So many people think raisins are nutrients and they are not. They might add a tiny bit of volume in the mouth. And a taste of sugar. But there is zero reasons to think a batch of mead can be successful using raisins as nutrients. That's just bad misinformation. Save yourself some trouble and feed your Mead. I have posted some info in the link on the raisin. Please look for yourself.
http://www.whfoods.com/genpage.php?tname=nutrientprofile&dbid=24
http://www.whfoods.com/genpage.php?tname=nutrientprofile&dbid=24