[tottiflames]

Mine is an iPod Classic 80G, here is how I do it. I believe the Nano1，2，3, Video5，5.5，4Gen，Photo，Mini all share the same procedure to do this。
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To make the testing result as accurate as possible, please make sure your iPod is fully charged.

then, we are going to explore your iPod in its "diagnostic Mode"

Press Central "select"+"MENU" button at the same time and hold for 3-4 seconds.
then you should see the screen turns off and the ipod restarts.

As soon as you see the "grey apple logo" appears on the screen, press "previous"+"select" button and hold for 2-3 seconds(do not exceed 3 seconds)

then you should see the black and white screen says:
MENU：manual test
Select：Auto Test

Press "MENU" button.

then you should see several selections listed.
Use “previous/next" button to choose up and down, and use "select" button enter to next step.
This time, you will enter the "Power" section.

Same rules apply, enter to "A2DTests", and then "BatteryA2d"

this is what appears on my Classic 80G:
BatteryA2D=4140

to go back to normal mode, just hold "MENU"+"Select" for 3-4 seconds. Your ipod will restart.
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I am pretty sure that this will not do any harm to you ipod, because I have done this for several time and played with other section. No signs of excessive heat or strange noises.

try it on your ipod and report your results.

please state:
Model of iPod
How long have you used it
Result

My result:
iPod Classic 80G
bought it brand new 4 days ago
4140

 

[tottiflames]

oh yeh, just forgot to mention, the read decrease as you use the your iPod, so I think this measures "power remaining". So make sure your ipod is fully charged prior the test.

 

[Oya?]

I've got a slightly different set of numbers showing up on mine. It's an 80GB Video, not yet a month old. Is the latter value the one that's important?

Quote:

battery=491 (4149mV)

 

[shigzeo]

Battery=4,044v
ACC=2,497V

6 month old nano 3g 4gb

 

[shigzeo]

i don't have a cable to test it, but evidently, it will record in wave format from this menu and you can play it back. im excited on this...

 

[PooJou]

Looks like it's measuring the remaining voltage of your battery - hence it decreases - I believe rockbox exploits this on startup

Interesting find - would be better if they could predict playing time left huh