From Newsgroup: sci.electronics.repair

My aging Apple power adapter requires either a new cable or being replaced
all together. Cable was replaced twice already.

I would like to take advantage of compact newer power adapters which
invariably offer a USB-C socket and digital Power Delivery (PD) controls.
Was reading about USB-C PD triggers/decoys which present fixed voltage one
side and PD interface on the other (*). So I thought USB-C to MagSafe 1/2 adapters available on the market implement that.

Then read about a MagSafe plug tear down revealing the connector itself provides a power adapter ID to the Mac laptop (**). Even if those cheap
cable adapters implement this feature, which I doubt, I am not sure it will
be the correct one. It may simply return the ID of the most powerful Apple power adapter of the line and leave it at that. As far as I know they donrCOt offer users any configuration option.

To be considered also third party power adapters are known to work with old
Mac laptops. But I donrCOt know if they also affect battery lifespan.

What are your thoughts about safety - for both user and equipment - of such solutions? Thanks.

* https://learn.adafruit.com/usb-pd-hacks/things-to-know
** http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

On Sun, 9 Aug 2026 02:34:36 -0000 (UTC), Wu Ming <wu.ming2@icloud.com

wrote:

My aging Apple power adapter requires either a new cable or being replaced >all together. Cable was replaced twice already.

I would like to take advantage of compact newer power adapters which >invariably offer a USB-C socket and digital Power Delivery (PD) controls.
Was reading about USB-C PD triggers/decoys which present fixed voltage one >side and PD interface on the other (*). So I thought USB-C to MagSafe 1/2 >adapters available on the market implement that.

Then read about a MagSafe plug tear down revealing the connector itself >provides a power adapter ID to the Mac laptop (**). Even if those cheap
cable adapters implement this feature, which I doubt, I am not sure it will >be the correct one. It may simply return the ID of the most powerful Apple >power adapter of the line and leave it at that. As far as I know they donAt >offer users any configuration option.

To be considered also third party power adapters are known to work with old >Mac laptops. But I donAt know if they also affect battery lifespan.

What are your thoughts about safety - for both user and equipment - of such >solutions? Thanks.

* https://learn.adafruit.com/usb-pd-hacks/things-to-know
** http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html

You drink (buy into) the Apple kool-aid; you live with it (keep on
buying).

RL
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

Wu Ming <wu.ming2@icloud.com > wrote:

My aging Apple power adapter requires either a new cable or being replaced all together. Cable was replaced twice already.

I would like to take advantage of compact newer power adapters which invariably offer a USB-C socket and digital Power Delivery (PD) controls.
Was reading about USB-C PD triggers/decoys which present fixed voltage one side and PD interface on the other (*). So I thought USB-C to MagSafe 1/2 adapters available on the market implement that.

Then read about a MagSafe plug tear down revealing the connector itself provides a power adapter ID to the Mac laptop (**). Even if those cheap
cable adapters implement this feature, which I doubt, I am not sure it will be the correct one. It may simply return the ID of the most powerful Apple power adapter of the line and leave it at that. As far as I know they donrCOt offer users any configuration option.

To be considered also third party power adapters are known to work with old Mac laptops. But I donrCOt know if they also affect battery lifespan.

What are your thoughts about safety - for both user and equipment - of such solutions? Thanks.

* https://learn.adafruit.com/usb-pd-hacks/things-to-know
** http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html

I have a couple of those adapters - both Magsafe 1 and 2. I haven't used
the 1 yet but the 2 works fine. From Aliexpress - the listing is gone but looked like this:
https://www.aliexpress.com/item/1005003915958424.html

According to the manuals, the Apple power supplies emit the following: https://cdsassets.apple.com/live/6GJYWVAV/user/locale/en-gb/ma1986_apple-magsafe-2-power-adapter-ug.pdf

Specifications
45W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 14.85V, 3.05A

60W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 16.5V, 3.65A

85W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 20V, 4.25A

The Magsafe 1 supplies are fractionally lower voltages/higher currents: https://www.allion.com/tech_syst_magsafe/

So in principle the Macbooks are capable of taking 20 volts. USB-C is only capable of generating 15V (typically 45W chargers are 15V at 3A) and 20V
(60W chargers and up) unless using PPS mode which most power supplies won't support. I expect the adapters just ask USB-C for a fixed 20V
and they may not work with a 45W supply.

The Macbooks will have their own independently controlled DC-DC converter to charge the battery so the battery won't care what the input voltage is. If anything a higher voltage might help as it reduces the current and makes
things run slightly cooler.

