Can power banks be recharged from both 120V and 240V?

All the devices you mentioned charge via USB, so really all you need to do is carry a USB wall adapter, that is compatible with USA / UK voltages.

I carry with me a macbook pro lightbar 2016 wall charger:

1. Easy to adapt to any wall adapter, since it comes with multiple wall heads and these are easily found in most local shops.

2. Has universal voltage support.

3. Has a removable USB cable; which means I can plug in (with a suitable adapter) any USB cable to charge any kind of device.

4. Supports "fast charging" on mobile phones that support it, since it has a higher amperage output.

I am talking about the 87W adapter (link at apple.com).

The good news is that from the last 5 years or so that I have been buying gadgets, all the chargers that I have bought - including laptop chargers with USB ports, cell phone chargers, smart phone chargers, wall adapters, multi-plug ports ... are all dual voltage.

If that fails, you can always charge those devices from another USB host, like a laptop or desktop computer.

I don’t have that much experience in power banks but I have yet to come across one that is fed mains voltage at all. All power banks I have seen to date are charged via a USB cable supplying them with USB voltage: +5 V DC.

All wall chargers for power banks I have seen to date are in fact mains to +5 V DC converters; they typically don’t even try to hide the fact by simply supplying a USB out socket (and in fact many if not most power banks simply come with a USB cable, not one for mains).

Since the 120/230 V AC mains voltage is scruntched to DC before any power reaches even the cable to the power bank, you need not worry.

They are only one voltage. 5 volt USB.

All of them use a USB port to charge. It is up to you to obtain USB power locally. How you do that is your choice. You may

• discover your own power blocks are multi-voltage (research, don't experiment!) and get a mains adapter
• borrow a USB power block from your host or hotel
• walk into a UK shop and buy a power block
• find your host has wall receptacles with USB outlets
• plug into your host's PC
• plug into your laptop which has a multivoltage power supply

Neither! Or both! Depending on what you like more.

Powerbanks are charged and discharged via USB (cable). And USB has 5V.