Had the P3227 reprogram done today: interesting results.

[TomT]

I think the problem here is semantics... I was talking zero power in to or out of the battery and he was talking zero power in to or out of the motor... For the equivalent of what he is describing, one would need to feather to the same power draw from the battery as that which occurs in N...

Of course, by simply feathering the accelerator pedal to the zero point you effectively accomplish the same thing as switching to N

I have tried feathering the accelerator pedal to the zero point and compared it to going Neutral. There is a big difference. Even with the accelerator pedal feathered to zero point, the LEAF does not coast as freely as in Neutral. The best way to prove this is when you have feathered the accelerator pedal to zero point, go neutral and you will notice that the LEAF actually coasts faster.

This is expected since the Leaf continues to draw 1-2kW of energy when moving *even if no traction power is applied*. Putting the car into neutral sets the traction power to zero so you end up pulling this overhead power from the battery. Whereas, if you feather the throttle to get to zero power to/from the battery, then regen is providing this overhead power and therefore you will decelerate faster. Which one is best for efficiency really depends on other factors but in general whichever one allows you to maintain the most constant speed is best (assuming the same average speed - if one of these techniques causes you to go slower then obviously that will be the best ).

 

[TickTock]

Yup. Holding the power at around 1.5kW would be equivalent to putting it into Neutral.

 

[kmp647]

so many have referred to the regen being reduced post update you have to wonder if the original regen rates were somehow damaging the cells or contributing to the degridation of the cells.

I'm sticking with what I have now, 31,500on the meter and I only have 14 months to go til the end of my lease

I like the way the car operates now.

 

[davewill]

... I think Nissan could have programed the LEAF in such a way that when going downhill if the grade is steep enough LEAF would automatically disengage the motor to allow the LEAF coast freely up to the speed desired by the driver through the accelerator and then intermittently engage regen when a particular speed has reached by driver input through accelerator. When the grade is not steep enough and the driver is still holding the same position on the accelerator pedal, LEAF would automatically engage the motor to maintain speed with power. When the driver wants to slow down, he/she reduces the accelerator pedal position or lets go the accelerator and again the motor gets engaged automatically to regen to slow down. ...

The car has this feature...it's called cruise control, and works pretty much exactly as you describe. I find it very handy when going downhill as it feathers the accelerator to keep regen at just the right level to maintain speed.

 

[dgpcolorado]

B-mode on the '13 Leafs is partway there. I usually drive around in that and when I need to slow down, I try to let it slow via that and avoid using the brake pedal much (since I don't know when the friction brakes kick in).

I am curious to know how B mode will work in cold temperatures. The older LEAFs have regen dialed back in very cold weather. Now with the P3227 update the regen is dialed back even more. Yet 2013 LEAFs have B mode, which has increased regen. Perhaps the update is intended to preserve the older model batteries. But, if not, it sure is a major discrepancy between older post update LEAFs with reduced regen and 2013 LEAFs with increased regen via B mode.

I am beginning to think that the reduced regen post-update was an unintended flub.

 

[DaveEV]

I am beginning to think that the reduced regen post-update was an unintended flub.

It would be very interesting to test a '11-12 post P3227 update and a '13 side by side with similar Ah readings and compare their regen behavior...

 

[EVDRIVER]

so many have referred to the regen being reduced post update you have to wonder if the original regen rates were somehow damaging the cells or contributing to the degridation of the cells.

.

No it does not. Regen is very low even at the max level and is regulated to never harm the pack. A QC puts far more into the pack for extended periods.

 

[Valdemar]

so many have referred to the regen being reduced post update you have to wonder if the original regen rates were somehow damaging the cells or contributing to the degridation of the cells.

.

No it does not. Regen is very low even at the max level and is regulated to never harm the pack. A QC puts far more into the pack for extended periods.

It is likely not a coincidence that they reduced the regen at higher speeds as a part of the software update that was produced to somewhat soften the whole battery degradation debacle and which is required before one can submit claims under the "enhanced" battery warranty. I also find it suspicious that they "forgot" to communicate to us that less aggressive regen is a part of the P3227 update. Nissan insisted that the only changes included in this update were the improved precision of the battery capacity calculations and compatibility with some never EVSEs. The lies continue, good job Nissan.

 

[abasile]

It is likely not a coincidence that they reduced the regen at higher speeds as a part of the software update...

This "reduced regen at higher speeds" bug has been there all along.

Why allow 15 kW of regen at 30 mph and only 5 kW at 55 mph, for example? It's actually counter-intuitive behavior - the faster you descend, the less the car helps you to slow down. As far as degradation is concerned, the battery doesn't care what speed the vehicle is traveling downhill; only the regen power level matters.

 

[Valdemar]

The fact that more regen is available at lower speeds doesn't necessarily mean you are going to get any close to the max allowed level, and if you do it will only be for a very short time when coming to a stop, unlike when you're going fast and can peak regen much longer, especially on a descent.

