Lithium DRILL Battery 18650




Introduction: Lithium DRILL Battery 18650

About: Hi! I make different things :)

Hi, everyone!

Today I'm gonna show you how I converted (replaced) my old Ni-Cd drill to li-ion using 18650.

Step 1: Parts

1) High-Amps (30A) Lithium batteries 18650, capacity 3000mAh (really, tested):

2) BMS Protection Board For Li-ion (12,6V/3S 20A):

3) 12,6V Lithium battery charger (adapter):

4) Battery level indicator:

5) Small push switch:

6) Some copper wires

Step 2: Disassemble a Drill

1) Disassemble a drill battery handle.

2) Separate contact block from old batteries ("+" on the top and "-" at the side).

3) Break off extra plastic elements.

Step 3: Fitting

4) Find place for all components. I used hot glue gun to make battery pack.

5) I also glued BMS to batteries.

Step 4: Soldering

6) I soldered batteries and BMS protection board together, like shows in the picture. Batteries can not be overheated! So I used soldering acid. I touched it no longer than 1 second. I used 2.5 mm² copper wire.


-Electric current. For drills or screw drive we should use high current batteries. I used 30A lithium.

-Voltage. My old batteries are rated at 12V. Every li-ion battery 18650 has 3-4.2V. And so I decided to connect 3 pieces in series. My battery pack has 3*3=9V (discharged) and 4.2*3=12.6V (charged).

-Capucity. My old Ni-Cd batteries had 1200 mAh. My new li-ion batteries has 3000 mAh. I tested it using my tester. So expect more than twice the run time than the original pack.

-BMS. Li-ion batteries must have protection. Batteries can be broken without protection. Short circuit may heat and make fire. For 3 battery in series exist special "3s BMS Protection Boards". Protection board watch for voltage of each battery. It turns off if one of battery has less then about 3V (2.75V maybe). It rated at 25A.

Step 5: Level Indicator

7) I soldered level indicator and button to BMS like in the photo. Don't confuse polarity! And then I covered up battery contacts using insulating tape.

There is special level indicator for 3 batteries 18650. It works from 9 to 12.6V.

8) I soldered contact group to BMS with 2 copper wires 4 mm².

Step 6: Inside Handle

9) Put it inside handle.

I guess I'm lucky :)
My battery handle fit perfectly! Batteries fit tightly, and there is place for indicator. It fit tightly too. I only drilled the hole and poured epoxy into it. I also drilled hole for button.

I'm so happy :D

Battery handle is ready!

Step 7: Charger

10) I disassembled my old charger. I removed all components between input connector and contact plates, and soldered piece of wire to unite input connector to contact plates.

Old adapter can't be used!

Theory: There is special charger for Lithium batteries. For my "3s battery pack" I use 12.6V charger. I chose 1A charger. So charge process takes 3000mAh/1000mA = 3 hours. You may buy 2A, and it will take 3000mAh/2000mA=1,5 hours.

I'm lucky again :) The new charger has plug-in connector like my old! Perfect!

Step 8: Conclusion

I tested my new battery. I cleaned my brick wall of old plaster dust (I'm doing repair). I started at 18:40 and finished at 20:30 nonstop.

1 hour and 50 minutes. Perfect!

Thank you for reading! I'm waiting your comments. Welcome to my YouTube channel.

And as always, sorry for my english :)

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    Question 1 year ago

    Im upto build a battery pack for my cordless drill.(drill has rs775 motor)

    Stock battery was 12v 1.5ah.
    Can i replace that with 3s2p pack with 10A BMS ??
    How to choose the amps rating of bms ???


    1 year ago

    The original charger should work fine, the BMS takes care of the Li Ion issues.


    Question 2 years ago

    1. I am curious to know why do you have to change the charger? It is just a transformer. I have a drill (14.8V) that I need to convert and the charger (the transformer) puts out 30V at 0.4A. Beside the fact that the battery will charge slower, what could be the problem?
    2. As Maker_exe said, apparently a 4S 30A BMS causes problems but it is recommended by the sellers on ebay for power tools. Could it be that his BMS is defective?
    Thanks for your answers


    3 years ago

    Hi, I recently made a similar drill battery (4s) and the current spike when starting the drill is enough to cause the BMS to cut the current even though it should be able to handle the current at full load anyway (Its a 30A BMS)
    I got around this using a 0.66 ohm power resistor but i feel this is causing me to lose power from the drill and they get quite warm,
    does anyone have a good way to get around this? Frankly i have no idea at this point.


    Reply 2 years ago

    I to would be interested to know the answer to your question


    3 years ago

    I see you tested the capacity of the batteries and thats wise. You might also weigh them and that should give about 45 gramms. If they are less they are fraudulent cells and there are lots around.

    If you are able to get these cells to explode please tell me how. I have pulled them apart charged and uncharged ,overcharged them and dead shorted them without getting a sucessful bang or even a high pitched whimper . Just a rapid heat up if you dead short them but there is not enough energy in them to light up or go bang.

    Unless you can demonstrate that you should take the statement out of your instructable.. Its just Wowserism. Worrying people without good reason.

    Also I would be interested in an update of how long these cells last before they are dead. In my experience used like this they don't last very long .


    Reply 3 years ago

    Hello, tytower! Thanks for reading.
    About capacity.
    There are many tests and measurements of this "Liitokala" batteries on the web. Their weight is 46.3 gramm. And their capacity 3000mAh. They have only one flaw - they heat more then LG cells when they work on 20A. But they 2 times cheaper ($8 vs $3,5).
    About explode.
    I corrected this sentence. I saw some videos with short circuit. It made fire. If you want to check it, you should take new chargered cell without protection, short thick wire and make the short circuit.
    Example 1:
    Example 2:
    But not all cells do this. I don't know why.
    Also you may hammer a nail into new chargered cell:
    I hope you can :)
    " long these cells last before they are dead..." - I don't know too. I will find out it. Ask me about my drill in 2021 or 2022 :)


    Reply 3 years ago

    I had a look at the first link and pretty obviously batteries are meant to hold large amounts of energy so if you intentionally short them then the short itself will heat up to ignition point and you will exceed the battery discharge limits so obviously things ignite .
    Notice though that the battery itself did not ignite!!! Fully charge it , punch nails through it , throw it around etc etc you won't get an explosion or fire no matter what you try. You can only short it to demonstrate the power which is what is being done and applies to all storage batteries.

    The second is exactly the same just producing a dead short. All the charge on the cathode can get out via the short.

    The last link appears to show what I could not achieve but analytically screwing a screw in slowly like that would short the case to the cathode at a point where almost all the energy can come out via the screw to the shell so its a dead short situation again . I think these are all staged .


    Reply 3 years ago

    If the battery case has the room, a second set of cells in parallel would likely eliminate the heat issue. By going 3s2p the draw at top amperage would be split between the cell groups. as a bonus, you may MORE than double run time.

    But only if there is room. it LOOKS like there is, but it would be tight and without having the case and cells on hand, it is just an educated guess.


    Reply 3 years ago

    It's good idea! Maybe I'll try