datalogging strategy

Projects General Guidance
1

I am re-inventing the wheel by making a datalogger using a Nano, a DS3231 RTC board, and a micro SD card board with on-board voltage level converters.

I was going to buffer a few hundred bytes of data in RAM (if there's that much unused RAM available) before writing it to the SD card. However, after googling/reading about SD card write "wear", I don't know if writing bigger chunks reduces "wear".

Does anybody know which of the 2 methods is best, or know of a better third method?

Method 1: Open the file, write 100 bytes, close the file.
Method 2: Open the file, write 1 byte, close the file, and do it 100 times.

2

I haven't verified it in the source by I've read comments here saying that the SD Fat library has an internal 500 byte buffer, in which case you could reasonably assume that represents the preferred approach.

3

That's great news, thank you.

I'll dig into the SD Fat library.