What happened to my Regen?

[JeremyW]

I'm expecting DCFC to take longer (much longer?) than in the past. Is Blink DCFC now reduced from 50kW to 15kW? Has anyone else looked at this?

I haven't noticed, but I haven't been quick charging as much as I use to (due to the faster L2 I've got now). My last two quick charges were on machines that could only put out 50 amps.

 

[ampitupco]

Regen performance pre- and post-update seems to be very similar. There may be minor differences, or it might be my perception. At any rate, the differences are minor.

I don't think you are seeing much of a difference because you live in a warmer climate.

I really seems to be that, once the battery gets below 55F ... 45F ... 32F and colder - regen is severely limited even at low SOC (20%, 40%). I never saw this before the P3227 update and I'm on winter number three with the LEAF. Couple low battery temperature with highway speed and the car will not regen at all.

 

[TickTock]

One possible explanation of the varying experiences is the update did change something - but only a little. Since there are at least 3 bubbles of regen past the 4 on the dash, the modulation in regen might be completely missed until it dropped to a point that it showed up on the dash.

 

[brettcgb]

Regen performance pre- and post-update seems to be very similar. There may be minor differences, or it might be my perception. At any rate, the differences are minor.

I don't think you are seeing much of a difference because you live in a warmer climate. It really seems to be that, once the battery gets below 55F ... 45F ... 32F and colder - regen is severely limited even at low SOC (20%, 40%). I never saw this before the P3227 update and I'm on winter number three with the LEAF. Couple low battery temperature with highway speed and the car will not regen at all.

The temperature has been getting down to about 40 most nights (some down to mid-30s), warms to 60's during the day... but I'm not seeing the battery temperature gauge move much.

I _AM_ seeing limited regen just as you described. The update didn't make any apparent changes.

I should try a DCFC to warm the battery and see what regen does...

 

[dgpcolorado]

...have to believe the SW update was flawed. picked up my 2013 today and had all my regen circles even at 70 % SOC and the 2013's were supposedly born with the SW we were updated to

That's pretty much the point: the 2013 software that was apparently adapted for the 2011/2012 models isn't handling the different measurement parameters correctly. The metering devices we use have shown that battery measurements are quite different for the 2013 models for capacity and H value; there are also only three battery temperature sensors in the 2013s. It is possible that other measurements have changed as well and that these changes are leading to a faulty regen protocol when adapted to readings from older LEAFs.

That's my hypothesis and I'm sticking to it!

 

[abasile]

...have to believe the SW update was flawed. picked up my 2013 today and had all my regen circles even at 70 % SOC and the 2013's were supposedly born with the SW we were updated to

That's pretty much the point: the 2013 software that was apparently adapted for the 2011/2012 models isn't handling the different measurement parameters correctly. The metering devices we use have shown that battery measurements are quite different for the 2013 models for capacity and H value; there are also only three battery temperature sensors in the 2013s. It is possible that other measurements have changed as well and that these changes are leading to a faulty regen protocol when adapted to readings from older LEAFs.

That's my hypothesis and I'm sticking to it!

Seems like a very reasonable hypothesis.

That said, if Nissan could fix the bug (I see no reason to consider anything other than a bug) that causes regen to diminish at higher speeds, that would certainly make my life easier. This morning I had to go down the mountain and was doing 25-35 mph (on a 55 mph road) because I needed regen. (I sped up to 40+ mph, then turned out, whenever cars approached from the rear.)

 

[FalconFour]

...have to believe the SW update was flawed. picked up my 2013 today and had all my regen circles even at 70 % SOC and the 2013's were supposedly born with the SW we were updated to

That's pretty much the point: the 2013 software that was apparently adapted for the 2011/2012 models isn't handling the different measurement parameters correctly. The metering devices we use have shown that battery measurements are quite different for the 2013 models for capacity and H value; there are also only three battery temperature sensors in the 2013s. It is possible that other measurements have changed as well and that these changes are leading to a faulty regen protocol when adapted to readings from older LEAFs.

That's my hypothesis and I'm sticking to it!

I'm sticking with that too... I've reported it to Nissan before I even took it to the dealer (at their request). Hopefully more people call in and mention that they'd like to put their name in the hat of people having regen problems. It still very much seems like an algorithm error, since regen ramps up as it's requested, but it isn't given immediately. Battery chemistry dictates that it should pull in the full power immediately with no ramp-up - but it's that "full power" that should be at a certain level depending on the SOC.

