How to properly choose Li-ion cells, BMS and balancer to power a 12V screwdriver

Hi. I am a layman and I hope that by asking forum members for help, I will not go to the rest. Well, I bought Littokalla 18650 Li-ion cells from a "Chinese" in the hope that I will replace the power supply of my beloved 12V screwdriver. Everything seemed simple at first ... But as it turns out it is not ... I have 6 of these cells. I wanted to make a power pack and even bought a balancer board which turned out to be a BMS And Ok. let it be. I have Imax, I have resolved the charging control, but now there is a problem with the package. Are 3 cells 20 A with a capacity 2400 mAh will be able to drive a 12v screwdriver or will I have to make a package of 6 cells? I'm confused, so I'm probably asking stupid questions. If someone wants to help me, I will be grateful and provide other relevant information about my components. Maybe something can be created. Regards and thanks in advance for your help.

Hello - please write what a screwdriver is (name, type).
Post a photo of this BMS, and write what the Imax charger is.
Is it like this;
http://modele-centrum.pl/p/763/12843/ladowark...o-automatyczna-polautomatyczne-ladowarki.html

Thanks for showing interest. Yes, yes. The charger is as in the link - https://pl.aliexpress.com/item/80-W-Balans-IM...-akumulator-litowo-UE-US/32861556057.html?spm = a2g0s.9042311.0.0.571a5c0fBvjGpt
The screwdriver is a Sparky 12 V model as here in the link - https://nexterio.pl/5851,Wiertarko-wkretarka-Sparky-12V-BR-12E-z-walizka.html
BMS as here in the link - https://pl.aliexpress.com/item/1-sztuk-3-S-20...owa-18650-adowarka-PCB-Pok-adzie-Ochrony-BMS/ 32835968605.html? spm = a2g0s.9042311.0.0.571a5c0fBvjGpt
i Charge indicator as in this link - https://pl.aliexpress.com/item/1S-2S-3S-4S-Si...-Battery-Capacity-Indicator-Module-4-2V-Blue- Display / 32859039150.html? spm = a2g0s.9042311.0.0.571a5c0fBvjGpt
It was powered by 10 NI-Cd 1.2v batteries, which gave 1.5 Ah in series, unless I am not mistaken in the value.
I wanted to power it with such cells - https://pl.aliexpress.com/item/Liitokala-For-...le-battery-18650HG2-3-6V-discharge-20A-Power/ 32834382833.html? spm = a2g0s.9042311.0.0.407b5c0fInVgUn
But I gave the bodies and didn't take into account the fact that the BMS I bought is just a BMS and not a balancer. I can always lead the charger cable out of the battery and control the charging using the IMAX capabilities. As long as I'm doing well Thanks again for your interest and willingness to help.

Hello - the charger has a balancer, you just need to buy a harness with a plug.
http://modele-centrum.pl/p/470/14144/przewod-...rzewody-balanserow-konektory-kable-wtyki.html
It is possible that the 3S1P system (three batteries connected in series) will pass the exam,
I suggest connecting three batteries to the BMS board and testing the screwdriver.

Hello.
I propose to make the 4S1P package. During operation, the cell voltage drops quickly and they work the longest between 2.7 and 3.5V. With the 3S1P, it will be well below 12V.
I have the same screwdriver and I know that this container is tight, but you can stuff there 4 cells with a BMS, e.g. CF-4S30A-A, which is a BMS with a balancer. You can put a small switching power supply in the original housing of the charger with a 40W plus step-up / down converter CV-CC and everything will look like the original, and much lighter.
I am putting together such a solution for the Dedra screwdriver, but due to the construction of the charger, I have to cram the converter into the battery housing and make a charging socket for a round plug.
Initially, everything is talking, the inverter is set to 1.9A charging, the expected charging time "from zero" to full is about 2 hours. My cells are provided with 4A fast charging and then the time is about 1 hour, but this is associated with a significant reduction in service life.
If it's okay with Dedra, I take it on Sparky.
Greetings.

