Although there are a wide variety of different power supplies, in our applications, power supplies typically convert alternating current (AC) power (from the "wall") to direct current (DC) power that is in turn then used by a device such as a battery charger.
The output voltage and output current is important when selecting a power supply. If your battery charger (or other device) requires 12 Volts of Direct Current (VDC) as an input then you must choose a power supply that provides 12 VDC output. The output current rating of the power supply is also important. If your battery charger (or other device) requires 12 VDC at 2 Amps you must choose a 12 VDC power supply that is rated at (can supply) 2 Amps or more.
A power supply must be capable of providing the correct voltage for your device and it must be capable of providing at least the current that the device requires. A battery charger that requires 12 VDC at 2 Amps will work fine with a power supply rated for 12 VDC at 5 Amps but will not work with a 12 VDC power supply that is rated capable of providing 1 Amp of current.
Never overload a power supply or under power a device. You run the risk of damaging the power supply and the device.
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