I have a 13,000mAh mobile charger with two usb outputs. One with 5.3V / 1A, the other with 5.3V / 2.5A
is it safe to charge my iPhone 6 Plus with the larger output or should I avoid it? Thanks!
volts is what is pushed amps is what the charger is max able to have drawn from it
devices don't draw more than they are able to cope with so if 5.3 volt is not too high where normally it's 5.0 volts and as long as the charger does not make spikes then you could charge it with a 5volt 1000000A charger
The USB spec says that a USB port must provide 5 volts +- 0.5 volts, or 4.5 volts to 5.5 volts. So 5.3 volts is OK and within spec. As Rudegar says, the current is irrelevant as long as it is at least 1 amp. More is better, up to 1.6 amps for a 6 series phone. Above 1.6 won't do any harm, but won't help either. BTW, the max that a 5 or earlier iPhone can use is 1 amp. Again, more won't hurt, but won't help either.
Is it safe to charge my iPhone 6 Plus with a 5.3V / 2.5A battery pack?
