Can't find low battery threshold setting (Samsung Galaxy S3) When the phone's battery reaches ~20%, I get the message to connect my charger on the lock screen. Is there a way to lower the threshold for the notification -- similar to the setting for a laptop?

For clarity, I want to change the settings so that the "Connect your charger" message appears when my battery is at 5%, instead of its current threshold, ~20%.

I should mention that I'm looking for a setting that's on the phone, without the need to modify back-end files. Also, I've actually gone through the whole settings section looking for the option and didn't find anything. Hopefully, I didn't overlook it.
There is no setting available in any Android ROM that has the battery threshold setting. 

From the previous answer given, it is built in.

Only course of option is to roll your own Android build, with the hard-coded value adjusted, but, and is a big but indeed, it is not the recommended route to take, as the code behind Android to handle the battery mechanism varies from chip-set to chip-set and to each and their own manufacturer. 

By adjusting it, there could be invariable damage to the battery as a result, since the threshold is specified, by "tweaking" it could affect the battery in the long run and possibly end up shortening the battery life also.