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Topic: Are data cables in USB necessary for recharging? (Read 412 times) previous topic - next topic

Bjack795

Hi all!

Stupid issue but important for me.
If I cut the two D+, D- cables of the four usb ones, the cable still works for recharging via USB port?

Open question for all the applications, from Arduino boards to smartphones.
Are data cables telling something about the state of charge so that the process is blocked if they're cut?

Thanks

Paul__B

And the answer is of course - yes and no!

There are various ways of the data lines being used to tell the charger what voltage and current to provide, beyond 5 V at about 1 A.

Bjack795

#2
Dec 04, 2018, 01:12 pm Last Edit: Dec 04, 2018, 01:13 pm by Bjack795
And the answer is of course - yes and no!

There are various ways of the data lines being used to tell the charger what voltage and current to provide, beyond 5 V at about 1 A.
So it depends on the device?

I was wondering to make a USB port battery pack with these boards here that I ordered for another project, for which I won't use USB port but simply connecting VIN and GND to output pins.

Since they're five, I was thinking about using one of them with some batteries and a voltage regulator to have 5V also in output, connecting the output + and - to the two feed cables of usb leaving D+ and D- not connected. So that this could be used as USB external battery for a device.

But maybe there could be some problems with the lack of signal on D+ and D- channels.


Paul__B

Not really.  For simply 5 V powering it will not be a problem, it only matters for some of the more exotic fast charging modes.

Bjack795

Not really.  For simply 5 V powering it will not be a problem, it only matters for some of the more exotic fast charging modes.
But if my phone has fast charge possibility, if I give simply 5V at 1A will it be fine?

WattsThat

You don't give anything an amp, a device will draw current at a rate it was designed for, if that current is available. If the power supply cannot meet the demand, a good one will shut down, a badly designed one will emit its magic smoke.

IIRC, older Apple devices (pre-Lightning connector) would charge at a maximum of 500ma with no data lines in the cable. As products have evolved and lawsuits have emerged, it would not surprise me that the stuff today will not charge at all without an official Apple charger and cable connected.

Other devices are a huge unknown. Testing is the only way to know.
Vacuum tube guy in a solid state world

Bjack795

Ok, got it.
Thanks, hoping not to see the magic smoke  ;D

olf2012

It is complicated. Just connecting 5V w/o the data lines will probably get you nowhere. A well designed modern device will not draw significant current before it knows what the power supply is able to provide. Good short overview here. An extended description regarding Apple devices here

Paul__B

A well designed modern device will not draw significant current before it knows what the power supply is able to provide.
Fortunately for most experimenters - and indeed general users - such "well designed modern devices" are singularly uncommon.

Nearly everything will operate and/ or charge at an adequate rate connected to a common "phone charger" with only 5 V and ground on the USB socket.

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