I wouldn't worry about it.

Theo
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

Theo <theom+news@chiark.greenend.org.uk> wrote:

Wu Ming <wu.ming2@icloud.com > wrote:

My aging Apple power adapter requires either a new cable or being replaced >> all together. Cable was replaced twice already.

I would like to take advantage of compact newer power adapters which
invariably offer a USB-C socket and digital Power Delivery (PD) controls.
Was reading about USB-C PD triggers/decoys which present fixed voltage one >> side and PD interface on the other (*). So I thought USB-C to MagSafe 1/2
adapters available on the market implement that.

Then read about a MagSafe plug tear down revealing the connector itself
provides a power adapter ID to the Mac laptop (**). Even if those cheap
cable adapters implement this feature, which I doubt, I am not sure it will >> be the correct one. It may simply return the ID of the most powerful Apple >> power adapter of the line and leave it at that. As far as I know they donrCOt
offer users any configuration option.

To be considered also third party power adapters are known to work with old >> Mac laptops. But I donrCOt know if they also affect battery lifespan.

What are your thoughts about safety - for both user and equipment - of such >> solutions? Thanks.

* https://learn.adafruit.com/usb-pd-hacks/things-to-know
** http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html

I have a couple of those adapters - both Magsafe 1 and 2. I haven't used
the 1 yet but the 2 works fine. From Aliexpress - the listing is gone but looked like this:
https://www.aliexpress.com/item/1005003915958424.html

According to the manuals, the Apple power supplies emit the following: https://cdsassets.apple.com/live/6GJYWVAV/user/locale/en-gb/ma1986_apple-magsafe-2-power-adapter-ug.pdf

Specifications
45W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 14.85V, 3.05A

60W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 16.5V, 3.65A

85W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 20V, 4.25A

The Magsafe 1 supplies are fractionally lower voltages/higher currents: https://www.allion.com/tech_syst_magsafe/

So in principle the Macbooks are capable of taking 20 volts. USB-C is only capable of generating 15V (typically 45W chargers are 15V at 3A) and 20V
(60W chargers and up) unless using PPS mode which most power supplies won't support. I expect the adapters just ask USB-C for a fixed 20V
and they may not work with a 45W supply.

The Macbooks will have their own independently controlled DC-DC converter to charge the battery so the battery won't care what the input voltage is. If anything a higher voltage might help as it reduces the current and makes things run slightly cooler.

I wouldn't worry about it.

Theo

According to a video (***), linked in the comments of (**), MagSafe charger detects resistance at the connection with the Mac and, if indicates charger
has the minimum required power, switches on at full power. Three
resistances offered by Macs according to their preferred power input.

Then the Mac reads the power adapter ID from the connector and powers the
Mac.

Finally a voltage controller and proper adapter ID allows battery to be charged. It also sends commands to switch LED on/off.

To be noted I donrCOt really understand electrical engineering. Here I am
just trying to summarize few points appearing relevant to me.

I realized USB-C to MagSafe 1/2 adapters most likely provide a proper
charger ID. Otherwise nobody would buy them. Do them also translate, for
the USB-C PD side, voltage controls which allow current to be extremely low
for one second after first contact with the Mac charging port?

*** https://youtu.be/bc5ttwMPWbw?si=XlbsrxW-Ht5wV6bB

--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

John Robertson <jrr@flippers.com> wrote:

On 2026-08-08 7:34 p.m., Wu Ming wrote:

My aging Apple power adapter requires either a new cable or being replaced >> all together. Cable was replaced twice already.

...

Then read about a MagSafe plug tear down revealing the connector itself
provides a power adapter ID to the Mac laptop (**). Even if those cheap
cable adapters implement this feature, which I doubt, I am not sure it will >> be the correct one. It may simply return the ID of the most powerful Apple >> power adapter of the line and leave it at that. As far as I know they donrCOt
offer users any configuration option.
...

What are your thoughts about safety - for both user and equipment - of such >> solutions? Thanks.

Unplug/power off the AC power supply from the mains before unplugging it from the laptop.

The MagSafe/USB-C connector will last a lot longer that way...

John :-#)#

HavenrCOt thought about it. Thanks.

--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

Theo <theom+news@chiark.greenend.org.uk> wrote:

Wu Ming <wu.ming2@icloud.com > wrote:

My aging Apple power adapter requires either a new cable or being replaced >> all together. Cable was replaced twice already.