It very well could be always falling-back to a very, very far mis-calculated figure for that "SOC-based limit", then as it operates (regens), it realizes it can pull in more power, so it slowly "un-limits" during deceleration. I don't think it has a single iota of relationship to speed, other than that we typically start decelerating from a high speed (and that high speed requires a lot of power input, which affects the limiter over time). Lately, I've been able to pull in 4 bubbles (out of 5) even with a half-charged SOC, but that's pretty rare. Trick is to put the brake pedal on as much as possible, which triggers that "request" to pull in more power than it (mis-)calculated as its limit. Just enough to trigger the brake light should do it.

But yeah, definitely call in and at least ask if they've noticed a trend yet. They won't try fixing the problem unless enough people make a squeak about it

:lol:

 

[TickTock]

I tend to agree that this seems like a bug to me but I also try to remember that the engineers at Nissan know a LOT more about battery chemistry and how to maintain one than me so I do allow that there is a reasonable chance that they do this for a very good reason. However, I would point out that this behavior has been present since the very first 2011's rolled off the line. I do think there may be something in the recent sw update that may have exacerbated this to the point that it is much more frustrating but the bug/behavior is not new. Also, we were a bit pre-occupied with the battery degradation during the early months. Now that that is better understood, I guess we're "peeling the onion."

 

[DaveinOlyWA]

with temperature playing a huge part in what regen is available, real answers are not likely til mid Spring at the earliest but then again, my 2011 is gone so its in "someone's" court. as for me? 82% SOC, batts at 51º F and all regen circles available...

 

[JeremyW]

Or, just live in so cal and/or quick charge a few times! I'm trying to see what temp the battery needs to be at for the controller to "relax" on limiting regen. I think 25-30c is where I see this happening...

 

[DaveinOlyWA]

Or, just live in so cal and/or quick charge a few times! I'm trying to see what temp the battery needs to be at for the controller to "relax" on limiting regen. I think 25-30c is where I see this happening...

SOC is the prime limiting factor. as far as limited due to temps? on my 2011, it was probably around 65º at the battery level. on the 2013, probably 45º but then again, not sure about the 2013. as soon as I start to see evidence of regen limitation, i will let you know

 

[FalconFour]

I've been noticing my regen's come back to life again (for the most part), with the only real "trigger" for crippled regen being going full-throttle for more than just a blip or so. Like, getting on the freeway. It kills *all* my regen, which seems exactly the opposite of what I'd expect from a battery... I'd think it would want to get that charge reclaimed quickly before the discharge "settles" throughout the cells.

I've also started to wonder if Nissan is just screwing with groups of regional test cars via Carwings. :lol:

 

[JeremyW]

Been a bit warm in Fresno? I saw 6 temperature bars on Christmas Day! :shock:

 

[johnrhansen]

On a cold day in seattle I saw the opposite. All the regen dots at 97 percent charge. Thats the most I have ever seen. At 4 temp bars.

 

[FairwoodRed]

I spoke to Nissan again today and I was told that they have noted a handful of owner’s with reduced regen and they are looking into if they can find an improvement.

No real solution, but a big improvement over how they responded to the grabby brakes by denying it totally. If I’m being honest, Nissan saying they see the concern and are going to see if they can improve it is the second best outcome I could hope for (the best is that it will be fixed today!).

 

[TomT]

Sorry, but I don't believe much of what CS tells me... I've been lied to by them too many times.

I spoke to Nissan again today and I was told that they have noted a handful of owner’s with reduced regen and they are looking into if they can find an improvement.

 

[brettcgb]

Regen performance pre- and post-update seems to be very similar. There may be minor differences, or it might be my perception. At any rate, the differences are minor.

I don't think you are seeing much of a difference because you live in a warmer climate. It really seems to be that, once the battery gets below 55F ... 45F ... 32F and colder - regen is severely limited even at low SOC (20%, 40%). I never saw this before the P3227 update and I'm on winter number three with the LEAF. Couple low battery temperature with highway speed and the car will not regen at all.

The temperature has been getting down to about 40 most nights (some down to mid-30s), warms to 60's during the day... but I'm not seeing the battery temperature gauge move much.

I _AM_ seeing limited regen just as you described. The update didn't make any apparent changes.

