i got this today from ebay.
very small compact and...
You can charge 2 units as you fly.
Can be charge from my car . power bank
Blinking light green..charging...solid light green....full charge
And -Outside of the tello .
Works very well
or any place .
There is not one supplied - it is built into the aircraft.
When I saw the description on the one in this thread I was a bit suspicious about it as any kind of 'Fast charging' of this type of battery is generally not a good idea but the specs read 4..35V @ 1A which is the same as all the other remote chargers so it is just marketing speak fortunately. The nice thing about this one is its size as it will probably just slip into the majority of the cases available for the Tello. I got this one and it fits my case but only just.
That is just a bit cheaper than Amazon in the UK (also shipped in from somewhere out east).
It always amazes me when a new product like this hits the market - you have the re-sellers all over all the outlets so quickly with the identical product and also badge engineered versions. A quick search shows it in Amazon, Ebay, Banggood, Aliexpress etc all at more or less the same price and at the moment all shipped in from China. In a month or two the first sea freight will arrive and then you will be able to buy them next day from Amazon (at a price premium) or in a few days (smaller price premium). Of course you can always buy them at the lowest price if you are prepared to wait. Every angle of the market is covered !