REGULARS
MAC AUDIO Sleep or Hibernation? Brad discovers an assault on his battery. Text: Brad Watts
Recently I had a bit of a hiccup with my now ‘past-itsuse-by-date’ MacBook. It’s an early 2008 model packed to the gills with RAM and hard drive space. It chugs along at 2.4GHz, it has a Firewire port, and I like it. However, due to a recent change in vocation, I’d left the good ol’ MacBook sitting around doing nothing for about a month. It had gone to sleep and, as is the standard operating procedure with relatively recent MacBooks and MacBook Pros, had used whatever remaining battery power it had to keep the RAM contents intact, waiting in vain until I opened the lid and let it all spring back to life. Unfortunately that didn’t happen. The computer said ‘no’. No biggie I thought. I’ll plug the machine into the mains and recharge the battery. To my joy, the MacBook booted as expected. Yet to my disgust, the battery menu told me the battery wasn’t charging and required immediate replacement – bugger. I attempted all the tricks; zapping PRAM, resetting the PMU, permissions, a clean operating system, but nothing resuscitated the battery – it had been keeping the RAM contents alive for ages and completely depleted its charge doing so. This is the death-nell for MacBook batteries. I was left no choice but to buy another battery – damned if I was paying through the nose for a battery through Apple itself. This was a job for eBay. Within 10 minutes I’d ordered a replacement for the princely sum of $38. Not a bad deal I thought, and kinder on the bank balance than the $149 genuine article… until I fitted the battery. But that’s another story which I’ll get to shortly. In the meantime, how does one avoid a battery completely discharging and performing the Apple Seppuku? There are three modes of sleep with Intel-based Apple laptops (and desktop machines, but it isn’t so much an issue with a desktop being powered via the mains always). The three modes are Sleep, Hibernation, and Safe Sleep, and they each work slightly differently. Sleep: This is the default setup for desktop machines. The machine’s RAM is left powered on while it’s sleeping, allowing the Mac to spring into life quickly, because there’s no need to load anything from the hard drive. Perfectly suited to a desktop machine. Hibernation: In this mode, the contents of RAM are copied to your hard drive before the Mac enters sleep. Once the Mac is sleeping, power is removed from the RAM. When you wake the Mac up, the hard drive writes the saved information back to RAM, so wake time is a bit slower. This is the default sleep AT 62
mode for laptops manufactured before 2005. Safe Sleep: The RAM contents are copied to the hard drive before the Mac sleeps, but the RAM remains powered – in the case of a MacBook, MacBook Pro or MacBook Air, that power is derived from the battery if the unit isn’t plugged into the mains power supply. The wake time is pretty quick because the RAM contains the necessary info. However, the RAM’s contents are still copied to the hard drive as a safeguard. Should something bad happen, such as a battery failure, you can still recover your data. The default sleep mode for laptops has been Safe Sleep since around 2005, although some earlier laptops also support Safe Sleep mode. Now if, like me, you leave your laptop sitting around for weeks without being connected to the mains power, you run the risk of draining your battery to zero power. And, as I’ve mentioned, this can kill a battery completely. Ideally the laptop would be set to Hibernation mode to avoid this. It’s a simple process to change the sleep mode with a quick command typed into the Terminal application found in the Utilities folder. To find out which mode your machine is set to, open the Terminal app and type: pmset -g | grep hibernatemode. You’ll get one of the following responses: hibernatemode 0, hibernatemode 1, or hibernatemode 3. For my machine I wanted it set to ‘Hibernation’. To change this setting, type this command into a Terminal window: sudo pmset -a hibernatemode x - replacing x with either a 1, 2, or 3. In this case I used sudo pmset -a hibernatemode 2. You’ll be asked for your account password and then the job’s done – no more RAM draining your battery to death. Now, about that cheap battery. While the battery does work, the actual battery housing was ever so slightly larger than a standard Apple battery, and after forcing it into its nest, the battery pushed against the underside of the trackpad and trackpad button and rendered the button in a perpetual state of pushed downedness – yeah, a right pain. So my next project is to remove the battery cells from the cheap battery and put them into the original battery casing. I’ve got them in pieces now. If it fails, I suppose I’ll end up stumping up for the real deal from Apple. I’ll let you know. Brad Watts has resigned from his role as AT’s Online Editor but will continue to contribute Mac Audio and equipment reviews – as he has done since Issue 1! Thanks for all the hard work while on staff Brad, and good luck. – Ed.