MacBook Pro tip: resetting SMC saved my day

I have the exact same problem with a 2007 MBP 15" over the last month or so battery life has reduced. Even more recently the mbp just shut down with no warning. Called Apple support today - eventaully told I had to buy a new battery (£97 in the UK).
As a test I decided to hold the power button (I didn't know about the smc thing) the computer did a long beep and now the "system profile" is telling me the battery has a max charge of 4400 mAh compared with 1176 before.
It's now charging and when it gets to 100% we'll see if it lasts longer than 20 mins

I had an issue where I would regularly get about 6-7 hours of Battery life on WiFi while browsing the web on a rev a Intel MacBook. It wasn't until about 3 months later I discovered I couldn't play any of the content from Joost. I looked for some utllities and noticed one showed my clock speed at 1ghz. After a bit of digging I discovered this was the problem with my being unable to use Joost but also a feature that was giving me an extra 3 or 4 hours of battery life as I quickly discovered after the motherboard swap from Apple. I wonder after reading this if the problem form the get go wasn't something wrong witht he SMC firmware.

I had to do the whole operation twice- "start" the machine with no power source, then plug the battery in while holding the power switch, that is.

first time, the fans are running at full speed & there's no battery status indicator on the menu bar, + the charger plug has no LED at all, making me think it's failed.
after leaving the machine on for a while, & after several reboots, the battery is still showing full on it's own indicator, but still no charger lamp & the fans are still going full speed.
I'm on 10.4 so the firmware update does not apply to my machine.

second time, ("start" the machine with no power source) & all seems to be well again. the charger cable is showing green & I see "charged" in the menu bar, & the fans are quiet again.
hope this helps someone.

duncan.

So cool! I thought my MBP was broken. It kept locking up soon after startup, if it finished startup at all, even when running through the low-level hardware tests using the install DVD. Then I read this tip and thought, "what the heck, let's give it a go", and, lo and behold, after resetting the SMC, it doesn't appear to be locking up any more.

Wow, brand new MBP 15" and haven't really used it without the power cord yet....only showed 1:40 when I unplugged in. Did the reset, now 4:45. Jeesh, glad I read this one!

I just re-set the SMC on my late 2008 MacBook Pro, and it fixed the "no warning" issue when the battery level was low. (e.g. no dialog warning comes up saying battery was low. Instead, it just suddenly went to sleep.)

I hope this fix sticks since the sudden shutdown was a serious pain.

Now I just need a fix for the serious wireless issues and I will be on my way to being a happy customer again...although the 'beta culture' Apple has embraced about 24 months ago is getting old and tires.

Thanks for the repost. Jason reposted this tip, originally by Big Scotty McN., in July. Glad to see it could help some people again.
http://www.tuaw.com/2008/07/30/battery-calibration-recommended-by-apple-why-no-utility/

This actually works on many Toshiba laptops too (I'm a ccity firedog tech) Also sometimes the screens of HP and Toshiba laptops stop powering on with the rest of the computer... this fixes that as well. How about that.

I tried this and no luck. My battery was replaced about 4 months ago even though it was out of warranty because it would die minutes after the mac was unplugged. I thought it was a battery problem, but when I checked this out and unplugged my mac I had 1:37 minutes on it and the battery had only gone through 5 cycles. I followed your instructions and it wasn't any better. I called applecare and they said it was probably a logic board problem. My powerbook pro is covered by applecare, but it's a hassle even if they repair it free.

Please take note that once you blasted the SMC, your battery calibration goes down with it. You have to re-calibrate using the usual procedure (attach cable, charge to full, leave it like that for some hours, unplug, run the battery down, let it sleep until sleep LED goes out, charge again).