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PMU reset issue, I think

Message #1 - Posted 2012/08/07 - Alan J Rosenthal

Hi,

I have a white MacBook which I bought in 2008. It's fine except for a problem which seems to be about the power management unit -- it often (perhaps increasingly often) decides not to charge when I plug in the power. The greyed-out menu item at the top of the battery indicator menu, where it lists status such as "1:10 until full", at times like that says "Battery is not charging". It's just happily sitting at 50% or whatever, and not bothering to charge. And the battery icon at such times is the same as the one it displays when it's fully charged but still plugged in.

So I think it needs a PMU reset. I followed the procedure I googled up, which was simply to shut down and remove battery and power, and then hold down the power button for five seconds. I didn't find this very convincing. And the behaviour didn't change.

This morning I ran down the battery on the train, so that it wouldn't come out of sleep mode when I got to my office, and still when I plugged it in it decided not to charge, so I still couldn't turn it on.

Oddly, if I unplug the power and plug it in again, it sometimes then starts charging. And sometimes it doesn't start until the third attempt. I haven't been aware of this issue long enough to have an idea of the overall statistics.

I suspect that the PMU reset didn't actually work. Is there a reasonable way to test whether the PMU reset is happening? E.g. some wacky thing I could write to, then do the PMU reset, then read it back and see if it actually got blanked?

thanks,
ajr

Message #2 - Posted 2012/08/29 - Alan Browne

On 2012.08.07 10:34 , Alan J Rosenthal wrote:

Hi,

I have a white MacBook which I bought in 2008. It's fine except for a problem which seems to be about the power management unit -- it often (perhaps increasingly often) decides not to charge when I plug in the power. The greyed-out menu item at the top of the battery indicator menu, where it lists status such as "1:10 until full", at times like that says "Battery is not charging". It's just happily sitting at 50% or whatever, and not bothering to charge. And the battery icon at such times is the same as the one it displays when it's fully charged but still plugged in.

So I think it needs a PMU reset. I followed the procedure I googled up, which was simply to shut down and remove battery and power, and then hold down the power button for five seconds. I didn't find this very convincing. And the behaviour didn't change.

This morning I ran down the battery on the train, so that it wouldn't come out of sleep mode when I got to my office, and still when I plugged it in it decided not to charge, so I still couldn't turn it on.

Oddly, if I unplug the power and plug it in again, it sometimes then starts charging. And sometimes it doesn't start until the third attempt. I haven't been aware of this issue long enough to have an idea of the overall statistics.

I suspect that the PMU reset didn't actually work. Is there a reasonable way to test whether the PMU reset is happening? E.g. some wacky thing I could write to, then do the PMU reset, then read it back and see if it actually got blanked?

Not sure.

There is an SMC reset procedure that also might help.

(See
http://osxdaily.com/2010/03/24/when-and-how-to-reset-your-mac%E2%80%99s-system-management-controller-smc/ )

Which includes battery issues as a reason to reset SMC as well as the procedure.

Also what is the life-use status of the battery? (Get via the "Power" state under hardware in the System info).

"C'mon boys, you're not laying pipe!". -John Keating.

Message #3 - Posted 2012/08/29 - Alan Browne

On 2012.08.29 17:15 , Alan Browne wrote:

On 2012.08.07 10:34 , Alan J Rosenthal wrote:

Hi,

Sorry 'bout that - thought it was a recent item...

"C'mon boys, you're not laying pipe!". -John Keating.

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