Fitbit Charge 3 charging pinout?

Appears that this info is also correct for the Fitbit Charge 4 as well.

I brought Fitbit charge 3 band for less than $1 at scrap store. Thank you for the information, i needed it finally, now I will hack into it

And add new battery and charge without the clip...

Also worked on a Fitbit Inspire 2, which looks similar on the underside. 5V (red) on the left contact, GND (black) on the right, when oriented like the photo.

YES! Wonderful, thank you so much. I taped carefully stripped USB-cables +5V and GROUND and it's charged from 7% to 56% now. Can't thank you enough. Charging my Fitbit Charge 3 right now. Saved me a three hour ride!

I've been using this Fitbit Charge 3 for so long now the display stopped working a year ago. Still tracks good though.

Can confirm this pic applies to Fitbit inspire 3 (orientated that was up it goes +5v, something, something, ground) so I connected my positive wire to the left and negative wire to the right.

I am surprised that, with a 1 amp charger, I was able to get it from dead to about 30 percent with only about 2 minutes of contact total (very fiddly, kept disconnecting and so this was the result of about 20x 6 second bursts, just keep retrying). Lasted the night anyway so got to record my sleep albeit this endeavour had me up until 6am so it was probably not wise.