regen bars sporadic now

[DrillbabyDrill]

I don't know when this started happening- only when I noticed it- within the past month during cold (30 degree) weather. That is, I don't have full regen bars even when only half charged. I first thought it might be some cold weather related behavior of the car to protect the car (are fast charges bad during cold weather??), but it's been 60 degrees and I still notice the same behavior. While I am driving the car will go between 2 and 4 available regen bars. I'm fairly certain, prior to me noticing this, the car always had the full 4 regen bars unless the battery was near full capacity.

Anyone have any idea what this is about? Anyone see this behavior? Is this normal?

 

[Boomer23]

I don't know when this started happening- only when I noticed it- within the past month during cold (30 degree) weather. That is, I don't have full regen bars even when only half charged. I first thought it might be some cold weather related behavior of the car to protect the car (are fast charges bad during cold weather??), but it's been 60 degrees and I still notice the same behavior. While I am driving the car will go between 2 and 4 available regen bars. I'm fairly certain, prior to me noticing this, the car always had the full 4 regen bars unless the battery was near full capacity.

Anyone have any idea what this is about? Anyone see this behavior? Is this normal?

I noticed the same behavior for the first time during the recent cold snap here in Southern California. I found that I had all 4 regen bubbles available when the car was at rest, but as my speed increased, I would lose first the leftmost, and then the second leftmost bubble. As the temperatures warmed later this week, this pattern stopped, but today when I was doing 70 mph on the freeway, I noticed that I had again lost the leftmost regen bubble. Again, when I slowed down, I had all of the bubbles back.

It is surprising to me that we haven't heard much about this on the forum from those in northern and eastern states where it gets very cold. I imagine that this reduced regen contributes to the reduced energy efficiency seen in cold weather.

I found this thread about it, ( beginning on page 9: http://www.mynissanleaf.com/viewtopic.php?f=31&t=5509&start=80" onclick="window.open(this.href);return false; ) and found that others have seen this as well, especially abasile, who lives in the San Bernardino Mountains and counts on using regen to reclaim charge as he descends to lower elevations.

 

[garygid]

Is it possible that those having this Regen Bubble problem
have battery cells that are not well equalized, and the BMS
is finding some cells that look like they cannot be charged
very much?

If you rarely ever charge to 100%, and keep the car plugged
in for something like 3 or 4 hours after the charging is "done",
it could be that your cells need some equaling sessions?

 

[DrillbabyDrill]

That does sound like my behavior... hmmm. So you suggest charging to 100% a few times. I've done it probably once in the past two weeks, and usually I charge the car when I get to work (to 80%) and it sits for 3 or 4 hours before I drive it again. Is that bad?

Is it possible that those having this Regen Bubble problem
have battery cells that are not well equalized, and the BMS
is finding some cells that look like they cannot be charged
very much?

If you rarely ever charge to 100%, and keep the car plugged
in for something like 3 or 4 hours after the charging is "done",
it could be that your cells need some equaling sessions?

 

[abasile]

I personally have not noticed any difference in regen behavior after obtaining a full charge with top balancing (assuming of course the battery is subsequently discharged enough to get regen).

I do believe there is a speed-related flaw in the algorithm used by the 2011/2012 LEAF to determine the amount of regen that is allowed at any given point in time. However, this bug might not be particularly noticeable unless one does significant descents. I think that you are generally observing normal behavior and have nothing to worry about. It is a fact that the LEAF needs to protect the battery pack by limiting the amount of charge it can accept when the battery is at cooler temperatures (and also at extremely hot temperatures) and after periods of heavier use. Also, the car is often fine accepting bursts of high-power regen under certain conditions as long as that level of regen is not sustained. Building an EV involves plenty of interesting engineering problems...

 

[EVDRIVER]

I personally have not noticed any difference in regen behavior after obtaining a full charge with top balancing (assuming of course the battery is subsequently discharged enough to get regen).

