

This fixed connector just won't plug into the Lumia 800.
These kinds of external batteries just won’t work with the Nokia Lumia 800. Instead, you’ll need something like this, which connects using a cable:
This one is called the Pama Plug N’ Go, and it seems to work quite well with the Lumia 800. The power pack provides 1000 mA of current to the 800, exactly what it needs, and can hold 4000 mAh (which, as you can expect, can charge the Lumia for four hours, which should be enough for several charging sessions).
So remember: If you’re looking for a Lumia 800 battery or external charger, remember that you’ve got to get one that includes a cable connection, like the Pama linked above.
I hope this is helpful – thanks for reading, and farewell for now.
Gotta love that Pama charger! I reviewed it and thought it was awesome :o)