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

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

You Just Made It

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11 Discussions


3 days ago

can i use this 3s battery pack that could act as ups? power interruption is quite annoying here in our country. atleast we could have time to power off 12v devices like diy tv and waking in the middle of the night with the tv still on when power back on

1 reply

Reply 3 days ago

the tv is powered 12v 1amp. also with your setup, how much amps does it require to charge?


3 months ago

Great little instructable and thanks for sharing. My only question is :
I did everything according to directions but don't get any voltage on P- and P+... Any thoughts?
edit : After looking on the net and reading the specs on the charger, there is a mention that you have to charge it first to trigger the output.... Who knew lol.
Problem solved


5 months ago

Hi, this is a fantastic post i will be trying this very soon. I was looking through your other posts and couldn't locate the 12v charger you mentioned you'd build for this please would you post that or post a way of charging this 3S 18650 piece with a charger around the house maybe. Thanks again (Y)


7 months ago

I plan to make a 3S battery pack like that, for a device, can I connect the pack to a TP4056 module to charge it?? even if it if be very slow charging.
I want the 3S pack to be embedded in the device,and be able to charge it, just by connecting to power charger,I dont want to remove everytime the 3S pack to charge it.
What do you think ? any idea ?


1 year 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

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...


1 reply

2 years ago

Hi Steve,

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


2 years ago

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

1 reply