LG MM-535 Owner's Manual page 28

Your Sprint PCS Vision Phone's LiIon battery is rechargeable and
should be charged as soon as possible so you can begin using your
phone.
Keeping track of your battery's charge is important. If your battery
level becomes too low, your phone automatically turns off and you
will lose all the information you were just working on. For a quick
check of your phone's battery level, glance at the battery charge
indicator located in the upper-right corner of your phone's display
screen. If the battery charge is getting too low, the battery icon (
blinks and the phone sounds a warning tone.
Always use a Sprint-approved desktop charger, travel charger, or
vehicle power adapter to charge your battery.
Plug the round end of the AC adapter into the phone's charger
jack and the other end into a standard electrical outlet.
It takes approximately 3 hours to fully recharge a completely
rundown battery. With the Sprint-approved LiIon battery,
you can recharge the battery before it becomes completely
run down.
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