No Full Available Regen at 30%

[minispeed]

All BEV vehicles definitely need something to burn off waste regen energy. It's just not practical to rely only on the friction brakes. I love the idea of using it to heat the battery, but this only works when the battery is cold. Summer, 100% charge going down a mountain and you really need something else. Maybe have a heat exchanger at the rear of the car that way you can create heat that can be transferred into a battery in the winter and be vented behind the car in the summer.

 

[johnrhansen]

How about just using regen to run the cabin heater?

It would be great if that worked as a solution. But it really doesn't. (Please see my comments above.)

Railroad locomotives use regen in this way. They have a huge bank of resistors that load the motor down on a long grade. They call it dynamic braking. I wasn't saying to run the heater in the car to help regen. I'm saying Nissan should have some resistors in place to make sure the same regen is available at all times. So the car always drives the same way. In the winter, the excess heat could be used to heat the cabin.

 

[abasile]

I wasn't saying to run the heater in the car to help regen. I'm saying Nissan should have some resistors in place to make sure the same regen is available at all times. So the car always drives the same way. In the winter, the excess heat could be used to heat the cabin.

That would be a nice, general solution. Even for those living on flat terrain, it would be great to have consistent driving behavior regardless of the temperature or state of charge. Of course, adding a system to dissipate large bursts of "excess" energy, or perhaps 20 kW continuous on some mountain descents, would have some non-trivial cost.

Regardless, even with the current hardware, I am convinced that Nissan could do better at supporting regen in some common use cases.

 

[minispeed]

As it`s gotten colder here, -5C, I`ve been looking at my 2015s regen more. I know at -20 it could change a lot but there is still a decent amount available. I can get it to bury the regen needle at low state of charge and at 97%ish I can get it to give 20kW of regen. I really don`t have a place where I can get up to enough speed to try to bury the needle of regen at anything higher than that charge.

This definitely doesn't solve the problem of going down a mountain that has enough energy to get you above 100% charge but it does sound like a big improvement to the older cars.

 

[Valdemar]

I can only get 20kW max while coasting after P3227 was applied on my 2011. Short bursts up to 30kW are possible at lower SOC while applying the brakes at low speeds. I don't remember exactly if the regen behavior was any different prior to P3227, but I have a feeling I could get more than 20kW from just coasting/going downhill.

 

[RegGuheert]

It was 30F last night and I didn't have four regen circles showing until the charge level got below LBW.

 

[dgpcolorado]

As it`s gotten colder here, -5C, I`ve been looking at my 2015s regen more. I know at -20 it could change a lot but there is still a decent amount available. I can get it to bury the regen needle at low state of charge and at 97%ish I can get it to give 20kW of regen. I really don`t have a place where I can get up to enough speed to try to bury the needle of regen at anything higher than that charge.

This definitely doesn't solve the problem of going down a mountain that has enough energy to get you above 100% charge but it does sound like a big improvement to the older cars.

The real question is what is the battery temperature? Even if the OAT is -5ºC the battery could be considerably warmer, depending on where you park the car overnight and your charging and driving pattern, both of which warm the battery a lot. When I've been driving at -5ºC in recent days my battery has been in the +7 to 8ºC range. That makes a significant difference in regen levels. If my battery was at -5ºC I'd expect little regen, but it almost never gets below 0ºC so I tend to have some regen at low SOC, albeit not nearly as much as I would like.

I expect that the 2015 regen will be considerably better than mine, but it is hard to compare without battery temperature readings.

 

[minispeed]

As it`s gotten colder here, -5C, I`ve been looking at my 2015s regen more. I know at -20 it could change a lot but there is still a decent amount available. I can get it to bury the regen needle at low state of charge and at 97%ish I can get it to give 20kW of regen. I really don`t have a place where I can get up to enough speed to try to bury the needle of regen at anything higher than that charge.

This definitely doesn't solve the problem of going down a mountain that has enough energy to get you above 100% charge but it does sound like a big improvement to the older cars.

The real question is what is the battery temperature? Even if the OAT is -5ºC the battery could be considerably warmer, depending on where you park the car overnight and your charging and driving pattern, both of which warm the battery a lot. When I've been driving at -5ºC in recent days my battery has been in the +7 to 8ºC range. That makes a significant difference in regen levels. If my battery was at -5ºC I'd expect little regen, but it almost never gets below 0ºC so I tend to have some regen at low SOC, albeit not nearly as much as I would like.

