E37e36 won't turn over without jump

[Pbinky]

My Z3 sat this winter, not good in the snow/salt. It started a couple times during the winter just fine. But the trunk light was on and the battery drained down to nothing in March. I put it on a charger and although it didn't want to take a charge, it finally did. it has been starting and running fine for the last couple weeks, although every time I go to start it it sounds like the starter didn't want to turn over as quickly as it use to. It seemed to hesitate just a little. This morning it hesitated but started. Got out of work, it cranked a little and stopped. I cranked it again it bearly cranked and stopped. After that it just clicked. I got a jump from a guy and it started right up. It ran just fine all the way home, shut it off. Tried to turn it over. Same problem that I had after work. Cranked a little, Cranked a little less, then clicked. Checked battery, full voltage. Windows and other electronics seem to be powering up just find. Jumped the car again, started right up with no hesitation from the starter.

Am I by passing a fuse or something else by jumping the car?

Don't know where to begin. Thanks for any help in advance!