Nissan Discusses Method For Topping Off LEAF Battery (0.7%)

[LeafMuranoDriver]

http://insideevs.com/nissan-discusses-method-for-topping-off-leaf-battery/
http://www.autonews.com/article/20160314/OEM06/303149956/nissan-batteries-are-inspired-by-the-bartender

It turns out there’s a way to stuff an extra 0.7 percent of energy into a Nissan LEAF battery pack and it’s easier than you might expect.

According to Automotive News:

“To cram more charge into the lithium ion battery of the Nissan Leaf electric car, Nissan Motor Co.’s battery engineers turned to the tap for inspiration.”

“Their breakthrough: Top off the battery with three extra minicharges at five-minute intervals at the very end of charging. It is similar to an expert bartender waiting for the foam to die down before topping off a beer with a couple of tap blasts.”

News of this topping off method comes from Taiichi Onoyama, leader at Nissan’s electric and hybrid system engineering department, who stated:

“In our company, we talk about additional charging using this example of how to pour beer.”

0.7 percent isn’t much, but it could be the different between arriving at your destination and getting stranded with no charge on the side of the road.

As Automotive News explains (via slides shown at a conference in Tokyo):

“The secret lies in allowing the cell voltage to dip a bit between charges, just like the foam on a beer. The lower voltage allows the battery to accept more charge.”

Of course, it does take a bit longer to get the extra charge into the LEAF, but it may be worth the wait in some situations.

Interesting but not totally sure if I'd ever do it. Good to know though.

 

[mwalsh]

Interesting but not totally sure if I'd ever do it. Good to know though.

So...does one still get dinged on the 5 start report for doing this? My assumption would be not, if this is the official word now, but you know what assumptions can lead to.

 

[Bob]

For all we know, they may already be doing this.

Bob

 

[Nubo]

A lot of palaver for a minimal result. And a poor analogy. A bartender wouldn't waste time "waiting for the foam to die down" if it only meant 2 extra drops of beer.

 

[garsh]

So...does one still get dinged on the 5 start report for doing this?

I would guess not. I charge to 100% every day, and hit VLBW every day. I've hit turtle 4 times, and had the car shut down two of those times.

And I've gotten a 5-star report for the battery inspection every single time.

 

[ElectricEddy]

In my case (20.2 KW H, 60.02 AH) that would gain me 700 meters @5 km/KW H, and all I have to do is hang around for twenty minutes plugin and unplugging 3 times at 5 minute intervals. But wait, I can walk 1250 meters in 15 minutes at 5 km/ hr. Surely Nissan engineers have better things to think about like " how to fit a 30 KW H battery into a 2013 " than beer

 

[mwalsh]

So...does one still get dinged on the 5 start report for doing this?

I would guess not. I charge to 100% every day, and hit VLBW every day. I've hit turtle 4 times, and had the car shut down two of those times.

And I've gotten a 5-star report for the battery inspection every single time.

I got dinged for "topping off" when I had my LBC changed out and was convinced that the new one was not properly (fully) charging the battery:

http://www.mynissanleaf.com/viewtopic.php?f=27&t=11303

 

[JeremyW]

My guess this is already happening in the background. The 2013+ cars can take quite a while to finish charging. There are instances where the car stops then resumes charging a bit later.

 

[DaveEV]

My guess this is already happening in the background. The 2013+ cars can take quite a while to finish charging. There are instances where the car stops then resumes charging a bit later.

Yep, and you can see this to a much lesser degree on the '11-12 LEAFs, too. You will notice that the finish voltage of the '13+ LEAFs is a decent amount higher than the '11-12 LEAFs, and better topping off of the battery is why.

 

[cwerdna]

My guess this is already happening in the background. The 2013+ cars can take quite a while to finish charging. There are instances where the car stops then resumes charging a bit later.

The '13+ (well at least 13 thru 15) Leafs when charged to 100% have the profile at http://www.mynissanleaf.com/viewtopic.php?p=338038#p338038. I can confirm that 2 or 3 bounces at the end always happen when going to 100% vs. the abrupt cut at 80%.

I've never observed any subsequent charging after the final bounce (at least via Chargepoint's site) for my '13 Leaf nor any other '13-15 Leafs I've plugged in, even after several hours. The only exception is if I try to start charging remotely or remotely/via timer turn on climate control.

I do wonder if it is doing the thing discussed in the OP.

 

[DaveEV]

I do wonder if it is doing the thing discussed in the OP.

Nice find - that's definitely what's going on there. You definitely don't see that on the '11-12 LEAFs.

 

[powersurge]

This is so stupid... All this to get an extra 2-3 miles. You can lose this gain by accelerating to 70mph for a 1/2 mile.

 

[Stoaty]

This is so stupid... All this to get an extra 2-3 miles. You can lose this gain by accelerating to 70mph for a 1/2 mile.

Yes, if you know you are going to need a bit of extra range, just slow down by 5-10 MPH. Works for me.

 

[DaveinOlyWA]

This is so stupid... All this to get an extra 2-3 miles. You can lose this gain by accelerating to 70mph for a 1/2 mile.

"All this to get an extra 2-3 miles."

what is stupid the plugging in or the thought that .7% would get you 2-3 miles?

 

[desiv]

i wonder if there would be any possible benefit in doing this from time to time (monthly? quarterly?) to "exercise" the battery (if there is such a thing)?
Or, would it be a bad idea to do this to the battery ever (although at L2/L1, I wouldn't think there'd be much extra heat from this)? If this is what model 13's and on do automatically (which I'm not saying it is), then it's probably safe.

Or would it all be so negligible that it wouldn't matter either way..

That said, I know there are people who do try to drive slower and still talk about sometimes hitting VLBW and even turtle getting home. So I wouldn't judge them and if it makes sense for some people, then it makes sense...

Not sure it'd be worth the hassle of doing that every morning for me tho.. ;-)
Maybe if there is a programmable EVSE that you can have do this automatically for you...

desiv

 

[arnis]

It's not worth the hassle. Just charge to 100% if range is really needed (to avoid VLBW).

It does make sense to periodically go to extremes (near turtle and 100%) if those are always
avoided in daily usage (once a month should be enough).

With my 2014 Leaf I always charged to 80% and almost never got below LBW during a two month period.
And when I finally went on a longer trip pack was heavily unbalanced; I went from VLBW to Turtle
in two minutes and ran out half a kilometer from my home. BMS tried to balance the pack but balancing
happens only in direction of discharge - so cells that are at higher SOC are discharged (no power to wheels).
I saw unbalanced cells in LeafSpy. All worked fine after 100% charge. Balancing was active for long period.
BMS is unable to balance cells if they don't get near full or near empty during long period of use.
It might be because cell voltage is very similar at medium states of charges (3,7-4,0 Volts).

 

[DaveinOlyWA]

its interesting they choose this wording to advise how important regular top end balancing is for maximum range

 

[powersurge]

I love how stories change back and forth. First, they tell us to not charge over 80% because 100% is "bad". Now the (whomever "they" are) are telling use to "double tap" at 100% for "OPTIMAL BATTERY HEALTH"... Next doctors will tell us that The triple bacon cheeseburger is good for us...