Summer’s drawing to a close. But the deals rolling into the Cult of Mac Store are showing no signs of slowing. This week, we’ve got a guide cryptocurrency investing for beginners started in, and a digital marketing masterclass. Additionally, we’ve got a stereo pair of portable Bluetooth speakers, and a powerful but slim backup battery. Everything is massively discounted, some by more than 90 percent. Read on for more details:

Apple’s notebooks pack some of the best laptop batteries out there, but you’re always going to find yourself low on power when using your MacBook on the road. Fortunately, Kanex’s new PowerGo battery pack can save the day.

Packing 15,000 mAh of power and USB-C connectivity, it’s capable of giving your 12-inch Retina MacBook a full charge on the go — and it’ll keep your iOS devices topped up, too.

At this year’s Consumer Electronics Show in Vegas, the only thing I was hunting down more than free drinks and after-parties, was power outlets. Yes sir, I love my purdy white iPhone 4S, but on days of heavy use, I find I need to charge it two times or more before the day is through.

The Dual USB Power Bank from Verbatim (about $65), provides a a massive amount of portable power that should keep anyone from outlet-hunting in the inky-shadows of Vegas convention halls. But the question is, how does it perform while charging two connected devices or the power-hungry new iPad?

One of the biggest customer complaints about the iPhone 4S is battery life. The battery never manages to last even a whole day and sometimes not even a half of a day. Although the iPhone 4 has always managed to last nearly a whole day, it isn’t much better. Apple is working on an iOS 5 software fix that might eventually take care of the battery draining issues that face iPhone 4S customers. Their first attempt, the release of iOS 5.0.1, wasn’t much help for some users.

If you cannot wait any longer and you own either of these phones one solution could be the MiLi Power Pack 4 ($60) from xengadget.com. The 3000 mAh slider case will give your iPhone 4 or 4S the extra power boost it needs to last until bed time. I tested it on my iPhone 4S and I’d like to share my experience with you.