I do believe there is a speed-related flaw in the algorithm used by the 2011/2012 LEAF to determine the amount of regen that is allowed at any given point in time. However, this bug might not be particularly noticeable unless one does significant descents. I think that you are generally observing normal behavior and have nothing to worry about. It is a fact that the LEAF needs to protect the battery pack by limiting the amount of charge it can accept when the battery is at cooler temperatures (and also at extremely hot temperatures) and after periods of heavier use. Also, the car is often fine accepting bursts of high-power regen under certain conditions as long as that level of regen is not sustained. Building an EV involves plenty of interesting engineering problems...

Burst of high power regen? The LEAF could do 80KW but they will not allow it so it is restricted to a level far below a QC station and I don't see anyone sustaining long term 35kw regen on the LEAF unless you live at the top of a huge 10% grade. MY LEAF wastes so much power to friction brakes at times when it can be avoided. The regen is restricted because they wan't a "car like" experience and the only engineering issue is regulating the regen under certain parameters because consumers that are afraid to make adjustments and auto makers are afraid to offer options. Nissan is already increasing the regen in the 2013 and some will say it is "too much" but it is all about what you are used to and it should be a choice but it can be done with zero issues for the pack.

I eat food called "spicy" al the time and it tastes like no spice at all. Too many things are dumbed down for mainstream consumers. This is going to change more and more but the LEAF is as dumbed down of an EV as I have ever owned in every aspect. Charge rate, regen, steering, styling, etc. Before the LEAF landed it was clear they would play it ultra conservative based on their PR quotes and lack of any real EV driving experience. Regen modes are easily solved with software selection by the user, Nissan is not a progressive company as they still are not listening. Even the SOC in the new LEAF mirrors their ICE cars.

 

[Stanton]

I notice this same regen behavior on cold mornings, and I think it is largely "normal" behavior. For example, it is colder outside my garage than inside, so after I've been on the road a couple of minutes, my regen bubbles start to decrease (assume 80% charge). Then, as the car/batts start to warm, the regen bubbles start to increase. I may never get them all back on a cold morning, but their behavior makes sense along the way.

 

[EVDRIVER]

I notice this same regen behavior on cold mornings, and I think it is largely "normal" behavior. For example, it is colder outside my garage than inside, so after I've been on the road a couple of minutes, my regen bubbles start to decrease (assume 80% charge). Then, as the car/batts start to warm, the regen bubbles start to increase. I may never get them all back on a cold morning, but their behavior makes sense along the way.

Same here. The irony is the car does not limit full pack discharge rates.

 

[abasile]

Also, the car is often fine accepting bursts of high-power regen under certain conditions as long as that level of regen is not sustained. Building an EV involves plenty of interesting engineering problems...

Burst of high power regen? The LEAF could do 80KW but they will not allow it so it is restricted to a level far below a QC station and I don't see anyone sustaining long term 35kw regen on the LEAF unless you live at the top of a huge 10% grade.

Well, "high power" is relative. 25-30 kW seems like high power when you're sometimes limited to a continuous rate of about 10 kW or less.

Even at a little below full charge, the LEAF will often allow "bursts" of regen when slowing for stoplights, etc. But that level of regen isn't sustainable.

As I've said before, hopefully 'B' mode in the 2013 model will represent an improvement. I recall TonyWilliams mentioning somewhere that he always drives in 'B' mode in his RAV4 EV so as to maximize A-pedal regen. I'd be inclined to do the same thing.

 

[GerryAZ]

I did not notice the reduced regeneration last year, but it started suddenly in early November this "winter". The start was about the time of our first "cold" weather. It seems to be a function of both ambient temperature and battery temperature because having the battery warm from freeway driving is not enough to help. I have seen single bubbles with 6 temperature bars. I suspect a bug in the regeneration algorithm that only shows up with some battery deterioration or a change was made during the software updates that were applied to my car last spring. I had the low-speed brake software fix applied in late November, but it did not seem to change the regeneration limitation. I always charge to 100% and usually discharge to LBW so I doubt that it is a cell balance issue. It has a significant impact on my efficiency and range during city street driving, but has less impact to highway range.

