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Do we have to have 20W or is 18W charger ok?

M

MrMister111

macrumors 68040
Original poster
Jan 28, 2009
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In the specs of the iPhone 12, it says “fast charge to 50% with a 20W or higher” yet says “..an 18W or higher” for the 11.

So I also know the MagSafe charger states 20W as well but will this also work with 18W charger?

It’s a little confusing to say 20W only now, I know Apple has stopped selling the 18W now, but I still have the 18W.

Do I really have to buy the 20W charger now as well?

Thanks
 

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Fast charging "up to 50% in 30 minutes" is rated for the 20W charger brick but it will definitely work with the 18W as well (albeit a little slower)

The MagSafe charger only charges at 15W regardless so the 18W or 20W would both be more than enough.
 
jvlfilms said:
Fast charging "up to 50% in 30 minutes" is rated for the 20W charger brick but it will definitely work with the 18W as well (albeit a little slower)

The MagSafe charger only charges at 15W regardless so the 18W or 20W would both be more than enough.
Click to expand...
Thanks. So that is poor info from Apple really. That screenshot shows a difference, why can’t they add “...18W or higher charger “ ?

On the 11 with a 18W used to get 50% in 30mins, why can’t the 12 do that with a smaller battery?
 
I’ve been using the 18w and it does not charge fast. Is there a battery app or something I could use to test it so I can show you guys? I also used the USB-C charger that came with my MacBook Pro and I get similar slow charging speeds when using MagSafe. It’s such a bummer because it’s what I was looking forward to most.
 
its93rc said:
I’ve been using the 18w and it does not charge fast. Is there a battery app or something I could use to test it so I can show you guys? I also used the USB-C charger that came with my MacBook Pro and I get similar slow charging speeds when using MagSafe. It’s such a bummer because it’s what I was looking forward to most.
Click to expand...
Do you have a review iphone 12 unit? If not, all QI based Apple products only charge at 7.5w with Magsafe.
[automerge]1603316936[/automerge]
dubels said:
Do you have a review iphone 12 unit? If not, all QI based Apple products (pre-12) only charge at 7.5w with Magsafe.
Click to expand...
 
its93rc said:
I’ve been using the 18w and it does not charge fast. Is there a battery app or something I could use to test it so I can show you guys? I also used the USB-C charger that came with my MacBook Pro and I get similar slow charging speeds when using MagSafe. It’s such a bummer because it’s what I was looking forward to most.
Click to expand...
You are using the 18W and a USB-C cable direct to an iPhone and it’s not charging fast?

If you mean with a MagSafe I think it’s only 12 iPhones that charge 15W wireless with that.
 
MrMister111 said:
You are using the 18W and a USB-C cable direct to an iPhone and it’s not charging fast?

If you mean with a MagSafe I think it’s only 12 iPhones that charge 15W wireless with that.
Click to expand...
Ah, thank you guys. I feel dumb right now. Haha. I am using an 11 Pro Max. I will test first thing I get my 12 Pro on Friday and report back.
 
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MrMister111 said:
Thanks. So that is poor info from Apple really. That screenshot shows a difference, why can’t they add “...18W or higher charger “ ?

On the 11 with a 18W used to get 50% in 30mins, why can’t the 12 do that with a smaller battery?
Click to expand...
It's probably that they've only rated/tested it for the 20W charger, 18W will still work just fine but might be slightly slower.
 
MrMister111 said:
In the specs of the iPhone 12, it says “fast charge to 50% with a 20W or higher” yet says “..an 18W or higher” for the 11.

So I also know the MagSafe charger states 20W as well but will this also work with 18W charger?

It’s a little confusing to say 20W only now, I know Apple has stopped selling the 18W now, but I still have the 18W.

Do I really have to buy the 20W charger now as well?

Thanks
Click to expand...

No.

The 18W adapter has been discontinued, and no longer offered for sale, so Apple's packaging is going to specify the new 20W adapter to be current (there's a pun in there for the initiated), and prevent confusion.

Technically, there is little difference between 18W and 20W. In the past, Apple has vacillated between bundling 10W and 12W adapters with the iPads. They juiced it up a bit from 10W to 12W with the iPad 4 and Air 1, but actually went back to bundling the 10W with the Air 1 before it was discontinued, then going back to 12W again. For all intents and purposes, they were treated as interchangable equivalents.

It should also be noted that these are all nominal figures. None of them are going to produce 20.0W or 18.0W exactly, for various reasons, including what the power company is supplying to the house, and how it is distributed throughout it.

So "20W" really only means it will be around 20W; it could be more, it could be less, depending on the supply, and the load being drawn (particularly for multi-port adapters). So that 2W theoretical difference is going to be further diluted by variances in actual output.

As practical matter, there is unlikely to prevent the use of the 18W adapter with the MagSafe; it will still work, but perhaps just a little slower. So, unless you're the kind to sit there with a timer, any difference will be not be noticeable anyway.
 
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A lot of people will be in this situation. Surprised none of the youtubers have tested to compare speeds with the two chargers
 
mrklaw said:
A lot of people will be in this situation. Surprised none of the youtubers have tested to compare speeds with the two chargers
Click to expand...
I’m surprised Apple hasn’t stated either. I want to know wether to buy the new 20W or just keep using my 18W.
 
TheIntruder said:
No.

The 18W adapter has been discontinued, and no longer offered for sale, so Apple's packaging is going to specify the new 20W adapter to be current (there's a pun in there for the initiated), and prevent confusion.

