18 July 2018

Zolo Liberty True Wireless In-Ear Headphones

I listen to a lot of music at work - easily 4-6 hours every day. For the past nine months, I’ve been using (and loving) the much-maligned Google Pixel Buds to get through the day. For the last week, though, I’ve been wearing the Zolo Liberty True Wireless In-Ear Headphones from Anker’s audio brand. These truly-wireless Bluetooth headphones sound great and have incredible stamina, but how do they compare to my beloved Pixel Buds?


Many have complained about the Pixel Buds’ one-size-fits-all approach, and those users will be pleased to learn that the Zolo Liberty headphones come with liquid silicone tips in four different sizes. Also included are GripFit “Jackets” in four sizes which can be slipped over the body of the earbuds to further adjust the fit. After selecting the best combination of tips and jackets for my ears, I gently pushed the Liberty headphones into my ears and rotated them to the rear as instructed to lock them securely in place. It’s a very solid fit, and these earbuds aren’t going to fall out even with heavy jostling from working out.

That said, fitment is a very personal metric to quantify, and every pair of ears is different. While the GripFit EarTips and Jackets provided a very secure fit, none of the various combinations I tried were particularly comfortable for me. The truly wireless design of the Zolo Liberty headphones means that each earbud needs to contain its own battery, Bluetooth radio, and other electronics, while the wire tethering the two Pixel Buds allows the left side to house the battery while the right holds the radio, touch sensor, and other electrical bits. The result is that the Liberty headphones are considerably bulkier and heavier than the Pixel Buds. I truly could forget that I was wearing the Pixel Buds, but I always felt the Libertys in my ears and often experienced a bit of soreness after extended listening sessions. Your mileage will likely vary, but the Pixel Buds are far more comfortable for me.

17 March 2018

Portable 45W Power for the Google Pixelbook!

I've been using a Google Pixelbook as my primary computing device for five months now. The Pixelbook has a ton of great qualities: it's unbelievably quick, has an incredible build quality, runs Android apps, packs a fantastic touchscreen that folds flat for tablet usage, and (with developer mode + crouton) can handle just about everything I need to do on a computer. I have also been pleased with the battery life; depending on what I'm doing, I tend to get 6-7 hours of use out of a charge.

Of course, even with great battery life it doesn't hurt to have backup power available - and the convenience of dual USB-C ports should make that pretty easy to accomplish, right? I should just be able to grab any power bank which advertises 30W or 45W USB Power Delivery and get started charging on the go, right? 

Unfortunately, it hasn't worked out to be that easy. I've been quietly and casually testing USB-C PD power banks for a month or two now, trying to find one which worked reliably with my Pixelbook. I don't have the skills, knowledge, or resources to do compliance testing like Nathan or Benson, but I used a Plugable USB-C power meter to monitor the current flow and make sure that it didn't drift wildly out of spec. I probably tested a half-dozen power banks before finding one that actually works to my satisfaction. 

I didn't encounter any that I'd consider dangerous; they just didn't work. Some would only draw power from the Pixelbook. One wouldn't pass any power when the Pixelbook was connected. One apparently provided enough power to activate the meter but the measured flow was 0V @ 0A. A few would constantly reboot; one only did so while the meter was connected and seemed to charge the Pixelbook okay without the pass-through meter in-line but that was still clearly incorrect behavior. Without a PD sniffer I don't know why these power banks didn't work but my hunch is negotiation problems. 

All of which brings me to the reason for this post: I found one that works! 

This is the ZMI PowerPack 20000, a 20000mAh battery pack with 45W USB PD output. I was a bit apprehensive since I hadn't heard of the brand before but this has succeeded where power banks from brands like Anker, RAVPower, and dodocool let me down.

While testing the ZMI power bank, I measured a pretty consistent 14.4V @ 2.7A - which exactly matches what my meter reports from the 45W wall charger that came with the Pixelbook. 

It charged the Pixelbook from 67%-87% in about 25 minutes. (The charging rate dropped from 45W (14.4V @ 2.7A) to 30W (14.4V @ 1.8A) somewhere around 85% so that did slow things a little bit. Again, I've observed the same behavior with the original charger). 

As a bonus, the ZMI power bank also has a USB 2.0 hub mode which works great for USB mice and USB storage drives - while still charging the Pixelbook at the appropriate rate.

In subsequent charging tests the ZMI power bank has continued to perform predictably. Again, I'm not able to comment on any of the PD negotiation traffic or USB spec compliance but it seems to me that it is doing exactly what it's supposed to. I haven't had any problems with the power bank trying to charge from the Pixelbook, failing to charge the Pixelbook, or trying to push an unexpected voltage/amperage combination. 

Consistent 45W charging in a small form factor with the added benefit of USB hub functionality at a reasonable $70 price makes the ZMI PowerPack 20000 an easy recommendation.