RoadTest: Product Review of the Megger EV Charger Checker – EVCC300
Author: Instructorman
Creation date:
Evaluation Type: Connectors & Cable
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: Fluke FEV100 Vehicle Charging Station Adapter with type 1 connector and cable
What were the biggest problems encountered?: Inability to complete EVSE Interface tests on a L2 charger. Every time I attempted the tests, the EV charger went off line and reported an error.
Detailed Review:
Megger EVCC300 EV charger checker road test
The EVCC300 from Megger is a portable battery-operated tool used to check the operation of electric vehicle chargers. As emphasized in this video from Megger, this tool is not used to certify or commission EV charge point installations, but rather to perform basic safety and operational tests. The EVCC300 is capable of testing single phase Level 1 (L1) and two-phase Level 2 (L2) chargers. In this road test, the EVCC300 was evaluated on a L1 Mitsubishi Plug-In Hybrid Electric Vehicle (PHEV) charge adapter that is provided as a standard accessory with Mitsubishi PHEVs. The tool was also evaluated on a Solar Edge L2 EV charger. I own a PHEV and have a roof top solar array connected to an inverter with an L2 charger installed in my garage.
The EVCC300 provided to me for this road test came in a sturdy plastic storage box that included an EVA-T1 adapter, four AA batteries, a quick start guide, and ground probes.
The tool itself is light weight and ergonomically designed to be handheld. A battery compartment is located on one side of the handle. Two screws hold the compartment cover in place. The four included AA batteries are inserted into the compartment in two layers.
On the right-hand side of the main body there is a compartment holding three protective fuses.
The front end of the tool, without the adapter attached, is shown in the photograph below. This connection shape allows the tool to be plugged directly into EV charge points where the charge cable would be attached. This design allows a technician to troubleshoot suspected cable faults by testing a charge point with and without a cable attached.
This road test was conducted on equipment distributed in Canada with cables attached to charge equipment. All tests described in this report, therefore, required use of the EVA-T1 adapter, shown below center with images of the corresponding pinouts on the left and right.
Ground continuity tests are performed with a test lead that plugs into the bottom of the handle. The lead cable can accommodate either an insulated alligator clip, or a sharp tipped probe. Both are provided with the EVCC300.
The user interface consists of a small colour display screen, four buttons, and a touch pad situated above the handle.
Level 1 tests
Many electric vehicles sold in North America come with an L1 adapter that allows the drive battery in an EV or PHEV to be charged from a standard 120 VAC outlet. An L1 charge adapter can be used if the owner does not have access to an L2 charger at home, at work, or on the road. Charging through an L1 charger can be a slow process. If my PHEV battery is completely discharged it can take 12 to 14 hours to bring it to full charge using an L1 charger. This isn’t really an issue if the car is going to be siting unused in a garage overnight but would be a problem for pure EV cars that need to be driven right away. The Mitsubishi L1 charge adapter is shown below.
In preparation for evaluation of the EVCC300 on the L1 charger, I slid the EVA-T1 adapter onto the connecter end of the tool so that it would mate with the J1772 connector on the charger (shown below on the right).
Attaching the adapter to the tool generated my first critical observation of this tool. The EVA-T1 adapter is designed to press fit onto the EVCC300 and onto a corresponding J1772 charger connector. It does not lock into place. Although the fit is snug, I would not call it secure. In my testing the adapter did not fall off the EVCC300, but it did come loose at one point. I would recommend a latching mechanism be included on the tool to secure the adapter in place during use.
The EVCC300 is shown attached to the J1772 connector on the Mitsubishi L1 charger in the 2 photos below. On the left the pair is sitting on the ground. On the right, I am holding the tool with the attached J1772 connecter, illustrating how the tool, and attached charger, would appear during an actual test (in this case, by a left-handed user).
The EVCC300 is reasonably light weight, however, when attached to a J1772 connector and several meters of heavy cable, the combination becomes heavy and awkward to manipulate. I found it best to hold the tool in front of me, near the center of my body, tilted down under the weight of the attached connector and cable. This stance puts the user interface screen and buttons at a comfortable angle.
