Rapid Acceleration and Battery Degradation: Facts- Opinions?

[cdherman]

OK, I've accepted that the top 20%(original post 80%) of my battery is "she who must be obeyed" and left alone, lest I be punished with eternal degradation....

And I've accepted that my penchant for finding the maximum velocity on a road at which the law enforcement seems to look away, must be tempered by the reality that higher velocity means the treble effect on energy consumed.

And, I shall not ever again sleep late in the Winter nor in the Summer, lest my conveyance be forced to park upon the exposed fields of the upper parking deck, where cold and heat may harm her sanctity.....

And lastly, I am told, that my one final joy, that rapid motion off the line, withwhich I can sometimes trounce my ICE adversaries, is also damageing...

But what of this last question?

What is really known about BRIEF rapid discharges? Floored off the line to 50 mph? Or a rapid burst in traffic from 30 to 45 to slip into another lane?

I accept that doing a brief rapid discharge if the battery is already hot, at the top or the bottom of its range, or really cold, is probably a bad thing....

But what about flooring it in the middle of the remaining charge range, with 5 bar temp on bat?

Facts (I assume none from Leaf proper, but what about literature from other bat technologies/studies)????

Opinions???

Anecdotes??

 

[Stoaty]

OK, I've accepted that the top 80% of my battery is "she who must be obeyed" and left alone, lest I be punished with eternal degradation....

Well, if you aren't going to use the top 80% of your battery, that only leaves 20% for your use. I don't think you will be able to do much rapid acceleration if you start out every day just above Low Battery Warning.

 

[surfingslovak]

Well, if you aren't going to use the top 80% of your battery, that only leaves 20% for your use. I don't think you will be able to do much rapid acceleration if you start out every day just above Low Battery Warning.

:lol:

On a more serious note. What you described above is how I drive the ActiveE every day. My long-term energy economy is 3.0 m/kWh. I hope to see something even lower when the winter starts. And why would I do such a foolish thing, you ask? Well, the car is essentially a test mule for the i3 drivetrain. I will have to return it in about year and half, maybe even sooner.

There is no point to baby the battery, quite the opposite. Yes, Virginia, there are some benefits to being a lab rat for an OEM. I'm giving the battery a good workout every day. 100% charging? Check. Full acceleration from every stop? Check. High-speed driving on the freeway? Check. Using insane regen level to brake? Check.

Ask me how the battery is doing next summer, and I will be happy to oblige. And before you wonder about that, the chemistry is similar to what's in the LEAF: BMW uses NMC cells from SB LiMotive (soon to be Bosch), and Nissan uses LMO cells from AESC.

 

[abasile]

Based on what I've read on this forum and personally experienced to a limited degree, the number one cause of battery degradation is sustained heat, particularly when combined with high SOC. Compared to that, quick bursts of speed here and there seem likely to be pretty minor. I wouldn't feel a need to deny oneself that pleasure.

 

[RedMapleLeaf]

And lastly, I am told, that my one final joy, that rapid motion off the line, withwhich I can sometimes trounce my ICE adversaries, is also damageing...

Excellent question. Now having read in MNL about the impending loss of capacity due to my previously unknowing but nonetheless negligent battery-damaging ways , I fear for the life of my battery. Is it true that this one last, previously guilt-free, pleasure is also to be torn from us? With my licence plate of "GAS LOL", is there nothing left to be righteous and superior about when compared with the ICEV-masses out there? Maybe I should trade in my non-green vanity plate for a generic green plate (they don't have stickers in Ontario) so at least I can wring some happiness from using the HOV lanes a few times per month.

Renny

 

[Nekota]

OK, I've accepted that the top 80% of my battery is "she who must be obeyed" and left alone, lest I be punished with eternal degradation....

And I've accepted that my penchant for finding the maximum velocity on a road at which the law enforcement seems to look away, must be tempered by the reality that higher velocity means the treble effect on energy consumed.

And, I shall not ever again sleep late in the Winter nor in the Summer, lest my conveyance be forced to park upon the exposed fields of the upper parking deck, where cold and heat may harm her sanctity.....

And lastly, I am told, that my one final joy, that rapid motion off the line, withwhich I can sometimes trounce my ICE adversaries, is also damageing...

But what of this last question?

What is really known about BRIEF rapid discharges? Floored off the line to 50 mph? Or a rapid burst in traffic from 30 to 45 to slip into another lane?

I accept that doing a brief rapid discharge if the battery is already hot, at the top or the bottom of its range, or really cold, is probably a bad thing....

But what about flooring it in the middle of the remaining charge range, with 5 bar temp on bat?

Facts (I assume none from Leaf proper, but what about literature from other bat technologies/studies)????

Opinions???

Anecdotes??

I think any abusive action is bad for the battery and hard acceleration is one of them. One indirect measure of hard acceleration is the tread wear on the front tires, has any thought gone into correlating tire wear from high acceleration to battery degradation? Of course there are other reasons for high tire wear, e.g. mountain road driving but I'm referring to the high acceleration tire wear. There were some reports of the front tires losing rubber by 'chunks' due to the high stress from acceleration but most passed it off as poor quality tires.

Just my opinion and others can chime in to refute or suggest other ideas.

 

[cdherman]

OK, I've accepted that the top 80% of my battery is "she who must be obeyed" and left alone, lest I be punished with eternal degradation....

Well, if you aren't going to use the top 80% of your battery, that only leaves 20% for your use. I don't think you will be able to do much rapid acceleration if you start out every day just above Low Battery Warning.

Ya know, gotta start proof reading my posts better...