Gerry

 

[abasile]

I did not notice the reduced regeneration last year, but it started suddenly in early November this "winter". The start was about the time of our first "cold" weather. It seems to be a function of both ambient temperature and battery temperature because having the battery warm from freeway driving is not enough to help. I have seen single bubbles with 6 temperature bars. I suspect a bug in the regeneration algorithm that only shows up with some battery deterioration or a change was made during the software updates that were applied to my car last spring. I had the low-speed brake software fix applied in late November, but it did not seem to change the regeneration limitation. I always charge to 100% and usually discharge to LBW so I doubt that it is a cell balance issue. It has a significant impact on my efficiency and range during city street driving, but has less impact to highway range.

That is quite odd. I'd expect to see only a single regen bubble at six temperature bars if the SOC is very close to 100%, but not otherwise. My LEAF's firmware was last updated in April 2012. You've likely experienced more battery degradation, however.

 

[EVDRIVER]

Also, the car is often fine accepting bursts of high-power regen under certain conditions as long as that level of regen is not sustained. Building an EV involves plenty of interesting engineering problems...

Burst of high power regen? The LEAF could do 80KW but they will not allow it so it is restricted to a level far below a QC station and I don't see anyone sustaining long term 35kw regen on the LEAF unless you live at the top of a huge 10% grade.

Well, "high power" is relative. 25-30 kW seems like high power when you're sometimes limited to a continuous rate of about 10 kW or less.

Even at a little below full charge, the LEAF will often allow "bursts" of regen when slowing for stoplights, etc. But that level of regen isn't sustainable.

As I've said before, hopefully 'B' mode in the 2013 model will represent an improvement. I recall TonyWilliams mentioning somewhere that he always drives in 'B' mode in his RAV4 EV so as to maximize A-pedal regen. I'd be inclined to do the same thing.

The issue is not when the pack is full since regen will be limited then, the point is the regen on the LEAF is very restricted when it should not be. Under many conditions my friction brakes are used too often. I had other EVs that had a button to turn off the regen just so the brake pads would seat to get off the rust. 27kw of regen in a LEAF is 30% of it's max regen capability.

 

[planet4ever]

27kw of regen in a LEAF is 30% of it's max regen capability.

You seem to be assuming that just because the motor can discharge the battery at 90kW you should also be able to charge it at that rate. DC Quick Charge is limited to about half that, and tapers much lower than that even when the battery is only half full. 90kW would be a 4C charging rate, which the battery experts here seem to think is extremely high and likely to significantly reduce battery lifetime. Do you have some reliable source for your 90kW regen claim?

Ray

 

[aqn]

Something is wonky of late with my regen as well, but I have not made any systematic observations to try to figure it out. I don't think it's the cool/cold weather because I don't remember seeing this behavior last winter.

I get no regen when battery is at or near 100%, which is normal. (I have charged to 100% several times recently, so it's probably not a cell balance issue.) But whereas I used to be able to trigger max regen (-30kW on the "Energy Info" display) with 5-6 SoC bars remaining, I no longer can. It seems the battery has to be down to 3-4 bars or less before I see the full 30 kW of regen.

I lost one capacity bar back in August. I wonder if that's related...

 

[Boomer23]

Something is wonky of late with my regen as well, but I have not made any systematic observations to try to figure it out. I don't think it's the cool/cold weather because I don't remember seeing this behavior last winter.

Maybe a combination of cold weather and battery aging? There are lots of newer LEAFs in the NE and upper Midwest cold winter areas, but I haven't seen these reports from those locales, possibly because their battery packs are newer.

 

[mynameisjim]

There was a short discussion about Regen and cold in November, perhaps it would be helpful. My experience is about halfway down where I first started noticing a lost circle at higher speeds in the 30s. Now that it's very cold Regen is always limited.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=10463&hilit=regen&start=30