I should try a DCFC to warm the battery and see what regen does...

On 12/28/2013 about 6PM, I repeated a test I had performed 11/3/2012. I performed a DCFC from a low SoC, and recorded "lap times" to reach each 5% (40%, 45%, 50%, etc). Both tests started with SoC <40% (2012=38%, 2013=32%). I selected 100% charge in both cases, and the charger stopped at <91%.

In 2013, the battery temperature did not change before/after charge, 5 temperature bars. The dash indicated 60degF air temperature. Battery health = 9 bars. Regen performance was unchanged between before/after charge, but had significantly degraded in the last couple months (pre-P3227 update, no apparent change post update). The Blink charger indicated 60kW available (does this mean anything?)

In 2012, the air temperature was warmer (not recorded, assumed >70deg F). Battery health = 11 bars.

Data (semicolon delimited):
SoC;Time to next 5% (2012);Time to next 5% (2013);Time to 90% (2012);Time to 90% (2013);ELAPSED TIME (2012);ELAPSED TIME (2013)
0.40;-------;0:01:50;0:20:40;0:36:16;0:00:00;0:01:50
0.45;0:01:31;0:01:35;0:19:09;0:34:41;0:01:31;0:03:25
0.50;0:01:01;0:01:48;0:18:08;0:32:53;0:02:32;0:05:13
0.55;0:01:19;0:02:32;0:16:49;0:30:21;0:03:51;0:07:45
0.60;0:01:42;0:03:04;0:15:07;0:27:17;0:05:33;0:10:49
0.65;0:01:45;0:03:10;0:13:22;0:24:07;0:07:18;0:13:59
0.70;0:01:42;0:03:37;0:11:40;0:20:30;0:09:00;0:17:36
0.75;0:01:57;0:04:00;0:09:43;0:16:30;0:10:57;0:21:36
0.80;0:02:30;0:05:05;0:07:13;0:11:25;0:13:27;0:26:41
0.85;0:03:08;0:05:20;0:04:05;0:06:05;0:16:35;0:32:01
0.90;0:04:05;0:06:05;0:00:00;0:00:00;0:20:40;0:38:06

Findings
2012 vs 2013
For SoC<=80%, times to add 5% capacity had roughly doubled.
For SoC>=85%, times to add 5% capacity were generally fixed at 2 minutes longer in 2013 vs 2012.
Overall charge time (SoC=40% to 90%) increased from 21 minutes (2012) to 38 minutes (2013).

2013 pre- vs post-charge (SoH=9 bars)(Air=60F)
No battery warming was observed.
Regen performance was unchanged.

I would have really liked to know the electrical measurements (DCV, DCA) during the charge.
Does anyone know if this data is available via OBD-II?

 

[DaveinOlyWA]

Brett; i can pretty much guarantee that your batteries were warmed up a least more than a few degrees. the average i see for a charge of that depth is 5-10º and once (last night) they warmed up from 45ºF to 58ºF for charge from 17 to 68%

 

[brettcgb]

Brett; i can pretty much guarantee that your batteries were warmed up a least more than a few degrees. the average i see for a charge of that depth is 5-10º and once (last night) they warmed up from 45ºF to 58ºF for charge from 17 to 68%

Dave - I expect you're right. Unfortunately, the only indicator I have is the dash board bargraph, and that's so vague that it's practically useless for this kind of experiment.

I've considered purchasing/building instrumentation that reads out such data, but I've got almost exactly one year left remaining on my lease. I don't yet know if I would lease another Leaf or other EV, or return to ICE. I wouldn't purchase my current Leaf if newer technology was available for lower cost.

On the other hand, I expect to be losing my 4th battery bar sometime in the next 2 to 4 months, resulting in battery repair or replacement (the dealer service manager told me that the entire battery is replaced with new - I don't know that I believe that). That would be an interesting time to have such instrumentation.

It would be a good learning experience to build my own, but I'd be starting from scratch WRT CAN bus. I'm an electrical engineer working with microcontrollers and laptop Li-ion batteries are not unknown to me. I design circuits, lay out PCBs, write code (C and assy for PIC18)... and I can solder!

Can someone suggest instrumentation that reads out battery status (SoC, Volts, Amps (charge, discharge, regen), temperatures, cell voltages), and offers data logging support?

 

[DougWantsALeaf]

Besides preheating the cabin, any other way to easily great up the battery in cold weather?