I would like to take advantage of compact newer power adapters which
invariably offer a USB-C socket and digital Power Delivery (PD) controls.
Was reading about USB-C PD triggers/decoys which present fixed voltage one >> side and PD interface on the other (*). So I thought USB-C to MagSafe 1/2
adapters available on the market implement that.

Then read about a MagSafe plug tear down revealing the connector itself
provides a power adapter ID to the Mac laptop (**). Even if those cheap
cable adapters implement this feature, which I doubt, I am not sure it will >> be the correct one. It may simply return the ID of the most powerful Apple >> power adapter of the line and leave it at that. As far as I know they donrCOt
offer users any configuration option.

To be considered also third party power adapters are known to work with old >> Mac laptops. But I donrCOt know if they also affect battery lifespan.

What are your thoughts about safety - for both user and equipment - of such >> solutions? Thanks.

* https://learn.adafruit.com/usb-pd-hacks/things-to-know
** http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html

I have a couple of those adapters - both Magsafe 1 and 2. I haven't used
the 1 yet but the 2 works fine. From Aliexpress - the listing is gone but looked like this:
https://www.aliexpress.com/item/1005003915958424.html

According to the manuals, the Apple power supplies emit the following: https://cdsassets.apple.com/live/6GJYWVAV/user/locale/en-gb/ma1986_apple-magsafe-2-power-adapter-ug.pdf

Specifications
45W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 14.85V, 3.05A

60W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 16.5V, 3.65A

85W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 20V, 4.25A

The Magsafe 1 supplies are fractionally lower voltages/higher currents: https://www.allion.com/tech_syst_magsafe/

So in principle the Macbooks are capable of taking 20 volts. USB-C is only capable of generating 15V (typically 45W chargers are 15V at 3A) and 20V
(60W chargers and up) unless using PPS mode which most power supplies won't support. I expect the adapters just ask USB-C for a fixed 20V
and they may not work with a 45W supply.

The Macbooks will have their own independently controlled DC-DC converter to charge the battery so the battery won't care what the input voltage is. If anything a higher voltage might help as it reduces the current and makes things run slightly cooler.

I wouldn't worry about it.

Theo

Thanks for the references. Collecting together all relevant data is useful
to me to better define the problem.

I currently use a 45W charger with MagSafe 1 cable. I may later switch to a
Mac laptop requiring only 30W and with native USB PD.

Following up on my previous, I just read USB PD does power negotiation with
low Initial power. So if MagSafe 1/2 adapter also implements the resistance check and sends proper PD signal to ramp up power it should be as safe as
the Apple old solution.

Something I noticed is USB-C chargers at 20V are not exactly delivering the current as by Apple chargers specs you noted above. If upper/lower could it become a problem?

Also some of the (second hand) charges I am considering do implement Programmable Power Supply (PPS). I donrCOt know if any of the adapters also implement that.

--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

Theo <theom+news@chiark.greenend.org.uk> wrote:

Wu Ming <wu.ming2@icloud.com > wrote:

My aging Apple power adapter requires either a new cable or being replaced >> all together. Cable was replaced twice already.

I would like to take advantage of compact newer power adapters which
invariably offer a USB-C socket and digital Power Delivery (PD) controls.
Was reading about USB-C PD triggers/decoys which present fixed voltage one >> side and PD interface on the other (*). So I thought USB-C to MagSafe 1/2
adapters available on the market implement that.

Then read about a MagSafe plug tear down revealing the connector itself
provides a power adapter ID to the Mac laptop (**). Even if those cheap
cable adapters implement this feature, which I doubt, I am not sure it will >> be the correct one. It may simply return the ID of the most powerful Apple >> power adapter of the line and leave it at that. As far as I know they donrCOt
offer users any configuration option.

To be considered also third party power adapters are known to work with old >> Mac laptops. But I donrCOt know if they also affect battery lifespan.

What are your thoughts about safety - for both user and equipment - of such >> solutions? Thanks.

