Looking at what battery is being used 4 x aaa ok 4 x aa ok usb runs at 5v.
5v 500ma usb power adapter.
The power supply requirements differ by raspberry pi model.
It s for a watch winder not anything too elaborate or expensive.
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So to power something off a usb port it has to be under 5 volts as thats how much a usb port gives out so you can check this by.
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High efficiency and low operation temperature compact size light weight compatible with your usb devices like mp3 mp4 player.
All models up to the raspberry pi 3 require a microusb power connector whilst the raspberry pi 4 uses a usb c connector.
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All models require a 5 1v supply but the current supplied generally increases according to model.
The max current you can draw is 500ma.
Documentation hardware raspberrypi power power supply.
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Dc 5v 500ma use this universal wall ac adapter with your existing usb charging cable usb cable is not included here us plug usb output.
Therefore the max load is 5v x 0 5a 2 5.