thid wrote:Hello
I recently bought raspberry pi b+ and ac adapter 5V 2100mA, but when I connect my sata drive 2,5 it doesn't start (lack of power), the cable have 3 usb-y outputs, 1 is for HDD, 1 for data and 2nd for extra power. I allready checked and when I connect power-only-plug to ac adapter 5V 1A the HDD starts. My question is, if I can damage raspberry pi this way?
It will not hurt the RPi to run the drive with external power. For a B model that is the only way to make it work. The B+ has ability to be set to higher current setting of 1.2A instead of the default 600mA. See link echoed above.
Unless specified otherwise my response is based on the latest and fully updated RPiOS Buster w/ Desktop OS.