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Thread: Noise issue related to Curtis 1238

              
   
   
  1. #11
    Empulse R #24 frodus's Avatar
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    OK, so no issues with the 12V wires being disconnected, correct? Does the battery power the left side devices and the DC-DC powers the right side devices?

    Was the same 12V connected when you measured the resistance from 12V- to B-?

    I'm thinking the noise is coming from the DC-DC converter. Even though it is isolated, it can be a source of noise.
    Travis

  2. #12
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    Quote Originally Posted by frodus View Post
    OK, so no issues with the 12V wires being disconnected, correct? Does the battery power the left side devices and the DC-DC powers the right side devices?
    Correct.

    Quote Originally Posted by frodus View Post
    Was the same 12V connected when you measured the resistance from 12V- to B-?
    Yes.

    Quote Originally Posted by frodus View Post
    I'm thinking the noise is coming from the DC-DC converter. Even though it is isolated, it can be a source of noise.
    OK. I can also try disconnecting the DC-DC from the system to see if that isolates the issue.

    Thanks for your time, Travis!

    I've updated the wiring diagram to include the AC input for charging and also the cell tap wires for the BMS... Hmmm it's amazing how obvious these possible paths become when you draw them out!

    Wiring Diagram.svg.zip
    Mike Pipes
    - Currently under analysis paralysis.

  3. #13
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    Alright, making some headway I think.

    Went out to take some more resistance measurements and at first I was stumped because the numbers kept changing and were literally all over the map. Every time I pulled the probes and re-set them, I got a different number. 50kOhm, 30MegOhm, 300kOhm, 8MegOhm...

    Then it hit me like a flash... literally... I had fired up the system and saw a bright glow from inside the DC-DC..... carbon fiber dust igniting. D'OH!

    Seems like I have the constant rapid-fire relays mostly under control. There's still an occasional random relay fire which could just be residual dust but the tail/brake lights are still on only while the Curtis is powered up. Not sure if that's because of the DC-DC or other issue. I'll find out tomorrow when I'm off work and have more time to investigate.
    Mike Pipes
    - Currently under analysis paralysis.

  4. #14
    Empulse R #24 frodus's Avatar
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    Oh no! Yeah, those enclosed DC-DC's may have issues with dust getting in.

    Do you have room for Sevcon DC-DC's? I sell 500W versions, not sure if that is enough to run some of the 12V system.
    Travis

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    I checked the dimensions on the Sevcon DC-DCs, I definitely have room for two.

    Did a little more testing today. This time I turned off the PWM driver for the main contactor to see if it's picking up noise from the PWM signal, and looks like just the Curtis logic alone is noisy enough to make that LED lamp module pass a weak signal. When I pull the ground off the B- post on the Curtis, yet leaving the rest of the system running, the parking lights switch off as they're supposed to.
    Mike Pipes
    - Currently under analysis paralysis.

  6. #16
    Empulse R #24 frodus's Avatar
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    When you say PWM driver for the main contactor, what do you mean?
    Travis

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    Quote Originally Posted by frodus View Post
    When you say PWM driver for the main contactor, what do you mean?
    Under the Main Contactor Menu in the programmer, I set the MAIN_ENABLE parameter to OFF and then cycle power to the controller so it turns on but doesnt close the contactor. This way I can take the contactor noise out of the equation.

    Today, I have power disconnected at the 12V battery (B+ and B-), the DC-DC converter is physically disconnected from both +B(96v) and -B(96v) so there's not even power connected to the 12V bus. The BMS is also 100% disconnected from power, cell taps, and all other I/O. I run the blue KSI wire on the controller directly to B+(96v) to power up the Curtis and the parking lights still power up.

    Unplug the 96VDC charging cables running to the Thunderstruck Charger, and now the parking lights go out. I plug the 96V side back into the charger, parking lights go on. Unplug the A/C mains input from the charger, parking lights go out. The A/C mains input is grounded to the 12V side, as per instructions from Thunderstruck: http://www.thunderstruck-ev.com/imag...%20v2.3.2b.pdf
    Mike Pipes
    - Currently under analysis paralysis.

  8. #18
    Empulse R #24 frodus's Avatar
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    OK, gotcha. That way it wouldn't power on.

    Sounds like there's a noise coupling somewhere. Maybe one of the chassis's of the devices is grounding to the chassis of the vehicle.
    Travis

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    OK, I will double check that. The chassis is all carbon fiber so it won't conduct very well, but I still used fiberglass or plastic enclosures at the 12V distribution points for safety. The mounting brackets for the controller and charger should have a solid film of a filled structural adhesive isolating them from the chassis but are worth a look.

    How about the motor? It's bolted directly to a carbon fiber mount on the swing arm which technically should be isolated from the main chassis via polyurethane suspension bushings but there's still an aluminum shock/air spring.
    Mike Pipes
    - Currently under analysis paralysis.

  10. #20
    Empulse R #24 frodus's Avatar
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    I just mean that something, like charger or DC-DC is injecting noise back into the system. When removed, things work. When put back, things stop. There's likely some sort of either EMI, or a ground loop.
    Travis

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