How much fermentable sugar in cranberries?

So, I made a belgian dubbel last week. After fermentation was done, I made some cranberry puree from fresh cranberries, added it to the empty secondary carboy, and racked the dubbel right on top.

Now, I figured that there would be some fermentation starting back up...but nothing so far. I know that cranberries are sour, but there's gotta be a modicum of fermentables in there. Anyone have any idea?

I have tried to ferment using cranberries before and failed. I imagine that the cranberries will impart flavor into the beer, which might be nice. Maybe you'll have better luck finding fermentables in cranberries than I did, but I'm not convinced that cranberries have enough sugar to make a significant meal for yeast.

Cranberries are less than 5% sugar. They are considered a free food for diabetics. No idea of how much is fermentable, but you aren't starting with much.

Well, that's actually the news I was hoping to hear! I don't necessarily want another fermentation, given that, after adding the cranberry puree, my beer now comes up to the neck of the carboy. I made a blowoff setup just in case, but it's good to know that there probably won't be any more significant activity in there. The flavor is really what I was going for, but I was prepared for the side-effect of more fermentation...

Anyone have any experience with cranberries in the secondary? Do the skins have a substantial amount of tannins? Should I leave the beer on the cranberry for long, or rack after a week or two?

I've made 2 batches of a Cranberry Ale that have turned out well, its been very popular. I basically brew my extract, pour wort into fermenter and add a pound or so of thawed cranberries. So far the beers have been a light beer with a hint of tart cranberry with good aroma. My only issue has been the cranberry skin has gotten into some bottles but think this can prevented going forward. But as said, this has been successful for me.

I like to use the cranberries as my father in law manages a cranberry marsh thus I have good access to berries and its something different.

If you add enough they'll ferment. I put 6+ pounds in a lambic and while i didn't get a krausen or anything there's been lots of bubbles produced.

Just do a Google search for "nutrition facts cranberries." You'll be able to calculate exactly how much sugar you're adding.

I just made a cranberry wheat. 1.052 OG used half wheat malt and half pilsner. I also added some 20L Crystal, little Vienna and roasted barley for color. Hopped to 18 ibu with perle.

Three pounds of crushed cranberry was thrown in the primary. After it was chilled I poured the wort into the bed of cranberries. Then pitched WB-06.

Waiting it out now.....