I expect that the 2015 regen will be considerably better than mine, but it is hard to compare without battery temperature readings.

I can look at that more but the battery temperature for me will be pretty constant since the car is driven daily. Typically I will drive 145km, 90miles for my commute. If I'm off the wife takes the car for 88km, 55 miles. The car will almost always be plugged in and left to charge with 20-40% SOC sometime between 530 and 730. I'll leave for work at 430am so it will have been sitting outside for a few hours after reaching 100% SOC.

From the few times I've checked it it has been at 6-9C first thing in the morning. I'd like to report info at -25C outside temp but I really don't want that to come. I've got a week in Winnipeg coming up in January. I'm not looking forward to -40C and lower..... which happens to be the point where F and C are the same!

 

[TimLee]

It was 30F last night and I didn't have four regen circles showing until the charge level got below LBW.

I have still avoided P3227 . With one missing capacity bar and soon to be two, my regeneration is still about like it was when the car was new.
Some small impact if battery is cold but rarely is mine cold enough to notice much difference.

Really sad that Nissan messed up the software change and so far more than a year later has done nothing to fix the problem.
Just sad

 

[TimLee]

... I've got a week in Winnipeg coming up in January. I'm not looking forward to -40C and lower..... which happens to be the point where F and C are the same!

Off Topic, but:
Surely someone in Canada has a 2011 LEAF without cold weather package or has messed up and let status of charge get below 30% and observed what a LEAF with its battery at lower than -30ºC does?
Will it allow low kW heater power draw that will slowly warm the battery above -30ºC and then you can drive the car?
Or is it dead in the water till the weather improves for long enough for ambient temperature to heat the battery?

Or maybe no one living in such weather would ever let such a thing happen :?

 

[Valdemar]

It was 30F last night and I didn't have four regen circles showing until the charge level got below LBW.

I have still avoided P3227 . With one missing capacity bar and soon to be two, my regeneration is still about like it was when the car was new.
Some small impact if battery is cold but rarely is mine cold enough to notice much difference.

Really sad that Nissan messed up the software change and so far more than a year later has done nothing to fix the problem.
Just sad

Do you ever get more than 20kW regen power without touching the brakes?

 

[minispeed]

... I've got a week in Winnipeg coming up in January. I'm not looking forward to -40C and lower..... which happens to be the point where F and C are the same!

Off Topic, but:
Surely someone in Canada has a 2011 LEAF without cold weather package or has messed up and let status of charge get below 30% and observed what a LEAF with its battery at lower than -30ºC does?
Will it allow low kW heater power draw that will slowly warm the battery above -30ºC and then you can drive the car?
Or is it dead in the water till the weather improves for long enough for ambient temperature to heat the battery?

Or maybe no one living in such weather would ever let such a thing happen :?

In Canada your best bet is to ask Quebec owners. There's 0 incentive from the federal government to get BEVs on the road. It's up to the Provincial Governments. I think BC's has run out, QC and ON still offer them with QC being the leader in all of Canada for BEVs and also public charging. Also there is a GM dealer in QC that sells the most plug in vehicles in Canada and also brings in a lot of auction US BEVs. They had the ex hertz spark electrics there that were tempting me but I didn't want to spend a whole day and 2 tanks of gas just to check it out.

Plugshare shows under 10 home chargers in all of Manitoba, 1 is just a dryer outlet that he'll loan out so he may not own a BEV yet, 2 are Teslas, 1 is a small electric scooter business the others just mention J1772.

Over all your best bet is to look for high altitude Northern / Central state owners. The majority of Canadians live south of there and close to large bodies of water that keep temperatures warmer. Also I don't think there were very many 2011 leafs in Canada and I'd give a good bet that almost all of them went to BC/ON/QC. Consider those our 3 ties for California.

 

[dgpcolorado]

I have still avoided P3227 . With one missing capacity bar and soon to be two, my regeneration is still about like it was when the car was new.
Some small impact if battery is cold but rarely is mine cold enough to notice much difference...

That's interesting. When we first reported the reduced regen due to P3227 the response from some here at MNL was that all we were seeing was the effects of battery aging and that the reduced regen from the update was a figment of our imaginations. That sort of BS was very irritating to me, especially as someone who needs regen for mountain driving and who lives in a place with real winters (it was a lovely sunny — highly scenic — day yesterday, with a high of 0ºC, i.e. quite ordinary).

