Hi, I have parallel 2x18650 @3.7v and boosted it using XL6009 to 5v, but after doing it my board now stir-fried lol. Can someone like tell me how this happen, its my first time using microcontrollers and doing power ESP32 through external source. After browsing the internet many proofed that ESP 32 can take power upto 5.2v through its 5v pin. Originally im using mt3608 but it cant power up the esp 32 because I need the wifi too and I have an LCD (5v i2c 20*4) causing the system to just boot infinitely everytime it open, and thats when i decided to upgrade my booster. Please enlighten me. Thankyou
First, do NOT use Lithium cells in parallel. They can catch on fire and/or explode. You can only do that with a BMS.
The esp32 is a 3.3VDC device. The 5V pin is an alternate to the normal USB. Is there a reason you can't use the USB power option?
It is clear from your post that you have much to learn. You need to learn about each component separately before putting everything together.
The first thing is to explain why you can not power with USB.
I can imagine a lot of ways to connect the parts you mentioned. Post an annotated schematic showing exactly how you wired it. Also post links to the technical information on the parts you are using.
Explain how you adjusted the output of the mt3608.
My project is supposed to operate outdoor independently that's why i used a battery in parallel and get it charged through tp4056 from a 6v solar panel (used a downbuck controller to minimize it to 4v).
I'll be setting it up using my tp5100 and set it to 2s mode later. I forgot to mention also that my board got fried while the solar panel is disconnected, its just I'm trying xl6009 and the battery to power my board
How does that change the fire/explosion part?
Is that what is going to happen to the schematic, and links, if so I am out.
sorry, it does not concern any part of the explosion part. The board got fried only includes Battery in parallel, xl6009 and ESP32
emphasized text
XL6009: XL6009 DC-DC Buck Boost Converter Module Pinout, Datasheet, Features & Specifications
Lithium batteries should not be connected in parallel without the use of a BMS.
That connection did not fry your board.
how is it possible 
I even used a multitester to ensure i am on 5v from by booster out. Aight I need to learn more deeper for this and each components before trying it out.
Looking at your schematic and the picture in the link you provided it seems you wired it wrong. Note the orientation of the converter is different in the picture in the link and in your
schematic.
Hi @schif3r ,
Welcome to the forum..
Sorry for your troubles..
Kind of looks like it's hooked up reverse polarity on both input and output..
good luck.. ~q
Do you need that many pins on your ESP board (LCD displays can have an I2C backpack).
Many small ESP boards,like the Seeed XIAO ESP32C3, have a battery connector and a built-in charger. Then you don't need a boost converter.
Leo..
Can i ask, how is it on reverse? Im sure the in + and - eill be comnected from the battery + & - and out going to esp32
Can you quantify the risk of connecting these 18650 cells in parallel.
The following post is an analysis of of a 2 cell 18650 boost converter module: At last -18650 charge/boost module with load sharing? - #36 by ShermanP
According to the schematic (and my measurements) the two cells are in parallel.
That is one of the threads that document the issues with all those single, 2x, 4x 'charger' boards.
The specific flaw I am referring to is that unless the two cells are IDENTICAL in SOC and discharge rate, one cell will try to charge the other, and the pair will oscillate back and forth. This can be prevented by using a BMS (Battery Management System)
in your diagram, black wires are going to + and red wires are going to -..
hard to see the + and -, look at the caps, the black half moon on top identifies the - pin..
maybe it was just wrong on your drawing??
good luck.. ~q