* https://learn.adafruit.com/usb-pd-hacks/things-to-know
** http://www.righto.com/2013/06/teardown-and-exploration-of-magsafe.html

I have a couple of those adapters - both Magsafe 1 and 2. I haven't used
the 1 yet but the 2 works fine. From Aliexpress - the listing is gone but looked like this:
https://www.aliexpress.com/item/1005003915958424.html

According to the manuals, the Apple power supplies emit the following: https://cdsassets.apple.com/live/6GJYWVAV/user/locale/en-gb/ma1986_apple-magsafe-2-power-adapter-ug.pdf

Specifications
45W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 14.85V, 3.05A

60W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 16.5V, 3.65A

85W Power Adapter
* Input: AC 100rCo240 volts (V), 50/60 hertz (Hz)
* Output: DC 20V, 4.25A

The Magsafe 1 supplies are fractionally lower voltages/higher currents: https://www.allion.com/tech_syst_magsafe/

So in principle the Macbooks are capable of taking 20 volts. USB-C is only capable of generating 15V (typically 45W chargers are 15V at 3A) and 20V
(60W chargers and up) unless using PPS mode which most power supplies won't support. I expect the adapters just ask USB-C for a fixed 20V
and they may not work with a 45W supply.

The Macbooks will have their own independently controlled DC-DC converter to charge the battery so the battery won't care what the input voltage is. If anything a higher voltage might help as it reduces the current and makes things run slightly cooler.

I wouldn't worry about it.

Theo

Thanks. You gave the full answer but took me a while to realize it.

I read enough to have a better understanding of the technology stack now.
Most useful source was Ken ShirriffrCOs disassembly account of MagSafe. And
the comments to it spanning over more than a decade.

My cable connector reports an 85W charger even though it is connected to a
45W one. Part of the new setup is already there.

--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

Wu Ming <wu.ming2@icloud.com > wrote:

Something I noticed is USB-C chargers at 20V are not exactly delivering the current as by Apple chargers specs you noted above. If upper/lower could it become a problem?

I expect that the charging circuit is already flexible as to the voltages
and currents it can accept - it has to accept 6 different chargers (3x
Magsafe 1, 3x Magsafe 2) with different voltages and currents.

As the charging is likely to be run by a microcontroller, I expect it will
aim to find the sweet spot in terms of power it can pull - eg before it
tries to pull 5A from a power supply only capable of 3A, it will try
increasing the current gradually and at say 3.5A the voltage will start to
sag (ie before the PSU completely cuts off due to overcurrent). A smart charger
design will then back the current off a bit until the voltage has risen to
its maximum - it works out that it can only pull 3A by observing the voltage/current curve for different current values.

I don't have any visibility into Apple's power supply design but I expect
the worst that can happen is it doesn't work rather than blowing something
up. But your own risk etc etc. As we know there's a genuine PSU outputting 20V then we know we aren't overvolting the input, which is a major worry out
of the way.

Also some of the (second hand) charges I am considering do implement Programmable Power Supply (PPS). I donrCOt know if any of the adapters also implement that.

I doubt it. That's mostly for superfast phone charging, where you match the power supply output to the current battery voltage - ie skipping the onboard DC-DC converter and instead using the much better heatsinked external converter. I don't think enough chargers are doing PPS up to 20V to make it
an option for these Magsafe adapters.

(I've been using my adapter on a non-standard 130W Dell PSU that only does
5V and 20V at 6.5A, skipping the intermediate voltages. It works fine)

Theo
--- Synchronet 3.22a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.repair

Theo <theom+news@chiark.greenend.org.uk> wrote:

I expect that the charging circuit is already flexible as to the voltages
and currents it can accept - it has to accept 6 different chargers (3x Magsafe 1, 3x Magsafe 2) with different voltages and currents.

Found one account of a 110W , 18.5V Mac Mini charger used with a MagSafe 1 cable attached to it. It works. MagSafe 2 goes up to 20V which is the same
as offered by USB PD. But not MagSafe 1. Clearly there is some leeway on voltage accepted by our Apple devices. But not too much because 29W ,
5.2V2.4A and 14.5V2.0A Apple charger does not work with HomePod Mini
accepting 9V2A.


Found account of a knockoff MagSafe 1 cable, attached to an original
charger, keeping voltage permanently at charging power. There is even a
video of the adapter head I am considering, USB-C to MagSafe 1, sparking
when in close contact with a piece of metal. Specs were never published but
it still surprises me considering power ramp up should be controlled
entirely by the charger. Not the connector.

(I've been using my adapter on a non-standard 130W Dell PSU that only does
5V and 20V at 6.5A, skipping the intermediate voltages. It works fine)

With a MagSafe 2 equipped Mac I assume. My MagSafe 1 equipped MacBook AirrCOs battery with 1,054 cycles still shows Normal status. Uncertainty about the slight over voltage, and possible inhibition of low power detached / fully charged mode, makes me a bit nervous to try.
--- Synchronet 3.22a-Linux NewsLink 1.2