Question: why is the DC to DC converter listed there is a 24 hour continuous use max? what if i exceed 24 hours is that dangerous?
Answer: If you mean this line in the description "1. Long working time: Can work on 24 hours." I think it boils down to being a bad translation. I would imagine with a good amount of certainty that they meant 24/7, meaning it should work continuously, non-stop, without issue.
I've certainly run mine past 24 hours. It's powered a CCFL backlit LCD in my bartop arcade for close to a week non-stop without any issues. Gets a little warm to the touch, but I've checked and compared it's temps with the power brick it's connected to and it remains cooler than the source powering it so I'm confident it should be fine at the rated power limits with 24/7 use