Autel MaxiSYS Ultra EV Offline Test 2021 VW ID4 Battery Pack

Autel has launched the MaxiSYS Ultra EV & 909 EV to provide intelligent battery pack diagnostics for European, US, Asian electric and hybrid vehicles. Users can perform focused battery pack diagnostics for EVs like BMW, Tesla, VW, Audi, etc.


If you already have Autel Ultra/ MS909/ MS919, you may just purchase the EVDiag to upgrade for same function. Following is using the Ultra EV to perform off-vehicle battery pack diagnostics on a Volkswagen ID4. The test is important because it can provide a focused test on a battery pack without any interference from the vehicle.



Ultra EV, VCI, EVDiag box, a low-voltage specialty cable.



Connect the VCI with Ultra EV via Bluetooth.

Connect one end of the VCI with EVDiag box, then connect the low-voltage specialty cable with the battery pack & EVDiag box.


Note: The EVDiag box has no built-in power supply and needs to be powered externally at all times. The Ultra must also be connected to the internet for this process.



Battery pack test >> Volkswagen >> OK >> Accept >> Select model, year & configurations >> Select battery pack type


After establishing communication, the offline diagnostic connection diagram will be displayed, including cable number, cable or jumper cable. Connect the corresponding low voltage specialty cable with EVDiag box & battery pack according to diagram.


This page will normally display 3 sections: battery pack status, battery pack information and other live data in battery pack status. You can see state of charge, state of health, total voltage, total current voltage, Delta temperature and maintenance recommendation. Each module in this pack is made up of 12 cells, each cell is 3.617 volts. We can see module 1 is normal.


However, we can see something wrong. Check for abnormalities with the “Maintenance Advice” message at the top. Thanks to this message, every module from M2 to M9 is displaying a voltage over 5 volts for each of its cells. That’s not right, each cell should be 3.617 volts the same as M1. So we can manually check the voltage for each module’s cells using our multimeter.


Cell monitoring units(CMU’s) read cell information and send it to the battery management unit(BMU). If you want to view module location in the vehicle, simply tap the module location button. It’s easy to understand graphical representation of each module and its corresponding location in the battery pack.


When we measure the cell voltages ourselves, we will find that the cells are actually normally at 3.617 volts. But the information we received from the pack is abnormal. That information is coming from the cell monitoring unit or CMU in the middle of the pack. Since the CMU from the M1 is displaying information correctly, the problem must lie with these two cmus collecting information from modules 2 through 9. So we can either reprogram the 2 cell monitoring units or replace them.


In fact the most likely reason for this abnormal information is the cmus were taken out at some point to do some work. Then put back in the wrong spot. They look the same and are easy to get mixed up if they are put in the wrong spot. They will deliver inaccurate information to the bmu or battery management unit.


So always be sure to run a test after doing work on the battery pack. To make sure everything is in the right place and it’s working properly in battery pack information: view battery pack capacity, dimensions, weight, coolant type, theoretical range and more. Here we can see our battery pack capacity is 62 kilowatt hours and rated at 396 volts with a liquid cooling system.


View live data for contactors and temperature sensors. Contactors are turned off since the pack is removed from the vehicle. You can also view the information on the side of the battery pack itself written on the label. 5 data displays parameters for contactors and sensors. We can see that the contactors are turned off that is because when taking the battery pack out of the vehicle, we need to make sure there is no live voltage turning. The contactors off makes the voltage zero and safe for us to take the battery pack out of the vehicle.


The Ultra EV makes it easy for technicians working on electric vehicles, especially Tesla, BMW, Toyota, VW, Audi and Honda. The Ultra EV and 909 EV allows you to view high voltage block diagrams, and helps you perform battery pack diagnostics for high voltage systems and module programming with remote expert service: redirect codes, view live data analyze, state of charge, state of health, view maps and diagrams for components and sockets. Even to get step-by-step disassembly instructions for the battery pack.


Buy the Ultra EV to be your guide on the road to a greener energy future.


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