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

Posted: Thu Jul 05, 2018 2:00 pm
by braebyrn
Thanks Mux for your help in figuring out that the pre-charge resistor in the battery junction box was bad. Also a big thank you to the others that have contributed videos and forum discussions pertaining to opening the case and troubleshooting the issue discussed here viewtopic.php?t=21776

What caused it to fail? I followed the steps on the service manual by checking ohms on the heater, compressor, inverter, and opened the DC to DC junction box and checked the fuses and came up blank.

Now that the precharge resistor is replaced, I don't want to have to drop the battery again because I missed a bad/failing part that caused it to fail to begin with.

Original error codes C118C, C1A6E, C1A70, P3176, P311C,

C118C 0109 ABS EV/HEV System BRC-126
C1A6E 0109 BRAKE EV/HEV System BR-146
C1A70 0109 BRAKE Brake Control System BR-160

Below codes are the real issue...
P3176 00C0 EV/HEV Inverter Condenser EVC-238
P311C EV/HEV High Voltage Sys EVC-204

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

Posted: Thu Jul 05, 2018 4:14 pm
by braebyrn
All the codes have cleared and the car now takes a charge. I haven't turned on the heater or cooling compressor. When I did turn on the car for the first time (not with brake depressed) the defrost button started flashing. IS THAT NORMAL?

The original owner said that she turned on the defroster, left the car for 20 minutes and when she came back the car was dead. After charging the 12 volt battery, the car would not go into drive or reverse and the heater and defroster would not work either. Nor could she charge the car.

Could that be the culprit causing the pre-charge resistor to blow?

I am afraid to put the car to the run (with the brake pedal depressed while pushing the ignition button) state for fear of blowing the new one....

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

Posted: Thu Jul 05, 2018 10:26 pm
by JeremyW
Well the new precharge resistor should have been used while "booting" the HV bus when initiating charging. I would start it up. It is a car after all, if something's still broken, no sense in having it sit at this point as a paperweight.

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

Posted: Fri Jul 06, 2018 6:28 am
by braebyrn
With a 2012 SL as my daily driver, it can sit until It can be determined what is causing the failure. It's not that hard to drop the battery, undo the cover and dig into the battery block, but it is time consuming.

Was hoping someone has some better idea where to look next for the answer.

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

Posted: Fri Jul 06, 2018 10:27 am
by Nubo
I understand the purpose of a pre-charge resistor, but don't know how it's implemented in LEAF. I would want to know whether the resistor is always in the circuit or if there is a relay or contactor intended to remove it from the circuit before the main contactor closes. If so, then perhaps the precharge relay is stuck closed.

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

Posted: Wed Jul 11, 2018 1:40 pm
by gugusse
Hello,

At work we have some precharge resistors on capacitors or large motor line.
Sometimes they burn, the reason can be multiple :
Failure of a capacitor
Failure of the contactor
Failure of the delay timer (precharge resistor beeing used to long)

Usually we change everything because the parts cost is over all lower than the labor and production lost.

I would check the main contactor. If it has some contact problems, it might be the cause.

Oddly enough, at some point you will have to try to start it and maybe blow more things.
I don't know about 2012 Leaf but the 2013 had a serie of bad heating resistances. They had to change ours when we bought it used last year (I don't know how the previous owner survived!).

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

Posted: Wed Jul 11, 2018 7:12 pm
by ElectricEddy
gugusse wrote:Hello,

At work we have some precharge resistors on capacitors or large motor line.
Sometimes they burn, the reason can be multiple :
Failure of a capacitor
Failure of the contactor
Failure of the delay timer (precharge resistor beeing used to long)

Usually we change everything because the parts cost is over all lower than the labor and production lost.

I would check the main contactor. If it has some contact problems, it might be the cause.

Oddly enough, at some point you will have to try to start it and maybe blow more things.
I don't know about 2012 Leaf but the 2013 had a serie of bad heating resistances. They had to change ours when we bought it used last year (I don't know how the previous owner survived!).

Gloves and wool blanket

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

Posted: Wed Jul 11, 2018 9:55 pm
by lorenfb
Nubo wrote:I understand the purpose of a pre-charge resistor, but don't know how it's implemented in LEAF. I would want to know whether the resistor is always in the circuit or if there is a relay or contactor intended to remove it from the circuit before the main contactor closes. If so, then perhaps the precharge relay is stuck closed.


Insight is provided here; http://www.mynissanleaf.com/viewtopic.p ... 10#p525611

Step 1 is to try to find out from previous owners (invest some time in this!) what may have happened. Your error codes are consistent with either the precharge relay driver (in the VCM) precharge relay, precharge resistor (both in the battery) or inverter capacitor (obviously in the inverter) having blown. This can be caused by anything from somebody trying to add an extender pack and accidentally shorting the relay wires to gross HV bus mistakes. Depending on what happened, the fix may be as simple as replacing the resistor or relay to having to find a new HV/body harness.


Remember, the basic max continuous voltage that can be applied to the 30 ohm (40W) resistor is 35 volts, i.e. without considering its mounting
and overall thermal resistance to ambient. With HV, e.g. 375V+, mis-applied, the 30 ohm resistor functions basically as a fast-blow fuse for
connection times of just a few seconds. It would be helpful if the circuit diagram of the resistor were posted.

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

Posted: Wed Jul 11, 2018 10:13 pm
by JeremyW
Nubo wrote:I understand the purpose of a pre-charge resistor, but don't know how it's implemented in LEAF. I would want to know whether the resistor is always in the circuit or if there is a relay or contactor intended to remove it from the circuit before the main contactor closes. If so, then perhaps the precharge relay is stuck closed.


Normally it's just on for a second or two. There is the possibility that the precharge contactor has failed short. Path of least resistance should mean not much current (theoretically none) would go through the resistor with the main contactor closed, but maybe a small residual current is enough to cause failure?

Strange problem. :|

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

Posted: Thu Jul 12, 2018 9:01 am
by lorenfb
JeremyW wrote:
Nubo wrote:I understand the purpose of a pre-charge resistor, but don't know how it's implemented in LEAF. I would want to know whether the resistor is always in the circuit or if there is a relay or contactor intended to remove it from the circuit before the main contactor closes. If so, then perhaps the precharge relay is stuck closed.


Normally it's just on for a second or two. There is the possibility that the precharge contactor has failed short. Path of least resistance should mean not much current (theoretically none) would go through the resistor with the main contactor closed, but maybe a small residual current is enough to cause failure?

Strange problem. :|


So without a schematic, the source of the problem is conjecture.