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Leaf - Gen 2 PDM/OBC/charger no output power - L1/L2 charging

1925 Views 50 Replies 4 Participants Last post by  kennybobby
I'm having a problem with L1 charging all of a sudden. This vaguely coincides with the time I put dielectric grease in the J1772 port for the winter and when the temperatures started to drop.

  • 2015 nissan leaf OBC
  • 2013 24kWh battery
  • 0 to -14C temperature outside. Battery temp is always above zero (i have the battery externally heat traced).
  • Resolve EV VCU


- When this first problem started in the fall with temperatures dropping, but with the battery well above zero, I originally plugged the EVSE in overnight and the next day it dropped 40% overnight. Indicating no charge. Then noticed with my smart outlet that there was no current draw from the vehicle. Strange. So i started investigating.

What's happening is the EVSE plugs in, I have verified the light on the EVSE says charging, I have verified the OBC is getting 100V AC inside the OBC. The OBC also registering 100V AC after the black relay before going into the underside of the OBC. So i know the OBC is getting AC voltage from the house. The EVSE does not complain with any fault lights or error messages. I have tested two different EVSEs. One stock Nissan EVSE that i've used since day 1 and my OpenEVSE.com evse. Both show that they start charging but 0 Watts are being drawn from the vehicle's OBC.

  • I check LeafSpy Pro, I am seeing a 1-2A (300-600W) draw from the battery when the car wakes up by the presence of the J1772 plug being connected.
  • I have pulled apart the OBC top and bottom to check from any blown components. Nothing seems out of the ordinary.
  • The OBC is getting 100V through the EVSE properly.
  • Disconnecting the HV battery mains at the EVSE and checking the output of the OBC. I'm getting around 2-4Volts DC. This is strange.
  • I have checked the D400 (or D408?) diode and the D108 diode inside the OBC. Traced it from the control pilot circuit. They seem fine. D400 has ~11Mohms of resistance forward. And 0.542V with the multimeter's diode tester. If I jump diode D400, then the OpenEVSE.com evse will stop charging and report a Diode check error. This helps me eliminate the diode as a symptom.
  • D108 also seems to be fine and reports 0.352V in the forward direction.
  • PP pin to ground is 4.74V DC
  • CP pin to ground is 11.78M Ohms forward
  • With logging EV-CAN messages. I'm seeing 0x679 register when J1772 plugged in. 0x390 - OBC_AC_status voltage is 100V, 0x390 - OBC_Charge_Power report 0kW. I'm seeing 0x390 and OBC_Charge_Status=charging or interrupted. Ox1DB seeing LB_Current with -0.5 to -1A.
  • 12V battery is charged and tested to be good.

Other things I noticed while in there:
Also, in this investigating R8000 and R80008 seem to be shorted. And with a magnifying glass I was able to see "0" printed on the top which makes me beleive these two resistors are just "jumper" resistors in the form of a SMD component.
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Discussion Starter · #22 ·
That is not good, should not be able to drive while charging.
No, not while charging. I'm just saying that obviously the main-relay does get Permission at some point since I can put the car in Drive and can rev the engine but not while the charging cable is attached. But for some reason while the car is IGN off, parked and charging, the main-relay is set to "No-Permission". That's odd to me.
 

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the "main-relay" It is an odd expression. There are 2 main relays in the pack, which we normally call Main Contactors to avoid confusion with low voltage relays. i wonder if this could be the "M/C relay", the motor control relay? That would make more sense because the 2 main contactors have to be energized in order to charge the pack or drive.

This diagram is for gen1 cars, i've never been able to find one for the gen 2 with the integrated PDM.

Schematic Font Parallel Engineering Technical drawing


This might be a good time to check out the work of Dala the Great, he is the expert for leaf controls.
 

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Discussion Starter · #25 · (Edited)
Attached is a Drive can log. With transmission in neutral (so very little torque). Conclusion, is that i'm still seeing:
0x1DB - LB_MainRelayOn_flag = "No-permission" even though there is HV battery making it through the inverter and into the engine.

Thanks for the video reference. I've seen this one long ago. Was the first video that helped me dive into the PDM and look for anything fried and burnt up. Haven't found anything yet.
 

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Maybe it's the little white relay on the Lithium Battery Controller (LBC); x01DB is carried in the HVBAT section of the dbc, where dala's notes indicate that is the LBC. That relay is used for checking the insulation resistance.

Passive circuit component Circuit component Green Hardware programmer Electronic engineering


Can you run laefsypy to read the DTCs?

What was the story with the 511 VDC pack voltage? And now it's reading ~5V
Input 243VAC, and the OBC is outputting 5.42VDC.
The VCM or OBC checks that AC is available on the input side and measures the pack voltage on the Output side, before it will turn ON charging. It sounds like a fuse on the output side is open such that it can't read the pack, or a main contactor is open, etc. Something is not making sense to have 5.42VDC output on OBC.

