Hello, I have a custom 24v scooter with two underpowered 12v DC computer fans, each rated at 0.16A. These fans are the 3 wire style, they just have hot, ground, and a feedback wire. They had previously been running in parallel from a 5v USB hub, but they are weak. I'd like to deliver proper voltage and hopefully control speed. I should add that the fan speeds are not super-critical, it would be cool if they reacted to increasing temps, but I'm fine with a simple pot

I thought about wiring them in series to the 24v power tap from my scooter's ESC, but I know they might wear unevenly, plus they'd always be going full speed. I figure the best option is to couple a 24-12v step-down converter and a fan governor board, but I have a lot of components and donor devices laying around, is there a simple circuit I can build to do the job? Or maybe an all-in-one component/product that would work?