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[tigertiger]

I have bought a mobile power supply/battery pack for a medical device. It can also be used generally for charging other items.
I know nothing about batteries or chargers, and I have a few question, I hope someone can help answer them.


I will give the specs then ask my questions.
Specifications
·         Battery type: Polymer Lithium ion battery.
·         Battery capacity: 40000mAh
·         DC port input: 5V-24V/2A
·         USB port output: QC2.0/QC3.0
·         USB port output current: 5.0V/3A, 9V/2A, 12V/2A.
·         DC port output: 5V/9V/15V/16V/19V/19.5V/20V current limit 6A, 12V current limit 8A, 24V current limit 5A.
·         Output current: 8A max.
·         Static current: below 150UA.





Questions.
DC port input: 5V-24V/2A. It says in the manual that any you can use any AC to DC adapter.
Assume in the range 5-24V?
Is there an Amp restriction on the adapter that can be used? the Adapter supplied is 19V-3.42A.
USB and DC port output current limits. What does this mean for the user? Is it anything I need to worry about?

Sorry if these questions are basic, I am new to all of this.

[kinmel]

The USB port output voltage is out of spec:....    5.0V/3A, 9V/2A, 12V/2A.
The official spec for all output USB connectors is 5v nominal. A limited number of devices have type C inputs that will automatically accept a 5 to 12v range from specialist charging devices.
A 5v/3a supply can safely supply a device rated up to 15watts.
The resistance of the unit itself defines the required input amperage, in this case 2amp, any  amps above that value are available but not used.

[tigertiger]

A 5v/3a supply can safely supply a device rated up to 15watts.
The resistance of the unit itself defines the required input amperage, in this case 2amp, any  amps above that value are available but not used.

 


Does that mean that it is unsafe to try to supply a device rated over 15W?

[kinmel]

Yes, a resistance greater than 15w at 5v will pull more than 3 amps and the unit will overheat, or fail. If you are lucky it will just  blow a fuse.
Everything obeys Ohm's Law.

[tigertiger]

Thanks. Very helpful.

[HMS Invisible]

 


Does that mean that it is unsafe to try to supply a device rated over 15W?

I've had a chance to look it up. The inputs and outputs are typical of modern high capacity lipo/life power banks.


DC Ports
You are quite safe with electronic protection within the DC output ports. This is where your lipo field charger and such like. The voltage stays fixed unless you get a safety cutout.
usb outputs
The quick charge usb ports are what they are.The Wiki describes how the usb load device controls the quick charge rate.   https://en.wikipedia.org/wiki/Quick_Charge
If you have bought a tablet or phone recently your mains to usb adapter will support quick charge. My android phone screen displays the difference while charging from the one supplied, which  ramps up in voltage and current where an old 5volt usb shows as "charging slowly"
DC port input
5V-24V/2A means it will take just about any laptop adapter.

[tigertiger]

Thanks again.