Posts: 612
Joined: Wed Oct 21, 2015 10:24 am
Delivery Date: 06 Dec 2014
Location: Long Island, NY

Re: Charging frequency

Mon May 22, 2017 10:07 am

Interesting facts... Thank you for your knowledge.

I think your statements also supports my feelings that the Leaf is the best value for a person that drives the car 24 hours/ day while the battery is young... The occasional driver does not get good use of batter price/ mile......

Gold Member
Posts: 11667
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 10 Nov 2016
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: Charging frequency

Wed May 24, 2017 5:30 am

2k1Toaster wrote:
DaveinOlyWA wrote:
hyperionmark wrote:I believe you, but what is the reasoning? Seems like every other degradation variable is based around time and heat. This seems independent of those things. Just trying to learn more.

your statement implies that jackrabbit starts create no heat. Or is it no "significant" heat. So the question becomes "What is significant?"

I have to say that is a question I cannot answer since nearly everything we see here is highly filtered based on what the poster deemed important. There seems to be dozens of ideologies on that .

I have been a long time fan of neutral driving. Started waaaay before the LEAF arrived. It is a "very" small fan club, especially here. But it is essentially "no strings attached" miles. Since the traction pack is all but removed during neutral, its a win win. In my situation, sometimes regen is not the best option. (In reality, it should be avoided as much as possible along with brake usage)

But many here feel likes its some sort of safety issue. I have yet to hear a good or even logical explanation why. So its all about familiarity and comfort. Should you use neutral? That is up to you.

But lets look at another perspective; Regen is putting power into the battery at greatly varying rates and barring super high heat, its max is nearly QC speeds but at a higher SOC (only true in 24 kwh packs. This restriction is removed for 30 Kwh packs)

So we have regen at an elevated power level that is NOT available during a regular, monitored, controlled QC beyond a similar SOC, right?

Well, jackrabbit starts are "exactly" the same but mirrored. Same components, just running backwards so to speak. Charge out instead of charge in, every step essentially the same but reversed. Again, MUCH higher currents and nearly unrestricted. Why is this? Driveability obviously. Who wants to drive a slug?

But nothing is free (except driving in neutral! 8-) ) so we have compromises. These compromises caused too much degradation too fast so the power was tweaked. IOW, slightly less power off the time. a few more milliseconds added to the power ramp up. Pretty minor stuff really. Some noticed, I didn't simply cause I knew it was a trade off and didn't need it all that much. Not lucky enough to be first at the light (probably based on my perception that red lights are only pink for the first 3 seconds... :roll: )

What was probably a better solution was putting in more modules to distribute the load. Now many here will say it doesn't make a difference but for no other reason than to justify their behavior because in reality, no one knows for sure and definitely cannot quantify the effect.

But the key thing is that its only my supposition. I have no proof and my logic, in most cases, only works for me.

To add some science to this, you should reconsider what charge-time and discharge-time do to lithium based cells. Look up couloumbic efficiency as it relates to lithium batteries. A battery that is slowly charged and discharged spends more time oxidizing the electrolyte than one that is charged and discharged quickly. Assuming the same temperature charging/discharging slowly is actually worse than than charging/discharging quickly because it spends less time in the charge/discharge zones.

Jackrabbit starts (high C discharge, short time period) coupled with gliding where you have minimal charge in/out could be construed as having the best battery health. It is very low in efficiency with EVs but should be good.

Just injecting some science.

You realize that you are talking to someone who does most of their charging @ more than 40 KW, right?

The difference between regen and charging is not the speed so much as the control. Charging a car is completely under the control of the BMS. Regen is not. It can vary from small to its max rate over of a HUGE range of SOC several times a minute.

So maybe my explanation has too many tangents in it but the takeaway is really the bottom line of any hypermiler which in this case is my contention that the battery long term health benefits from this and that is "ease in, ease out"

In the EV World this is a double benefit.
2011 SL; 44,598 miles. 2013 S; 44,840 miles. 2016 S30; 13001 miles. 363 GIDs, Ahr 82.34, Hx; 102ish% kwh 28.1 QCs 112
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

Posts: 41
Joined: Mon Jun 20, 2016 3:47 am
Delivery Date: 19 Jun 2016
Leaf Number: 311414

Re: Charging frequency

Wed May 24, 2017 10:34 am

Hi 2k1Toaster,

(just for curiosity)
did your lab do a study on LiMnO battery shelf life at different SOC?
someone did it for cylindrical cell of three different chemistries, but not on LMO. All shows a jump of shelf life if SOC is below certain % (75% for LiFePO4, 55% for another). the different is not a lot, really. but i am curious to know for LMO.

btw, from https://avt.inl.gov recorded data, early 2013 Volt, which pays energy price for active battery thermal management, does suffers less battery degradation (about 8% in 3yrs), then early 2013 Leaf (about 16% in 1.7yrs). I am wondering what result will be, if we put together
improved 2015 leaf battery + active thermal management.
(and of course, I suspect that DOD of Volt is much shallower than that of Leaf)
May-2017 6866mi 72.98Ahr 91%SOH 87.43%Hx
Feb-2017 4442mi 73.9Ahr 93%SOH 88.6%Hx
Sep-2016 1050mi 74.3Ahr 93%SOH 89%Hx
2016 Leaf White SV + no premium package + rain visor + 40psi :roll:

Posts: 41
Joined: Sat Apr 15, 2017 12:54 pm
Delivery Date: 15 Apr 2017
Location: East Bay Area, CA

Re: Charging frequency

Wed May 24, 2017 2:06 pm

Recently purchased a late model year 2013 SL to replace my primary commuter. ~50 mile round trip commute on a single charge currently, but that will change once charging at work becomes available in the next year. I charge to 100% (L2) on workdays, which is about 19 days a month for me, and 80% the rest of the time (all on timer). The area I live in has temps that exceed 100deg F during the summer, but I garage the car and park in the shade at work. I charge the car to fit my use.

When I purchased the car, the AHr was at 58.8, SOH 89%, and only 1 QC. Haven't really decided on whether or not I'll track the battery stats, but may just for a data point here.

Love driving the car and moreso the fact that I won't have to deal with fluid leaks, head gaskets, water pumps, timing belts, transmissions, radiators, alternators, smog, and the other issues I've been plagued with on previous used cars. Wrenching on cars isn't as much fun as it used to be, and although the range is limited on the leaf, it fills 90% of my driving needs. I have 2005 Honda Odyssey for longer family trips and the occasional ICE needs.
2013 Leaf SL (12/2013) + Premium package 31,000 miles - 58.8AHr - 89%SOH

Return to “News & Main LEAF Discussion”