Edit 2018.09.29:
Charging time from "zero" to full is 1h20min. The cells are supposedly Samsung NCR-16850-25R. The BMS cuts off from the bottom at 2.5V (3A continuous discharge), and charges to 4.25-4.26V (1.9A current, voltage limited to 17.1V).

Hello. I am an initial layman in this topic, but when it comes to saying a pyrzan, I know that the cells load to 4.2V. So the 4s package will have 16.8V, is it not too much for a 12V screwdriver?

And I didn't even notice ... It actually seems too much to me. Recently, I have converted a colleague of Black Decker 14.4 v into 4 pcs. 18650 cells and a good balancer with BMS and it flies so that he bends his hand at the start ? ... My friend is happy and I am richer in knowledge. My Sparky has a too weak balancer and it sometimes stops at startup ..
But it doesn't bother me ... Best regards and good luck with your projects. ?

oliwek99 wrote:

And I didn't even notice ... It actually seems too much to me. Recently, I have converted a colleague of Black Decker 14.4 v into 4 pcs. 18650 cells and a good balancer with BMS and it flies so that he bends his hand at the start ? ... My friend is happy and I am richer in knowledge. My Sparky has a too weak balancer and it sometimes stops at startup ..
But it doesn't bother me ... Best regards and good luck with your projects. ?

could you write what bmw balancers do you use?

I have the same idea - a screwdriver - modification of the 12V / 10x1.2V NiCd battery, for 16850. My container holds 4 16850 pcs. NiCd originals have 1.2V / 1600mAh, so 16850 would have a greater capacity. I know from experience that the voltage of a fully charged 16850 is max 4.2V but when discharging it quickly drops to about 3.3-3.5V. Since NiCd charged to 1.4V, they initially gave 14V. So it seems to me that the voltage from 4x16850 will not hurt them. In the case of 3 16850 cells, the OPERATING voltage would be about 10.5V, so not enough. I am enclosing a quite specific diagram of the original NiCd charger.

Col. My screwdriver was originally on 9.6V, I put a 3S2P package. Voltage 12.6V and flashes 2 years. Nothing warms up and when starting my hand will tremble. Screws and drills in steel up to 1.5mm without a problem. If the Col. will insert the 3S2P, the voltage will initially be only 0.6 V higher, as long as this charger has the ability to regulate the voltage and current. If not, it will only charge up to 12V. if there is no additional electronics in this screwdriver. Measure the container and maybe a 3S3P package will fit. Assuming the cell's capacity at 1800mAh, the result would be 5400mAh, or almost 5.5 Ah. Buy high-current cells of a good brand with a capacity of 2000-2200mA. in the catalog note with the charging current permitted by the manufacturer.
The network is full of it. You can even order a ready-made package of the required size together with the BMS and balancer, they do not call much too much and the robot with soldering cells is out of the question. I personally prefer a balancer outside the container with batteries. This li-on charger won't do.
You have to do another with the balancer and only the package and in the screwdriver
bms.

It charges up to almost 16V. Unfortunately, no more than 5 batteries will enter the container. I can handle charging, I have a 4S module, it fits.

You have no control over the charging process to the li -on. Overheating protection is a little bit low. With 3S you will have 12.6V after full charge at 4s 16.8V on the original package after charging you had about 15V, unless the charger was rigidly set to 12.2V but I don't think so.
Check with the power supply how it will endure continuous work for about 5 minutes with a power supply of 16.8V and you will know everything
https://www.elektroda.pl/rtvforum/topic3548594.html in this topic you have 2 balancer solutions -1 with a charger and the other without, but in the subject. there is also another power supply that can be used. If there was a 4S package, it belongs to these balancers to add after 1 section and the power supply voltage within 20V, there will be current and voltage regulation. If necessary, I have a reasonable and understandable translation for the balancer from the Czech side.

