TickTock wrote: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).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.
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).
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).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.