After powering up the EVCC300 with a press of the left button I noticed what I would say is a significant problem with the user interface. To understand the issue, let me describe the conditions under which the tests were conducted. The tests for this road test were conducted outside on sunny days in March. Some were conducted in shade, some in direct sunlight, and some in a residential garage. The problem I encountered concerns the readability of the small display screen. The image below shows a typical test result screen. This shot was taken outdoors in mid afternoon shade. The image brightness and contrast have not been altered from the original capture. I would say the image faithfully matches what I saw while using the EVCC300.
Notice that the display lacks contrast and brightness. There is a significant amount of information crammed onto the approximately 6 cm (2 3/8”) diagonal screen. All the text is readable, but it may be difficult to discern at first glance. The screen is backlit and is quite readable in a typically lit indoor setting, as evidenced by the photo below, taken in my shop.
The problem, of course, is that most EV charging takes places in the great outdoors where you may encounter equipment obscured by the dark of night to equipment bathed in the brightness of a summer afternoon. Chargers may be inside a garage, out in the open on a street corner, or in a parking lot. The lighting conditions encountered in daily use by a technician are likely to be varied and numerous.
Because users are likely to encounter variable lighting conditions, it would be beneficial to have control over screen contrast and brightness. Alas, I could find no such controls. The problem gets worse in direct sunlight. The pair of photos below show the same screen image in direct sunlight (on the left) and in shade (on the right). Neither is particularly readable. In bright sunlight one could be excused for assuming the EVCC300 was turned off.
Readers of this review will also notice that all test result data is presented in the form of photographs taken of the display screen on the EVCC300. That is because there is no computer interface built into the EVCC300. No USB, Bluetooth, or Wi-Fi connectivity is available.
Depending on how one views the typical use case for this instrument, the lack of connectivity may or may not be problematic. If a technician intends to only use the EVCC300 for quick spot verification of EV charger functionality after installation or after performing repairs, then the lack of connectivity probably isn’t an issue.
On the other hand, if a technician needs to make a record of test results to support reports to customers or for corporate record keeping, then we have a problem. A complete test sequence produces several result screens, some with eight or more numeric data points. An example of a data rich test result screen is shown below. The contrast, brightness, and saturation of the image have been adjusted to improve readability.
My preference would be to log each test result as part of a due diligence process and for historical performance tracking of customer equipment. I would not want technicians to write test results into paper logs or into a spreadsheet to avoid transcription errors. Nor would I burden them with having to fiddle with a smartphone camera to snag screen shots. What I would like is a Bluetooth connection and an application that allows real time upload and recording of test results. Even better would be some internal memory, a time and date stamp capability, and a USB interface to facilitate daily uploads of a technician’s test results from multiple site visits.
I plugged the Mitsubishi L1 charger into a GFCI protected outdoor outlet, then plugged the J1772 connector on the charger into the Megger EVCC300 tester. I powered up the EVCC300, then set it to do “Via cable” tests with VTOUCH set to 25V and VMAINS set to 120V, 60 Hz.
The Protective Earth (PE) test
The first test usually performed is a Protective Earth contact test to determine if the service equipment is grounded. This is a good place to bring up a detail that I will call “Learning the Goldilocks Button Press”. There is a user interface navigational feature that allows the user to back out of a selection to the previous level within the operating system. The prompt “BACK 2s” appears above the center button when this option is available. What this prompt means is that in order to back up one level the user must press and hold the center button for 2 seconds. Not 1 second, not 5 seconds, but for 2 seconds. If you hold the button too long, you get a chastising cadence of continuous beeps. Too short and you get a dismissive single beep. A little too long, or a little too short and nothing happens. Only when you hit the Goldilocks sweet spot around exactly 2 seconds will the step back work. Once the Goldilocks button press is learned and committed to muscle memory, all is well and you can carry on.
The PE contact test requires the user to press and hold a finger, or a thumb, on the touch panel and press the Test button. If the PE test passes, the screen below is displayed.
Because I took time to practice and learn the Goldilocks Button Press, I could then back up one level and move on to the RCD/GFCI tests.