 

[EVDrive]

.
There is no point to baby the battery, quite the opposite. Yes, Virginia, there are some benefits to being a lab rat for an OEM. I'm giving the battery a good workout every day. 100% charging? Check. Full acceleration from every stop? Check. High-speed driving on the freeway? Check. Using insane regen level to brake? Check.

I drive the same way. Life is too short.

 

[LTLFTcomposite]

For purposes of this discussion what constitutes "rapid acceleration"? My experience is that 7 of 9 bubbles has the ICE-pack fading away in the rearview mirror.

 

[TickTock]

<snip>
And lastly, I am told, that my one final joy, that rapid motion off the line, withwhich I can sometimes trounce my ICE adversaries, is also damageing...

But what of this last question?

This has been discuss many time before. Short answer is rapid acceleration probably has a very small impact on both efficiency and degradation. The losses in the battery are quite low. It does have a small, non-zero impact but is so far below the primary contributors like speed, heat, and charging habits that you may, for all practical purposes, ignore it and enjoy yourself.

 

[surfingslovak]

This has been discuss many time before. Short answer is rapid acceleration probably has a very small impact on both efficiency and degradation. The losses in the battery are quite low. It does have a small, non-zero impact but is so far below the primary contributors like speed, heat, and charging habits that you may, for all practical purposes, ignore it and enjoy yourself.

Well said. There is also a vague reference to moderate driving in the owners manual on page EV-23 in the section named Li-Ion Battery Life.

 

[TickTock]

To put it into perspective. At full throttle (80kW) you can hit 60mph in 7 seconds which comes to 0.156kWh. At .1Ohm battery resistance, this results in about 5.5% losses in the battery (.0086kWh wasted). If you accelerate at half this rate (40kWh), it will take 14 seconds since energy is the same (E=mv^2 regardless of how fast you get there). In this case you lose 2.7% of the 156kWh to battery losses (.0042kWh). So you burn .0044kWh more to accelerate to 60 at full accel versus a more leisurely pace. For comparison consider what it takes just to maintain 60mph. If you drive 60mph for 20 minutes, you will consume about 5kWh. That same .0044kWh you saved by accelerating more slowly would allow you to drive 0.03 mph faster and use the same total energy. Do you get more satisfaction driving 60.03 mph instead of 60 or by dusting everyone off the line?

 

[Nubo]

OK, I've accepted that the top 20%(original post 80%) of my battery is "she who must be obeyed" and left alone, lest I be punished with eternal degradation....

And I've accepted that my penchant for finding the maximum velocity on a road at which the law enforcement seems to look away, must be tempered by the reality that higher velocity means the treble effect on energy consumed.

And, I shall not ever again sleep late in the Winter nor in the Summer, lest my conveyance be forced to park upon the exposed fields of the upper parking deck, where cold and heat may harm her sanctity.....

And lastly, I am told, that my one final joy, that rapid motion off the line, withwhich I can sometimes trounce my ICE adversaries, is also damageing...

Funny, but lest someone new get the wrong idea there isn't any "scripture" demanding that you forgo any and all pleasures of driving or cover the car with bubble wrap. A car is an Earthly thing, like us, so it has its imperfections. Understanding them is a way to maximize your enjoyment, not minimize it.

 

[adric22]

I'm quite certain that both the battery pack and motor are capable of more than 80Kw of power delivery. For example, I believe the Nismo uses the same battery and motor, but performs much better. In which case, I suspect Nissan has limited us to 80Kw for the good of the battery, motor, and other electronics. I have no reservations about using all of that available power when I feel the need. However, I rarely use it in daily driving.

 

[cdherman]

I'm quite certain that both the battery pack and motor are capable of more than 80Kw of power delivery. For example, I believe the Nismo uses the same battery and motor, but performs much better. In which case, I suspect Nissan has limited us to 80Kw for the good of the battery, motor, and other electronics. I have no reservations about using all of that available power when I feel the need. However, I rarely use it in daily driving.

You bring up a thought that I had as well -- if its honestly hard on the battery to accelerate strongly, then Nissan failed a design point there as well. I mean, ICE cars are not generally going to harm themselves when asked to accelerate rapidly (hot rods excepted). So if Nissan designed the thing right, you'd think they would not have designed it to consume its battery during rapid accelerations....

But we know they did not get all of the design perfect, now don't we.....

 

[cdherman]

To put it into perspective. At full throttle (80kW) you can hit 60mph in 7 seconds which comes to 0.156kWh. At .1Ohm battery resistance, this results in about 5.5% losses in the battery (.0086kWh wasted). If you accelerate at half this rate (40kWh), it will take 14 seconds since energy is the same (E=mv^2 regardless of how fast you get there). In this case you lose 2.7% of the 156kWh to battery losses (.0042kWh). So you burn .0044kWh more to accelerate to 60 at full accel versus a more leisurely pace. For comparison consider what it takes just to maintain 60mph. If you drive 60mph for 20 minutes, you will consume about 5kWh. That same .0044kWh you saved by accelerating more slowly would allow you to drive 0.03 mph faster and use the same total energy. Do you get more satisfaction driving 60.03 mph instead of 60 or by dusting everyone off the line?

I'm still not completely convinced (though certainly tempted)... I mean, TickTock certainly nails the issue of energy loss (which of course, MUST result in heat to maintain physicial laws). But could there be some other, chemistry related issue that occurs with large bursts of electrical draw? Just wondering....

I don't know much about battery chemistry. What I know, I know from lead acids, and I know that rapid discharges are hard on them. Someone say it ain't so for Leaf bats!

 

[Herm]

Obviously high energy driving will generate more waste heat deep in the core of the battery, and it takes time to dump that excess heat.. so perhaps it will degrade the life of the battery in the long term, perhaps a couple of days after 10 years per event?.. obviously again this wont matter with Phoenix cars.