Inconsistent instruments

[Levenkay]

I know that reporting that the LEAF's "distance to empty" reading can be inaccurate isn't going to get me that Pulitzer, but what's up with the "fuel bars"? On the return trip from a brief weekend appearance at work, I noticed that the bars intended to display the battery charge had dropped from the ten I'd set out with down to seven. With the anemic arithmetic skills that I can muster while driving, I figure that each bar would represent about 2KWh, if all 24KWh of a new pack were distributed linearly across the twelve bars. My pack isn't new (has all 12 capacity bars, though), and maybe only 22KWh or so are officially available. So maybe I've only got 20/12 KWH per bar. The three bars would then represent somewhere between 3.3 and 5KWh. All good. But at the same time, the dash is claiming a distance of 12.6 miles driven and an average energy economy of 6.0 mi/KWh (my trip into work is noticeably downhill, and I'd reset the trip odometer and energy efficiency display before setting out). At that rate, even the minimum 3.3KWh ought to have gotten me 20 miles, not 12.6. By the time I got home, the displayed efficiency was down to 5.0 mi/KWh, the distance traveled was 23.7mi, and the "charge" display was down to six bars. A loss of 4 to 5 bars would represent between 6.7 and 8.3KWh, which ought to have taken me 34 to 42 miles, not 24. Given that all the readouts are coming from a single system's data, why should the figures be 50 to 90% in error?

 

[LeftieBiker]

<Garbled, inaccurate answer deleted!>

 

[GerryAZ]

I saw considerable inaccuracies in the SOC bars and the information available on the CAN bus as the original battery deteriorated in my 2011. If your car has not had the P3227 software update, you should get that done to improve the accuracy of the battery instrumentation. As an example of the instrumentation problems I saw, I "used" 9 SOC bars going downhill on the way to work several times and made it home on the remaining 3 bars going uphill with A/C keeping me cool. The watt-hours remaining in the battery (Gids) read from the CAN bus matched the bar display (in other words, the CAN bus data showed 75% of available charge was used to get to work with 25% remaining when I parked). On the way home, the Gids stopped counting down just above the LBW threshold and held steady until I truly reached low battery warning about where it usually happened. The very low battery warning also happened about in the normal location. The original battery was down to 8 capacity bars at that point so I scheduled a dealer visit to confirm the battery capacity and have the P3227 software update. The software update greatly improved the accuracy of the dashboard instrumentation and the data available on the CAN bus so I always arrived at work with about 6 SOC bars and a little over 55% SOC as shown from CAN bus data until Nissan Customer Service called me and asked to schedule the battery replacement. Even the "GOM" was more accurate after the software update, but it was still a "guess-o-meter".

Just to be clear, the SOC bars (long bars that represent how full the battery is or its state of charge) are reasonably linear, but they are not exact. A full charge will always display 12 SOC bars, but the amount of energy (kWh) represented by each bar decreases over time as the battery deteriorates. The capacity bars (short bars that show the capability of the battery to store energy) are not linear. The loss of the first capacity bar represents a loss of battery capacity of about 15%.

Gerry

 

[dhanson865]

I'll quote myself on the skinny of the variable percentage bars.

The top bar is worth more than two of the lower bars. With 2 bars lost you'd get more like 70% of the original range and only if you drive to VLBW.

I'm not going to worry about duplicates at the cusp, I'm sure you aren't worried about the last tenth of a percent. Oh and there are two kinds of bars

capacity bars
100% to 85% = 12 bars (15%)
85% to 78.75% = 11 bars (6.25%)
78.75% to 72.5% = 10 bars (6.25%)
72.5% to 66.25% = 9 bars (6.25%)
66.25% to 60% = 8 bars (6.25%)
60% to 53.75% = 7 bars (6.25%)
53.75% to 47.5% = 6 bars (6.25%)
47.5% to 41.25% = 5 bars (6.25%)
41.25% to 35% = 4 bars (6.25%)
35% to 28.75% = 3 bars (6.25%)
28.75% to 22.5% = 2 bars (6.25%)
22.5% to 16.25% = 1 bar (6.25%)



charge bars http://www.mynissanleaf.com/viewtopic.php?p=101293" onclick="window.open(this.href);return false;
100% to 91.5% = 12 bars (8.5%)
91.5% to 84% = 11 bars (7.5%)
84% to 77.9% = 10 bars (6.1%)
77.9% to 70.8% = 9 bars (7.1%)
70.8% to 66.2% = 8 bars (4.6%)
66.2% to 58% = 7 bars (8.2%)
58% to 50.9% = 6 bars (7.1%)
50.9% to 43.4% = 5 bars (7.5%)
43.4% to 36.3 = 4 bars (7.1%)
36.3% to 31.3% = 3 bars (5%)
31.3% to 26% = 2 bars (5.3%)
26% to 17.4% = 1 bar (8.6%)*
Low battery
Very low battery
Turtle