RCD/GFCI tests
These tests allow the user to verify operation of a current leakage detection device, either a Residual Current Device (Europe and Australia) or a Ground Fault Circuit Interrupter (Canada/USA). Several parameters need to be selected before the tests are executed including the trip current for nuisance trip tests, the personal protection current level for normal trips, and the phase angle (0° or 180°). You should heed the note that appears at the bottom of the set-up screen that reads “GFCI will trip. Can you reset?”, because the GFCI will indeed trip (if its is working correctly) and if you can’t reset it, well then running this test will place the charge point into a non-functional state and perhaps you had best be on your way. In my case I was plugged into a GFCI outlet that had local reset capability, so I was confident I could indeed reset following a trip condition.
Running a 6 mA 180° protection trip test takes a few seconds because three tests are executed. First, the EVCC300 puts the charger into Charge mode via the Control Pilot (CP) signal line. It then measures the incoming charge voltage to make sure the charger is in the correct mode. Next, it performs a touch voltage test to evaluate the safe operation of the charger earth ground connection to make sure it does not exceed the selected threshold (25 or 50 V). If everything looks good, the EVCC300 concludes with a leakage test to ground. This final step is what should trip the RCD/GFCI protection circuit. The GFCI did indeed trip at 79 ms with 6 mA of current being shunted to ground. The test result screen looks like this:
I am not an electrician. I am a Professional Engineering Technologist (P.Tech (Eng)), so I did some research, and it seems that UL943 is one of the standards for GFCI operation. I found this equation which specifies the maximum time to trip a GFCI with a given leakage current:
Where i is leakage current in mA. With the selected leakage current of 6 mA, Ttrip(max) is 5.59 s, so 79 ms is well within specification. However, to PASS the 6 mA personal protection test the EVCC300 requires that the GFCI trip within 90 ms. Trip times > 90 ms but <5.59 s are rated as QUESTIONABLE. If the GFCI does not trip by 5.59 s, it is ranked as a FAIL.
I followed the personal protection test with a >4mA nuisance trip test. Nuisance trip tests check to see if a GFCI will trip too quickly. The >4mA test generates a stepped leakage current ramp in 500 µA steps of 100 ms duration starting at about half the selected trip current up to the selected limit. The test stops before Ttrip(max). In the case of the >4mA nuisance test, the user manual suggests the test will run for no longer than 4.5s (or 1.2s – more on this discrepancy later). When I ran this test, the GFCI tripped at 5 mA and was given a PASS. The test result screen is shown below.
The image above provides a summary of the suite of tests that are included in a GFCI nuisance trip test. The CP state indicates the charger was successfully moved into a charging state. VMAINS of 124 V indicates the charging voltage is as expected for a single-phase charger in Canada. VTOUCH of 0V indicates the ground connection is acceptable, and an ITRIP of 5 mA indicates the GFCI receptacle is not likely to produce nuisance trips.
The image above also reveals another minor issue with the EVCC300 display. The display window is somewhat reflective. Indistinct shapes are visible on the screen. This reflectivity can make displayed data more difficult to read.
Documentation issues
I encountered a few version-related documentation issues during this road test review. Several versions of the User Guide and Quick Start Guide are available. The package I received for this road test included a printed quick start guide, version number EVCC300-2014-075_QS-SW_en-de-fr-es-nl_V02 08 2021. I take this to mean it is version 2, published August 2021. The quick start guide available for download on the US Megger website (as of April 2024) is version EVCC300-2014-075_QS-SW_en-de-fr-es-nl_V05 12 2023, presumably from December 2023. Neither version agrees with the actual operation of the unit I was provided for this test. The sequence of start up menus differs from the pictorial description in the quick start guides. The quick start guides suggest that the language selection menu comes up first after power on. On the unit I tested, language selection is the third setup step, following Connection and Settings. Language selection coming first makes more sense to me, but this is not what firmware version 1.18 does.
The version of the User Guide available on the US Megger website (April 2024) is EVCC300_UG_EN_V04 07 2022. I could not find any indication which firmware version the User Guide corresponds to, but there are differences between how the User Guide shows tool operation should work and what I encountered on the road test unit.
For example, layout of the RCD/GFCI selection menu in the User Guide does not correspond to the menu that appears on the tool. The menu below on the left is from the User Guide. The menu on the right is from the tool I tested.
