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Discussion Starter · #1 ·
I am working on connecting my Orion JR BMS to my Tesla LDU. I'm at the point where I can talk to the BMS via CAN and once I connected the High Voltage to the drive, I started getting an error code on the Orion BMS

P0AA6 - High Voltage Isolation Fault

So myself and a fellow EV enthusiast have been double checking every wire and connection, disconnecting each component one at a time to trace the problem. Along the way, we discovered a strange short between the Tesla High Voltage wiring and its shielding. The ohm meter is reading about 6 Mega Ohms across. It reads this short on both the + and - leads. I even pulled the cables out of the drive and tested continuity between the invertor connection and the case of the drive, and I get the same reading. As you can see from the picture, I have everything disconnected from the drive. (see the picture)

I would expect the high voltage connections on the invertor to be 100% isolated from the case of the drive, but I'm not completely sure. Does anyone know if what I am seeing is normal?

122519
 

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Discussion Starter · #2 ·
As a quick follow up, Tesla says in Tech article SB-10052460-6095 :


As part of the Model S high voltage safety philosophy, the high voltage electrical system is isolated from the vehicle. This
means that there is no electrical current carrying path between the vehicle and any high voltage conductor.


So I guess I have an issue inside the drive that is causing this short. Time to take off the cover ...
 

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As a quick follow up, Tesla says in Tech article SB-10052460-6095 :


As part of the Model S high voltage safety philosophy, the high voltage electrical system is isolated from the vehicle. This
means that there is no electrical current carrying path between the vehicle and any high voltage conductor.


So I guess I have an issue inside the drive that is causing this short. Time to take off the cover ...

I just went back over the TSB. Step 15 you're metering the Drive unit to ground. It appears anything over 3.5 Meg Ohms is g2g. I'm going to do some more research on the Orion BMS and see if it's a settings issue.

Mine however, by the TSB would require replacement. So Time to tear mine down further. I've got some stuff to clean up the connections. But I still need to pull the motor side and look into that.

Tony
 

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I just went back over the TSB. Step 15 you're metering the Drive unit to ground. It appears anything over 3.5 Meg Ohms is g2g. I'm going to do some more research on the Orion BMS and see if it's a settings issue.

Mine however, by the TSB would require replacement. So Time to tear mine down further. I've got some stuff to clean up the connections. But I still need to pull the motor side and look into that.

Tony
Hi,

I believe that is your BMS Isolation detection system at work but I'm not 100% sure. That could be something for you to check out.
 

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Discussion Starter · #5 ·
In case anyone else runs into this error code (P0AA6) in the future, the Orion BMS has four settings for the Isolation Fault detection circuit. By default, it is set to 'Normal Sensitivity'. According to my reseller, that setting is too sensitive for most builds, and he recommends changing it to 'Low Sensitivity'. Changing the setting to Low has kept the BMS from throwing that error, in my case.

So I didn't really solve the issue, but the Orion BMS is not throwing that error now. For what its worth ...

122731
 

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Discussion Starter · #6 ·
Also, for more reference, if you get this error, you can see the actual reading it is getting that causes this Isolation error to be thrown. Its under the Live Text Data tab, Advanced parameters pulldown (at the bottom of the screen), the value it is tracking is the Shortest Wave (Isolation) and the Average Wave Isolation. In the screen shot below, you can see a 'normal' reading. This is what my BMS reads when the High Voltage (HV) is not connected to the Tesla drive.

Once I turn on the HV, the Shortest Wave reading drops to about 2.6V. Then, after about 30 seconds, the lower reading will drag down the Average Wave number and the Isolation Fault error code gets thrown. But as I mentioned above, changing the sensitivity to 'low' on the BMS kept it from throwing the code.

I hope this info helps someone down the road.

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