Bests & Worsts Reviews from Amazon

UPDATED REVIEW (April 26, 2016) : Tronsmart has followed up with me about the problems I found with their original 2 port Type-C + Type-A car adapter. Over the last several months, they have tasked their engineers and suppliers with redesigning their charger. Let's see how they did. Full dislosure : Tronsmart provided me with two updated versions of this charger for free to replace the defective one I purchased last year. The first big change that Tronsmart did was they modified the source capability of the Type-C plug to actually supply 3A instead of only 2.4A in the 1st gen. The rating text on the side of the charger now clearly states that the Type-C port outputs 5V/3A max. My test device is the same as before, a Chromebook Pixel 2015 and the Twinkie USB PD sniffer. I've plugged Pixel 2015 into the Type-C plug from the new Tronsmart 36W charger. Let's run the ectool command from Pixel's command line : localhost ~ # ectool --dev 1 usbpdpower Port 0: SNK Charger Type-C 4927mV / 3000mA, max 5000mV / 3000mA / 15000mW Port 1: SRC As you can see, Pixel has identified the charger as a 3A Type-C charger, and the charger is able to maintain 4.9V while Pixel is drawing 3A. This is a good result. The first generation of this product would not get this far : Pixel would try to draw 3A, but that would result in the charger tripping overcurrent protection because it was not really rated at 3A. In my testing, even when plugged in for a full charge cycle over several hours, the Tronsmart charger would not trip overcurrent. Let's check twinkie : > tw cc CC1 = 1727 mV ; CC2 = 27 mV > tw vbus VBUS = 4971 mV ; -3059 mA The "cc" command reads the voltage levels on the two CC pins. In this case, you can see that 1.727V is on CC1 which falls within the expected range of a 3A Type-C source. This indicates that the charger has a 10kΩ resistor. The tw vbus command reads the current and voltage on Vbus. As you can see, Pixel is stably drawing 3A at 4.971V. The final change that Tronsmart made to this product is that they clearly marked the Type-C port as only a 3A port. The 1st generation of this product claimed that both ports (Type-C plug and Type-A receptacle) were capable of Qualcomm Quick Charge at 9V and 12V. Doing so is actually a violation of Type-C spec, section 4.8.2, which prohibits proprietary charging methods on Type-C connectors from changing Vbus voltage beyond 5V. Tronsmart corrected this spec violation by removing the QC functionality on the Type-C plug. The Type-A port is now QC3 compatible. Unfortunately, I do not have the equipment to test QC3, so I will not comment any further about that port. Overall, this product is significantly improved from the 1st version I saw last year. I recommend it for car charging fast charging Type-C devices such as Nexus 5X/6P or Pixel 2015 or Pixel C. ORIGINAL REVIEW (November 12, 2015) : Hi, Benson again reviewing USB Type-C accessories. After many requests, I am finally reviewing the Tronsmart 36W 2 Port Car charger. The Tronsmart 2 port car charger has one green USB Type-A port on top, and then a USB Type-C captive cable, meaning it has a Type-C plug on one end, and the other end cannot be removed from the charger. For this review, I am going to focus closely on the Type-C captive cable. For my analysis I am using my Chromebook Pixel 2015 and my USB PD Sniffer device (search chromium.org for twinkie), also available here : Plugable USB 3.1 Type-C (USB-C) Power Delivery Sniffer According to the USB PD sniffer, the CC line on the charger connected via the captive cable is pulled up to Vbus using a 10k resistor. According to the USB Type C specification Section 4.11.1, this indicates to the device being charged that this power source is capable of supplying 5V 3A. However, please look carefully at the rating text on the side of the charger. I have attached a picture of it. It says "Output(each port): DC 5V/2.4A" This means that the tronsmart charger is using the incorrect CC pullup, as the charger itself is not rated at 3A. When I plugged in my somewhat discharged Chromebook Pixel 2015, the Pixel would not charge (my twinkie current meter measured 0mA current), and it appeared that the charger itself had browned out. The Chromebook Pixel made a high pitched squealing sound until I disconnected it from the charger. As an experiment, I also tried connecting Pixel to the Tronsmart's OTHER usb port using a compliant (56k terminated) USB A-C cable. Using the other port, the Pixel charged properly. In conclusion, this charger is using the wrong CC termination given its rating of only being able to handle 5V 2.4A out of each port. Fast charging Type-C devices like the Chromebook Pixel may try to pull 3.0A out of the captive cable, improperly browning out the charger.