Opened the traction battery and found the Pre-charge resistor was bad. What caused it to fail?

[nlspace]

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Answer: After driving the car for 40 miles, I discovered an inconsistency between the battery display and regeneration behavior and the initial 100% SOH reading. While it still shows 12 battery bars, SOH is now 60% on LeafSpy. It appears that a service tech did a BMS reset in an attempt to fix the error codes the disabled car was throwing,

Thank you for getting back to answer this very puzzling situation.

i suppose that you have some weak cells or modules. i wonder if just some few modules could be replaced to restore capacity and some range, or if it is more widespread across the pack?

 

[transamhun]

"When I did turn on the car for the first time (not with brake depressed) the defrost button started flashing. IS THAT NORMAL?" - did you ever find out why this happens? My 2020 ZE1 also does this.

 

[Tony 240]

I inquired about upgrading my account to be able to post the picture of the service diagram, but haven't gotten a reply.

After finally getting up the nerve to turn on the heat and A/C to check if the precharge resistor would blow again, I heard the A/C compressor struggling and making a slight squealing sound, not similar to my 2012 Leaf. It turned off by itself after about 10 seconds. Worried I blew it again, I checked and the car still turns off, and on, goes into drive and reverse unlike when the precharge resistor was blown.

So putting the puzzle together, the previous owner was using the A/C defroster to clear the window this last winter. She came out to the car after 20 minutes had passed and the car would not go into drive or reverse, charge, or heat or defrost the car. Did all of the diagnostic flow charts from the service manual and upon advice from Mux, tested the precharge resistor in the battery junction box in the traction battery and verified the precharge resistor was fried. By the way, Thanks Mux for helping from long distance!

Maybe the FAILING High Voltage A/C compressor had put a large load on the precharge resistor and caused it to burn out? Would the HV compressor come on if it didn't have enough refrigerant? I wouldn't think so. Also, I read that these electric compressors must use a different oil than a regular conventional PAG compressor oil or it will cause it to fail. It calls for ND-11 ester oil made for electric compressors.

I will have my brother put some gauges to the A/C lines to verify refrigerant, but I suspect the compressor was the culprit. Anybody concur?
Should I have the compressor oil tested? As soon as my upgrade to Gold is active, I will post the wiring diagram.

I had my precharge resistors fail l 2 winters ago on the coldest day of the year but I contributed it to the fact that the car was charging and the cabin heat came on at the same time. After having changed the resistors I changed the timers on the climate control and battery charger to be not on at the same time. By the way I got stung badly by the dealer to take the traction battery out and install used resistors back in. they charged 8 hours flat rate to drop and reinstall the battery , the actual time was 3 hours.

 

[jstroud48]

I had my precharge resistors fail l 2 winters ago on the coldest day of the year but I contributed it to the fact that the car was charging and the cabin heat came on at the same time. After having changed the resistors I changed the timers on the climate control and battery charger to be not on at the same time. By the way I got stung badly by the dealer to take the traction battery out and install used resistors back in. they charged 8 hours flat rate to drop and reinstall the battery , the actual time was 3 hours.

tony i have a question, i have a 2018 leaf and my question is the car wont start, it says warning service 12 volt charge system and warning service ev system no power. could this be a blown pre-charge resistor?

 

[Tony 240]

tony i have a question, i have a 2018 leaf and my question is the car wont start, it says warning service 12 volt charge system and warning service ev system no power. could this be a blown pre-charge resistor

 

[Tony 240]

First I would make sure your 12 volt system is up to charge with a external charger or jump start the 12 volt battery with another car and try to start again.