7747 Views Previous 1 2 3 4 Next 55 Replies Latest reply: Dec 11, 2006 11:30 AM by SimonHobson Go to original post
Although this follows a similar post, here is what I
Kensington now offer a car/airline charging solution
for the MacBook Pro and MacBook Pro. Its relative
small size makes it convenient.
Actually, I don't see how this avoids the issue being originaly discussed. It's a 150W adapter, so the same thing is going to happen when you plug the MBP into the plane; it will trip the breaker because you'll be drawing more than the 75W that the plane provides.
Has anyone actually tested this? Sadly, I'm pretty sure it's not going to work. Looks like we're still out of luck.
MBP 15" Mac OS X (10.4.7)
So, in absence of commercially available solution, here is a link to someone who noticed the opportunity and is trying to make it into a business.
I have no knowledge of who this person is, other than the fact that he has the right technical solution - DC to DC and forget inverters!!!!
As for his pricing and the business model, well that is all together different story...
Well I suppose it's a step in the right direction !
It still isn't optimum on two counts :
There's still a DC-DC conversion which is probably unneccessary - but until Apple release technical details we won't know.
It still allows the MacBook (Pro) to draw more than 75W
In the meantime, it's something any reasonably competent diyer can do. You just need a DC-DC converter with not less than the rating of the power supply you're butchering, two inline sockets, and one plug.
But I suspect that if Apple have the same design flair with the MacBook (Pro) supplies as they did with earlier ones, we'll soon have a ready supply of dead supplies to salvage the cable & connector from !
"There's still a DC-DC conversion which is probably unneccessary - but until Apple release technical details we won't know."
If you are going to require 16/18volts and your power supply from your car is 12v, then you MUST have a conversion... No way to get around it. Just look at the power output on the adapter.
2 powerbooks G4, 1 Macbook Pro, G5 server. Mac OS X (10.4.7)
If you are going to require 16/18volts and your power
supply from your car is 12v, then you MUST have a
conversion... No way to get around it. Just look at
the power output on the adapter.
That's a big IF there. Remember that the G4 I'm typing this on takes a 24V input from the mains supply, but it will also run from a 14V supply direct from a vehicle - no DC conversion, nothing (apart from a coding resistor that tells it what supply it has). What it can't do (I believe) is charge the battery.
I posted a link on 29th June to a developer note for the G4 17" on this subject - it would be nice if Apple would do the same for the MagSafe powered systems.
It may have an 18V (or whatever) supply from the mains adapter, but I bet it works off a significantly wider voltage range - and it WILL have some sort of identifier signal so it know what sort of supply is connected.
That's a big IF there. Remember that the G4 I'm
typing this on takes a 24V input from the mains
supply, but it will also run from a 14V supply direct
from a vehicle - no DC conversion, nothing (apart
from a coding resistor that tells it what supply it
has). What it can't do (I believe) is charge the
Yes, it'll run 12 (or 14v) from the car, but it'll be in 'assist mode', but if you try to get it to run at full speed and charge the battery at the same time, I won't work. Why do you think they are having so much problems with the inverters, etc? and one solution was to take out the battery... that's so the power is dedicated to running the computer and not shared with everything else.
I find it hard to belive that apple designs an adapter that outputs 16/18v just for the heck of it. Why else all of a sudden it jumped up to 85w for the macbook pro line?
Bottom line, in order to get the laptop running at top speed and at the same time rapidly charge the battery in ~couple of hours or so, they need the higher voltage.
Currently the 85w adapter output a constant 6v when unpluged. As soon as it senses resistance, it jumps up to 16v and since it can output 18v, I bet it'll sense that and step up if needed.
Yes, it'll run 12 (or 14v) from the car, but it'll be
in 'assist mode', but if you try to get it to run at
full speed and charge the battery at the same time, I
But all people are after (in this thread at least) is to be able to USE the MacBook (Pro) in-flight. One thing about the Apple portables is that they do have a good power management system that allows for things like limiting the power drawn from the supply (so as to be able to use different wattage supplies to best effect for example). IF the management processor has the capability to control power demand to 75W and run the system from 14V then there is no need for the electronics - just a simple cable and appropriate identification is all that required.
Why do you think they are having so much
problems with the inverters, etc?
Because it's the wrong way to tackle the problem ! If you want to run from an aircraft supply that is limited to 75W, then the right way to do it is for the system to control it's draw to 75W - you can't achieve that effect reliably if the system thinks it's OK to draw 85W so you end up drawing 90+W after the extra conversions.
I find it hard to belive that apple designs an
adapter that outputs 16/18v just for the heck of it.
