Phones & Accessories

Zenfome 2 ( ZE551 ML) Charging Analysis

HI Guys

Today we will do a charging analysis for Zenfone 2, Model: ZE551ML.

Zenfone 2 has a 3000 mAh Li-Polymer battery and support boostmaster technology, which is compatible with quick charge 2.0. and Qualcomm also list Zenfone 2 as supported device in their official site.


The model we test is ZE551ML, 4G/32G, We are surprising to see ASUS don’t include the fast charger in this model, just regular charger, here is the photo:



The standard charger just can offer 5.2V/ 1.35A. and ASUS includes a short usb cable ( about 0.9cm length) , see here:




and we test the no-load volt for the stock charger, see here:


Now we begin to test the total charging time with stock 5.2V/1.35A power adapter and usb cable. We have made our Zenfone 2 battery to 0% and here is the test result:

Time Battery level Volt Current
PM 1:34:00 0 4.9V 1.13A
PM 1:44:00 Battery is low, can’t power on to show the battery level
PM 1:54:00
PM 2:04:00
PM 2:14:00 23% 4.9V 1.13A
PM 2:24:00 29% 4.92V 1.12A
PM 2:34:00 36% 4.92V 1.12A
PM 2:44:00 43% 4.92V 1.1A
PM 2:54:00 49% 4.92V 1.1A
PM 3:04:00 55% 4.92V 1.1A
PM 3:14:00 61% 4.92V 1.1A
PM 3:24:00 68% 4.92V 1.1A
PM 3:34:00 74% 4.92V 1.1A
PM 3:44:00 80% 4.93V 1.03A
PM 3:54:00 86% 4.97V 0.8A
PM 4:04:00 90% 4.97V 0.75A-0.55A
PM 4:14:00 94% 5.02V 0.38A
PM 4:24:00 97% 5.02V 0.32A
PM 4:34:00 99% 5.04V 0.2A
PM 4:41:00 100% 5.08V 0.16A


The total charging time is 3 hours 7 mins with regular charger, and you just can get 20% battery in 30 mins (PS: we found an interested thing, the zenfone 2 can’t be powered on if the battery is lower than 20%, i am not sure if it is my phone problem or you guys also have this problem?). After charging for 1 hour, we just get 36% battery, charging 2 hours, we get 68% battery, charging 3 hours, the battery is almost full. The Charging current will become smaller as the battery growing. but max, you just get 1.13A. Here is a photo we take when we test:



Frankly speaking, If we don’t test with quick charge 2.0 chargers, we might think the charging speed is OK, Most people might think they just leave the phone to charge overnight, and if it can charge full during the sleep, then it is ok. :) However, if you tried with quick charge 2.0 chargers, i thought you should change your mind.


Now we begin to test with our chargers and cable:

Test with Tronsmart WC1Q wall charger (Qualcomm Certified, support quick charge 2.0), and Tronsmart USB cable (20AWG support high current):


Time Battery level Volt Current
AM 8:45:00 0% 9.15V 1.65A-1.56A
AM 8:55:00 Battery is low, can’t power on to show the battery level
AM 9:05:00 27% 9.15V 1.5A
AM 9:15:00 43% 9.15V 1.5A
AM 9:25:00 54% 9.16V 1.32A
AM 9:35:00 68% 9.19V 1A
AM 9:45:00 77% 9.19V 0.87A
AM 9:55:00 84% 9.2V 0.62A
AM 10:05:00 88% 9.22V 0.39A
AM 10:15:00 92% 9.23V 0.28A
AM 10:25:00 95% 9.23V 0.17A
AM 10:35:00 98% 9.23V 0.16A
AM 10:45:00 100% 9.23V 0.14A


With our chargers and cable, we get zenfone 2 from 0% to 100% in 2 hours, When it detects Zenfone 2 support quick charge 2.0, our charger just give 9V volt instead of 5V. and you get 54% battery in the first 40 mins, and in 1 hour, you get 77% battery. (while with stock standard charger, in the same time, you just get half battery). Our chargers can give 15W power to zenfone 2 at first, while the regular charger just can give 5W. That’s a big difference. We also can see in the above table, while use our charger,in the whole charging progress, Zenfone 2 always get 9V high volt , but the charging current is becoming smaller as the battery growing.

We take a photo after charging a while with our charger to show the quick charge:



So from the above testing, we can see, use our quick charge 2.0 charger, you can save 36% total charging time , it can offer double battery level at the first 1 hour compare with regular charger. Like Qualcomm said, Less time charging, More time doing. And not just our wall charger, our quick charge 2.0 car charger also support Zenfone 2, you can get similar charging time when you use our quick charge 2.0 chargers.

In the end, Here is our suggestion to charge your Zenfone 2 faster:

1 If your zenfone 2 don’t equipped with a fast charger, just get one asap :)

2 Pick up some high quality usb cables, it do effect the charging, i take a photo to compare our usb cable and asus one:


The above one is Tronsmart, the bottom is Asus, Our cable is thicker than ASUS because we use the 20AWG cable, i guess asus just use 24awg or 28awg. It’s good for regular charger, but for quick charge 2.0, we suggest to get the 20awg cable.

That’s all. Thanks for reading our charging analysis for Zenfone 2. If you want to read more charging analysis for other popular smartphone, check here. Any questions feel free to leave comment below.

Why Choose Tronsmart chargers:

All of Tronsmart Chargers are get certified by CE, ROHS, FCC and other certifications, all of our quick charges are certified by Qualcomm(you can find our name in the Qualcomm quick charge list), and we are also proud to be the featured quick charge brand in Qualcomm Official site. So You don’t need to worry the quality of Tronsmart chargers.

More and more flagship smartphone will support quick charge 2.0 technology, Samsung, Sony ,LG, Moto, all of these brand flag ship support quick charge, Tronsmart offer the world’s most abundant quick chargers. From 1 port usb wall charger to 5 port and from 1 port usb car charger to 4 port.


Thanks for the review.

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