Newbie here, I am looking for batteries to power my Arduino Nano. It is important that the battery measures less than 12mm in diameter in order to fit into a dedicated space. Length isn't that important, but it would be nice if it was smaller.
I found LH1130H - 1,5V / 60mAh / 11,5mm
Can I use them and how much should I use?
3 = 4.5V Can it even run?
4 = 6V More than 5V (saw 5V being recommended)
6 = 9V also saw it recommended
How long can I expect them to last (I don't know how to calculate it)? I'm running Arduino Nano with 0.91 inch OLED screen and microSD card reader
About 1 hours if you're lucky. As your batteries are tiny they don't provide much Energy (60mAh). The Nano for itself needs about 35mA, the OLED (at least the version I found, you failed to provide a link to it) should be below 1mA (which is quite surprising) and the SD card needs about 30mA (depending on which card you're using and how much you write on it). This sums up to over 65mA so the battery energy lasts for less than an hour.
The LM1117 voltage regulator has a minimal dropout voltage of 1.2V which increases to about 1.3V if you draw the current you're using.
So the input voltage should be at least 6.3V, so you need at least 5 batteries to get that voltage. You need 6 of them if you want to have enough voltage when the batteries are getting discharged and the voltage of each decreases.
Theoretically yes, but you'd need two of them and that a lot of energy wasted in the voltage regulator. And these will last about 1.5 hours approximately.
I strongly recommend against that. A battery voltage isn't stable enough to do that.
Considering the dropout voltage, I should aim for higher than 5v.
I chose to go with 6 x LR43.
This part I don't understand. Would I be able to simply wire 6 x LR43 in series, plus side to the 5V pin on an Arduino and the minus side to GND, or would I need to use some sort of regulator, resistor, etc.?
Plus side to VIN, not 5V! You can provide power to the 5V pin but that must be a regulated voltage, not simply a battery. The Nano has a regulator on-board and by powering by the VIN pin you're using that one.