Does USB cable affect charging speed.

bob_a_builder

Chart here shows relationship between wire thickness and cable length at different charging currents

Indicating USB cable construction is pretty important

https://goughlui.com/2014/10/01/usb-cable-resistance-why-your-phonetablet-might-be-charging-slow/

TELLIT01

I should have said that I am charging from a mains connection, not from a USB port on a computer. The information about cable construction is still relevant. I bought a couple of long cables so I could more easily use the tablet whilst it was charging. Maybe not such a great idea after all.

DoaM

The_Fat_Controller wrote: »

If you charge from another device's USB port, the current is normally limited to 500mA .

The supplied charger for a device will be able to supply the correct matched maximum current for charging, which could be over 2A.

However, at such small currents, the cable itself is highly unlikely to affect the situation.

2A is not a small current. 15mA at 230Vac can kill a person. Also, 2A at 5Vdc is 10W power source. 1 Ohm resistance in the cable would lead to 4W power dissipation in the cable, and also a reduced voltage source at the device end.

As said in post #2 ... I = V / R thus V = I x R, which means 2V drop across the cable. Also, P = I^2 x R, hence 4W dissipation.

#OhmsLaw

that

https://www.digitaltrends.com/mobile/how-does-fast-charging-work/

Here is the usb data pin joining trick - do it at your own risk
https://www.androidauthority.com/how-to-fast-charge-samsung-galaxy-phone-using-any-usb-charger-66256/

almillar

I should have said that I am charging from a mains connection

Well, from a transformer. And it should state what the output is. Very likely to be 5V, then 2A, 1A or 0.5A (500mA). Once you work that out, you plug the cable in and see if you get the maximum. A nice fancy 2A cable won't get 2A out of a 0.5A charger!

Biggus_Dickus

OP, ...it’s probably/possibly a usb-A to usb-C cable that you use to charge your Samsung.

Just because the usb cable end’s looks the same and fit the same, and are described as usb-a to usb-c, it doesn’t mean that the actual wiring itself is necessarily manufactured to the same specification as a good quality cable.

That’s why some crappy cables you buy from eBay et al appear, to all intents and purposes, the same as properly spec’ed cables,... and they will charge your device,...but the charging rate you get from them is often abysmal.

The_Fat_Controller

DoaM wrote: »

2A is not a small current. 15mA at 230Vac can kill a person. Also, 2A at 5Vdc is 10W power source. 1 Ohm resistance in the cable would lead to 4W power dissipation in the cable, and also a reduced voltage source at the device end.

As said in post #2 ... I = V / R thus V = I x R, which means 2V drop across the cable. Also, P = I^2 x R, hence 4W dissipation.

#OhmsLaw

Charger voltage is nominally 5 V

My mobile battery is 3.7 V

If you had a 2 V drop across the cable then the battery would not charge.

https://www.omnicalculator.com/physics/wire-resistance

Biggus_Dickus

that wrote: »

https://www.digitaltrends.com/mobile/how-does-fast-charging-work/

Here is the usb data pin joining trick - do it at your own risk
https://www.androidauthority.com/how-to-fast-charge-samsung-galaxy-phone-using-any-usb-charger-66256/

...that article should be headlined “DON’T TRY THIS AT HOME!” :eek: