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18w vs 20w for iPhone 12 Fast Charging

N

NiCk-

macrumors regular
Original poster
Jun 11, 2007
198
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Is there a substantial difference ?? On Apple's website it says that fast charging is only available on iPhone 12 with the 20w charger but people are saying that they can get similar results with the 18w.

If someone can provide their own results I would be grateful as I already have an 18w charger that I'm planning on using with the iPhone 12.
 
NiCk- said:
Is there a substantial difference ?? On Apple's website it says that fast charging is only available on iPhone 12 with the 20w charger but people are saying that they can get similar results with the 18w.

If someone can provide their own results I would be grateful as I already have an 18w charger that I'm planning on using with the iPhone 12.
Click to expand...

I bought an 18w charger and use the provided charging cable.

Yesterday I had 7% battery left and charged it. It took an hour to get to 87%.

I believe if you’re using the MagSafe puck and want fast charging you need to get the Apple 20w NOT a 3rd party charger.
 
macher said:
I bought an 18w charger and use the provided charging cable.

Yesterday I had 7% battery left and charged it. It took an hour to get to 87%.

I believe if you’re using the MagSafe puck and want fast charging you need to get the Apple 20w NOT a 3rd party charger.
Click to expand...

Thanks for answering ! I'm not interested in Magsafe, I just want to charge it with the USB-C to Lightning cable. Did you get those results with Magsafe or with a wire ?
 
NiCk- said:
Thanks for answering ! I'm not interested in Magsafe, I just want to charge it with the USB-C to Lightning cable. Did you get those results with Magsafe or with a wire ?
Click to expand...

I used an 18w brick and the USB c charging cable that came with my 12P. Went from 7% to 87% in and hour.
 
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Debi Martocci said:
This video explains that the 18w charger wont fast charge the iphone 12 series. Also apples website specifically states that only the 20w or higher charger will fast charge the iphone 12 series.

Fast charge your iPhone - Apple Support

Fast charge some iPhone models.
support.apple.com support.apple.com
Click to expand...

What’s considered fast charge? I used an AT&T branded 18w brick with the USB c that came with the 12P and I went from 7% battery to 87% in an hour.

If you’re going MagSafe and want fast charging then it looks like you need it he Apple only 20w brick.
 
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Apparently some people from Netherlands made some tests and found some very interesting results. Looks like there isn't much difference between the 18w with the 20w, so this should be very nice for those who don't want to buy another charger.

https://www.reddit.com/r/iphone/comments/jhaok2
 
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NiCk- said:
Apparently some people from Netherlands made some tests and come out with some very interesting results. Looks like there isn't much difference between the 18w with the 20w, so this should be very nice for those who don't want to buy another charger.

https://www.reddit.com/r/iphone/comments/jhaok2
Click to expand...
The complete opposite of what people here have experienced including myself. Something very strange is at play. I believe there is an inherent fault with some of the magsafe pucks.
 
I paid the apple tax and bought a 30W USB-C charger off Amazon. It was 15 bucks. I had no need for USB-C charging until the 12 Pro and guess what? I still don't. I'm back to 7.5 W overnight charging on my cheap qi mat. When the world returns to normal and I'm traveling with overnight stays again, I'll definitely have a use for a new brick and cable. You can never have too many chargers and lightning cables, right?
 
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Debi Martocci said:
This video explains that the 18w charger wont fast charge the iphone 12 series. Also apples website specifically states that only the 20w or higher charger will fast charge the iphone 12 series.

Fast charge your iPhone - Apple Support

Fast charge some iPhone models.
support.apple.com support.apple.com
Click to expand...

Woah! This video was a revelation, had no idea about this, Apple has complicated the situation quite a bit it seems.
 
Debi Martocci said:
This video explains that the 18w charger wont fast charge the iphone 12 series. Also apples website specifically states that only the 20w or higher charger will fast charge the iphone 12 series.

Fast charge your iPhone - Apple Support

Fast charge some iPhone models.
support.apple.com support.apple.com
Click to expand...
The video is incorrect and the author doesn't understand basic electronics.

Any iPhone with fast charging, ie models 8 and above, supports either 5v (normal charge) or 9v (fast charge).

The iPhone 11 will allow up to 2A on it's 9v mode, whereas the iPhone 12 will allow up to 2.2A. This does not preclude the 12 from using the 18W charger to fast charge, it will simply be supplied with a little less wattage than it's maximum.

As already stated the Magsage inefficiencies result in about 5W dropoff from wired power. This is effectively the same dropoff with either 18W and 20W but starts from a lower point with the former.

He then goes on to recommend a bunch of random power adapters. However the apple ones provide a far cleaner signal with a steady voltage over time and no spikes and better insulation from noise on the powerline. Plus most OEMs do not deliver the wattage they claim (or at least not for prolonged charging). A few brands like Anker are exceptions to this.

You are better to get 18W apple than 20W of most OEM brands.

I recommend this video instead..
 
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seawolfxix said:
I may have missed it in the video, but why wouldn’t the iPhone 12 pull 18W (9V/2A) from an 18W charger?
Click to expand...
Yes, you are correct in questioning this. The 12 will simply pull 9V/2A and ends up charging fractionally slower with the 18W.

The video is clueless. It acts as if there is a magic cutoff wattage for the adaptors that support 9V at which fast charging doesn't work on IPhone 12s
 
I made a post you can check out. I've used a wattage meter. Anything less than 20 watts the magsafe won't pull the full amount, but adaptors that support 9V 3A that are higher than that do charge magsafe at 100% speed. My post has my results over 4 chargers
 
TokyoFerret said:
The video is incorrect and the author doesn't understand basic electronics.

Any iPhone with fast charging, ie models 8 and above, supports either 5v (normal charge) or 9v (fast charge).

The iPhone 11 will allow up to 2A on it's 9v mode, whereas the iPhone 12 will allow up to 2.2A. This does not preclude the 12 from using the 18W charger to fast charge, it will simply be supplied with a little less wattage than it's maximum.

As already stated the Magsage inefficiencies result in about 5W dropoff from wired power. This is effectively the same dropoff with either 18W and 20W but starts from a lower point with the former.

He then goes on to recommend a bunch of random power adapters. However the apple ones provide a far cleaner signal with a steady voltage over time and no spikes and better insulation from noise on the powerline. Plus most OEMs do not deliver the wattage they claim (or at least not for prolonged charging). A few brands like Anker are exceptions to this.

You are better to get 18W apple than 20W of most OEM brands.

I recommend this video instead..
Click to expand...

Yea that’s why I got the Apple OEM 20w.

Lot of people here say fast charging is bad for the battery and battery life. I would say with the 20w OEM technology it’s not bad for battery life. Now it’s possible maybe likely using the 20w OEM combo that your battery might be lower battery health after 2 - 3 years vs what’s called slow charging but IMO t won’t be significant to even matter.

The OEM is more efficient IMO than even the Anker one.

From watching that video you posted I hope others can see why it’s not bad but good to use the combo.
 
Ok I’m confused. Putting the MagSafe charger aside, how fast (and at what wattage) will the 18W charger that came with the iPhone 11pro charge an iPhone 12 with the lightning cable? Thanks.
 
Aceroller said:
Ok I’m confused. Putting the MagSafe charger aside, how fast (and at what wattage) will the 18W charger that came with the iPhone 11pro charge an iPhone 12 with the lightning cable? Thanks.
Click to expand...

Watch this video

 
Aceroller said:
Perfect. Thanks so much. So seems that if you are going to lightning cable charge the 20W is not better than the 11pro 18W. Sweet!!
Click to expand...
I have an amp meter. It doesn't really matter. Even with the 20 watts the iPhone pulls about 18-20. With the magsafe it almost maxes out but that's because of wireless inefficiencies.
 
Aceroller said:
Perfect. Thanks so much. So seems that if you are going to lightning cable charge the 20W is not better than the 11pro 18W. Sweet!!
Click to expand...

True I have an AT&T branded 18w too and there isn’t much difference in charging speed.
 
NiCk- said:
Is there a substantial difference ?? On Apple's website it says that fast charging is only available on iPhone 12 with the 20w charger but people are saying that they can get similar results with the 18w.

If someone can provide their own results I would be grateful as I already have an 18w charger that I'm planning on using with the iPhone 12.
Click to expand...

I have an Apple branded 20w and an AT&T branded 18w and there isn’t much difference in speed to get to 80%. However it looks like the Apple 20w does a better job at optimizing after 80%. The AT&T branded 18w seems to get from 80 to 100 faster. The Apple 20w seems to trickle charge a lot more which I think is better.
 
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