Solar power phone charger and battery packs are getting too mainstream. But you know what the problem with each of them is? If it's the middle of the night and your phone dies, your solar power charger won't be much help. And battery packs? It's hard enough to remember to charge your phone everyday, what makes you think we would remember to charge our battery packs after using it?

So why not have the best of both world? Here are instructions and parts you need in order to build a solar/wall charged battery pack/flash light

Warning!

This is my first instructable, so I'm sorry in advanced for any missing or unclear steps.
This is my school project for creating a gadget, so this design might be unsafe and I wish for feedback to improve on this.

Step 1: Parts to Use

Electronic Parts:

-5V .25 A Solar Panel

-5V Step up boost module

-Dual-USB Output 5V Boost Module

-Nokia BL-5C 3.7V Battery

Tools:

-Wire Strip

-Soldering Iron

-Hot Glue Gun

Other Parts:

-Extra wires

-Plastic or anything to use for houseing

Step 2: A Housing for Your Components

In order to keep this on a pocket safe device, I advised you getting something to attach to the back of the solar panel to keep all your components safe. If you want to be lazy about it, buy a mini box from the dollar store and glue it to the back of the solar panel. If you want to be crafty, cut acrylic to the shape that you desire.

Before you glue the housing to your panel!

-Remember to make two holes for the positive and negative

-Remember to make holes for all the other USB outputs, it's difficult to make holes once you glue it on.

Step 3: Solder Your Wires (Panel to Step-up Module)

Make sure to leave the wire longer in case you end up routing it differently than you originally would have, better to have it long than short. Also be careful when using the hot glue, I accidentally glue my paper to my desk and burned my fingers. :(

Start with:

Solder your positive lead from the solar panel to the IN+ hole on step up module.
Solder your negative lead from the solar panel to the IN- hole on the step up module.
Hot glue the step up module to the side near the middle of the panel, with the USB facing out.

EDIT: It has been pointed out to me that I am missing a diode to prevent back flow of electricity.Link to buy one 1N914 Diode. Even though your cellphone will still charge with just those, it is always better to be safe than sorry. New steps with the diode are below

New steps:

Solder your positive leader from the solar panel to the positive side of the diode (orange side). Twist the wires together with the diode lead before you solder it down.
Solder your negative end (black band side) of the diode to the IN+ hole on the step up module.
Solder your negative lead from the solar panel to the IN- hole on the step up module.
Hot glue the step up module to the side near the middle of the panel, with the USB facing out.

Reason for leave space above and below is to put the LCD Dual USB PCB Module above it, and leave space below for batteries.

Just like that, the solar panel charger part of this 2 in 1 project is now done and ready to be used.

Step 4: Solder Your Wires (LCD Boost Module to Batteries)

This was by hard the most difficult part of the project. This part alone took me over an hour. There's a reason why your cellphone battery should not exposed to heat higher than normal. The BL-5C Nokia battery has little bits of black soft plastic between the positive lead and the negative lead. The amount of heat to melt this piece of plastic is way less than solder. I ended up melting the top plastic before my solder even melted. I ended up having to redo this many times due to the melted plastic acting as an insulator.

Start with:

Assuming you have multiple battery, solder the positive leads of the battery together in a parallel. (Same 3.7V double/triple/.... capacity)
Do the same for your negative leads, solder them in a parallel.
Solder the red wire (positive) of the LCD boost module to the positive end of the battery.
Solder the black wire (negative) of the LCD boost module to the negative end of the battery.
Hot glue the connection where the leads come out the battery (as picture shown) this is to prevent a short from wiring touching.
Hot glue the battery to your housing to make sure it wont go anywhere.
Hot glue the LCD boost module to the top of the housing, make sure the lcd is facing outward so it can be seen.

TIPS:

Avoid using old cellphone battery if you could. It might be cheap and cost effective, but it's a hassle to deal with. I recommend using 18560 Lithium battery and buying a pre-made housing for it.
Remember to keep the black button on the LCD boost module at a convenient easy to reach spot, as it is needed for many of its functions.

Now you are finished with the rechargeable battery pack part of this 2 in 1 project.

Step 5: Extra Tips to Know

WARNING AND TIPS:

The specification on the LCD boost module is unclear, so here's two pages you get from buying it.
DO NOT use your solar output to charge your battery without having the diode. Bad things will happen, very bad things.
If you decided to cut or melt acrylic sheet like me, please do it outside in a well ventilated area while wearing a mask. Burning/melting plastic releases dioxins which should not be inhaled.
Again with the battery, if you can afford 18650 Lithium battery with a pre-made holder, you can save yourself tons of hours and hassle with this.
Try to insulate any wiring and protect all your components with a housing. You don't want your stuff to short circuit.

And one last time, this is my school project and I am looking for feedback on improvements for a version 2 of this. Thank you guys for taking your time to read this :)