Via 761 HP, I've been able to vote via Hive Vote at 2.15% at the lowest via the Curation Trail and Fanbase. The creator says that his app and/or the Hive Blog blockchain has a minimum requirement of 15 HP per upvote.
Therefore, based on the total HP I have, I'm assuming that means 2.15% is the lowest I can vote at a fixed rate. I doubt that it would be possible to vote at 2.15% at scale as that would attempt to make it an even smaller number.
So far, I've not been able to vote at 2.15% fixed when my total voting power is under 90% as far as I can tell assuming it is not due to other reasons.
I tested at voting via a higher number and was able to do it. The founder said you can vote at a minimum of 100% weight if you have at least 15 HP. I'm guessing that means you can vote at a minimum of 50% if you have 30 HP. The math might be slightly off, I'm not totally sure.
One thing that confuses me is how am I able to vote at one percent via the Hive Blog or PeakD app? I guess the answer is that the Hive Vote app was setup not to go under 15 HP per vote and that other apps allows 1% voting as long as you have enough HP in your wallet. I forget how much HP is required in order to vote at 1% but I know I didn't really notice that I was able to vote at 1% until like a month or so ago, I'm guessing early in January of 2021 is when I first saw this option available for my account via Hive Blog, PeakD, Ecency, etc. I like it.
I believe you can set your HIVEPOWER threshold.
For example, I have mine set to only autovote if my HIVEPOWER is over 80%.
That way I'm not "losing" rewards if I step away for a week or two.
I set my threshold or minimal voting limit to 70% Voting Power total but it stopped at 90% when I voted at 2.14% Vote Weight. But if I was voting at a higher weight, then it continues to vote as my voting power went below 90%.
It might be that it will not upvote lower weighted votes under 90% power, so far that looks to be the case. But I have picked to vote for a few accounts at 100% weight which means my voting power could drop a lot if I'm voting a lot or too much.
I may change my threshold to 80% or 90% in the future. For now, my limit is set at 70% and I will see how that works out.