Hardware Nintendo switch Battery Mod (No PowerBank)

[Laytor]

Hi everyone , i just made a simple battery mod with 4 Li Ion (18650) cells .

I just added 4 cells in parallel with the og battery , those cells are directly soldered the positive and negative of the og battery before the protection board .
The enclosure is 3d printed , i used 4 3100mah 18650 cells , a small voltmeter and a button .
So now i have a grand total of about 16,800mah of capicity , i got 10h on Zelda botw with mid brightness and wifi on ,and 23h on Terraria.
The device weight 620g with joycon , i can still dock it on my small dock and it also fit in my switch bag .
There is still one "bug" , the battery pourcentage on the system is slightly off , it sometimes says 1% but there is still plenty on battery and also says 100% of charge but the battery are still charging . (FIXED)
Thats why i added a voltmeter to see the real voltage of the battery and it works flawlessly now.



PS: sorry for my bad english , im french .


EDIT : It take 11h to charge from 0% to 100% the console.
The battery indicator is fixed until you completely charge it and discharge it about 15 times . like this --->(FIXED)

EDIT 2 : Its safe to mix different battery capacity if they have the same voltage when connecting them together , they are in parallel and you dont exceed the max C rating per cell. --->HERE

EDIT 3 : This is a proof to show that its possible and it works flawlessly , but i should have gone for two 18650 cells instead of 4 , 640g is heavy for some people and 16000 mah is overkill xD

 

[andyhappypants]

Awesome DIY project! 18650 cells are really cheap these days.

 

[Agilato]

Interesting prototype, would be cool to see advanced version with something like apple magnetic laptop connector.

 

[redmagejosh]

Interesting prototype, would be cool to see advanced version with something like apple magnetic laptop connector.

That'd be cool, something you can plug and remove as needed. Cool stuff!

 

[wiewiec]

Cool stuf, but I think powerbank is more practical

 

[eyeliner]

Cool project. What is the weight of the console, now?

 

[andyhappypants]

Be carefull you arent pushing the charge current limit of those cells, they have a habit of going into thermal runaway if pushed too hard which always ends in fire!

 

[Laytor]

Cool project. What is the weight of the console, now?

640g

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That'd be cool, something you can plug and remove as needed. Cool stuff!

I thought about that , but when you plug in parallel the battery , they need to be at the same voltage(+-0.05) otherwise there will be a massive current rush.
And also , a latching mechanism is hard to 3d print

Be carefull you arent pushing the charge current limit of those cells, they have a habit of going into thermal runaway if pushed too hard which always ends in fire!

Those cells are charging at the same speed than the og battery , slowly but surely. (Via the USB C charger)
They are also plugged in the protection board of the og battery , it's safer.

 

[Sherks]

Really nice project . I am going to follow you . May i ask you a question ? You soldered 18650 cells directly to original battery before protection board of original battery ? That mean you teardown the original battery to take out the board and soldered behind it ? Or just soldered to the copper connection points of original battery ?

 

[Kitsune_sempai]

do you have a schematics as to how you soldered the battery together? I want to do a similar project but the battery's 5 wires are making me doubt myself

 

[coffinbirth]

I'm fairly certain this Frenchman blew himself to smithereens.

 

[The Real Jdbye]

Hi everyone , i just made a simple battery mod with 4 Li Ion (18650) cells .

I just added 4 cells in parallel with the og battery , those cells are directly soldered the positive and negative of the og battery before the protection board .
The enclosure is 3d printed , i used 4 3100mah 18650 cells , a small voltmeter and a button .
So now i have a grand total of about 16,800mah of capicity , i got 10h on Zelda botw with mid brightness and wifi on ,and 23h on Terraria.
The device weight 620g with joycon , i can still dock it on my small dock and it also fit in my switch bag .
There is still one "bug" , the battery pourcentage on the system is slightly off , it sometimes says 1% but there is still plenty on battery and also says 100% of charge but the battery are still charging .
Thats why i added a voltmeter to see the real voltage of the battery and it works flawlessly now.

View attachment 175033 View attachment 175034 View attachment 175035 View attachment 175036 View attachment 175037 View attachment 175032View attachment 175038

PS: sorry for my bad english , im french .

