Can the remote controller powered by cr2450 button battery be powered by an external 3 volt power supply?

It is absolutely possible, because the power supply method is the same as the battery model, so there is no problem, but it is not recommended to use it.

First of all, the current used by various remote control boards is small, and the basic standby is only a few microamperes. Generally, ordinary dry batteries are used, with large internal resistance and low output current. The internal resistance of the rechargeable battery is small, and the output current is relatively large.

Because the remote control consumes too little power, it will not be able to complete the cycle charge and discharge, which means that the standby time is short.

Are cr2450 and cr2032 common?

cr2450 and cr2032 are not universal. Cr2450 and cr2032 batteries are different in size. CR2032 has a diameter of 20mm and a height of 3.2mm, and CR2450 has a diameter of 24mm and a height of 5mm. The rated capacity of the battery is different, CR2032 is 200-240mAh, CR2450 is 520mAh. CR2450 can be used instead of CR2032 when there is no external size limitation; if CR2032 is used instead of CR2450, the capacity will be less than half of it.