Q&A: MacFixIt Answers

MacFixIt Answers is a feature in which we answer questions e-mailed in by our readers.

This week readers wrote in with questions regarding an odd APSD-related firewall error in OS X, the utility and risks of having Java runtimes installed, options for maintaining Mountain Lion on corporate networks, and MacBook battery charging. We welcome views from readers, so if you have any suggestions or alternative approaches to these problems, please post them in the comments!

Question: Best practices to prolong battery life
MacFixIt reader Jonathan asks:

I recently bought a MacBook Air, first-time Mac buyer, and I love it! Anyways, I charge it every night, does charging it every night ruin/destroy the battery capacity to hold the charge much faster than usual? I use it till is about 5% left then charge it.

Answer:
There is a balancing act that goes on with batteries. If you use them all the time then you will deplete them faster than if you use them less often; however, if you don't use them at all then you also accelerate their depletion. My general suggestion is to use them so they deplete fully at least once a month, and allow them to be used (in other words, the laptop is not on wall power) for at least a few hours every week. These suggestions are really a ballpark guideline, and also do not take into account manufacturer defects and other variances in battery construction that might play into the situation, but should be good for most situations.

Question: How to determine whether or not Java is needed
MacFixIt reader Stephen asks:

How do I know whether or not I need Java?

Answer:
If an application you use requires Java, then the system will prompt you to install a Java runtime when you load the application. Therefore only install the Java runtime if you get a prompt for it in an application that you need. Besides applications, some Web content uses Java applets (small Web-based Java programs) that are a requirement for some Web sites; however, these likewise will prompt you to install Java if you don't have it.

Question: Benefits from clearing the browser cache and history
MacFixIt reader Sean asks:

Is there a concise method of clearing the browser cache and history from the Mac's hard drive? To ensure there is no memory unnecessarily being wasted and used.

Answer:
If you are worried about memory usage, the browser's cache is not a culprit. This cache is stored on the hard drive and will not occupy RAM, so you will not need to actively clear it to maintain free memory for other uses. The cache only is used to speed Web page loading. If there are no detected changes to a Web site then the cache will be used to load the page and therefore quickly show you the contents, instead of always loading from the remote server.

The caches for Safari are located in the system's temporary directory and user Library, which can be manually deleted by running the following commands in the Terminal:

rm -rf $TMPDIR../C/com.apple.Safari

rm -rf ~/Library/Caches/com.apple.Safari

Most Web browsers have a history- and search-clearing option. In Safari this is at the bottom of the History menu. Alternatively you can use the Reset Safari option in the Safari menu to do this.

Question: Monitor resolutions limited on external display
MacFixIt reader John asks:

I have a mid-2011 Mac Mini with the AMD Radeon HD 6630M 256 MB. I'm using it with a Dell S2330MX. My problem is that the display does not take up the full screen, that is there are black bars all the way around. The puzzling thing is that this does not happen during boot up, in recovery, or in Windows 7. All of those take up all the real estate as it were.

I've tried it with an HDMI cable and the Dell-provided DVI adapter as well as a DVI cable and the Apple-supplied adapter with no success. I even updated to Mountain Lion with no success.

Answer:
Do you have any other displays that you can test with the system? Usually this type of problem is because of a firmware incompatibility with the display itself and not with the Mac's video output. Does this happen if you boot into Safe Mode (hold Shift at startup)? Lastly, try resetting the system's PRAM to see if this helps.

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