Innokin asked me to test the functionality and safety of the charging circuitry for the Endura T18 device. The tests were done over a six day period, Dec 15th-20th.
Full Disclosure: I was paid by Innokin to perform these tests due to the amount of time it takes to run them. I requested a fee equal to one third of my usual rate for this kind of testing. I assure you that this had no effect on how I did the testing or interpreted the results. I have no qualms about calling out a company when they do something I feel is unsafe or deceptive. 100% of the money is going towards purchasing an additional data-logging digital thermometer (to measure battery temperature) and additional batteries for testing.
Summary: No major issues were discovered. While I can't predict how the Endura T18 will perform over a long time period, in my opinion the Endura T18 seems to be quite a well designed and built device. There were button-sticking issues with some of the units in the first batch but Innokin has been replacing those units. Both disassembled Endura's I received only got a bit warm during charging, the charging voltage was correct and consistent, frayed/damaged cables and connections weren't a safety issue, and they handled both low and high charging voltages without problems.
In my opinion, the only weak point in the device's charger is the Micro USB connector. After about 40 very aggressive and off-angle insertion/removal cycles with an Innokin USB charging cable the connection was becoming loose. This is a common limitation of the Micro USB connector though and the connecting/disconnecting was not done gently at all. With a bit of care the connector should function well for a long time.
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The technical details of the testing follows....
- Two devices without their external case were received, tested for basic functionality, and then tested as detailed below.
- Each charging and USB connector circuit board was examined. All were clean with good hand soldering of the wires. Only a small amount of flux residue was present.
- Charged each device using a 5.0V, +/-0.010V power supply three times, measuring the final charge voltage to the battery. The battery was directly discharged to 3.0V after each charge at a 2.0A rate. Device #1 charged to 4.19V, 4.21V, 4.20V. Device #2 charged to 4.20V, 4.21V, 4.21V. The charging voltage was correct and very consistent.
- Measured the peak temperature of the charger circuit board during each charge. The board was wrapped in Kapton tape to prevent convective cooling. Neither board exceeded 53°C at any point. This is a low temperature and shouldn't cause any thermal fatigue of the solder joints of the components or accelerated aging of the components.
- Interrupted and restarted the charge cycle as it began, at random intervals, for each device 25 times by disconnecting the USB 5V line to the device. This was done to try to force the them to lock up or malfunction. Both units operated perfectly every time.
- Interrupted and restarted the charge cycle as it began, at random intervals, for each device 25 times by disconnecting the USB ground line to the device. This was done to try to force them to lock up or malfunction. Both units operated perfectly every time.
- Cut the USB cable and reconnected all but the USB 5V line ends. Both ends of the 5V line were then quickly brushed past each other over 100 times over a 2 minute period, forcing the charging cycle to stop and start over and over. This was done to simulate a frayed or damaged cable being moved around. Both units operated perfectly.
- Cut the USB cable and reconnected all but the USB ground line ends. Both ends of the ground line were then quickly brushed past each other over 100 times over a 2 minute period, forcing the charging cycle to stop and start over and over. This was done to simulate a frayed or damaged cable being moved around. Both units operated perfectly.
- Did informal EMI/RFI susceptibility testing that simulated a typical environment the charger's electronics might have to operate in.
Wrapped the USB charging cable three times around an iPhone 4S that was used in an area where reception was bad, forcing the phone to operate at full signal strength. During charging five calls were made and five calls were received by the phone. No change in the operation or output voltage of the charger was seen in either unit.
- Charged both units atop a TP-LINK C7 dual band WiFi router, directly next to the antennas, while it was streaming video to three mobile devices. No change in the operation or output voltage of the charger was seen in either unit.
- Variable-voltage power supplies were set to 4.00V and connected to the 5V and ground wires of USB charging cables. The cables were plugged into the micro USB connector of each unit, which had their batteries previously discharged to 3.0V. The indicator LEDs functioned normally and the batteries charged to 4.00V, which was expected. But the constant-voltage (CV) stage of the charge cycle was significantly longer than usual.
- The voltage was increased to 6.00V and both units immediately restarted their charge cycle. The units charged the batteries to 4.20V and 4.21V without any malfunction.
