Samsung SPH-A620 Owner's Manual page 13

Charging the Battery
Your Sprint PCS phone comes with a rechargeable battery. You
should charge the battery as soon as possible so you can begin
using your phone.
Keeping track of your battery's charge is important. 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 gets too low, the battery icon
( ) blinks and the phone sounds a warning tone.
Always use a Sprint PCS-approved desktop charger, travel
charger or cigarette lighter adapter to charge your battery.
Warning!
Using the wrong battery charger could cause damage to your
phone and void the warranty.
Using the Travel Adapter
Plug the connector of the supplied travel adapter into the serial
connector at the bottom of your phone, and then into the AC
wall outlet.
When the travel adapter is plugged in and charging the phone,
the phone displays a charging light and the battery icon starts to
blink. The phone can still be used while it is plugged into the
travel adapter, but this will cause the phone to charge more
slowly. To quickly charge the phone, turn the power off.