Curiosity Only - Near-100% Charging Behaviour

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
S

Superchewie

Member
Joined
May 1, 2017
Messages
23
Location
Vancouver, BC
Hi folks,

During a recent ChargePoint charging session (in which I needed a battery level near to 100% at the end), I noticed some interesting behaviour by the EVSE close to the end of the charge. It seems like the EVSE would ramp down to near zero amps, then up for a bit, then back down.

This should be a link to a photo of the charge record on Imgur:
https://imgur.com/gallery/vwHYe

I suppose this is actually controlled by the Leaf?

If anyone cares to "explain like I'm 5" this behaviour to me, I'd appreciate it! I'd like to sound smart to my new-to-EV friends.

Thanks!
 
Superchewie said:
Hi folks,

During a recent ChargePoint charging session (in which I needed a battery level near to 100% at the end), I noticed some interesting behaviour by the EVSE close to the end of the charge. It seems like the EVSE would ramp down to near zero amps, then up for a bit, then back down.

This should be a link to a photo of the charge record on Imgur:
https://imgur.com/gallery/vwHYe

I suppose this is actually controlled by the Leaf?

If anyone cares to "explain like I'm 5" this behaviour to me, I'd appreciate it! I'd like to sound smart to my new-to-EV friends.

Thanks!
Click to expand...
Cells balance at the end in an attempt to equalize (minimize the voltage differential)...routine.
 
The pack can't be fast-charged as it nears full. Thus the charger tapers the charge. As it gets full, an equalizing charge is applied, which involves the up & down pattern you observed. This gets the cells in balance.
 
The newer Leafs keep trying to get more charge into the battery by ramping up the charge rate after it tapers due to reaching maximum cell voltage. As you can see from the charge profile, they will do this several times. My 2011 would charge at its normal rate until almost the end of the charge cycle and then taper briefly (to keep charging without exceeding maximum cell voltage) before considering the charge complete and shutting down the charge process. At first it seemed strange to have the charge rate taper, but keep charging for nearly an hour after I purchased the 2015.
 
Yes, it's been speculation that some sort of battery balancing was going on in the '13+ Leafs (which are the first to have this bouncing behavior). Both my current and previous '13 looked just like that when going 100% (most of my charging is on Chargepoint EVSEs at work).
GerryAZ said:
The newer Leafs keep trying to get more charge into the battery by ramping up the charge rate after it tapers due to reaching maximum cell voltage. As you can see from the charge profile, they will do this several times. My 2011 would charge at its normal rate until almost the end of the charge cycle and then taper briefly (to keep charging without exceeding maximum cell voltage) before considering the charge complete and shutting down the charge process. At first it seemed strange to have the charge rate taper, but keep charging for nearly an hour after I purchased the 2015.
Click to expand...
Yes, it seems likely that it is to cram more charge in. We learned of it via the articles that http://www.mynissanleaf.com/viewtopic.php?f=31&t=21628 references. That might be responsible for a small part of the higher EPA range rating of the '13 to '15 24 kWh Leafs (84 miles at 100% instead of 73).
 
I don't know about the extent of the voltage fluctuations, but my '13 also does some balancing at 80%. I know because all three charging lights glow steadily for about 5 minutes as it reaches 80%. (Then my car, for some unknown reason, maybe a cell with different capacity, drops back to 79% like clockwork.)
 
LeftieBiker said:
I don't know about the extent of the voltage fluctuations, but my '13 also does some balancing at 80%. I know because all three charging lights glow steadily for about 5 minutes as it reaches 80%.
Click to expand...
I don't know that the all 3 lights on for 5 minutes necessarily means anything (balancing or otherwise). It's in the manual that they'll stay on for 5 minutes.

The '13 Leaf manual says
When fully charged
All of the indicator lights1 to3 illuminate when
the Li-ion battery is fully charged to the selected
charging mode level.
The indicator lights turn off after approximately 5
minutes or when the charge connector is removed.
Click to expand...
Oddly, from the '11 Leaf manual
When fully charged
All of the indicator lights *1 to *3 illuminate
when:
. The Li-ion battery is fully charged
. 80% of a charging timer is completed
. When 90% of a quick charge is completed
The indicator lights turn off after approximately
15 minutes or when the charge connector is
removed.
Click to expand...
 