Full Disclosure: I was paid by Innokin to perform these tests due to the amount of time it takes to run them. I requested a fee equal to one third of my usual rate for this kind of testing. I assure you that this had no effect on how I did the testing or interpreted the results. I have no qualms about calling out a company when they do something I feel is unsafe or deceptive. 100% of the money is going towards purchasing an additional data-logging digital thermometer (to measure battery temperature) and additional batteries for testing.
Summary: No major issues were discovered. While I can't predict how the Endura T18 will perform over a long time period, in my opinion the Endura T18 seems to be quite a well designed and built device. There were button-sticking issues with some of the units in the first batch but Innokin has been replacing those units. Both disassembled Endura's I received only got a bit warm during charging, the charging voltage was correct and consistent, frayed/damaged cables and connections weren't a safety issue, and they handled both low and high charging voltages without problems.
In my opinion, the only weak point in the device's charger is the Micro USB connector. After about 40 very aggressive and off-angle insertion/removal cycles with an Innokin USB charging cable the connection was becoming loose. This is a common limitation of the Micro USB connector though and the connecting/disconnecting was not done gently at all. With a bit of care the connector should function well for a long time.
**********************************************
The technical details of the testing follows....
- Two devices without their external case were received, tested for basic functionality, and then tested as detailed below.
- Each charging and USB connector circuit board was examined. All were clean with good hand soldering of the wires. Only a small amount of flux residue was present.
- Charged each device using a 5.0V, +/-0.010V power supply three times, measuring the final charge voltage to the battery. The battery was directly discharged to 3.0V after each charge at a 2.0A rate. Device #1 charged to 4.19V, 4.21V, 4.20V. Device #2 charged to 4.20V, 4.21V, 4.21V. The charging voltage was correct and very consistent.
- Measured the peak temperature of the charger circuit board during each charge. The board was wrapped in Kapton tape to prevent convective cooling. Neither board exceeded 53°C at any point. This is a low temperature and shouldn't cause any thermal fatigue of the solder joints of the components or accelerated aging of the components.
- Interrupted and restarted the charge cycle as it began, at random intervals, for each device 25 times by disconnecting the USB 5V line to the device. This was done to try to force the them to lock up or malfunction. Both units operated perfectly every time.
- Interrupted and restarted the charge cycle as it began, at random intervals, for each device 25 times by disconnecting the USB ground line to the device. This was done to try to force them to lock up or malfunction. Both units operated perfectly every time.
- Cut the USB cable and reconnected all but the USB 5V line ends. Both ends of the 5V line were then quickly brushed past each other over 100 times over a 2 minute period, forcing the charging cycle to stop and start over and over. This was done to simulate a frayed or damaged cable being moved around. Both units operated perfectly.
- Cut the USB cable and reconnected all but the USB ground line ends. Both ends of the ground line were then quickly brushed past each other over 100 times over a 2 minute period, forcing the charging cycle to stop and start over and over. This was done to simulate a frayed or damaged cable being moved around. Both units operated perfectly.
- Did informal EMI/RFI susceptibility testing that simulated a typical environment the charger's electronics might have to operate in.
Wrapped the USB charging cable three times around an iPhone 4S that was used in an area where reception was bad, forcing the phone to operate at full signal strength. During charging five calls were made and five calls were received by the phone. No change in the operation or output voltage of the charger was seen in either unit.
- Charged both units atop a TP-LINK C7 dual band WiFi router, directly next to the antennas, while it was streaming video to three mobile devices. No change in the operation or output voltage of the charger was seen in either unit.
- Variable-voltage power supplies were set to 4.00V and connected to the 5V and ground wires of USB charging cables. The cables were plugged into the micro USB connector of each unit, which had their batteries previously discharged to 3.0V. The indicator LEDs functioned normally and the batteries charged to 4.00V, which was expected. But the constant-voltage (CV) stage of the charge cycle was significantly longer than usual.
- The voltage was increased to 6.00V and both units immediately restarted their charge cycle. The units charged the batteries to 4.20V and 4.21V without any malfunction.
