How to Make a 3S 18650 Battery Pack




About: Hi my name is Steve and i'm a Creative and I got Technical skills i can build anything just stick to my account . I'm a YouTuber so you also can see my all videos here

Intro: How to Make a 3S 18650 Battery Pack

Hey! everyone My name is Steve .

Today i'm going to show you How to make a 3S 18650 Battery Pack

3S batteries are widely used in many application such as Bluetooth Speaker , Rc Cars & and many things you can think of .

it can easily power any 12v application with no issues

Let's Get Started

Click Here to See The Video

Step 1: Features

Supply Output

  • Nominal voltage - 11.1 v
  • Maximum voltage - 12.6 v
  • low voltage - 9 v

Safety Features

  • Over-Discharge Protection
  • Over-Charge Protection
  • Short-Circuit Protection

Step 2: Stuff I Used

  • 18650 Battery " i've salvage this battery from a laptop battery Click here to see how "
  • 18650 Battery Holder
  • 10 A BMS Board

Buying Links



Step 3: The Things You Need to Know

• It is necessary to use same capacity battery little up and down will be be ok ( example - 1750 mah , 1740 mah , 1730 mah )
• If you want to know how to check your real battery capacity "Click Here to See The Video "
• And it is very necessary to keep all the battery at same voltage " I found a best way to do this by connecting all the batteries in parallel and leave it over night "
• Be careful while doing this don't reverse the polarity

Step 4: Attaching the BMS & Battery Holder

  • Put 3 battery on the 18650 Battery Holder
  • Use a double sided tape to stick BMS on the batteries

Step 5: Connection

  • Connect all the battery as shown in the schematic

Step 6: How to Charge Them

  • you can just use a 12.6 v lithium battery charger to charge this battery
  • By the way i'll make a lithium battery charger later on so stay tuned for that

Step 7: Finishing

  • Now check the output voltage

Click Here to See The Video

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    10 Discussions


    9 months ago

    Hi, just a little clarification. in your 1st picture, the red and black wire is soldered to b- & b2, where does this wire go to?


    1 year ago


    Where is the input = recharge? Where is the output = charge? You got me lost there?

    3 replies

    Reply 1 year ago

    DOH Kiselin please pay attention it's a balance charge board B+ & B- are the input/output.

    Please correct me if I am wrong as I have amassed the parts and about to commence building this for a solar garden lamp PSU.

    I will bookmark so if any help advice shortfalls...



    Reply 1 year ago

    Hi. Isn't the charger U'r using here a balanced charger for "2" batterys only? You have 3 batterys here. As I understand the 3'rd battey wan't be charged? Hmm.. maybe I'm wrong


    1 year ago

    Hi Steve,

    How long with this 12V last playing on a Bluetooth speaker?


    1 year ago

    Do you know if I can put cells in parallel to make a 3S2P battery pack?

    1 reply

    1 year ago

    A Li-Ion battery like a 18650 has a "nominal" voltage of 3.7Volts, (and ewen then there are 2 cell's connected in serious, thus ewery individual cell producing a voltage over a potentional of appr. 1.85Volt/cell). Still, to "recharge" a battery, it requires a higher potential of voltage to be done, You can't just "take" some You allso need to "give" some

    Your picture shows with the multimeter some 12.4Volt. Right? You'we just recharged them batterys.... but just wait for an 2 minutes and do the measurement again.... TaDaa,,,, it want read ower 12V again... Hmmmmmmm..


    1 year ago

    Don't bilieve this explained above