Furthermore, there are discrepancies between the User Guide operating instructions and the specifications. In section 5.5.1 of the User Guide (Nuisance trip check) page 25, the USA 120 V tests are described as follows:
Note a maximum test time of 4.5s for the 6 mA current ramp test
Later, in Section 8 (Specifications) page 41, a different set of criteria for 120V tests are presented.
Note the maximum test time for 5 mA nuisance test is specified at 1.2 s.
To conclude testing of the L1 charger, I ran the available EVSE Interface suite of tests. These tests allow the EVCC300 to simulate some of the Control Pilot (CP) signals that an EV would send to a charger. The simulations include vehicle disconnected, vehicle connected, vehicle charging, vehicle charging with ventilation, CP to PE fault, and charger fault.
A result screen for the vehicle charging interface test is shown below, as presented on the tool, and edited to improved readability.
The caution triangles with exclamation points are reminders that the values are snap shots and are not being updated. To refresh the display, the user must press the TEST button again.
From the information on this test result screen one can determine that the charger and EVCC300 agree that the two are connected, that the charger and EVCC300 are in a Charging state, and that the charge voltages and available current (12A) agree with the capabilities of the L1 charger.
Solar Edge L2 EV charger tests
My second set of tests were conducted on a Solar Edge level 2 charger that is part of an 8.6 kW roof mounted solar PV array. The inverter and charger are shown in the photograph above. Tests on this charger allowed Protective Earth continuity to be evaluated using the provided probe because there are exposed metal surfaces available. A check of the exposed metal on the side of the charger is shown below.
I discovered that it is important to make firm contact with the metal. The threshold for a failure is 0.5 Ohms. I had to press the probe tip firmly into any metal surface to get a resistance below 0.5 Ohms but was eventually successful.
The next check was on the metal conduit that brings DC into the inverter from the PV module array.
The next tests would be the GFCI trip tests. These tests gave me pause because I did not know how to reset the GFCI protection in the Solar Edge charger. I checked with the electrician that installed the equipment and he thought the GFCI trip tests would likely generate an error message in the user application but would otherwise not cause any damage. He appears to have been correct. I first tried a 6 mA personal protection GFCI test. That resulted in a “No trip fail” as shown below.
Next, I stepped up to a 20 mA personal protection GFCI test. The result for this test was successful, generating a GFCI trip in 19 ms.
Thankfully, it seems the Solar Edge charger automatically resets when a GFCI fault condition clears, so I was ready to proceed to nuisance trip tests. I ran the >10mA nuisance test twice. The first time the GFCI tripped at 18 mA, which resulted in a QUESTIONABLE rating (the “?” appearing after the ITRIP reading on the left image below). Running the test again resulted in a PASS with an ITRIP reading of 19 mA, shown on the right below.
Level 2 EVSE interface tests
Unfortunately, the Interface tests that ran successfully on the L1 charger did not go well on the L2 charger. Problems occurred with each test, starting with the Disconnected test. The images below show the Megger test result and the corresponding status of the charger as provided by the phone application.
A-Disconnected test
B-Connected test
This test also produced odd results, as shown below.
C-Charge test
I have tried this test three times on the Solar Edge L2 charger. Each time the test is executed, the charger goes offline for 12 to 18 hours, and the Error Log reports the following error:
I submitted a help request to Megger through their website on March 21, 2024. I received an automated acknowledgement from Megger that the submission was received. In the submission I detailed the sequence of events and the error messages. It is now the 20th of April and I have not received a response from Megger. I just tried the Charge interface test again, and once more, the charger went offline and Error 1CxD was reported.
Even if I am operating the EVCC300 incorrectly, it is disturbing that it is possible to unintentionally knock a charge point out of commission (albeit temporarily) using this instrument. I have run out of time to complete my review, so I will include these findings as they stand.
Conclusion
Apart from the inability to successfully run EVSE Interface tests on a Solar Edge L2 charger, the EVCC300 performed adequately. There are some user interface and documentation issues, as detailed in the review, and improvements could be made with the inclusion of a Bluetooth, USB, or WiFi connection to allow logging of test results.
