An old toolbox? an old pc speaker? an unused 12 volts battery?
You can make a radio (with usb + sd card reader) + usb charger + emergency light (or daily use? why not?) + energy bank.
Sorry for my english, I try but, is difficult.
Its my Dakar Rally radio
Step 1: What Do You Need
-Old pc speaker (used)
-A battery 12 volts, I recommend 7 a/h
-Voltage regulator for speakers. If the speaker is 12 volts, is not necessary (US$1 in aliexpress.com)
-Car power point (female) (2 dollars or less)
-Usb charger, used in a car (2 dollars maybe?)
-Radio panel (without amplifier) (US$6,29 aliexpress.com)
-Led light 12 volts, 3 or 5 watts (US$3)
-Mini Solar regulator (US$6,22 aliexpress.com)
-Voltmeter (US$2,15 aliexpress.com) (optional)
-dc power jack (male - female)
-1 solar panel: for diary use, you need 10 watts, for non diary use, 5 watts or less.
Step 2: Layout
Step 3: Connecting
-Use the voltaje regulator for the electronic of the speaker amplifier (pc speaker). In my project, is 9 volts.
-The radio module, the car power point and the led light are 12 volts.
-It is recommended to use a mini breaker or fuse.
-The 10 watts solar panel charge 0,58 amperes by hour. In 8 hours of charge are 4,64 amperes. Full charge in a 1 1/2 day approx.
- The solar panel of 5 watts full battery charge in 3 day for emergency case.
-The solar regulator is behind the solar panel.
-The dc power jack (female) is for connect the solar panel or other supply 12 volts (for charge) or the led light.
General fuse: 2 amperes
Other fuses : max 1 ampere.
Step 4: Instructions
-The switch 2 for charge or turn on the connector for the light.
The switch 3 for turn on the power point for usb charge.
-The general switch turn off the battery (no charge)
-The radio need FM antena. You can use an recycled antena or a simple wire (2 meters).