I have a Samsung galaxyS3 the battery has been charging really slow. It can take up yo 10 hours to charge 100%. I have tried every thing I can think of. I've tried a new charger, new battery, shut down all apps running in the backgrond, taken out the battery and held down the power, volume and home screen button, deleted junk apps. I've thought about reseting my phone but idk if that would help or just make more work for me. Also I put both my old and new battery in a friends phone and both batteries worked fine. Any ideas?
It might be worthwhile to invest in a charge only cable. I use one for my tablet at home and in my car.
The quality of the usb cable will also make a difference. Cables do go bad. It sounds like you have ruled out all the other options so this might be worth trying.
Charging is a simple process and can be represented by the below (simplified) equation:
Rate of Charge = Rate of Electricity Flow - Rate of Depletion
To maximize the rate at which your phone charges at, you want to reduce the rate it's using up your battery as far as possible, and increase the speed at which current is flowing into your phone as much as possible.
Reducing Battery Usage
This is pretty standard stuff, turn off all unnecessary toggles and apps. Disable WiFi, Bluetooth, GPS, and any constantly running apps. If you happen to be charging your phone in an area with poor or no cellular signal, the constant searching for mobile networks could be a significant contributing factor.
Go to Settings->Battery Usage (or something similar, I don't own a Samsung device so I can't be sure), and look at what's using up your battery.
If possible, consider turning on airplane mode, or even turning your phone off completely to minimise battery usage.
Increasing Speed of Current Flow
Look at the thing you're plugging your USB cable into. If you're charging it via your computer, chances are the current flow is around 1A or lower. That's okay, but not great. Look around your house, or see if you can get your hands on a tablet charger. Those often provide current at 1.5A or even 2A at times. That's twice the speed of a 1A charger.
Also, look at where you're plugging your charger into. If the socket is already heavily overloaded, consider plugging it in somewhere else, for safety's sake at least
Still very slow...
If at this stage, it's still charging very slowly, your battery may be the issue. Since it seems to work fine in your friend's phone, it may simply be your phone providing inaccurate information. Try calibrating your phone's battery and see if that helps.
Take a tooth brush and clean off the battery connector points in the battery casing of your phone.
Using a 5v-2A charger will reduce the charging time. It works for me.
i just checked charging details of my phone through this app :