*see range chart and other threads for how dangerously quick you can drop from 1 bar to turtle. Don't rely on expected range at low states of charge.

and note the charge percents I gave were based on a 100% capacity battery all the charge bars get modified if the capacity is below 100%.

as you can see a significant portion of your battery is hidden at the bottom end by the low battery warnings so if you aren't pushing the low battery warnings you are giving up a big chunk of range in a moderate environment at slower speeds (the typical end of trip driving to a parking space or charging station).

Also notice the wide variety of percentages for "one bar" it can be as little as 4.6% and as much as 8.5% on one scale and as little as 6.25% and as high as 15% on the other scale.

also the battery is 24kWh but only about 21 kWh is available to you. So with 2 bars lost you have somewhere between 78.75% to 72.5% of 21 kWh which is 16.5 to 15.2 kWh usable as a rough estimate. Note that is close to the kWh you though you had but I'm assuming you are relying on the GOM and not pushing LBW.

 

[Valdemar]

My pack isn't new (has all 12 capacity bars, though), and maybe only 22KWh or so are officially available.

22kWh was available, or rather accessible, when the car was new, maybe. If your delivery date is correct you're probably close to losing the 12th capacity bar after 4 years in PNW, so my guess your accessible capacity is in the high teens. Do you use Leaf Spy?

 

[iamchemist]

At 3 1/2 years and 27,000 miles a surprising thing about our LEAF is how horrible the GOM accuracy is, as compared to real miles that we can drive. I don't know, if our car has had the P3227 software upgrade that many of you have discussed. I will check with our Nissan Dealer to see. I would be interested to know, if others are seeing similar LEAF characteristics and if the P3227 upgrade is likely to help.

I would say that our GOM frequently reads 30% to 50% high, as compared to real miles that can be driven. That is so terrible that the GOM is almost entirely worthless. I could take a WAG and be about as close. The GOM also reads a surprisingly wide range of numbers in Eco Mode in the morning just after a full charge. We see anywhere between 63 and 80 on the GOM, remembering that those number are likely 30% to 50% too optimistic.

Having lost one battery capacity bar (11 showing), I would say that the range of our LEAF on a full 100% charge with the air conditioning running is only 50-55 miles.

 

[GerryAZ]

Please read my post earlier in this thread. The P3227 software update significantly improved the instrumentation accuracy of my 2011. Also, I was still making my 52-mile round trip (26 each way) mostly freeway commute with A/C keeping me cool after dropping to 8 capacity bars. There is a lot of range (energy storage) hidden below low battery warning and very low battery warning if the software update has not been done (as noted in my earlier post).

Gerry

 

[iamchemist]

Gerry,

Could you tell me about when the P3227 software upgrade became available? My LEAF has been in to Nissan 5 or 6 times since about mid-2012 for routine maintenance visits. I thought such software upgrades were a standard part is such visits - is that right?. Of course, my Nissan Dealership is pretty lame! I would not be at all surprised to learn that they simply had not done the upgrade for some reason.

 

[iamchemist]

dhanson865,

How confident are you in the percentage ranges that you have posted for each of the 12 LEAF Capacity Bars? I have a 2012 LEAF, and my GID Meter reads 197 Gids at full (100%) charge. Assuming 281 Gids as the original battery capacity, that means I'm at about 70% of original capacity. Yet I still have 10 Capacity Bars showing. Based on your table I should have only 9 bars showing. Am I misunderstanding something, here?

 

[Valdemar]

It appears that the algorithm for capacity bar calculation is based on averaging of samples collected over fairly long time, so the display may lag behind actual capacity level. You will lose your 10 bar fairly soon, if this makes you feel better

 

[Nubo]

A lot of mumbo-jumbo goes into the LEAF instrumentation, all the while obfuscating and obscuring the one simple fact any sentient driver wants to know: "how much fuel do I have"? And the answer would be "You have X.xx kiloWatt-Hours. Instead of Nissan's best guess, we get unequal "bars", and an addled guess-o-meter. Why not horsetails and cloud fragments per cubic furlong?

