You could make a sketch that reports an 'alive' status every minute or so to a file on an SD card. That way, even if it has died days ago, you'll be able to retrieve exactly the moment when it stopped working.
How many Ah were the batteries?
You could make a sketch that reports an 'alive' status every minute or so to a file on an SD card. That way, even if it has died days ago, you'll be able to retrieve exactly the moment when it stopped working.
How many Ah were the batteries?