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Re: LEAF CANbus decoding. (Open discussion)

Posted: Sat Aug 31, 2013 6:11 am
by TickTock
TickTock wrote:
TickTock wrote:It appears the temperature messages (EVcan 546:D7 and CARcan 510:D8) do not suffer from the same long delay/time_constant as the dash eyebrow display. I added the ambient to the debug screen on CANary and although I am within 1 degree when the car is at equilibrium, the message is much more responsive to outside changes. I ran an errand this afternoon. When I left the garage (80F), CANary and LEAF dash matched. Within minutes of driving in 110F weather, the CANary (msgID 546/510) temp quickly rose to 109F but the dash only increased to 84. I double-checked the owners manual and it is, indeed, supposed to be outside air temperature (I thought maybe it was showing cabin temperature). I wonder why the dash temp has so much filtering - makes it rather less useful. I think I will add outside ambient to one of the operational screens.
OK. Even more strange - the filter appears to be asymmetrical. This morning my garage was warmer than outside. As expected, the canbus message matched the dash outside temp display when I got in but unlike before when it was warmer outside, it continued to track the dash display perfectly as it dropped from 90F to 86F. So, it appears the dash display delays or filters rising temperatures but not falling. This would be consistent with my prior experience at car washes (temperature quickly drops after passing through the car wash but takes 20 minutes or so to return to something resembling the outside temp).

The Leaf is the nicest car I've ever owned so I've never had an outside temperature gauge before. Do ICE ambient gauges do the same? I wonder if this is a carry-over from ICE vehicles (maybe they were trying to compensate for engine compartment heat skewing the sensor and the same algorithm was copied to the LEAF even though there is no significant heat buildup to speak of).
drees wrote: Very plausible theory. I imagine that stopping at a red light in an ICE when there isn't any wind (especially at a large and busy intersection mid-day with the sun out) would see a large spike in temperatures.
Since adding ambient to CANary, I have confirmed that this asymmetric filtering wasn't my imagination. It tracks very close after a long soak (overnight in the garage or at the end of the day at work) and as temperature falls, but not as temperature rises. I drove through a carwash yesterday. Both started at 96F and dropped together to 85F as I passed through. After leaving the carwash, the CANary ambient display climbed at a rate of about 1 degree per minute and got all the way to 97F before the dash ambient display changed from 85 to 86F. By the time I got home CANary was settled at 98F but the dash was only at 92 (but still climbing presumably).

Re: LEAF CANbus decoding. (Open discussion)

Posted: Mon Sep 23, 2013 1:07 pm
by brad370
TickTock wrote:On the Leaf, 292:G appears to be brake pressure or applied friction rather than brake pedal position.
You may be right. I'll experiment a little more with this one to differentiate between the two.
TickTock wrote:Also I do not think 292:D is battery voltage. It mostly hovers around 7f-80 for me too but I know the battery voltage fluctuates from 11-14.
I didn't think the numbers seemed right, but it has to be something similar. It seems to dip when I roll the windows up and down, which may be from the inrush current for the motors.
TickTock wrote:Have you tried querying the 370Z with the 79b/7bb message pairs like we do on the LEAF?
I have OBD querying working for the 7DF/7E8 message pairs. What is 79B/7BB? Is it specific to a module in the LEAF?

Re: LEAF CANbus decoding. (Open discussion)

Posted: Mon Sep 23, 2013 1:39 pm
by Turbo3
brad370 wrote:
TickTock wrote:On the Leaf, 292:G appears to be brake pressure or applied friction rather than brake pedal position.
You may be right. I'll experiment a little more with this one to differentiate between the two.
TickTock wrote:Also I do not think 292:D is battery voltage. It mostly hovers around 7f-80 for me too but I know the battery voltage fluctuates from 11-14.
I didn't think the numbers seemed right, but it has to be something similar. It seems to dip when I roll the windows up and down, which may be from the inrush current for the motors.
TickTock wrote:Have you tried querying the 370Z with the 79b/7bb message pairs like we do on the LEAF?
I have OBD querying working for the 7DF/7E8 message pairs. What is 79B/7BB? Is it specific to a module in the LEAF?
79B/7BB is the HV Battery. There is no 7DF/7E8 on the Leaf.

