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dgpcolorado
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Re: I Beat EPA's 73 Mile Range : Report your experience

Tue Nov 18, 2014 8:34 am

JPWhite wrote:The effect is worse in winter with a cold battery, I get virtually no regen at highway speeds, but a reasonable amount at slow speeds. Not only is it annoying from a fuel efficiency point of view, but slowing down without braking doesn't occur as you'd expect on the highway and you end up hitting the brakes harder than you'd like. Regen should be consistent regardless of season or speed.
Exactly what I see as well. I hope this is a quirk of the older LEAFs and has been fixed on the newer ones.

Now that my battery is routinely in the 7-9ºC range I see two things: my degradation for the season has finally stopped, and my regen — even at fairly low SOC levels — is largely gone. Regen will get worse as the temperature continues to fall.
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kikngas
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Re: I Beat EPA's 73 Mile Range : Report your experience

Tue Nov 18, 2014 10:25 pm

dgpcolorado wrote:
JPWhite wrote:The effect is worse in winter with a cold battery, I get virtually no regen at highway speeds, but a reasonable amount at slow speeds. Not only is it annoying from a fuel efficiency point of view, but slowing down without braking doesn't occur as you'd expect on the highway and you end up hitting the brakes harder than you'd like. Regen should be consistent regardless of season or speed.
Exactly what I see as well. I hope this is a quirk of the older LEAFs and has been fixed on the newer ones.


Sorry to report that I'm seeing what I'd call the same behavior in my 2015 S. I too think it a bit dangerous to NOT slow me by the normal regen just because this time the battery is colder or I happen to have a full charge. You'd think it could dump the power into the accessory battery or the heater or something. I mean when it is cold and you're showing two regen bubbles available, you'd think if you flip on the heated seat, stirring wheel and defrost, you'd at least get a third bubble. But it doesn't seem to work that way.

I've been wondering why they don't arrange some sort of two stage battery. That way you could get the best properties of both energy storage types. For example, a supercapacitor that can take a very fast charge. Then it could send power to the Li-ion over a period of time as it can accept it. So it could take the quick charge immediately and then work to get the Li-ion warmed up enough to accept the charge. And if you leave it charging longer, then it works like normal. Such an arrangement would generally then have available capacity in the supercapacitor where it could send full regen most all of the time.

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Re: I Beat EPA's 73 Mile Range : Report your experience

Wed Nov 19, 2014 1:09 am

JPWhite wrote:Regen should be consistent regardless of season or speed.

I can understand why battery temperature has an effect on maximum regen level, but speed makes no sense to me. Having regen go away at higher speeds is not intuitive at all.

dgpcolorado wrote:I hope this is a quirk of the older LEAFs and has been fixed on the newer ones.

Anyone with a '13+ LEAF see a reduction in maximum regen at higher speeds compared to around 20 mph where it maxes out?

kikngas wrote:Sorry to report that I'm seeing what I'd call the same behavior in my 2015 S. I too think it a bit dangerous to NOT slow me by the normal regen just because this time the battery is colder or I happen to have a full charge. You'd think it could dump the power into the accessory battery or the heater or something. I mean when it is cold and you're showing two regen bubbles available, you'd think if you flip on the heated seat, stirring wheel and defrost, you'd at least get a third bubble. But it doesn't seem to work that way.

To be clear - are you seeing a drop in regen at higher speeds (55 mph+) compared to lower speeds (25-35 mph)? There's not much to be done to avoid a reduction in regen at low temperatures unless you artificially limit regen at high temperatures. Cold batteries have higher internal resistance so can't be charged as quickly. Fully charged batteries have no where else for the energy to go. It's too bad Nissan eliminated 80% charging (and I wish they had an adjustable slider like Tesla), as then you could get more regen if you don't need a full charge every day.

The heater might add 5 kW of buffer for additional regen. But unless you're actively using the heater or add a bunch of water onboard to store the heat or an extra radiator to dissipate the heat, that might only help for a couple stops. Not worth the complexity and the cost.

kikngas wrote:I've been wondering why they don't arrange some sort of two stage battery.
Easy: Complexity and cost. Nissan needs to reduce the cost of the LEAF further and add more energy dense batteries. Adding expensive high power, low energy density batteries is counter to this goal.
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kikngas
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Re: I Beat EPA's 73 Mile Range : Report your experience

Thu Nov 20, 2014 4:46 pm

drees wrote:To be clear - are you seeing a drop in regen at higher speeds (55 mph+) compared to lower speeds (25-35 mph)?


