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dukebound85

macrumors Core
Jul 17, 2005
19,114
4,092
5045 feet above sea level
If you're asking, you're not qualified. I do a lot DIY stuff and I don't go onto some random forum asking people if it's possible; even I'm not very qualified. I've fried a lot of stuff, including myself.

In answering your question, the MagSafe charger is self sensing. Assuming you have the 85W adapter, it can provide 45W, 60W, or 85W based on if you have a MacBook Air, 13" MacBook [Pro], or a 15" and 17" MacBook Pro, respectively.
Isn't that just a function on the load the computer requires and the rating of the power brick?It shouldn't be software...

I have made many power adapters in the past and it really is just knowing the wires. It's not hard
 

danbates

macrumors newbie
Nov 19, 2018
7
1
Wales, UK
Hello,
afaik, the Magsafe 85W has a voltage of 18,5V.

So if I buy an 18,5v supply and put a magsafe connector on it, there would be no problems right?

I'm asking because the macbook pro changes voltage on demand. When charging, on idle.... is the power adaptor doing that or a converter on the logic board inside the mbp? :confused:

I have a MBP, the genuine power supply literally blew up on me, pop and a bright spark..
The laptop says on it 16.5 - 18.5V input DC.
I take the magsafe cable and chop it, get a standard 16V laptop power supply and soldered it up with heat-shrink.
Works fine, and better than the official adaptor as the buzzy sensation in the aluminium case is now gone.

The answers by so many here, as if they know anything about electrical engineering 'oh no don't do that!!'...

UPDATE: I used a variable voltage adaptor, the kind with different voltages selectable and different adaptor Barrel Pins to connect different Laptops.
18.5V was a better voltage for charging my MBP. Although!... Once charged, the Laptop wouldn't like the 18.5V and disconnect the power.
It seemed also, that an adaptor like this provides all of the current it can upon Connection, whereas a genuine apple charger provides very Little current until the Connection is made, and communication between the adaptor and Laptop is happening.
This low-current start PROTECTS the magsafe Pogo Pins. The arc of electricity, at the pogo-pins upon Connection of this Standard Laptop power supply has caused my Pogo Pins to stick. Nothing unsafe has happened as arcing is very normal for a power supply Connection. Also, the macbook is fine, I'm using a friend's genuine charger to check. To be fair, if the Laptop was not able to handle current surging from arcs like this, or a continuous 18.5V, then there wouldn't be a chance in hell of it getting through the regulatory hoops. This is because the regulations have to protect not only the safety of the user, but also the longevity and operation of the device in event of common issues.

I will next be unscrewing the magsafe Connection block inside my MBP, and will Bypass this magsafe Pogo pin B.S. with my own plug and socket.

A German spell-checker has copitalised my words here in an interesting way!

UPDATE UPDATE: The use of a non-standard apple charger, which can deliver the current quickly, has unfortunately damaged the pogo-pins in the magsafe end-piece. It has rendered the GND pogo-pins in my magsafe unusable. Yesterday evening, to bypass the magsafe, I opened the laptop to access the power-connector block inside, and I (with the help of a retired German electrical engineer!) soldered and glue gunned into place my own cable directly to the power block. However, as I found out, the laptop would be powered by the adaptor, but NOT CHARGE THE BATTERY. This is why:

As the 'magsafe teardown' article shows, the magsafe end-piece contains a chip which communicates via the central pin with the laptop to establish the charger type, ONLY then will the laptop charge.
I had to get my magsafe end-piece, the one with the LED indicator, and reuse it. It's important to reuse the magsafe connector with it's orange/green indicator LED, as it contains the ID and communication chip.

When I hacked the laptop-side magsafe block and connected the 18.5V directly to the input pins, the laptop would indicate having power, but not actually charge.
Thus, I had to also connect the magsafe with it's LED indictor and ID chip, I simply connected the GND of the magsafe to the GND of the adaptor along side my own cable. This means I don't rely on the (previously damaged) GND of the magsafe end-piece.

Photos here.
Working by this one here. It needs a more.. versatile connector lets say ;)

My version of macbook pro (late 2011) freaks out if the variable voltage thing doesn't respond, so when my battery is fully charged, the computed actually disconnects the power supply until I'm down to 90%, then it charges back up.
This is completely rediculous design for laptop power-supply, where normally the voltage is fixed at the adaptor and the laptop manages the power. It's another case I think of Apple trying to lock it's customers into using Apple only products. The absurdity of the variable voltage situation is evidenced by the fact that this morning, I check on my friends more recent macbook pro, to find it's a FIXED voltage of 20.0V on both the laptop etching underside, and power-block. As it should be!
 
Last edited:

danbates

macrumors newbie
Nov 19, 2018
7
1
Wales, UK
I figured out the way to use a non-apple adaptor was to connect the magsafe first, then turn the charger on at the wall, this avoids the arcing issue and mages use of the magsafe as-is without hacking as I had to do above.
A side-discovery, interesting to consider charging to 80% and blocking out the central pin to stop the charging process for battery health.
https://superuser.com/questions/463187/how-do-i-keep-a-macbook-battery-charged-to-only-70
A user posts a photo making use of a strip of paper, ingenious.
 
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jamesfrancesnew

macrumors newbie
Dec 4, 2023
4
0
I figured out the way to use a non-apple adaptor was to connect the magsafe first, then turn the charger on at the wall, this avoids the arcing issue and mages use of the magsafe as-i as I had to do above.
A side-discovery, interesting to consider charging to 80% and blocking out the central pin to stop the charging process for battery health.
https://superuser.com/questions/463187/how-do-i-keep-a-macbook-battery-charged-to-only-70
A user posts a photo making use of a strip of paper, ingenious.
I cut nibs of tiny copper wire and put one on the burnt pin position. If the charger can’t reach laptop (pins) bring MacBook port to the charger .
 

jamesfrancesnew

macrumors newbie
Dec 4, 2023
4
0
Hello,
afaik, the Magsafe 85W has a voltage of 18,5V.

So if I buy an 18,5v supply and put a magsafe connector on it, there would be no problems right?

I'm asking because the macbook pro changes voltage on demand. When charging, on idle.... is the power adaptor doing that or a converter on the logic board inside the mbp? :confused:
Bring the MacBook charging port to the charger by putting a small noob of copper on the Mac port it’s a tiny cup Barbourville it’s so small
 
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