You can upvote with zero power. Your power just determines your monetary contribution, but your vote shows your appreciation and still counts towards the popularity of the post. The number of votes determines the position it takes in trending. You do want to be careful with your voting power. You gain a small percentage back each hour. So, in a 24 hr period, you can power up 20%. Each vote eats about 2%. If you stick to a daily 10 vote quota, you can start each day back at about 100%. If you only log on a couple times a week, you can vote more during your online time and still be back at 100% at your next log on. What to keep in consideration is your earning potential for curation or voting/commenting returns. If you contribute $.01 at 100% you only contribute $.005 at 50%. So your return from a post you curated on is affected by your power. I hope this was detailed enough, my friend.