Voting mana is your vote power under the new HF20 steemscape. The more you have, the more your upvote will be worth within your steempower amount. So, for me, with 800 or so SP, my upvote can be worth up to a whopping 4 cents. That is... if I have 100% voting mana. If I throw around a lot of votes and drain my voting mana down to 50%, for example, my vote will only be worth 2 cents. Do the math, the rest is easy.... 25% = a penny etc.
So, Steempower is not the only thing that determines how much your vote is worth, voting mana is the other half of the equation. The more you vote, the more you deplete your voting mana. So, use your votes wisely and reward those you want to reward knowing that your voting resources are finite. They are finite day to day, but replenish infinitely. So, if you can't vote for someone today, you can always wait until tomorrow to get that vote in.
I hope you find these little tips helpful.