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Is 2.4A USB on power inverter safe to charge phone?

Rupertrealbear

Mar 31, 2021
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Mar 31, 2021
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Hello there

I have a new phone (Oppo Find X5 Lite) with a rechargeable Lithium-ion battery described as:-

DC 7.74V 2200mAh/17.02Wh(Min)
DC 7.74V 2250mAh/17.41Wh(Min)
Equaling to
DC 3.87V 4400mAh/17.02Wh(Min)
DC 3.87V 4500mAh/17.41Wh(Min)

The supplied ultra fast charger (one hour) has an output described as:-

5.0V -> 2.0A to 10.0V -> 6.5A (Max)


I acquired a Bestek 300W power inverter which plugs into my car's cigar lighter into which I can plug the supplied ultra fast charger.

The inverter also has two USB ports marked 2.4A and are described in the specifications:-

5V -> 4.8A, 5V -> 0-2.4AX2

I suspect that my best plan [with the power inverter] would be to plug in my ultra fast charger.

I could see how quickly the USBs on the power inverter charge my phone but I don't know if it would be safe to do that (or even to plug in other, fairly recent phones with chargers described as 5.0V -> 2.0A)

Are the specifications I have provided enough to go on?

Many thanks
 

Martaine2005

May 12, 2015
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Each phone or device will only draw the current it requires. You can supply 100 Amps, but the phones circuitry may only require 1 or 2A and that’s all it will draw.

Martin
 

Harald Kapp

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Nov 17, 2011
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I could see how quickly the USBs on the power inverter charge my phone but I don't know if it would be safe to do that
It is likely to work, but not at the high charge rate you expect.
Standard USB is rated 5V, max. 500 mA. Quick chargers, as the one supplied with your phone, are able to deliver higher currents and, as in your case, even higher voltages to deliver more power to the phone. This requires a handshake between the phone and the charger - by way of said handshake the phone informs the charger about the higher charge parameters. This is required to prevent damage to standard conforming USB devices (5 V only) from overvoltage.
The charge ports in your inverter are unlikely to have the required interface circuit for this handshake. Therefore these ports will deliver only 5 V. Whether the phone will draw more than the standard 0.5 A from the 5 V line depends on the design of the phone.
The better option is using the quick charger and plug it into the inverter. Then the handshake can be performed and the phone should really charge faster.

As @Martaine2005 said: from teh inverter's 5 V output the phone will draw only as much current as it needs. It will not be damaged (provided teh 5 V port of the innverter is designed correctly).
 

Rupertrealbear

Mar 31, 2021
9
Joined
Mar 31, 2021
Messages
9
Thank you very much. I think that these "charge" USBs
are quite slow (there is even one coming out of the car radio). It seems that plugging in the phone's charger is always going to be the best "rescue" option on a long car journey - and probably looking at the scenery, singing songs and playing I Spy rather than being glued to their phones all the time.
 
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