That being said, I do commend Nissan for actually making an attempt to make battery degradation apparent to the consumer in some form. Seeing as how this eventually bit them hard (and rightfully so) due to their initial poor battery performance, it will probably serve as a textbook case on why NOT to provide consumers with details like that.

 

[dgpcolorado]

dhanson865,

How confident are you in the percentage ranges that you have posted for each of the 12 LEAF Capacity Bars? I have a 2012 LEAF, and my GID Meter reads 197 Gids at full (100%) charge. Assuming 281 Gids as the original battery capacity, that means I'm at about 70% of original capacity. Yet I still have 10 Capacity Bars showing. Based on your table I should have only 9 bars showing. Am I misunderstanding something, here?

The calculation of capacity fluctuates somewhat depending on battery temperature and other factors. The capacity will need to be below the threshold for some unknown period of time before the capacity bar drops. This helps prevent the bar from coming back as battery temperatures change and measurements of capacity fluctuate.

By way of example, I lost my first CB in the late spring at a reported capacity — 55.75 Ah — well below the -15% threshold (~56.3 Ah). Since then, my battery temperatures have been consistently higher as have my capacity measurements. But never high enough for the lost CB to come back. If it weren't for this designed-in lag, the CB might flicker on and off, which would be annoying.

 

[dhanson865]

dhanson865,

How confident are you in the percentage ranges that you have posted for each of the 12 LEAF Capacity Bars? I have a 2012 LEAF, and my GID Meter reads 197 Gids at full (100%) charge. Assuming 281 Gids as the original battery capacity, that means I'm at about 70% of original capacity. Yet I still have 10 Capacity Bars showing. Based on your table I should have only 9 bars showing. Am I misunderstanding something, here?

The capacity bar ranges are 100% confidence, they came from a Nissan document. If you Google enough you can find mention of it here on mynissanleaf.com and on the wiki.

State of charge bars are variable. The percentages listed in that post come from Tony Williams range chart for a 12 bar leaf. The SOC bar in that case is relative to the overall capacity loss of the car in question.

Capacity bar losses aren't based on GIDs. They are based on AHrs. I don't have the post on my work PC but as a rough number you should expect that bar to drop when leafspy says you are around 47.x AHr. I don't even look at GIDs on my car, too much variation in GIDs from model year to model year, easier to use SOH% as a proxy of AHr since SOH% roughly corresponds to the percentages of the bar cutoffs.

Also worth mentioning that the AHr value is updated more accurately when you turn the car on and AHr can thus bounce back up from a prior less accurate low reading. It has to stay below the trigger value for some unknown period or number of detection events to actually cause the bar loss to show on the dash. It's not a super long period of number of events, just enough to keep the bar from disappearing and reappearing more than once or twice (reappearing bars are rare and go back away quickly).

If you don't have a way to see SOH% or AHrs you can use the max GIDs and the cutoff percentage I listed to back it out and figure out roughly what your max GIDs at new was. Odds are it wasn't 281. But that will be inaccurate as the bar doesn't drop at a set AHr/SOH% due to the delay. The only way to know your original max GIDs would be to go back in time.

 

[Valdemar]

Do we know if the AHr value gets reset when historical capacity loss data is cleared via Consult? I would think so.

 

[GerryAZ]

Do we know if the AHr value gets reset when historical capacity loss data is cleared via Consult? I would think so.

Yes, AHr value is reset to what is considered 100% for the model year and style of battery. It will soon drift to the actual battery capacity (as determined by the lithium battery controller). When the battery was replaced in my 2011, it showed full AHr capacity when I picked it up at the dealer (plugged ELM unit into OBDII port in parking lot across street from dealer) and had already dropped a little by the time I got home.

Gerry

 

[TimLee]

I know that reporting that the LEAF's "distance to empty" reading can be inaccurate isn't going to get me that Pulitzer, but what's up with the "fuel bars"? ...

Nissan's LEAF instrumentation has been inadequate from day one.
I just barely tolerated it for 31 months till I got a smart phone and LEAF Spy Pro.

As capacity degrades Nissan's poor instrumentation gets more problematic.
Get LEAF Spy Pro.
You will have the info you need and be happier.

I mainly follow remaining kWh.
I set the miles calculator to 1 kWh remaining and a very conservative 3.3 miles per kWh.

Low battery warning can occur with three or more kWh remaining.
A lot of range in those last 2 1/2 kWh.

