FS: 2012 RAV4 SF South Bay / San Jose Area

[ChuckEV]

We're looking to sell our 2012 with 83k miles on it. It runs great and has good range and is in good clean physical condition.

However, there's some issue where it's blowing the charging fuse. We've had the fuse professionally replaced twice by Earthling Automotive and each time it worked for a few months, but it's blown again. The car still has some charge in it.

Taking offers and feel free to ask any questions.

 

[Melnric495!]

does the heat work and can you ship it to kentucky

 

[ChuckEV]

does the heat work and can you ship it to kentucky

Yup, the heat does work. Of course, the hear on these is really inefficient and you lose a lot of range when it's running. As for Kentucky, if you would pay for shipping we could probably arrange something.

 

[fred_dot_u]

Will a leaking LDU that's migrated into the inverter section cause blown fuses?

 

[asavage]

No. The OBC's AC input fuses cannot be affected by a flooded inverter, because the BMS would not enable the contactors due to low HV insulation isolation resistance, which is a check that the BMS perform during to every startup. Iso under 1.8M (or something)? No contactor closure. Iso drops below 1M (or something) during Ready (driving)? Contactor immediately opened.

If the inverter somehow became flooded during a charging session, the same would occur, as the BMS monitors iso at all times when it's active. (Posts below confirm that this doesn't happen)

Aside from that, the OBC itself would fault and go into overcurrent mode if the HV bus suddenly dropped in voltage (raised current demand to achieve the target voltage, due to lowered resistance on the HV isolation). It would turn off, not cause a fuse failure.

It seems that in most cases the OBC's input fuses really are just getting old and fail too easily. I came to that conclusion because several people have replaced a single failed fuse, only to have the other fuse fail within a year. For that reason, I do not replace the OEM fuses with Mersen/Ferraz Shawmut units and install Eaton/Bussman (Cooper) instead.

 

[hokiematt]

FYI - I recently did an experiment where I placed a resistor between one of the HV leads and chassis ground, to simulate degradation of the HV isolation. I was surprised that it took a value <500k ohms to see any response from the system (by monitoring CAN data), and even then the system changed other status bits without ever changing the one applicable to the RAV4 (to trigger a BMS_f035 error). Even for a measured isolation value of 120k ohms, I was able to achieve READY and place the car in drive. No 'Check EV System' or similar error was ever displayed. While the system properly measured the reduction in HV isolation, it doesn't appear there's any programming in the RAV4 do actually do anything about it.

 

[asavage]

No way!

 

[hokiematt]

No way!

Way, indeed I was honestly surprised, but the CAN data doesn't lie. I'd be happy to walk you through what I did if you'd like to repeat my experiment, and see what results you get.

 

[alflash]

FYI - I recently did an experiment where I placed a resistor between one of the HV leads and chassis ground, to simulate degradation of the HV isolation. I was surprised that it took a value <500k ohms to see any response from the system (by monitoring CAN data), and even then the system changed other status bits without ever changing the one applicable to the RAV4 (to trigger a BMS_f035 error). Even for a measured isolation value of 120k ohms, I was able to achieve READY and place the car in drive. No 'Check EV System' or similar error was ever displayed. While the system properly measured the reduction in HV isolation, it doesn't appear there's any programming in the RAV4 do actually do anything about it.

This video shows good movement of RAV4EV despite the fact that the Isolation Resistance parameter = 0 kOhm (!)

 

[asavage]

Wow. TIL . . .

 

[TinkerTan]

That's really surprising. I wonder what shorting conditions must occur in order to fault the EV system... because I know how sensitive my LDU has been to glycol in there.

-Perhaps low isolation resistance to chassis on both the + and - battery terminals, it would fault and open contactors? I know there is one displayed iso value but I wonder how it is measured and whether it is measured on both + and - (if so, then the single displayed value might be the lowest of the two).
- Errant current is measured by the battery pack shunt with no commanded throttle, due to a short through + and - via glycol?
-Stator current discrepancy due to short across two of the 3 phases when wet, since the sleeves on the stator phases can wick up coolant and the air gaps in that central gallery are not very large.
-Induced inverter switching noise related, from stator windings shorting to the housing?

I'm just really surprised the LDU didn't respond simply to low isolation resistance.

 

[hokiematt]

The HV isolation resistance is measured by the BMS. I don't know the specifics of how Tesla does it, but other systems I've worked with use a divider network of resistors across the HV DC, with the middle tied to chassis ground; a crude layout is: (HV+)-R1-R2-gnd-R3-R4-(HV-). R1 and R4 are on the order of a few megaohms each and of equal value; R2 and R3 are a few hundred ohms and equal. If there is no leakage path to ground, the current will be the same through all of the resistors, and the voltage measured across R2 with respect to ground will be the same (but polarity flipped) as R3 with respect to ground. If a leakage path is introduced, we will now have a few extra milliamps flowing between chassis ground and one of the high voltage legs, and an imbalance in voltage will be seen between R2 and R3.

The BMS in the RAV4 broadcasts this calculated isolation resistance over CAN, and will also set various flag bits for isolation degradation and isolation loss as appropriate. Surprisingly these flags are not shown in the Tesla RAV4 powertrain software, the gateway does not send a 'Check EV Systems' message to the Toyota side, and the contactors do not open.

With regards to using the current sensors in the motor to detect errant current: typical leakage thresholds for safety are generally 20 mA or less. Trying to accurately measure that kind of current loss in a noisy environment with sensors sized for perhaps 1000A full-scale is not practical. There is a fault code for 'motor current imbalance' that I assume would be tripped if one of the phases was drawing notably more current than the other two phases (with a threshold of amps if not 10's of amps).

 

[ChuckEV]

Checking in to see if anyone is interested in this vehicle.

 

[gpearce]

Checking in to see if anyone is interested in this vehicle.

I would be interested but it would have to be really cheap as I would be shipping it to Canada where I would have source parts and do repairs myself. Basically it would be my classic car. Something to tinker with in my retirement. You could probably part it out for more than I would pay for it though.

 

[hokiematt]

Checking in to see if anyone is interested in this vehicle.

Asking price? Is the charger the only issue?