MBP Battery life while connected to ext. power supply.

My old Powerbook G4 Laptop battery life went to null capacity in 3 years, even though it was always connected to the power supply.
This was why many took the battery off if always connected to external power.

Does anyone know if the new MBP's use battery when they are connected to the power supply.
My 11 month old MBP has not yet showed any substantial battery life shortage.

the issue is that Li-Ion batteries do not like to be stored at full charge which is exactly what you want from a laptop when you unplug it.

Li-Ion batts much prefer to be stored at about 60% capacity but it's difficult to get the Apple power management system to NOT charge a battery while AC is connected. There may be an API some programmer can exploit but in general, if AC is connected, the battery will be charged to max capacity.

I bought one of the 17 power macs and at a Mac show they had a usb device that turned on the power supply when warning to plug in power came up . It does not / did not work on MBP . The company went out of business .

One of the mac sites had a thing that plugged into a usb port and timed out turning charger on . The problem was , you had to restart mac to reset it .
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I think the new MBP's will charge while connected to a power source. If you dont use your battery, i.e. keeping it plugged in to the wall at all times, you will wear our battery, actually shorten the life of it. One article I read said this guy needed a new battery after four months of keeping it constantly plugged in. They need to be charged, then used up till they need to be charged again, this keeps the battery in better condition. They are rated for something like 5000 complete charges before you need to take into an Apple store to have the battery replaced. 5000 charges is allot, and it may be more than that. On my new MBP, I run the battery down, and re-charge when it tells me I need to, then repeat.
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If it helps , I use 2 kensington masterpiece plus [ older than dirt ] . Between the 2 there are 10 switches / outlets . I turn on / off printer [ 2 ] , DVD burner , a power strip for all battery chargers , different HD's
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1st it's a hobby
7D gripped XTI gripped
Canon - efs 10-22 , 17-55 , ef 18-55 IS
EF 28-90 , 28 @ 2.8 , 50 @1.8 , 28-135 IS
L's 35-350 , 70-200 MK II IS
Quantaray lens 70-300 macro
Sigma 135 - 400 , 180 MACRO
2X III , Life Size converter
KSM filters for all
kenko auto tubes , EF 25

Thanks for the info, so nothing has changed since Powerbooks, beside better batteries.

It would have been nice to be able to bypass completely the battery via some kind of switch when plugged to power almost constantly. Maybe it won't be a big problem with the new MBP's. My old Powerbook lost significant battery capacity in half a year.

it's possible to turn off the charging circuit since the Apple battery calibration software can but perhaps the API is private or no one has ever built external software to shut off the charge circuit.

Howard Moftich said:

the issue is that Li-Ion batteries do not like to be stored at full charge which is exactly what you want from a laptop when you unplug it.

Li-Ion batts much prefer to be stored at about 60% capacity but it's difficult to get the Apple power management system to NOT charge a battery while AC is connected. There may be an API some programmer can exploit but in general, if AC is connected, the battery will be charged to max capacity.

Click to expand...

This is not strictly true, and is a common misinterpretation of the battery tech literature. The 40-60% figure for storage cited by Apple and others is specifically for long-term storage, not the short-term cycles of normal use.

According to the same tech notes, Li-ion batteries like shallow discharge cycles. Keeping a Li-ion battery near full is not a problem in and of itself as long as it is fully discharged once a month or two (and no more frequent than that).

The primary issue with keeping plugged in is the specific combination of a battery being both full and hot. If the battery was full and not hot, capacity would not decrease as much.

Source:

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Howard Moftich said:

The smaller the depth of discharge, the longer the battery will last. If at all possible, avoid frequent full discharges and charge more often between uses...Partial discharge on Li-ion is fine; there is no memory and the battery does not need periodic full discharge cycles other than to calibrate the fuel gauge on a smart battery...

Lithium-ion suffers stress when exposed to heat and kept at a high charge voltage...Exposing the battery to high temperature and being at full state-of-charge for an extended time can be more damaging than cycling.

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