Extremely slow charging

The Xr has a much larger battery than your previous iPhones, so it will take longer to charge. The Xr has a 3,000 MaH battery. Your 6S has a 1700 MaH battery. Based on that alone, from the same power source your Xr will take almost twice as long to charge as your 6S.

If you are using the cube that came with it that is part of the problem. It can only supply 1 amp (1,000 Ma). If you are using a computer to charge it will take even longer, because most computers only supply 500 Ma. Other options:

• The Xr has a fast charge mode using a USB-C power source. With that it will charge to 50% in 30 minutes, and 100% in 1 1/2 hours.
• The Xr will charge twice as fast as it does with the cube if you use an iPad 12W adapter.
• In the middle, with a Qi wireless charger it will charge at 7.5W, between the cube and an iPad adapter.

Also, if you are using the phone while it is charging your usage takes almost half of the incoming energy, so it will take a very long time to charge with the 1 Amp adapter.

If you want to continue using the cube and not buy another power source then just charge it overnight. That way it won't matter how long it takes. It's also a best practice, because you can enable automatic iCloud backup and the phone will back up everything that has changed when the phone is locked, connected to power and connected to Wi-Fi. So you will never lose more than 1 day's content.

The 8 Plus has a 2700 MaH battery, so it is close to the Xr. I said the Xr should charge to 100% in 1 and 1/2 hours (90 minutes) when charged using a USB-C power source. If you are using the 1 amp cube 30% in one hour is about right. All assuming the phone is locked when charging. If it isn't then it will take much longer because the phone is using energy as it is charging.

Doing the math: A 3,000 MaH battery. Power source 1,000 Ma. (1,000 Ma x 1 hour) / 3,000 MaH = .33 or 33%. The wireless pad is 7.5 watts, but wireless charging is less efficient than wired charging, so it won't be that much better than a 1 amp power source.

If you are not going to charge overnight you will be much happier if you get a USC-C power source such as 30W USB‑C Power Adapter - Apple

I've already explained why it takes longer - it's got a bigger battery, and Physics Rules! Not just a good idea, it's the law. The laws of thermodynamics, that is.

Anyway, a 15 watt USB-C source will be slightly faster, but you need a 29 watt or larger USB-C charger to get the best charging performance.

Well, 12W @ 5.2 volts = 2.3 amps or 2300 MA, so yes, 25% in 35 minutes is reasonable. And a USC-C power source would charge even faster than that.

The 10 ampere-hour power bank would not be any faster; it is the output current it can deliver, which is probably 2.2 amps, that matters. However it is a great thing to have for those situations when your battery is low and you're away from mains power. I carry one when I travel.

Thank you! I’ve just got a 12W cube and it charged about 25% in 35-40 minutes which is definitely an improvement, is that normal for that type of charger with the XR would you say? Also, do you know anything about portable power banks? If so how long do you think a 10,000 MaH power bank would take to charge the XR?

Right okay thank you very much for that! And ah right do you think a higher one would be better then like I’ve found a 28,800 MaH it’s for 15 watts it says on the description do you think that would be any faster?

Oh right okay well the portable charger is a USB-C portable charger I’ve just checked on the box then and I don’t it’s just a bit annoying the way it’s a brand new iPhone and it’s really slow at charging especially if I’m out and the phone dies it’ll take ages to recharge it

Yes I know but the apple shop and phone shop where I purchased it aren’t saying that, I’ve took it to apple as well for an appointment and they’ve said it isn’t normal for it to take this long to charge and I’ve had it exhanged 3 times this is the 4th phone now that’s the only reason I was so concerned because the apple shop said that and right okay thanks for everything you’ve really helped

The higher capacity only means the number of times you can charge the phone before having to recharge the battery pack itself. For a 10,000 it can recharge the phone about 3 times; for the 28,800 it can recharge it 8 or 9 times. The 15 watts is more than the phone can use, so it won't be any faster. The only option that would be faster is a USB-C power source.

But why do you need it to be faster? If you charge overnight it doesn't matter how long it takes.