Well, seems to me that as I regen down from 40 that it seems to kick in harder right at around 30MPH. But I'm not positive if that's what you are describing. If I'm going 55MPH, there is a lot of energy there. Grab too hard and you'll quickly have more than the battery can absorb. But grab the same level of kW of regen at 30 and you'll FEEL it slowing you more. So, I've been thinking that we're experiencing the same behavior and describing it a little differently.

Everything else on the throttle is variable. The zero spot to cost varies with speed (which is why it's so much easier to just throw it in neutral). The spot to maintain current speed varies with speed. So, if fully OFF the throttle varies as well, it sorta makes sense. Because at a high speed, (perhaps... I am assuming) the battery cannot accept the charge as fast as regen could deliver it with 4 regen bubbles.

With the S model, I believe I am lacking an indicator that tells me how much regen. I'm actually getting in kW or kWh. I just see the energy meter pegged at 8mi/kWh.

I seems to me that if there are regen bubbles unavailable due to battery temp. that there is clearly a productive place to dump power. That being the fluid that warms the battery. That way at least I might be able to regen more of the NEXT stop sign.

I am still unclear on the battery warming. Does this ONLY run while plugged in? If I'm parked, not charging, on a cold day, am I going to see my SOC drop at the end of a day with sub-zero(F) temps?

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Re: I Beat EPA's 73 Mile Range : Report your experience

Thu Nov 20, 2014 5:06 pm

kikngas wrote: That being the fluid that warms the battery. That way at least I might be able to regen more of the NEXT stop sign.



The Lithium-Ion Battery in the LEAF is not liquid cooled/heated. The liquid cooling the LEAF has is for the power electronics.

The LEAF battery is very mildly air cooled. The blanket (where equipped) that can warm the battery only does so in very cold temperatures well below freezing. It's my understanding it will come on at a preset temperature regardless if it is plugged in or not as long as there is a minimum charge for it to draw upon.
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dgpcolorado
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Re: I Beat EPA's 73 Mile Range : Report your experience

Fri Nov 21, 2014 11:14 am

kikngas wrote:Well, seems to me that as I regen down from 40 that it seems to kick in harder right at around 30MPH. But I'm not positive if that's what you are describing. If I'm going 55MPH, there is a lot of energy there. Grab too hard and you'll quickly have more than the battery can absorb. But grab the same level of kW of regen at 30 and you'll FEEL it slowing you more. So, I've been thinking that we're experiencing the same behavior and describing it a little differently.
What drees and I were referring to was an actual reduction in regen power at higher speeds versus lower speeds, which makes no sense at all. For example: being able to regen at 20 kW at 25 mph but only able to get 10 kW of regen at 50 mph. This is a known bug in the 2011/2012 LEAFs. The question is, does it occur in newer LEAFs?
Everything else on the throttle is variable. The zero spot to cost varies with speed (which is why it's so much easier to just throw it in neutral). The spot to maintain current speed varies with speed. So, if fully OFF the throttle varies as well, it sorta makes sense. Because at a high speed, (perhaps... I am assuming) the battery cannot accept the charge as fast as regen could deliver it with 4 regen bubbles.
While it is true that the battery can't accept regen power at certain high charge levels and at lower temperatures, that isn't at all what we are referring to. We are talking about the same power being unavailable at higher speeds versus lower speeds. It makes no sense.

As for the accelerator pedal mapping, yes you can coast at any speed at the same pedal position in Eco (at least on older LEAFs, not sure about the newer ones). In Eco the pedal is mapped at constant power: if you hold the pedal at a constant position you will get constant power, whether 20 kW, 10 kW, zero kW (the equivalent of neutral), or whatever. By contrast, D is mapped completely differently and it is harder to hold a constant speed, never mind zero power, using that mode. D is acceleration mapped and it makes for the "spirited" driving that so many seem to prefer. But it is more difficult to drive efficiently in D. This is the case with older LEAFs, whether or not it has been changed in the newer ones, I couldn't say.
With the S model, I believe I am lacking an indicator that tells me how much regen. I'm actually getting in kW or kWh. I just see the energy meter pegged at 8mi/kWh.
Yes, the S model does not have an energy gauge. The SV/SL models have a gauge on the console that gives power used/regenerated in kW. It is very useful in learning to drive efficiently and it makes it easy to coast at zero power without shifting to neutral.
I seems to me that if there are regen bubbles unavailable due to battery temp. that there is clearly a productive place to dump power. That being the fluid that warms the battery. That way at least I might be able to regen more of the NEXT stop sign.