 

[abasile]

The fact that more regen is available at lower speeds doesn't necessarily mean you are going to get any close to the max allowed level, and if you do it will only be for a very short time when coming to a stop, unlike when you're going fast and can peak regen much longer, especially on a descent.

I routinely drive slowly down "our" mountain in order to maximize regen. From my day to day experience, and some trial and error, there is no question that I'm able to get far more regen by keeping my speed down. Taken slowly with a reasonably warm battery (5 temperature bars), I can pick up at least 12% (in gids) in regen on the 4900' descent. Increase speed, and I might only get a few percent at best (and unhappy brake pads and rotors).

 

[Valdemar]

^^^ Sounds like your case is not very typical. I rarely max out regen during normal city driving. Frankly I don't fully understand if we are in any disagreement, all I'm saying we now get less regen on average and this change was introduced to help batteries last a bit longer.

 

[DaveinOlyWA]

I do not think we can compare regen in the two very different scenarios described above. One is an extreme case while the other is normal day to day stuff.

I agree that long downhill stretches the regen only effectively slows the vehicle as long as the vehicle speed is kept below a certain threshold. I found this to be true when doing some coasting experiments and expecting my shifting back to Eco would slow me down enough to make the curve at the bottom of the hill. I misjudged that badly. My speed did not bleed off nearly as fast as expected. In fact, it really only slowed the acceleration requiring use the brake pedal

 

[Valdemar]

Yes, I find myself using the brakes more frequently after the update.

 

[JeremyW]

Why allow 15 kW of regen at 30 mph and only 5 kW at 55 mph, for example? It's actually counter-intuitive behavior - the faster you descend, the less the car helps you to slow down. As far as degradation is concerned, the battery doesn't care what speed the vehicle is traveling downhill; only the regen power level matters.

It doesn't matter for the battery, but does for the motor. Essentially if you try to regen too hard with a permanent magnet motor, you can heat the rotor and potentially damage the magnets. Need to find some data to back this up but it is a concern, and perhaps Nissan was worried that sustained high speed regen could potentially damage the rotor.

Of course the motor was redesigned for 2013, and there we see higher regen levels. It was also mentioned they did so with less magnets (or expensive magnetic materials?) so I'm not exactly sure how that's working. Perhaps some sort of 'hybrid' inductive design with a rotor that has magnets but also a squirrel cage?

All that said, I'd like my regen back please, Nissan!

 

[TickTock]

I don't have any hills to test this on so I was wondering: Is the regen just reduced when your foot is off the brake or is the max available regen reduced even when brake is applied? If the former, then I think it is a good thing. If the latter then, yeah, not good.

 

[Valdemar]

I don't have any hills to test this on so I was wondering: Is the regen just reduced when your foot is off the brake or is the max available regen reduced even when brake is applied? If the former, then I think it is a good thing. If the latter then, yeah, not good.

I'd say it is the latter at least subjectively, and if the missing regen bubbles mean anything. But the regen is also reduced when foot is off the brake. Even with all regen bubbles available at lower SOC it feels that the leftmost one is more hesitant to turn on now.

 

[TomT]

It's definitely the latter, alas...

Is the regen just reduced when your foot is off the brake or is the max available regen reduced even when brake is applied? If the former, then I think it is a good thing. If the latter then, yeah, not good.

 

[DaveEV]

It doesn't matter for the battery, but does for the motor. Essentially if you try to regen too hard with a permanent magnet motor, you can heat the rotor and potentially damage the magnets. Need to find some data to back this up but it is a concern, and perhaps Nissan was worried that sustained high speed regen could potentially damage the rotor.

Doesn't make any sense to me - if that were the case they should limit regen based on motor temperatures along with battery temperature (and SOC).

I'm not really sure what Nissan was doing.

When regen is not limited, if you just let off the accelerator and regen down to slower speeds, you get more regen at higher speeds than lower speeds and it smoothly tapers.

But when regen is limited (especially noticeable while pressing the brake pedal or when battery is over 80%), regen peaks between 20-25 mph and goes down at speeds both higher and lower than that.

I don't have any hills to test this on so I was wondering: Is the regen just reduced when your foot is off the brake or is the max available regen reduced even when brake is applied? If the former, then I think it is a good thing. If the latter then, yeah, not good.

I'm seeing both. With battery temp at 70F charged to 80%, I am seeing about 16-17 kW max regen. At 75% SOC it goes up to about 20-21 kW and down to 60% It lets me regen up to 25 kW. It seems that I have to get down to 40% or lower to see 30 kW of regen now...

 

[TimLee]

I haven't had P3227 done yet, mainly waiting on getting devices for data collection prior to having it done.
But for those who had it done and don't like the change in regen, if you had to do it over it again, would you delay having it done as long as possible?
As long as you don't use any EVSEs that can destroy the on board charger, seems like the only thing you're missing is better capacity accuracy (so you don't know near as accurately how much capacity you've lost and whether you project to qualify for batter capacity warranty or not) and maybe missing out on some slight improvement in GOM that some have reported.
If you had it to do over again, would you wait on having P3227 done?