USB Charger Specifications and Measurements

This is a list of USB power supplies / chargers that I own. I measured their properties like how they identify themselves as charger devices, I measured their open circuit voltage but also the behaviour under load.

Nominal Specifications:

Supply for Voltage Current Imprint
Google Nexus 4 5.0 V 1.2 A Model: MCS-01ER
Apple iPad 4 5.2 V 2.4 A Model A1401 Flextronics LPS 0012ADU00
TP-Link TL-MR3020 5.0 V 1.0 A HuntKey Model HKA00605010-3B
EasyAcc Charger 5-Port 5.0 V 5.0 A K-5B25
ASUC42e-050100 5.0 V 1.0 A
HNP06-USBV2-Black 5.0 V 1.2 A
USB Travel Charger 5.0 V 2.0 A RG-TC-2300-S
iProtect Slim Charger 5.0 V 1.0 A
230V Outlet 20EUCBUSB 5.0 V 0.7 A
Sony SRS-X3 5.0 V 1.5 A Sony AC-E0515
OTB TR-005 micro-USB 5.0 V 1.0 A
Busch-Jaeger 20EUCBUSB 5.0 V 0.7 A
Pollin Mini-USB 351382 5.0 V 1.2 A GlobTek GT-41076-0605
Jabra Stealth 12V Car 5.0 V 0.75 A SIL-050075A-CLA
Bose Color SoundLink 5.0 V 1.00 A PSA05F-050QBT1
Ravpower Wireless Charger 5.0 V 1.50 A UWP-12W-0515T
Netgear AirCard 762S 5.0 V 1.0 A AD631M0
Amazon PowerFast 5.0 V 1.8 A A02760
Samsung Galaxy Tab 3 7.0 lite 5.0 V 1.0 A ETA0U81EBE
Sennheiser MM 400 5.0 V 0.5 A PSC03R-050

Here is how they tell connected devices that they are for power supply only. This is done with the data lines (D+: green, D-: white).

Supply for Setup
Google Nexus 4 D+ and D- short
Apple iPad 4 D+ and D- on special voltage levels
TP-Link TL-MR3020 D+ and D- short
EasyAcc Charger 5-Port D+ and D- short (Android socket), voltage levels (iPhone/iPad socket)
ASUC42e-050100 D+ and D- on special voltage levels
HNP06-USBV2-Black D+ and D- on special voltage levels
iProtect Slim Charger D+ and D- on special voltage levels
230V Outlet 20EUCBUSB D+ and D- short
Sony SRS-X3 D+ and D- short
OTB TR-005 micro-USB D+ and D- short
Busch-Jaeger 20EUCBUSB D+ and D- short
Jabra Stealth 12V Car D+ and D- short
Bose Color SoundLink D+ and D- short
Ravpower Wireless Charger D+ and D- short
Netgear AirCard 762S D+ and D- short
Amazon PowerFast D+ and D- short
Samsung Galaxy Tab 3 7.0 lite D+ and D- short
Sennheiser MM 400 -none- (D+, D- are floating)

Open circuit voltage Voc (measured, no load):

Supply for Voc
Google Nexus 4 4.91 V
Apple iPad 4 5.19 V
TP-Link TL-MR3020 5.11 V
EasyAcc Charger 5-Port 5.01 V
amzdeal 4-Port 5.20 V
ASUC42e-050100 4.85 V
HNP06-USBV2-Black 4.86 V
iProtect Slim Charger 5.25 V
230V Outlet 20EUCBUSB 5.07 V
Sony SRS-X3 4.97 V
OTB TR-005 micro-USB 5.17 V
Busch-Jaeger 20EUCBUSB 5.06 V
Pollin Mini-USB 351382 5.12 V
Jabra Stealth 12V Car 5.21 V
Bose Color SoundLink 5.05 V
Ravpower Wireless Charger 5.14 V
Netgear AirCard 762S 5.05 V
Amazon PowerFast 5.05 V
Samsung Galaxy Tab 3 7.0 lite 5.08 V
Sennheiser MM 400 5.10 V

Electric potential with respect to ground (no load):

Supply for D+ to GND D- to GND
EasyAcc Charger 5-Port (iPad) 2.66 V 1.97 V
EasyAcc Charger 5-Port (iPhone) 1.98 V 2.66 V
amzdeal 4-Port (1A) 2.05 V 2.76 V
amzdeal 4-Port (2A) 2.77 V 2.06 V
ASUC42e-050100 1.92 V 2.60 V
HNP06-USBV2-Black 1.94 V 2.61 V
iProtect Slim Charger 2.12 V 2.73 V

