What happened to my Regen?

I recently had my car software updated and it seems that the regenerative breaking performance has been curtailed significantly. It can't seem to get more than 15-20 kW at the most even with the brakes full on and freeway speeds. Before, I could get the full 30 kW whenever prudent, but now it's just not doing it. Usually it won't go above 10 or 15 at all.

Any ideas? I thought it might be the temperature, but it worked last winter and it hasn't even gotten down to freezing yet. Also, I only charge to 80% so the battery is not full.

Is this the P3227 update? If so, yes, it's a known and unwelcome artifact.

It's also discussed in some detail in this thread: http://www.mynissanleaf.com/viewtopic.php?f=27&t=13273&hilit=p3227+regen&start=340" onclick="window.open(this.href);return false;

Much more drastic than what most people have been reporting, but perhaps because it's colder where you are?

Make sure you complain to your dealer about it - perhaps the EV hotline, too. Appears that your LEAF is a 2012?

Thanks all for the replies.

It shouldn't be much colder here, as I said, hasn't even gotten to freezing yet and I've never seen the battery temp below 4 bars. It is a 2012. I was one of the fools who bought the car (at $6k off the sticker price) the day before the 2013 info came out at a lower price still.

I do pay much more attention to the power usage screen, almost never look at that bubble gauge on the instruments panel. I personally do not believe that the regen in the Leaf is adequate, even before the update. 30 kW out of an 80 kW motor is laughable. Any AC regen is practically capable of crashing the car if not controlled properly.

I am becoming a little disappointed with this car. There's no reason why it shouldn't work better all-around. I would pay dollars for a software kit that lets me pick the regen rate. I can't sell this car or trade it in, so it might as well do what I want warranty or no.

WiredForStereo said:

I personally do not believe that the regen in the Leaf is adequate, even before the update. 30 kW out of an 80 kW motor is laughable.

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I think the problem from Nissan's perspective may be that putting 30 kW regen into a 24 kWh battery is a bit too close to the edge for a battery that has a history of degrading rapidly when it overheats. Nissan has put itself on the hook for batteries that degrade by more than 33% within 5 years/60K miles.

I rarely use QC, and then only enough to get myself home, but the impression I get from others is that the QC rate drops to less than 30 kW when the battery is more than half full. It sounds to me as if what you really find laughable is that an EV with an 80 kW motor has only a 24 kWh battery, or a battery that isn't cooled.

Ray

planet4ever said:

... the impression I get from others is that the QC rate drops to less than 30 kW when the battery is more than half full. ...
Ray

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I don't think the fall off is quite that severe, but I'll have to check several instances to see how it compares to my pre-P3227 software change original regeneration. It does vary with battery temperature. The DCQC current reduction may curtail a bit faster than the original regeneration. Not an unreasonable speculation that the P3227 may have made the regeneration fall off match what is done for DCQC.

planet4ever said:

... the impression I get from others is that the QC rate drops to less than 30 kW when the battery is more than half full. ...
Ray

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The highest I have seen is 47kW at 52%, charge rate dropped quickly after 1 minute or 2. That was this summer in June 1st, warm day but the battery was not too hot. It was before the P3227, that we did last week.



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planet4ever said:

WiredForStereo said:

It sounds to me as if what you really find laughable is that an EV with an 80 kW motor has only a 24 kWh battery, or a battery that isn't cooled

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Yes, those too. But I can deal with the battery. Tell me if I'm wrong, but there is no reason why it should not be able to regen at anything near the rate of the CHAdeMO plug in the front of the vehicle (62.5 kW?). Sure, take battery temperature and charge into account to regulate it (and whether or not you're in ECO mode, or give me an ECO2X mode) and any other setting you might want to apply. It should work better. This is what Li-ion batteries are supposed to be able to do. Nissan has been tiptoeing around this battery since the beginning. They made a mistake.

I'd be satisfied for now if it just went back to working how it did. I'd be ecstatic if it would work better.

I'm participating in a research project for the next month so I have the ability to directly compare regen over known routes. My car is a 2011 with P3227 and the research car I'm driving is a 2012 without P3227. Everything else being equal, I am consistently seeing about two bubbles (around 15Kw) less regen on my morning downhill run and under a number of other conditions. I am also seeing a reduction in the amount of regen bubbles available on the P3227 car as compared to the non-P3227 car under similar circumstances, and a wider range of conditions where regen bubbles are reduced... I wonder if this was intentional or an error induced as part of the P3227 update...

An interesting side note: The 2012 has about 12,500 miles on it, spent the summer in Phoenix, and has lost a capacity bar...