I have a 4S charge / discharge balancer. https://allegro.pl/oferta/modul-ladowania-i-ochrony-ogniw-li-ion-4s-14-8-7377454085

Ie you have a bms module with balancer. You have to acknowledge that such modules usually have charge cycle counters.
the bat is weak after 5 minutes of work. I converted it into a bat. After 2 years, he started reporting problems with the battery. After charging, it lasts for 5-6 days and I have these messages in deep respect. Of course, they do not show up for 1.5 years and the battery is fine.
The difference is that the bms module counts the charging cycles and cuts off the power when the battery is low. When a certain number of charge cycles are reached, reports a problem with the battery. This is deliberate aging of the product.

Read the description in the link ......

I read .. And what? . Colleague thinks that the manufacturer will write that, for example, above 500 charging cycles, the system will be freaking out. After all, it would be a homicide for this product. No producer wants that, but it uses it. Remove the battery from the laptop. Remove the bms and charge with the balancer. I guarantee you that the allegedly dead battery will last for about 5-6 days. My lap has been working like this for 1.5 years and is doing well. Instead of bms I gave a battery discharge indicator.

Jesus ..... Hrrrrrrrrrrrrr !!! Read from the beginning .....
1. I assemble SAM from single 4 16850 batteries with laptop battery removal. I seal the package myself.
2. I have a Li-Ion battery charging and protection module - 4S - 14.8 (link).
3. For the hell I have to "throw the battery from the laptop" as it is DISMANTLED and disassembled into a single battery. Disassembled because of 6 batteries in the battery, 2 of them were POTENTLY dead so the battery was not suitable for further explosion in the paw.
4. The 4S battery with the Li-Ion - 4S charging and protection module is mounted in the battery housing of 12V SCREWDRIVERS. For safety, I add a 45 ° / 5A thermostat in series.
5. Charging and protection module THERE IS NO SYSTEM TO COUNT THE NUMBER OF CYCLES .... READ THE TITLE OF THIS POST ......

Then explain to me why 1 battery lasted 5 years before it started freaking out. 2 after 2 years and 2 months, it is not able to work for more than 3 minutes. now there is a 3rd battery from scratch. For now, it requires charging after 3-4 days. Village batteries are charged with the same power adapter. In addition, whip # 1 and 2 was smashed - I made 2 3s2p packets
and after charging without electronics using a balancer from the Czech p. These packages have a negligible self-discharge current. The battery pack No. 1 works in the basement, supplying 3 12V LED strips and will last about 3 months before the control system activates the LED signaling low status. Battery cell pack # 2 is currently being tested. None of the cells from package 1 and 2 showed deviations from the norm after depriving the famous electronics and charging with a charger with a balancer - i.e. they kept voltage and current.
The third package of high-current 20A cells powers the screwdriver. A professional carpenter worked for me for 5 hours on the construction of a house on the plot and after work he requested a conversion of his to a li-on. He had exactly the same model and withstood a maximum of 1 hour of work. He did not complain. He got 2 packages because he had 2 batteries. He stated that it was enough for him for 8-9 hours of work and during this time 1 package is already charged. Because my daughter's father-in-law did everything at cost.

And why in my lapka 2 batteries from the batteries (6 pcs) died after 6 months? Well, because I bought a whole "new" "replacement" battery on Allegro. The original worked for 3 years. Mine are secured EXTERNALLY by the factory IN / OUT balancer system and the battery itself is not.
By the way, WARNING in front of the baskets 2 * 18650 from a well-known Warsaw store. The baskets have MARKED "+" and "-" polarity inside, as for serial connection (2 pcs - 7.4V / 2400 mAh). It's just that both the springs and the foot contacts are connected ... PARALLEL, i.e. for 3.7V / 4800 mAh operation. I almost set fire to the workshop. Additionally, the connection of the poles is a wire .... steel, nickel-plated, it starts to glow at 5A and of course melts the plastic.