Do you have another EVSE that you could try to rule out basic issues?

Sorry without a schematic i'm not much help here, i'm not set up to do anything with the CAN logs.
 

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Discussion Starter · #27 · (Edited)
Maybe it's the little white relay on the Lithium Battery Controller (LBC); x01DB is carried in the HVBAT section of the dbc, where dala's notes indicate that is the LBC. That relay is used for checking the insulation resistance.
This is interesting. And could be leading to my QC issues as well. I'm assuming there that the HVBAT only checks insulation on a charge? Why would it start charging but not give any DTCs if this insulation check fails though?

Can you run laefsypy to read the DTCs?
Yes i have Leafspy since the beginning. No DTCs thrown during charging except a generic U100A CAN which has always been thrown since upgrading to v2.0.0.0 of Leafspy that Turbo released.

What was the story with the 511 VDC pack voltage? And now it's reading ~5V
511VDC is what's being read by the ECUs at the start of a charge then it eventually comes back down to Pack Voltage of ~344VDC.

5VDC is what is outputted from the OBC without the HV Pack voltage connected. If you see the picture above I have a 4-bolt plate disconnected that normally connects the output of the OBC to the big copper bus bars connected to the HVBAT input. Earlier versions or just 3.3kW versions of the OBCs (The one Johu dissects) there is a choke ontop of this plate. I temporarily disconnect this plate before charging to see if I could read OBC output voltage without the HV bat input connected. When connecting this plate and therefore connecting the output of the OBC ouput to the input of the HVBAT, I get Pack_Voltage during charging and no power transfer happenning.
Circuit component Green Passive circuit component Hardware programmer Electronic instrument


The VCM or OBC checks that AC is available on the input side and measures the pack voltage on the Output side, before it will turn ON charging. It sounds like a fuse on the output side is open such that it can't read the pack, or a main contactor is open, etc. Something is not making sense to have 5.42VDC output on OBC.
Yes this makes sense when the connecting plate is off. On Gen 1 OBCs there is a choke ontop of this plate.

Do you have another EVSE that you could try to rule out basic issues?
Yes. I have the factory EVSE and an OpenEVSE. Both say the unit is charging but the OBC has no output power.
 

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Ok i see that output board on johu's video, and now i understand the 5V. But there was an error previously when the control board was reading 511V.

i've never tried running a charger unloaded but i'm sure it will set fault codes in the OBC, maybe temporary or permanent.

Has anyone else ever tried to run a charger when not connected?
 

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Discussion Starter · #29 ·
Also what's weird is the +1 to 2A (300 to 800W) HV battery draw when charging or just IGN On. These kind of watts makes me beleive it's the HV battery heater but it's only +2C inside the battery. Is this a cuase for concern? I've seen this 300 to 800W draw even when it's upwards of +6C inside HV battery.

Manual states the heater shouldn't be turning on until under -20C. Maybe this draw isn't the HV battery? Anything else it could be?
--or maybe the LB heater relay is erroneously stuck on, and causing the charging to not commence until it turns off. But with a stuck heater relay it won't ever stop the battery heater.


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Discussion Starter · #30 ·
But there was an error previously when the control board was reading 511V.

i've never tried running a charger unloaded but i'm sure it will set fault codes in the OBC, maybe temporary or permanent.

Has anyone else ever tried to run a charger when not connected?
Every time I plug in the J1772, and after CAN message 0x679, the voltage is read as MG_InputVoltage (Inverter) 510V then reduces back down to the HV batt Voltage of ~344V. As shown in these images. Also the MG_OutputRevolution is obviously wrong at +16383rpm. With this, I would not take the +510VDC seriously.

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Discussion Starter · #32 ·
Yeah, we have extreme cold days but I have the pack lined with a 300W heat traced cable underneath the HV battery and the van's interior is heated during the day when working in there. The HV battery temp sensors are registering +3C as per the Leaf Spy Pro screenshots in the second last post. The HV battery pack is inside the van and not exposed to outdoor temps. It's not that cold right now (not below -20C), and the motor temp you can see is -8C which is exposed to outdoor air.
 

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Discussion Starter · #33 ·
When the charge level of the Li-ion battery is low during the Li-ion battery heater operation, LBC stops the Li-ion battery heater operation even if the temperature in the battery pack is insufficient.
My SOC is 6% now due to this 300-800W draw everytime the car attempts a charge or the IGN is ON. It's widdled down from 40% from November. Not sure why the battery heater would be turning on. 6% seems low enough to engage this state.

