Having a working smartphone during a disaster could be a lifesaver. But a phone is only useful if it has power.
What if your phone is in dire need of a charge but your home is still flooded and there is no electricity? YouTuber Berani Buat suggests you make a Universal USB Charger.
All you need is:
- A USB car charger.
- A couple of wires.
- A charging cable.
- And a power source over 5 volts.

He explains that the USB car charger is basically a Direct Current (DC) converter and a voltage regulator.
Connect a wire to the positive (centre) terminal, and a wire to the negative (side) terminal and you’ll have a Universal USB Charger.
Just touch the positive and the negative wires to the correct terminals on a DC power source – for example, 4 AA batteries connected end to end in a series, a 9V battery, or vehicle battery–, plug in your smartphone using a charging cable, and you’re set.

A few caveats though.
The DC power source must be more than 5V and less than 30V, and with small power sources like AA batteries, don’t expect it to charge your phone to full capacity.
This trick does not work with the charger you plug into the wall outlet because that uses Alternating Current (AC).
Also, some smartphones can be picky and might not want to charge this way.
Alternatives
Berani Buat also suggests a few other alternatives like a USB Module which is available in quick charge and potted (sealed) version.