S7 keeps turning on

[S7user]

So I bought the s7 from someone and it came with unofficial charger, LG (didn't notice).

So when I use the original cable to charge with that charger, it says slow charging. If i use phone while it's charging, the battery will drop some % after a few mins.

Second, on my surface pro 4, the brick thing has USB slot in there. If i connect original charger, same "Slow charging." But if i use different cable, it charges, but when screen turns off, the screen turns back on and the loop continues. It also vibrates everytime the screen turns on and there is bubble near the home button, which I see when I plug in a charger.

I want to avoid paying $45 for official charger. So I've been using a different cable into the LG charger (that cable has 5 pins which goes into the s7, as opposed to 4. It charges fine, but is "Cable" charging.

I bought unofficial charger for $12 which claimed to do fast charging but it does "cable" charging only.

 

[chanchan05]

Just looks like that the output of the charging brick is low. Charging bricks for low end phones range from 500mah to 1000mah (1Ah), and the one that comes with the S7 is 2Ah.

You could get a charger that outputs 2Ah, but that doesn't mean you'll get fast charging to work if the charger isn't Fast Charging 2.0 compatible. But it will charge faster than you do now.

And cable charging is fine. Using fast charging always can potentially hasten battery deterioration if the phone heats up a lot during charging.

 

[S7user]

Yes it's 1ah. But I didn't notice this with iPhone. Just weird how the phone keeps turning on when plugged on.

Also the Samsung cable I use does the slow charge. If I use different Cable then it does cable charging, which is faster.

Right now I'm using the LG charger that has output of 1.2ah at 5v.
Also is using those small external cheap Chinese charger going to damage my phone? I don't have warranty

 

[chanchan05]

Yes it's 1ah. But I didn't notice this with iPhone. Just weird how the phone keeps turning on when plugged on.

Also the Samsung cable I use does the slow charge. If I use different Cable then it does cable charging, which is faster.

Right now I'm using the LG charger that has output of 1.2ah at 5v.
Also is using those small external cheap Chinese charger going to damage my phone? I don't have warranty

I've experienced using those cheap chargers a few times and haven't noticed any deterioration in the battery lives of my phones. The things do break down after a couple of months though and I end up buying again which was frustrating. I just got an original charger.

If the Samsung cable is older, it may be that it's just not capable of holding much current anymore. Just the usual wear and tear.

 

[Toto39]

Also keep in mind that many cheap wall chargers immediately drop from full wall voltage to the 5v needed instead of using several step downs to reduce heat. This can overheat the phone and potentially damage it.

 

[mikedt]

Also keep in mind that many cheap wall chargers immediately drop from full wall voltage to the 5v needed instead of using several step downs to reduce heat. This can overheat the phone and potentially damage it.

All USB chargers only have one step-down.

Which is that yellow and black square component, the step-down transformer.

This isn't a Samsung charger, but they all have similar looking components anyway, and only one transformer.

A serious problem with many cheapo chargers is safety, like it might catch fire or electrocute you, due to cheap substandard unsafe non-approved components. Or inadequate isolation clearance between the line high-voltage side and the secondary low-voltage side.