That is a very bad idea, the 18650 cells have less capacity than the built in battery thus they will be depleted sooner than the internal battery while the average voltage will still be high enough for the system to think it still has charge, causing the 18650 cells to be discharged below their minimum safe limit (typically 2.5V)
When charging up the reverse will happen, as they will reach full charge before the internal battery, which might cause them to be overcharged which is much more harmful and in the worst case can make them catch fire or explode.
Repeat this cycle many times and you will at best severely degrade the capacity of the batteries or cause them to die completely and not hold a charge, or at worst result in thermal runaway.
This will also get worse over time, as even if they are the same model of battery, they are not 100% identical (they do not have the exact same mAh capacity) causing uneven wear and tear. When multiple batteries are used together like this they should be paired from the factory so they are as identical as can be.
It would be much safer if you got rid of the original internal battery and used cells that were measured to have near identical mAh capacity.
I hope the batteries you are using have protection circuitry built in to avoid the overcharging and undercharging issues I mentioned, as the protection circuitry likely built in to the Switch's charge controller can't do its job properly when it sees the mishmash as one big battery.

 

[Laytor]

Hi , i already said that to Sherks but im gonna resend it here:

Sorry for my late reply , I soldered the 18650 cells before the original bms , I torn down the og battery to get to the connection of the cell (it's not the original switch battery.
I bought an aftermarket one on AliExpress but I seems to be exactly the same) , that was the hardest thing to do , the bms doesn't seems to care if the cell is not 4130mah anymore , the pourcentage calculation is done by the software of the console, it takes several full charge and discharge to get the real pourcentage of the new capacity ,about 15 times (That fixed the 1% "bug"). FIXED

--------------------- MERGED ---------------------------

That is a very bad idea, the 18650 cells have less capacity than the built in battery thus they will be depleted sooner than the internal battery while the average voltage will still be high enough for the system to think it still has charge, causing the 18650 cells to be discharged below their minimum safe limit (typically 2.5V)
When charging up the reverse will happen, as they will reach full charge before the internal battery, which might cause them to be overcharged which is much more harmful and in the worst case can make them catch fire or explode.
Repeat this cycle many times and you will at best severely degrade the capacity of the batteries or cause them to die completely and not hold a charge, or at worst result in thermal runaway.
This will also get worse over time, as even if they are the same model of battery, they are not 100% identical (they do not have the exact same mAh capacity) causing uneven wear and tear. When multiple batteries are used together like this they should be paired from the factory so they are as identical as can be.
It would be much safer if you got rid of the original internal battery and used cells that were measured to have near identical mAh capacity.
I hope the batteries you are using have protection circuitry built in to avoid the overcharging and undercharging issues I mentioned, as the protection circuitry likely built in to the Switch's charge controller can't do its job properly when it sees the mishmash as one big battery.

This is absolutely true for series connection but here all the cells are conected in parallel to the bms , you can mix different battery capacity if they are connected directly in parallel , just be careful to not exceed the max charging current of each cells , and also to not mix battery with more than 50% of capacity difference to be extra safe , but in the switch the charge speed i so low that you mix it with one flat lipo 15000mah cell if you want .
Those 18650 cells (3000mah) have about 1C rating which means 3A max of continuous charge until full and the original switch cell (4310mah) as about 5C = 20A max current , the switch bms give about 10W that equal to 4.15V at 2.35A , those 2.35A will be proportional to the capacity of each cells (about 0.4A for each individual 18650 cells and about 0.6A for the original lipo ) , this is the same thing but in reverse when discharging , those cells are 2.6A away from being charged too fast .

HERE

do you have a schematics as to how you soldered the battery together? I want to do a similar project but the battery's 5 wires are making me doubt myself

I tried my best :

Unwrap the tape around the bms , unfold the bms , solder 2 small wire directly out of the cell (on the bms side because you dont want to heat the cell too much with your soldering iron) and youre done .
Be carefull when you connect them that they have almost the same exact voltage , if not there will be a big current flow that can damage the cells

 

[Kitsune_sempai]

thank you for the schematics looks pretty clear!
I'll do a similar edit but soldering two switch batteries together (parallel with non-matching mah is too hardcore for me!)

 

[berkcan00]

is there a safer solution? eg: parallelly connecting two switch batteries?

 

[LinkX5]

@berkcan00 safer?
18650s are safer. people get them confused with li-po packs like what the switch uses.
A Li-Po will explode if charged incorrectly, hit with a blunt object, shorted out, or drawing too much power from. like 50A from a 30A battery
whats not safe is charging batteries of different capacitance simultaneously. doesn't matter what type. also mixing types is bad.

i've experienced one of 2 lead acid batteries exploding in a truck while driving. one had a different rating than the other.
its not just li-po or li-ion that you need to be careful of while charging. i have a pic of the lead acid batt that exploded.