When the temperature in the battery pack is low outside the timer charge set time, VCM transmits a keep SOC request signal to LBC via EV system CAN communication. In this case Li-ion battery is not charged, and only Li-ion battery heater is activated
If this is the case then something is malfunctioning. As per the documentation: the battery heater should only engage the heater when below -20C or until the pack temp reaches -10C. The battery pack i dont think has gone below -10 degrees and definitely not below even 0C back in November 2022 when this problem started.
 

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I saw your request to @Electric Land Cruiser for a canbus dump of a normal charging situation. Here is a dump from my 2015 Leaf. The car had the timer delay turned on, so you may see some activity then it stops before I push the timer-off button to have it continue charging for a bit. Then pulled the plug for it to stop charging. Hopefully it is helpful. Sounds like a heck of a problem to debug.
Rectangle Font Slope Parallel Pattern
 

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Discussion Starter · #35 · (Edited)
I saw your request to @Electric Land Cruiser for a canbus dump of a normal charging situation. Here is a dump from my 2015 Leaf. The car had the timer delay turned on, so you may see some activity then it stops before I push the timer-off button to have it continue charging for a bit. Then pulled the plug for it to stop charging. Hopefully it is helpful. Sounds like a heck of a problem to debug.
Thanks! So far been horrible. I can't seem to graph any values. Might have to switch to a Windows desktop as it looks like your SavvyCan graphing is working.

Here's some differences and similarities:
Similarities:
  • Both start off spiking to 511V on 0x1DB - LB_Total_Voltage and 0x1DA - MG_InputVoltage
  • 0x1DB starts off with -1A for LB_Current
  • Ox1DA - MG_OutputRevolutions starts off with erroneous 16383rpm. then drops to 0.
  • 0x1DB - LB_INTER_LOCK is "Not interlock connected" for a while. Then changes to "Interlock connected"
  • 0x1DB - LB_Voltage_Latch_flag are both 0MODEMASK when charging
  • 0x1DA - when charging - MG_InputVoltage is ~LB_Total_Voltage+1V (when yours bumps to LB_Current +16A)
  • 0x5C0 - LB_heatExist = 1
  • 0x5C0 - LB_NextWakeUpTimeForBatterHeater = 17mins and mine 29mins
  • 0x390 - OBC_Status_AC_Voltage = 200V
  • 0x390 - OBC_Charge_Status = "Charging or Interrupted"
  • 0x1D4 - ChargeStatus = "Charging"
  • 0x1D4 - Relay_Plus_Output_Status = "Main Relay Plus On"
  • 0x5C0 - LB_Diagnosis_Trouble_Code = 0DTC

Differences:
  • 0x1DB - LB_MainRelayOn_flag = "No-permission" then eventually switches to "Main Relay On Permission" mine stays = “No-permission”
  • 0x1DB - LB_Current drops to 0A. Mines stays around -1 to -2A forever
  • 0x5BC - LG_Output_Power_Limit is "Normal" where mine is always "Capacity Drop"
  • 0x5C0 - LB_HiostData_Temperature_Min = 4degC whereas mine is 2degC
  • 0x390 - OBC_Charge_Power = 6kW and mine 0kW
  • 0x390 - OBC_Maximum_Charge_Power_Out = 6kW and mine 0kW (mine does bump up but goes back to 0kW)
  • 0x1DB - LB_Usable_SOC = 73 and mine is 1
 

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Discussion Starter · #38 ·
Looking into CAN logs I see two fairly important values being reported. Can anyone shed some light on any of these?

1. 0x5BC - LB_Power_Output_Power_Limit_Reason = "Capacity Drop"
2. 0x1DB - LB_MainRelayOn_flag = "No-Permission"
3. I do get a DTC code U100A when plugging in the charger. - U100A is a Fail-Safe condition that stops charging because of a missing CAN message.
4. When J1772 plugged in, I always have a large draw 300-800W on the battery even though HV battery temp is above 0degreesC. As reported by Leafspy. Maybe the LBC uses a different temperature sensor and the HV battery is actually below -20C? I think is odd.
5. Yes the 12V battery has been load tested and is good.


Also in this script here is the mimimum amount of CAN messages required to enable charging in the OBC. It's written well and most people should be able to read the code
  • 0x11A every 10ms
  • 0x1F2 every 10ms
  • 0x1D4 every 10ms
  • 0x1DB every 10ms
  • 0x1DC every 10ms

  • 0x55B - every 100ms
  • 0x5BC - every 100ms
  • 0x50B - every 100ms

- 0x59E - every 500ms

But it requires an Ardiuino Due, so at the moment i'm rewriting 49thDriver's arduino code over to python using python's threading library (so far has good timing results for 10ms resolution). I've got it written and tested on my setup. No charging so far. The testing i'm doing is removing each CAN messages listed above in the sequence to see if I can get the U100A DTC to dissapear and/or reappear consistently. Currently getting mixed results and no charging yet. Next steps will be to remove the OBC from the car and bench test it with this code.
 
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