Mine showed 50% charge as it should when I plugged it in to power and it turned it self on. (using an ifixit replacement battery for 3gs.)

It took a some real pressure to push the battery toward the doc connector to get the connector that is attached to the battery to be able to slide over the pin/ screw hole that it mounts to and once it did that whole connector was a little twisted but the contact pints it hits on the board are pretty big so i don't think it will be a problem... and no problem its back together and working now.

Battery I was sent by ifixit is longer and wider then the original in my 3gs. i think it all due the orange tape they use to hold the side flaps and bottom circuit board on. just poorly taped. not sure i am going to be able to make this fit with out re taping the sides and bottom. guide is great. i am surprised no one else has commented about the battery being a hair to long and wide.