All I have is my one car, but I could tell the difference pretty easily, because like many Leaf drivers, I enjoy driving and getting good efficiency, and practice at it. There's a short stretch of downhill (45 mph) right down from my house. Previously, the car could maintain the correct speed in cruise control, now it overspeeds. A little further on the way to my son's school, there's a downhill stretch at 35 mph. Without the brake pedal, it could not previously maintain speed, but would get up to 39 or so. Now it gets in the upper 40's, giving only 10 kW of regen. At least it rolls well, right?

I was accustomed to controlling it quite adequately by just barely pressing the brake pedal which would cause the regen to jump up to or near 30 kW without much if any friction braking. By timing it well, I could get down to acceptable speeds when exiting the freeway without using friction brakes. Now, there just isn't enough regen to get the job done in the space of the off-ramp. Even using the brakes will not cause the regen to approach 30 kW, and often has no effect at all on the regen rate. This is all in ECO mode.

How do they put the regen power back into the battery? isn't the output of the motor AC? If so it needs to be rectified and conditioned back to the DC the battery wants. Sounds like the same thing the charger does, and all it's good for is 6 KW.. so how can they put 30 in on regen?

johnrhansen said:

How do they put the regen power back into the battery? isn't the output of the motor AC? If so it needs to be rectified and conditioned back to the DC the battery wants. Sounds like the same thing the charger does, and all it's good for is 6 KW.. so how can they put 30 in on regen?

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You are right, and that may well be part of the explanation. It doesn't literally go back through the charger, but it goes through circuitry in the inverter to "uninvert" the AC coming from the motor.

WiredForStereo said:

planet4ever said:

It sounds to me as if what you really find laughable is that an EV with an 80 kW motor has only a 24 kWh battery, or a battery that isn't cooled

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Yes, those too. But I can deal with the battery. Tell me if I'm wrong, but there is no reason why it should not be able to regen at anything near the rate of the CHAdeMO plug in the front of the vehicle (62.5 kW?).

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What I was trying to say was that it is the battery size which is limiting the regen. The CHAdeMO interface is defined for up to 62kW, but the LEAF never pulls more than about 45kW from it. That is nearly 2C for a 24kW battery. And Nissan throttles QC charging down to less than 30kW for most of the time after the battery gets to 50% charged.

Ray

I'm participating in a research project for the next month so I have the ability to directly compare regen over known routes. My car is a 2011 with P3227 and the research car I'm driving is a 2012 without P3227. Everything else being equal, I am consistently seeing about two bubbles (around 15Kw) less regen on my morning downhill run and under a number of other conditions. I am also seeing a reduction in the amount of regen bubbles available on the P3227 car as compared to the non-P3227 car under similar circumstances, and a wider range of conditions where regen bubbles are reduced... I wonder if this was intentional or an error induced as part of the P3227 update...

An interesting side note: The 2012 has about 12,500 miles on it, spent the summer in Phoenix, and has lost a capacity bar...

I cancelled my appointment Wednesday for the update. With the range hit from the new tires, there is no,way I can accept another hit from reduced regen. If the update is necessary for the battery warranty, I'll have it done just prior to making a claim, and not a minute before.

If the update is necessary for the battery warranty,

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Did they ever say that it was required?
I see no reason to get the update.
I don't charge anywhere but home

there's one thing I've noticed about the regen is that it's suddenly stops sometimes when I go over a bump in the road and I'm wondering if traction control has something to do with inadvertently turning the region off. I've noticed but not well enough to really say for sure but I think the region may work better with the traction control off. has anyone else ever noticed that?

I've noticed that both before and after P3227...

johnrhansen said:

there's one thing I've noticed about the regen is that it's suddenly stops sometimes when I go over a bump in the road and I'm wondering if traction control has something to do with inadvertently turning the region off. I've noticed but not well enough to really say for sure but I think the region may work better with the traction control off. has anyone else ever noticed that?

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johnrhansen said:

there's one thing I've noticed about the regen is that it's suddenly stops sometimes when I go over a bump in the road and I'm wondering if traction control has something to do with inadvertently turning the region off. I've noticed but not well enough to really say for sure but I think the region may work better with the traction control off. has anyone else ever noticed that?

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I've also noticed the regen drop from 30 kW to less than 10 after going through some potholes. The only way to get it back was to get completely off the brake pedal and then back on it. It came back to it's pre-pothole level of regen.

Yesterday, I had the opportunity to run the battery just about all the way down due to forgetting to plug the car in after an errand. It seems the lower the battery is, the better the regen works.