Do you mean that the battery drains quickly?
I own a J3 Emerge but I don't keep mine on all the time.
I also don't have a lot of background apps running.
Open Settings then Notifications. Turn off all but the most critical.
Open Settings then Device Maintenance.
There are 4 choices: the big bull's eye has a button below it that says Optimize now.
Before doing that, it might be worth it to click one of the 3 smaller icons, in this case Battery.
1. There are 3 settings under Power saver mode. If the current one isn't working well, try another.
2. App Power Monitor: Put apps to sleep so that they do not use battery power when not in use. Tap Save power to enable.
