I’ve not done beans. I have done Du Puy lentils at Christmas time.
When I looked for information I found recommendations ranging from the 190F for 6 hours to 196C for 90 minutes and 183F for 12 hours and a whole lot more.
Vegetables cook at 183F (pectin conversion point) so the temperature had to be at least that. I decided to go for 186F and start with 90 minutes. Lentils were washed and placed in a quart Mason jar. 1.5 cups of lentils to 2 cups of stock, some bay leaves and thyme (I don’t usually add herbs to a sous vide cook, but seeing as it was over the vegie temperature). No salt, because my stock had been salted when I cooked it.
After 30 minutes in the jar I was a little concerned that I’d over filled the jar, but it turns out all the swelling happens in the first 30. I checked the lentils at 90 minutes and found them cooked, but still a little firm for my liking and decided to give them another 30 minutes. I got caught up in other things, so by the time I checked the lentils again it was 2 hours later. The lentils were softer, still with some bite. As I wanted them for a salad this was fine for me. I drained a bit over half a cup of stock from the jar and 1 quart of lentils.
I will try them again and give them more time, perhaps overnight. I find there is such a brief time between cooked to perfection and mush doing them the traditional way that it’s worth testing this way further.
I have no doubt that they could be cooked to a point where they no longer maintain their structure, but I’ve a sneaking suspicion it would require way more than 24 hours to do it.