Here's an isolation biceps exercise I think you'll enjoy.
It's great as a finisher -- when you're completing your workout. You don't need to go heavy. I never do. A full range of motion is great for this exercise. Focus on the quality of the exercise instead of going really heavy or forcing too many reps. Don't use momentum to swing the weight. Don't bounce the weight at the bottom of the rep. That will lead to injury. Use a nice, consistent movement, as in the video.
Have a wonderful day!