
Well, that’s what I called her.
A minus, then okay ..
About the alteration of the memory, you can read the continuation.
Quote: popvovka
You probably know that any 18650, and not only, has protection?

Do you know why you got a bunch of minuses from people who are superficially familiar with the issue for the right thought? Because they could not formulate it correctly, but all that was needed was to write a “safety valve” instead of the abstract word “protection”.
Thanks . clear, we will move on.
We can’t cure by the photo, Chumak was in this case. ;)
Now on to the case. First you need to understand that we have:
1. What are the parameters of the memory in reality, and not on a piece of paper?
2. In any case, a 12 V charger is only suitable for three lithium batteries.
3. What are the batteries? If the capacity is 3000 mAh, then 2.8 A with a creak, but it suits, if less, then it is necessary to reduce the current.
4. Is it possible to restore overcharged batteries? If you manage to run them, then it’s already easier.

In order not to write a lot, I’d better advise you to read it. A man is seriously dealing with this issue, his opinion is trustworthy.
Also .
Read not only articles, but also, necessarily, comments. There you can find a lot of useful things.
Good luck
the first message didn’t go away - the reasons are clear, but there is a way out of this situation, or start all over again
or everything is hopelessly ruined and should be started anew
the reasons are clear, but is there a way out of this situation?
Quote: 712 sergey
12 V, 2.8 A

The voltage is too small and the current is too large.
I apologize, it just wasn’t at hand, I’ll write it off, now I’m at home, I'm sorry I couldn’t answer right away, due to the lack of information at hand, the charger says 12 V, 2.8 A, and indicators - green - network, red - charging.
Quote: 712 sergey
charger native from interskol,

It seems to be asking clearly:
I clarify the question: what are its parameters?
, but still did not receive a response. ((
I’ve connected the charger from the Interskol, I checked the connection three times, everything is according to the diagram, but I don’t know how to check the serviceability of the board (and I wonder why they were discharged in progression. And most importantly, how can I fix this, if possible, of course, the experiment was started out of economy, since screwdriver from case to case, and the screwdriver fully meets the needs.
Quote: 712 sergey
on all jars, respectively -3.4, 2.6, 1.2, 0.2, what could be the problem?

Either the board is malfunctioning or the connection is incorrect. This is the first. And secondly - what is your charger? I clarify the question: what are its parameters?
I'm sorry, not 3.8V but 3, 6V

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