OK When you said universal battery charger, I figured something like these: https://www.amazon.co.uk/gp/product/B00TXEF8P6/ https://www.amazon.co.uk/gp/product/B002NTVN7A/ which do exist on amazon.co.uk, and work on any phone battery. I guess you mean something like this: https://www.amazon.com/Deep-Stretch-1Batteries-1Charger-Replacement/dp/B07VFZB8K7 that I could only find on amazon.com

Good digging there!

The 2 UK Amazon UK ones are similar to what I got from Ali. One (for US market, have to use plug adapter) has an monochrome, simple LCD display (not seen on any of these 3). Another one with EU-adapter had a multicolor status indicator light similar to the Amazon US link (which seems exact fit, so is not universal).

I originally got one from renowned brand Ansmann. However, its spring-holding mechanism was not big enough for the V20's size. So I returned it to Amazon (Spain).

So I cannot blindly recommend the 2 UK ones. They may still be too small. Only testing can make sure. So make sure that you can return it.

The V20's battery is both taller and wider than many camera Li-Ion and older phone 's Li-Ion batteries for which some of the universal chargers are made.

OK

When you said universal battery charger, I figured something like these:

https://www.amazon.co.uk/gp/product/B00TXEF8P6/

https://www.amazon.co.uk/gp/product/B002NTVN7A/

which do exist on amazon.co.uk, and work on any phone battery.

I guess you mean something like this:

https://www.amazon.com/Deep-Stretch-1Batteries-1Charger-Replacement/dp/B07VFZB8K7

that I could only find on amazon.com