We recently noticed that the battery life of our original Pebble was reducing, and it was becoming borderline if it would make it through the night (we need it to run from about 19:00 to 08:00 the next day – 13 hours).
I was surprised to find that increasing the “Data Transfer Period” from 20 seconds that I was using to 30 seconds made a huge difference to battery consumption – it easily lasts over night now with significant margin.
I think this must be because the gap between bluetooth transmissions is now long enough to allow bluetooth to go to sleep in between, which it was not doing previously, but I don’t know enough about bluetooth to know if that is true or not.
So, if you are having trouble with battery life, change Data Transfer Period (in pebble settings) to 30 seconds.
I would only do this once you are happy that the system is working properly, because it means that the data on the phone display will only update every 30 seconds, which is a long time to wait if you are testing it. It also means that initial start-up will take longer, because the system waits on the start-up screen until it receives a routine data update.
Changing the Data Transfer Period does not affect the alarm response though – if the watch detects a warning or alarm condition it sends data immediately, irrespective of the Data Transfer Period setting.
Hope that Helps!