I just want to ask how many volts of battery should I use to power my arduino project. I have 5 buttons, 2 DC motor, 2 servo motor, 2 HC-SR04 sensor and a bluetooth module if I want it to last for about 5-10hrs. Thank you!
Just imagine your design needed a 1.5V battery. There are various sizes around, like AAA, AA, C, D and so on. They all provide 1.5V nominally. The difference is the amount of power they can provide, namely the number of mAh (milliamp hours).
Therefore the size of your battery depends on how many milliamps each device uses, and how many hours you want it to run.
How will I compute for the mAh my device uses?
Some devices will tell you on the device or on the datasheet. Otherwise you could measure it with a multimeter. Make sure you understand how to measure current with a meter. There will be many web pages with guides about that.
And by the way, it doesn't use mAh it uses mA.
Look, if you have a room heater that draws 1000W, then it draws 1000W while it is on. So, if you run the heater for an hour then it will use 1000Wh (1000 watts for one hour). That will use twice as much energy as running it for half an hour.
So, if your device takes 100 mA, and you want to run it for an hour, then you need a 100mAh battery. If you want to run it for two hours, then you need a 200mAh battery. Same mA from the device, but you are using it for longer.