Turtle always happens at 0.4 kWh remaining.
Stops aoon thereafter as high voltage disconnect is at 0.3 kWh remaining.
But those last few tenths can be a bit flaky.
That is why it is best only to count on going to 1.0 kWh remaining.

 

[Valdemar]

I rely on gids, at least on my daily commute. I remember typical gid drops between waypoints which are close to charging locations, so I always know if I make it home or not just glancing at the gids when driving by a waypoint.

 

[dgpcolorado]

I rely on gids, at least on my daily commute. I remember typical gid drops between waypoints which are close to charging locations, so I always know if I make it home or not just glancing at the gids when driving by a waypoint.

I do the same. On my 70 mile grocery shopping trips I know that 170 Gids will get me home — including 2300 feet of elevation gain — even in winter, so I charge to at least that level at the public charge station in my destination city.

 

[dhanson865]

dhanson865,

How confident are you in the percentage ranges that you have posted for each of the 12 LEAF Capacity Bars? I have a 2012 LEAF, and my GID Meter reads 197 Gids at full (100%) charge. Assuming 281 Gids as the original battery capacity, that means I'm at about 70% of original capacity. Yet I still have 10 Capacity Bars showing. Based on your table I should have only 9 bars showing. Am I misunderstanding something, here?

The capacity bar ranges are 100% confidence, they came from a Nissan document. If you Google enough you can find mention of it here on mynissanleaf.com and on the wiki.

State of charge bars are variable. The percentages listed in that post come from Tony Williams range chart for a 12 bar leaf. The SOC bar in that case is relative to the overall capacity loss of the car in question.

Capacity bar losses aren't based on GIDs. They are based on AHrs. I don't have the post on my work PC but as a rough number you should expect that bar to drop when leafspy says you are around 47.x AHr. I don't even look at GIDs on my car, too much variation in GIDs from model year to model year, easier to use SOH% as a proxy of AHr since SOH% roughly corresponds to the percentages of the bar cutoffs.

Also worth mentioning that the AHr value is updated more accurately when you turn the car on and AHr can thus bounce back up from a prior less accurate low reading. It has to stay below the trigger value for some unknown period or number of detection events to actually cause the bar loss to show on the dash. It's not a super long period of number of events, just enough to keep the bar from disappearing and reappearing more than once or twice (reappearing bars are rare and go back away quickly).

If you don't have a way to see SOH% or AHrs you can use the max GIDs and the cutoff percentage I listed to back it out and figure out roughly what your max GIDs at new was. Odds are it wasn't 281. But that will be inaccurate as the bar doesn't drop at a set AHr/SOH% due to the delay. The only way to know your original max GIDs would be to go back in time.

OK, found the thread where mwalsh was discussing this. Below is my reply summarizing the AHr at loss discussion

Losses are triggered at
56 AHr (12 down to 11)
52 AHr (11 down to 10)
48 AHr (10 down to 9)
44 AHr (9 down to 8)

with a disclaimer that you may see it drop 2.x AHr past that if in extremely hot conditions.

or if you prefer bands maybe something like

Loss of bar 12 - between 53.75 AHr and 56 AHr
Loss of bar 11 - between 49.75 AHr and 52 AHr
Loss of bar 10 - between 45.75 AHr and 48 AHr
Loss of bar 9 - between 41.75 AHr and 44 AHr

edit: fixed type of 42 where I meant 44.

 

[mwalsh]

OK, found the thread where mwalsh was discussing this. Below is my reply summarizing the AHr at loss discussion

Losses are triggered at
56 AHr (12 down to 11)
52 AHr (11 down to 10)
48 AHr (10 down to 9)
42 AHr (9 down to 8)

with a disclaimer that you may see it drop 2.x AHr past that if in extremely hot conditions.

or if you prefer bands maybe something like

Loss of bar 12 - between 53.75 AHr and 56 AHr
Loss of bar 11 - between 49.75 AHr and 52 AHr
Loss of bar 10 - between 45.75 AHr and 48 AHr
Loss of bar 9 - between 41.75 AHr and 44 AHr

Again, and with all due respect, I don't think it's necessary to tweak the numbers I've used unless more data to support the range you've suggested is forthcoming. For example, bar 9 - we have never seen anyone loose it as low as 41.75AHr and only one person thus far (whom I personally think was either mistaken or is a complete outlier) who lost bar 9 (well) below 42AHr. We have also never seen anyone loose bar 9 at anything close to 44AHr, with 43.56AHr being the highest reading at bar loss thus far.