I am still unclear on the battery warming. Does this ONLY run while plugged in? If I'm parked, not charging, on a cold day, am I going to see my SOC drop at the end of a day with sub-zero(F) temps?
The battery heater is a set of electric heating elements attached to the battery case. It comes on at -20ºC (-4ºF) and goes off at -10ºC (14ºF) and draws 300 watts. The purpose of the heater is to keep the battery from freezing and allow the car to be drivable at very cold temperatures. LEAF owners have found that the battery doesn't charge well near -20ºC but driving it heats the battery up and makes charging work better. Regen at battery temperatures around -10ºC is pretty much nonexistent IME.
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kikngas
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Re: I Beat EPA's 73 Mile Range : Report your experience

Fri Nov 21, 2014 2:38 pm

dgpcolorado wrote:What drees and I were referring to was an actual reduction in regen power at higher speeds versus lower speeds, which makes no sense at all.


Right, so I don't believe I have enough info. to confirm whether this is the behavior with 2015.

I drive in eco all the time, and the setting is now retained when you start the day. And I don't believe there is any throttle difference between D and B drive mode (on the plus side of zero). But if I want to feather the throttle to zero and let wind and friction slow me down, I have to steadily ease off the throttle as my speed reduces to remain in the zero throttle spot. That is to say the zero spot at 10MPH is very different than the zero spot at 40MPH. Trying to track zero as your speed changes is rather tedious, so neutral works well, and ensures zero unintended power applied, and zero unintended regen is applied as well.

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dgpcolorado
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Re: I Beat EPA's 73 Mile Range : Report your experience

Fri Nov 21, 2014 3:24 pm

kikngas wrote:
dgpcolorado wrote:What drees and I were referring to was an actual reduction in regen power at higher speeds versus lower speeds, which makes no sense at all.
Right, so I don't believe I have enough info. to confirm whether this is the behavior with 2015.
Yes, this experiment will need to be done by someone with a 2015 SV or SL.
I drive in eco all the time, and the setting is now retained when you start the day. And I don't believe there is any throttle difference between D and B drive mode (on the plus side of zero). But if I want to feather the throttle to zero and let wind and friction slow me down, I have to steadily ease off the throttle as my speed reduces to remain in the zero throttle spot. That is to say the zero spot at 10MPH is very different than the zero spot at 40MPH. Trying to track zero as your speed changes is rather tedious, so neutral works well, and ensures zero unintended power applied, and zero unintended regen is applied as well.
You should be correct about the difference in D and B modes on the plus side of the throttle. All B mode does, as I understand it, is add more regen on the "minus" side of the throttle position.

That said, there is no simple way, short of an aftermarket meter of some sort, to know when you are at zero power on the S model, save for shifting to neutral. And even when you are coasting in neutral the deceleration due to drag will decrease as your speed decreases. That should be the same as when you hold the accelerator at zero power in Eco, except that you have no way to accurately determine where that position is, unlike those with SV or SL models. For coasting in the S model, neutral is your best option, as you suggest.
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JPWhite
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Re: I Beat EPA's 73 Mile Range : Report your experience

Fri Nov 21, 2014 7:45 pm

dgpcolorado wrote:Yes, this experiment will need to be done by someone with a 2015 SV or SL.


Or someone with LEAFSpyPro
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Re: I Beat EPA's 73 Mile Range : Report your experience

Tue Mar 31, 2015 7:23 am

I drive a '15 S. Left the house yesterday on full charge. No AC or heat needed, just had the windows slightly open. Drove 82.5 miles around town, in regular mode with occasional shifts into B mode. Mostly surface streets, though about 25 miles were on the expressway at 65mph. I did put it into neutral and coast down a few hills on the final leg home and arrived home with 8% SOC remaining. I was greatly tempted to circle the neighborhood to see what I could get but opted not to.

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