Charger wattage detection

[Zotaccian]

I now and then buy used old iBooks and PowerBooks repair and/or upgrade them. If they don't come with a charger I will always get the cheapest possible because I don't feel like it's reasonable to pay (sometimes) as much for a charger than I paid for a whole (well, broken) machine.

Many times I however see that even though the case of the charger says 65W, the machine detects the charger as 45W. Does anyone know what kind of mechanism iBooks and PowerBooks use to detect which type of charger is? I'm thinking that maybe some of those just are fake 65W chargers and only supply 45W or because of manufacturing or something they really are 65W but the machine just detects them wrong. One common thing seems to be that those chargers do not include that "light ring" which indicates charging state.

Just wondering

 

[micahgartman]

Take a look at this article:

http://support.apple.com/kb/ht2346

In essence, a higher wattage power adapter "steps down" to meet the requirements of the lower wattage needs of the computer.

 

[Zotaccian]

Yes I know that you can use higher wattage charger if voltage / connector is correct type, but at the moment I have two 65W chargers and one of them gets detected as 65W by the PB 12" but the other is detected as 45W despite the case saying 65W. When you check system info there is that power section.

With this machine I cannot test whether or not maximum stress would be too much for that charger detected as 45W because this machine only needs max. 45W.

 

[micahgartman]

Gotcha

If the battery continues to charge while you're using the PowerBook, the adapter should be safe to use.

But, it definitely sounds like there's an issue with the adapter.

 

[eyoungren]

You get what you pay for.

When you're paying $9 on eBay (or somewhere else) for an adapter you can't expect it to be exactly what it's advertised to be.

I had a vendor on eBay that advertised 65W. I got 45W. I sent it back. The replacement was 45W too. Sent it back and demanded my money back.

I have a vendor I pay about $30 each time I need a power supply. But the adapters are 65W and they last longer than three years.

I know that's not a price you want to pay, but the cheap route isn't doing you much good either.

Pay a little more from a reputable vendor and recover the cost when you sell the Mac.

But any way to detect this before hand, I don't know of.

 

[Zotaccian]

OK, so both of you vote for faulty / fake charger. I think I'll contact the seller.

 

[666sheep]

Detection is most likely done via sense pin resistance on charger jack. Not 100% sure about that, but seems logical.

 

[tampasteve]

I also repair iBooks, I used to include the power adapter, but after multiple auctions it seems that the cost of a decent adapter does not bring in the difference in ending auction price. Now I just advertise them as no charger included. People seem to not care.

 

[micahgartman]

Detection is most likely done via sense pin resistance on charger jack. Not 100% sure about that, but seems logical.

From the Developer Note for the 17-inch PowerBook G4:

A device’s ID voltage limits determines how the PMU identifies the power adapter. The 17-inch PowerBook G4 is designed to use the 65-Watt Apple Portable Power Adapter which ships with it. Although you can use a 45-Watt Apple portable power adapter with a 17-inch PowerBook G4, it may not provide sufficient power during some activities and power may be drawn temporarily from the battery. Should the battery become discharged, you may need to plug in the 65-Watt Apple Portable Power Adapter that came with the computer in order to start it up.

See: http://powerbook.micahgartman.com/dev/dn_g4_17_167_dlsd.pdf

 

[eyoungren]

Now I just advertise them as no charger included. People seem to not care.

Speaking as a buyer, but for myself, you are correct. But the reasoning behind not caring, at least in my case, is that I don't know the history of the charger I'm getting.

When I bought my very first PowerBook off eBay, the charger was included. And it was mentioned in the auction that in order for the charger to work the power cable had to be looped back (bent) at a 90º angle or more in order for it to work.

The seller didn't mention that there was cut in the charger cable!

My reaction was to toss the entire thing in the trash the moment I got it. And use a brand new adapter I bought for the purpose. Had the seller not included the power adapter I would have been fine. As it was I became responsible for the seller's eWaste.