Re: LEAF CANbus decoding. (Open discussion)

Posted: Tue Sep 24, 2013 11:56 am
by brad370
The 7DF command is a general broadcast OBD2 command. Responses are in the range of 7E8-7EF depending on which module responds. This is standard since 2008. OBD2 PIDs

Edit: I should clarify that it's standard, but maybe not on hybrid/electric vehicles. I'll stay out of your LEAF business and just try to contribute any info I find on the 370Z.

Re: LEAF CANbus decoding. (Open discussion)

Posted: Tue Sep 24, 2013 11:11 pm
by garygid
To avoid confusions, perhaps start another thread for the 370Z CAN bus?

Re: LEAF CANbus decoding. (Open discussion)

Posted: Fri Oct 04, 2013 11:45 am
by TickTock
Looks like my prior post got missed. I am reasonably certain that CarCan 5B3:D2>>1 contains the SOH value that is read by the Nissan DV-R test equipment and have it on good authority that this is the first thing they look at for any 4 bar losers brought in for warranty work. I have gathered a few datapoints (three cars - mine and two 2013 models) and from those those it appears to be very strongly correlated to AH/65.xx. My car, immediately after getting reset plus the two 2013's indicate Ah/65.6. However, once my car established it's true capacity near 70%, I occasionally get 1% error between the read SOH and the computed Ah/65.6 value. I was hoping we could get this measurement into some more devices so we can get more datapoints and work on a formula to compute this SOH for those devices without access to passive CarCan data.

Re: LEAF CANbus decoding. (Open discussion)

Posted: Fri Oct 04, 2013 11:52 am
by Turbo3
I would like to add this to Leaf Spy. By D2 you mean the second data byte (numbering 1-8).

Use only the high 7 bits or are we dividing by two so the number is xxx.0% or xxx.5% where xxx=0 to 100.

I would just read this number once when Leaf Spy is started as it needs special listen code.

Re: LEAF CANbus decoding. (Open discussion)

Posted: Fri Oct 04, 2013 12:03 pm
by TickTock
Yes, I am using Gary's nomenclature so D2=the second data byte. Appears to be just the upper 7 bits (bit 0 does not give a 0.5% resolution). Lucky for you, this is the same CarCan message containing gids so I suspect you are already reading it :-).

Re: LEAF CANbus decoding. (Open discussion)

Posted: Fri Oct 04, 2013 12:24 pm
by TickTock
Gary, you asked if this tracked cap bar loss. The answer is "it should." However, cap bars appear to have ~2month time-constant associated with them whereas this reading is more immediate.

This is what I read from my car when I dropped it off for the sw update on 7/10:
  • Ah = 45.59
    SOH = 68%
    Xfactor = 62.4%
    Cap bars = 9
When I picked it up I read:
  • Ah = 65.6 (seeing this along with the 100 reset value led me to the conclusion that 65.6 is considered 100%)
    SOH = 100%
    Xfactor = 100%
    Cap bars = 12
About 3 miles down the road it changed to:
  • Ah = 65.6
    SOH = 100%
    Xfactor = 50.9%
    Cap bars = 12
The next day after a 100% charge, I read:
  • Ah = 46.92
    SOH = 72%
    Xfactor = 50.9%
    Cap bars = 12
My cap bars are presently at 11 (re-lost the top bar on 9/4). SOH appears to get updated after each charge, but it takes months for the cap bars to reflect this. Since degradation is actually much slower than the step function caused by the reset, I suspect that cap bars should track SOH much more closely than my present condition.

Re: LEAF CANbus decoding. (Open discussion)

Posted: Fri Oct 04, 2013 12:25 pm
by Turbo3
Now the hard part. What do we call it? If we make this health what do I call the old one? Do you think we need both?