Resistance between:

Supply for D+ and D- D+ and Vcc D- and VCC D+ and GND D- and GND
Google Nexus 4 0.0 Ω ∞ Ω ∞ Ω ∞ Ω ∞ Ω
iPad 4 44.9 kΩ 40.0 kΩ 21.9 kΩ 22.5 kΩ 24.0 kΩ
TP-Link TL-MR3020 0.0 Ω ∞ Ω ∞ Ω ∞ Ω ∞ Ω
EasyAcc Charger 5-Port iPhone 13 kΩ 0.46 kΩ ∞ Ω ∞ Ω
ASUC42e-050100 52.6 kΩ 29.8 kΩ 22.8 kΩ 29.7 kΩ 22.6 kΩ
HNP06-USBV2-Black 52.2 kΩ 30.3 kΩ 22.9 kΩ 30.0 kΩ 23.1 kΩ
iProtect Slim Charger 53.0 kΩ 33.0 kΩ 23.0 kΩ 32.0 kΩ 26.0 kΩ

Behaviour under load

Supply for Current Voltage
Google Nexus 4 0.93 A 4.98 V
HNP06-USBV2-Black 0.93 A 4.91 V
HNP06-USBV2-Black 0.58 A 4.90 V
ASUC42e-050100 0.9 A 4.88 V
iProtect Slim Charger 0.43 A 5.20 V
iProtect Slim Charger 0.89 A 4.49 V
230V Outlet 20EUCBUSB 0.45 A 5.22 V
230V Outlet 20EUCBUSB 0.75 A 4.31 V
HuntKey HKA00605010-3B 0.92 A 5.24 V
HuntKey HKA00605010-3B 1.06 A 5.26 V
Sony SRS-X3 1.20 A 5.07 V
OTB TR-005 micro-USB 0.82 A 4.82 V
Busch-Jaeger 20EUCBUSB 0.70 A 5.23 V
Busch-Jaeger 20EUCBUSB 0.47 A 5.19 V
Pollin Mini-USB 351382 0.44 A 4.95 V
Pollin Mini-USB 351382 0.69 A 4.77 V
Jabra Stealth 12V Car 0.47 V 5.20 V
Bose Color SoundLink 0.45 A 5.00 V
Bose Color SoundLink 1.00 A 4.98 V
Ravpower Wireless Charger 1.16 A 5.62 V
Netgear AirCard 762S 0.45 A 5.03 V
Amazon PowerFast 0.45 A 5.04 V
Samsung Galaxy Tab 3 7.0 lite 0.45 A 5.04 V
Sennheiser MM 400 0.45 A 5.05 V

Subjective Comments

  • I didn't like the amzdeal 4-Port. It was bulky (compared to the EasyAcc Charger 5-Port). In addition it made an annoying high frequency noise. So I returned it to Amazon.
  • The 2-port USB Travel Charger RG-TC-2300-S worked well for a couple of days. Then it stopped working and only provided around 3 Volts. The PCB is of a very bad build quality.
  • The ASUC42e-050100 and HNP06-USBV2-Black is built quite OK. But the output voltage is quite low (0.1 V below the specified 5V). The only reason it works quite well is that the output voltage doesn't drop, even when you pull 0.9 A out of it. Nevertheless I don't like that low open circuit voltage.
  • The iProtect Slim Charger is not perfect. It makes a high frequency noise with no load and its voltage drops to 4.5 V under 0.9 A load. But with light load its voltage is good/a little high at 5.2 V.
  • The 230V Outlet 20EUCBUSB makes some high frequency noises and the voltage drops to incredible 4.28 V under 0.75 A load when charging an iPad. That is however above the 0.7 A it is specified for. When only 0.45 A are being consumed then the voltage is at decent 5.22 V
  • The power supply that came with the TP-Link TL-MR3020, a HuntKey Model HKA00605010-3B performs quite well! I have two of them and one makes high frequency noise.


  • Recording power curves (with an Arduino?), Change a poti, press a button, values in your PC...
  • Load tests could be done with high power resistors like Reichelt's 7W AXIAL 3,3. Or with the Potentiometer P4W-LIN 22...


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