 

[Roadburner440]

So this is what happened to my regen bubbles... I took the car in to the Nissan dealer for a flat repair last week, and the told me I had an outstanding campaign on my car. Ever since I have had it back I noticed the regen was even weaker than before. Well at least now I know it isn't an issue with the car, but rather a software change that was done on purpose. What I read on it just said that it only changed the behavior of the capacity gauge so figured why not get it done while it was in. Oh well.

 

[minispeed]

So yesterdays drive home and todays drive in with battery temp.

1600, 100% charge off L1 finished appox. 1500, -1C outside, 8.7C battery temp, pretty even on all 3. (Had been 17ish after the morning quick charge)
Just at the second it went from 100% to 99% I could get 8 kW ish of regen. First stop sign at 97% I got 15 kW. There's no where around work I can try to sustain it.

Today 0400, 100% charge off 20 amp L2 finished approx. 2230-2330. -3C outside battery at 7.8C. 95% going down the escarpment 18 kW ish of regen for a few seconds. It's not really steep enough to maintain speed at that regen. 50% charge an easy 30 kW of regen at 10.5C battery, by 35% battery had warmed to 14.5 then I did a quick charge 30-70% and the battery was 14.5-16.5-18.5%. Checked right after the QC which I had never done before and the first time I ever saw a noticeable difference in the battery temp.

As I said before my driving is pretty constant. I can take similar numbers when I see a big change below -10C but I really don't wish for that. Unless we have a winter like last year we really won't see many days with -10C and below consistently.

 

[abasile]

When we first reported the reduced regen due to P3227 the response from some here at MNL was that all we were seeing was the effects of battery aging and that the reduced regen from the update was a figment of our imaginations. That sort of BS was very irritating to me, especially as someone who needs regen for mountain driving and who lives in a place with real winters (it was a lovely sunny — highly scenic — day yesterday, with a high of 0ºC, i.e. quite ordinary).

I admit that I wasn't sure about the cause of the reduced regen for a while. I think I wasn't seeing the effects as severely because I was driving down and up our big mountain most days for a commute, and my LEAF's battery temperature usually didn't have a chance to get all that low.

Nowadays, however, our LEAF isn't driven quite as much (no work commute), so the battery tends to get a lot cooler, just as in our first year of ownership when I also didn't have a commute. We drove down our mountain (4900' descent) yesterday evening at ~ 50% SoC and four battery temperature bars, and the regen was pretty lame, much worse than in late 2011. At a downhill speed of 35 mph, the regen generally stayed below 10 kW. At higher speeds (up to 55 mph) there was virtually no regen. Thankfully our friction brakes didn't overheat, but I still don't consider this behavior to be acceptable.

 

[minispeed]

2015 cold battery regen update.

Today was the coldest day I've seen in my leaf. -10C outside when I got in, 30 min of pre heating the car and the battery was at 97% and battery temp was -1.4C. Right off the bat I had about 8 kW of regen available. By the time I was going down the escarpment I was at 94% with around 13 kW. At 69% the battery had warmed up to 0.4C and I could get 25 kW. As soon as my fourth battery temp bar came on I got 30 kW (don't know what temp it was as I didn't look at leaf spy).

Again none of them were sustained, the one I held the longest was the 13 kW at 94% for a few seconds and 2 attempts (top and bottom of escarpment).

Maybe on a day off where I'm not going far I'll let the battery sit the night before and see if a lower SOC and cold battery gets higher regen.

 

[dgpcolorado]

2015 cold battery regen update...

Your data is more evidence that the 2015 regen is much better than that of the 2011/2012 LEAFs, especially those that have had regen crippled by the P3227 software update.

 

[DaveEV]

Sounds like the latest LEAF has much improved regwn even in cold temps - thanks for the report and keep them coming.

With my coldest sensor at 16C, I can't even get more than 20 kW of regen at lower speeds and 50-60% SOC. At 20C SOC needs to be below 40% to get more than 25 kW.

 

[dgpcolorado]

^One thing that jumps out at me wrt the 2015 regen is that it has some regen even at very high SOC levels. I don't see more than a trivial amount until I get down to 85% or so. And that's with warmish battery temps. That's an improvement.