No they don't, they select the input voltage to suit the requirements. I don't know the battery voltage for the MacBook Pros, but the G4 17" is 12V. It makes the conversion circuitry simpler if you only have to convert one way (eg step-down) rather than two ways (ie step down or step up). Since the voltages used internally are all probably 5V or lower, then it's still a down-conversion from 12/14V.
That doesn't mean that they can't design the system to cater for other voltages with some loss of functionality - such as accepting a lower input voltage but losing the ability to charge the battery.
Why else all of a sudden it jumped up to 85w for
the macbook pro line?
For the same reason the G4 PowerBooks hiked it to 65W from the previously standard 45W - it takes more power to run the system than to run the older ones. However, I can tell you that the G4 17" does run very happily from a 45W supply (it will even charge the battery), but it will draw more power from the battery to satisfy peak demands than it will running from a 65W supply.
That is the way Apple portables (and probably many other makes) have always worked - they rely on the battery being there to cover peaks in demand that would otherwise take them over the capacity of the PSU. When the peak is over they will top up the battery again. That BTW, is the reason Apple has always stated that their portables should not be run without the battery - and I assume that would be the same for the newest models.
Bottom line, in order to get the laptop running at
top speed and at the same time rapidly charge the
battery in ~couple of hours or so, they need the
It would IF that is what people are asking for, but if you go back and read the thread, people are not looking to charge the battery, just to be able to use the system on a flight that's longer than the unassisted battery life.
I'd be very surprised if a 14V supply limited to 75W couldn't supply at least 95% of the systems power requirements - that means at least 20 times the battery life, well enough for a 10 to 20 hours flight. After that, you recharge the battery wherever you can find a mains socket (hotel room anyone ?).
Currently the 85w adapter output a constant 6v when
unpluged. As soon as it senses resistance, it jumps
up to 16v and since it can output 18v, I bet it'll
sense that and step up if needed.
What is needed is some real technical details, without those then it's all just speculation. Unfortunately, the way Apple has gone over the years I don't expect them to release those details without extracting a sizable wad of cash and a non-disclosure agreement.
You know, I think we are talking in circles. Big waste of time.
-We both know that the extra power is for bringing the system up to snuff as quickly as possible, while using being in full power
-Yes, we can go direct with just 12v and the system will work, but it'll be in as you said work in low power mode, but I bet you it'll croak if you crank the laptop up to full speed, full brightness, and a dead battery.
-Inverters are plain waste of energy in application such as this. A direct car adapter will give people more to work with without the wasted DC to AC to DC again. We all learn that in Electrical engineering class. Without that wasted energy, there's more to go around specifically in running the laptop and probably even charge a dead battery. If you can get a little more out of a car adapter, why just go direct 12v? you have the resources, use it!
- Not complete speculation. Have you taken apart the apple adapter yet? You'll find that it's 6v unloaded, 16 volts loaded. Have seen what the voltage it pumps out at when the battery is taken out? How about with the battery out and laptop off? You'll see that it's still 16v.
Recent user who used the car adapter with the Macbook Pro:
Mike! You're a frigging genious, my man!
I wish I had a camera easily accessible here, because I'd take a picture of my MacBook
Pro sitting here on American Airlines flight 2003 en route to Chicago, power adapter
connected, and glowing... orange!
You got that right... my MacBook Pro's running and my battery is charging right here
on the plane.
You did it!!
Of course, you won't get this e-mail until after I land, but... I couldn't possibly wait
any longer to type it!!
I'm a pilot for Continental Airlines who also carries a Macbook Pro on flights. The Continental website says that customers may use the Empower system to power their laptops but are not allowed to charge the batteries. Rechargeable batteries should be removed from the laptop before connecting to the Empower system. I was unable to determine what the wattage limit is on our systems.
The computer boots up just fine with the battery removed. This should enable you to get some work done and eliminate the high wattage power draw that seems to be causing the headaches. Just be careful with the open battery bay on the bottom of the computer.
Word is that Continental is now in the process of converting their laptop power systems to eliminate the need for an Empower connector, instead allowing customers to simply plug their laptops into a standard power plug in the seat.
PowerMac G5 Quad, 15" Macbook Pro Mac OS X (10.4.7) 4 GB RAM, (2)-500mb HDs, external OWC 500mb RAID, 23" cinema display
This is the 'Duh' question of the day but I've got to ask - do all the airlines have power connectors at the seats and if so, where are they? I recently flew both Delta (several different aircraft types but all Boeing I believe) and Southwest (Boeing 737's) but do not remember seeing anywhere to plug in (other than the headphones on Delta). Is this a First-Class option only on certain Airlines?