USB Portable Charger (3A w/ flexible input)

This thing is a portable USB charger, which can be powered off of any battery that puts out about 8V or more. I use commercially available portable chargers, but also keep a few of these around for emergencies. After all the available portable USB chargers are dead, but you have some random batteries laying around the house, this thing can really save the day.

BOM:

-1@ printed top

-1@ printed bottom

-4@ M3x16 allen head bolts

-1@ USB 2.0 plug adapter (https://www.amazon.com/gp/product/B07W7XMV3W/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1)

-1@ MP1584 3A buck regulator module (https://www.amazon.com/gp/product/B01MQGMOKI/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1)

-4" 16awg wire

-1@ battery connector of your choice (my RC fleet uses Dean's Ultra, as shown in the photo)

Printing

Nothing special here. No supports needed, unless you are picky about your counterbores then add buildplate only supports for the top. Most filaments and printers should easily be able to print this either way.

Assembly

It's easiest to first solder your battery connectors to the wires, then solder all the wires to the regulator, then solder the wires to the USB board.

When everything is soldered, insert the boards into the bottom half of the case as shown in the photos. Hold the regulator down firmly with one finger, while using a nail heated up with a lighter to melt down the side rails in at least 2 locations so that they hold the board in place (see photo for an example). Do not release the board with your finger until the plastic has cooled for about 15sec. Note that if during melting the plastic bulges up or outward, it will interfere with assembly. Trim any bulges with a knife, or melt them down with the nail. Alternatively, you can add a few drops of hot glue around the board to hold it down. However you do it, be careful not to get glue near the adjusting pot.

Now push the USB board all the way down and slide it back such that the holes line up with the case. Play with the wires inside as needed so they will not get pinched when installing the top. With the battery wires run through the strain relief hole, finish assembly by securing the top to the bottom using four M3 bolts. Tighten the screws all the way until the 2 halves touch all the way around; the strain relief applies pressure to the wires, which will make the 2 screws on that side harder to tighten all the way.

Before first use, be sure to use the adjust pot to set your output voltage to 5.25V. There is a hole in the top to access the pot after assembly if needed. The USB board makes it easy to add resistors or whatever else you may need to add (for example, some phones need a resistor between the data lines to enable fast charging).

Enjoy!

Print Settings

Rafts:

No

Supports:

Category: Electronics