Technically, there is little difference between 18W and 20W. In the past, Apple has vacillated between bundling 10W and 12W adapters with the iPads. They juiced it up a bit from 10W to 12W with the iPad 4 and Air 1, but actually went back to bundling the 10W with the Air 1 before it was discontinued, then going back to 12W again. For all intents and purposes, they were treated as interchangable equivalents.

It should also be noted that these are all nominal figures. None of them are going to produce 20.0W or 18.0W exactly, for various reasons, including what the power company is supplying to the house, and how it is distributed throughout it.

So "20W" really only means it will be around 20W; it could be more, it could be less, depending on the supply, and the load being drawn (particularly for multi-port adapters). So that 2W theoretical difference is going to be further diluted by variances in actual output.

As practical matter, there is unlikely to prevent the use of the 18W adapter with the MagSafe; it will still work, but perhaps just a little slower. So, unless you're the kind to sit there with a timer, any difference will be not be noticeable anyway.
Click to expand...

from my understanding, as long as the actual output of the actual plug itself is at least 15w, using an 18 or 20 should make no difference at all?

i have the 18w for my 11 pro max and it charges slow as ****, i have it plugged in my mbp plug and seeing the difference now... will report back
 
It’ll charge slowly above 50% regardless of power - fastest will be 0-50
 
TheIntruder said:
The 18W adapter has been discontinued, and no longer offered for sale, so Apple's packaging is going to specify the new 20W adapter to be current (there's a pun in there for the initiated), and prevent confusion.
Click to expand...
This is quite the juicy topic! I'm amped to see how this all works out. It sure has sparked some discussion, but I'm sure it's fine to charge ahead with 18W for now.
 
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macnmac said:
from my understanding, as long as the actual output of the actual plug itself is at least 15w, using an 18 or 20 should make no difference at all?

i have the 18w for my 11 pro max and it charges slow as ****, i have it plugged in my mbp plug and seeing the difference now... will report back
Click to expand...

It would have to be more than 15W, because the circuits in the MagSafe will consume some of that energy, and losses in the inductive coupling, which is not 100% efficient.

How much more depends on how efficient those two things actually are.

As noted, Apple specifies the 20W adapter for practical purposes -- it's the current product, and its rated capacity will assure the promised level of performance.

However that doesn't preclude the older 18W adapter from functioning with the MagSafe. It might have to operate at closer to full capacity, and/or simply not provide the same level of performance if the MagSafe isn't super efficient. End result -- it will work, but a bit slower.

Also keep in mind that Lithium batteries have a specific charging strategy, which draws maximum current only during the first phase of the process, before it switches to the second phase were the current is tapered down until the cell is fully charged. That tempers the time period the adapter needs to provide full power, and thus its effect on the overall process.

In some ways, batteries are like BBQ -- low and slow provides better results, and has benefits in terms of durability. Unless a user's practical needs are demanding, to utilize full capacity, and replenish with shorter periods of time, those who can afford to use slower charge rates, and are able to avoid the extremes of the state of charge will benefit from longer service life from their devices. If there's no need to rush it, taking it easy has benefits.
 
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Glad this thread exists...was wondering the same thing.

Thanks, All!
 
Has anyone with the 12/12 Pro tried the MagSafe with 18w charger? I’m going to collect mine this evening and if it doesn’t work well I’ll buy a 20w adaptor while I collect.

Am I right in assuming I can also use the power brick from my MacBook air?
 
TheIntruder said:
It would have to be more than 15W, because the circuits in the MagSafe will consume some of that energy, and losses in the inductive coupling, which is not 100% efficient.

How much more depends on how efficient those two things actually are.

As noted, Apple specifies the 20W adapter for practical purposes -- it's the current product, and its rated capacity will assure the promised level of performance.

However that doesn't preclude the older 18W adapter from functioning with the MagSafe. It might have to operate at closer to full capacity, and/or simply not provide the same level of performance if the MagSafe isn't super efficient. End result -- it will work, but a bit slower.

Also keep in mind that Lithium batteries have a specific charging strategy, which draws maximum current only during the first phase of the process, before it switches to the second phase were the current is tapered down until the cell is fully charged. That tempers the time period the adapter needs to provide full power, and thus its effect on the overall process.

In some ways, batteries are like BBQ -- low and slow provides better results, and has benefits in terms of durability. Unless a user's practical needs are demanding, to utilize full capacity, and replenish with shorter periods of time, those who can afford to use slower charge rates, and are able to avoid the extremes of the state of charge will benefit from longer service life from their devices. If there's no need to rush it, taking it easy has benefits.
Click to expand...

so its like using an electric pokemon attack on a grass type pokemon...
 
H-B0mb said:
Has anyone with the 12/12 Pro tried the MagSafe with 18w charger? I’m going to collect mine this evening and if it doesn’t work well I’ll buy a 20w adaptor while I collect.

Am I right in assuming I can also use the power brick from my MacBook air?
Click to expand...

on the 18w charger, it took around 1.5 to charge from 60 to 70%

on the mbp powerblock, it took 30 mins to charge from 60 to 90%

these were both done the an iphone 12 pro
 
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Anker is 20w and RAVpower is 30w.
Output to my iPhone 12 is the same. 10.5w up to 80%.
7.85 w from 80%.
2.2w measured at 96%.
Temperature gets up to 95°F on the MagSafe and on the back of the iPhone near the power button.

I am not getting 15w as advertised.

CD1E1776-89C0-49E1-A58F-943A3FB19D3F.png
 
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