DIY Switch for Windows Games With a Big Battery

Hello community,

as the Nintendo Switch was a big success I thought that I also need some cool mobile gaming console (other then the typical NDS or PSP ....). I had laying around a Chuwi Hi8 (Dual boot: Android and Windows) and some batteries (18650). My tablet didn't last that long with the stock battery, so I tought I'll add a big battery to it. My Idea was to play typical Windows games mobile (like Trackmania, Gothic 2, Borderlands, N64 Emulator ...).

Step 1: Aquire the Parts You Will Need

For a project like this you will need these parts

Windows/Android cablet (eg Chuwi Hi8) (Gearbest 98$)
Gaming controller (eg Ipega PG.9023) (Ebay ~ 28$)
4x 18650 batteries (eg NCR18650B 3400mah) (Gearbest ~28 $)
Step-Down converter (eg Step-Down Led Voltmeter 4.5-24V To 0.93-20V Dc-Dc)(Ebay ~5$)
Balance cables from RC Hobby (eg 1x 5s and 1x2s Cable) (Ebay 5 $)
Balanced charger for 2s (eg Balance Charger For 7.4-11.V 2-3S 2S 3S Cells Li-PO) (Ebay ~ 11$)

Simple switch (eg took from broaken electronics or ebay)(Ebay 0,1$)

3D printed parts if you want the battery compartment like mine (you could also build it somehow yourself) STL-Files: https://www.thingiverse.com/thing:2783700

Tools:

Hot glue gun, soldering iron, maybe voltmeter, wrench, drill, (3d-printer)

Step 2: 3D Print the Battery Compartment

If you want to use my design, you have to 3d-print my design and glue the parts together

Design:

https://www.thingiverse.com/thing:2783700

Step 3: Solder Everything

Now you have to solder everything and glue all the parts together.

first remove the stock battery
then put the batteries as depicted (circuit diagram) together and solder each side two batteries in series (to get 2x 2s = 8,4V)
be careful when soldering the batteries, that you not short the + and - cables
before you glue everything in place, please test the electronics first (otherwise it will be difficult to change something)
in my case I had to set the output voltage to 3,6V, otherwise the tablet won't turn on
since the description of the step down converter says that the input voltage sould be always 2V higher then the output, our batteries can be run until 2,8V for each cell (check the datasheet of your battery)
if everything is working, then glue the battery to the case and drill beforehand a hole into the back of the case of the tablet and solder the wires to the tablet

Step 4: Have Fun

If all works, just have fun. The battery should last more then 8h and up to 10h I guess (depending on the game you are playing). Since in my case there are 4x 3400 mah (13 600 mah x 3,3 V = ~ 45 Wh) and the CPU has a max. TDP of 4 W. If we say, that the step down converter is around 90-95% efficiency (typical), then we are around 8-10 h gaming time wich is at least twice as high as the Nintendo Switch.

Video: