SEGA Nomad - External Battery (18650 + USB-C)

About the design

I wanted to have a Nomad battery design that can be built cheap, and printed easy.
This version can be printed without any supports, and offers 4 variants (see Variant choice chapter for more info).
It's using cheap and common parts from AliExpress (not affiliated), and I wanted to offer this design for free commercial use (attributed) for everyone to enjoy this!

It's not meant to be super pretty, like the original battery - no major design features to it, and a bit bulky in appearance due to the parts used. However, in it's usage, you wont even notice the bulkiness, and it super efficient! With quality cells, you can run for over 12 hours off of this.
Additionally, you can charge the battery while continuing to play, so you can hook it up to a powerbank without losing progress during a long session of your favourite game!

there is some soldering required, the easiest version only requires you to solder on 2 wires, others are a bit more advanced, so make sure you are comfortable with that before starting this project!

How to Build one?

Variant choice

You'll first have to choose what version you want, there's a combination of 4 total variants available to make from this.

Listed from easiest to more difficult in terms of soldering:

• Wired connection without power switch

• Wired connection with power switch

• Back connection without power switch

• Back connection with power switch

The power switch allows you to cut the boost circuit off, prolonging the battery life between gaming sessions.

Hardware required

For all versions, you have to get a battery charging module, with built in boost converter.
Make sure you get the 9V version!

I have used this one: Type-C 15W 3A 18650 Lithium Battery Charger Module

Any M3 screws, ranging from 8-20mm long, you need 2 to hold the charger module in place!

Glue - I personally prefer this UV curing glue (the pen variant), as it cures fast and holds up really strong!

Switch versions

1x Switch (SS12F15): https://aliexpress.com/item/1005005644705097.html

Wired versions

1x Connector (4.8 * 1.7): https://aliexpress.com/item/32801958317.html

Back connection versions

2x BC-36 (1 Pin) battery connector: https://aliexpress.com/item/1005009174320987.html
2x M2.5 x 4mm (countersunk): https://aliexpress.com/item/1005010412843698.html

Batteries (important!)

You need to use 18650 cell, but there are a lot of fakes ones around!
Ensure you purchase yours from a legit place (Mouser, Digi-key, Reichelt, Conrad, etc).

You need the flat-top variants, otherwise they don't properly fit in the shell.

18650's don't go above 3500MaH (as far as I am aware), any that do advertise this are gonna be fake!
I tested this with the "worst" cells I could find locally (1250MaH from a vape shop), and still got ~6 hours continuous use on them. If you care about really long gaming sessions, again make sure you buy from a quality place, with a quality manufacturer (LG and Samsung are my personal go-to).

Assembly

Base

For all versions, you need to print 4x "BackConnector" and 1x "PowerConnector" - even if you dont plan on using a back connector variant, it's required for proper alignment.
Tip: print the back connectors on their side, and try to slow the print down a bit, this ensure strength and detail to make fitting them easiest!

You need 1x "Shell-Bottom" of the version of choice (switch or switchless).

The connectors slot into place from the inside, where you can hold them into place using friction, as you apply the UV resin glue to securely lock them into place.

Next steps are all based on which variant you want to make.

Switch

If you want to include a switch, you're going to have to modify the PCB slightly, and add 3 wires.
This is so we can enable/disable the boost circuit externally (otherwise it's always going to be on).

The circuit is based around the XR2981 IC (datasheet), for which pin 5 is the enable pin.
Logic high enables it, logic low disables it - by default it's connected to 5v.

You need to lift this pin, and isolate it to the center of the switch.
Ground will go to the "off" position (bottom), and +5v goes to the "on" position (top).

you can then snap-fit the switch into the housing over the tabs, and either use UV curing glue to hold it in place, or melt the tabs with a soldering iron to secure it.

Wired version

This one has the wire coming out of the top, connecting it directly to the Nomad (next to the power switch).

All that is required is to solder your ground and positive wires to the respective UPS+/- pads.
I personally prefer to feed the wires through the mounting holes below it, and snake the wire to the left and out.
Additionally, you can add a little zip-tie to the wire before it exits as a strain-relief.

Back Connector version

This version requires the "Nomad-PowerConnector" PCB (available under the "other files" as zip containing gerbers), and 2x BC-36 connectors soldered on.

You need the m2.5 screws to securely mount the PCB to the housing.
As with the wired connector, you'll have to connect the UPS+/- to the pads on the PCB, and that's all!

Optional

I have also added the "Logo_infill" as a separate model, in case you want to do some crazy multi-colour print build, have fun!

The end!

Snap on the top of your choice, and install the batteries on the bottom.
That's it, you're all done!

Hope you get to enjoy your Nomad as much as I am again <3

The back connector versions are compatible with Oleg Endo's mod btw - I have it installed in mine, and extends the time on batteries even more (as his also has a built-in one!), and it evens allows for hot swapping in/out between them without resetting!

Please share your builds if you end up making one - and feel free to ask me any questions (I am most active over on BlueSky: @PointerFunction