My OpenEVSE logs something that's even more pronounced:

s32lc1o.png
 
Yes, it seems likely that it is to cram more charge in. We learned of it via the articles that viewtopic.php?f=31&t=21628 references. That might be responsible for a small part of the higher EPA range rating of the '13 to '15 24 kWh Leafs (84 miles at 100% instead of 73).
Click to expand...

On the MY 11 and 12 cars a factor in the lower EPA rating was because for the test they had to show the 80% charge range result and not the 100% rate. With the 80% rate removed in 2013, then they could now list the higher range rate.
 
2011 did not do the top off charging shown in the graph. I was surprised to see that nearly one hour of tapered and cycling charging when I first got the 2015, but it does result in a higher SOC. My 2011 would show a maximum of 394 volts at full charge (usually between 392 and 394, but never above 394). My 2015 shows at least 395 volts (usually higher) at full charge so the cycling charge for the last hour does result in slightly higher volts/cell and, therefore, slightly higher SOC. The actual driving range at steady speed is no different between a 2011 with new battery and 2015 with new battery. The 2015 has a bit more aggressive regeneration which contributes to a bit more range in stop/go driving and is why it is rated higher on the EPA test cycle. I believe the 80% charge rule first applied in 2013 and the 80% charging option was eliminated in 2014. FWIW I found that the 73 miles listed by the EPA for 2011 is realistic for both the 2011 and 2015 with 100% charge.
 
OrientExpress said:
Yes, it seems likely that it is to cram more charge in. We learned of it via the articles that viewtopic.php?f=31&t=21628 references. That might be responsible for a small part of the higher EPA range rating of the '13 to '15 24 kWh Leafs (84 miles at 100% instead of 73).
Click to expand...

On the MY 11 and 12 cars a factor in the lower EPA rating was because for the test they had to show the 80% charge range result and not the 100% rate. With the 80% rate removed in 2013, then they could now list the higher range rate.
Click to expand...

You got this completely wrong, making other info you provide suspect. The 80% charge limit (different from an 80% timer setting) was implemented in 2013, the EPA lowered the range rating because of averaging in 2013, and the 80% charge option, including 80% charge timer, was then removed in 2014 in the US. It was left in place in other countries.
 
OrientExpress said:
cwerdna said:
Yes, it seems likely that it is to cram more charge in. We learned of it via the articles that viewtopic.php?f=31&t=21628 references. That might be responsible for a small part of the higher EPA range rating of the '13 to '15 24 kWh Leafs (84 miles at 100% instead of 73).
Click to expand...

On the MY 11 and 12 cars a factor in the lower EPA rating was because for the test they had to show the 80% charge range result and not the 100% rate. With the 80% rate removed in 2013, then they could now list the higher range rate.
Click to expand...
No, 80% charge setting existed on '13 in actually 2 places, both the timer and and a new "long life mode" setting. I'm on my 2nd '13 SV.

All references were removed on '14+ US Leafs, which gave an artificial EPA mileage boost from "75 miles" on the '13 to "84 miles" on the '14.

http://www.autoblog.com/2013/02/21/2013-nissan-leaf-revealed-gets-75-mile-range-actually-84-in-n/
http://insideevs.com/2014-nissan-leaf-mostly-unchanged-as-range-technically-moves-up-to-84-miles/
 
GerryAZ said:
The 2015 has a bit more aggressive regeneration which contributes to a bit more range in stop/go driving and is why it is rated higher on the EPA test cycle.
Click to expand...
That also could contribute. There's are also some motor efficiency improvements shown in a graph at http://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/e_powertrain.html. Wouldn't surprise me if that benefited the EPA tests since 3 of the cycles have very gentle acceleration (http://fueleconomy.gov/feg/fe_test_schedules.shtml under Test Details).
GerryAZ said:
I believe the 80% charge rule first applied in 2013 and the 80% charging option was eliminated in 2014.
Click to expand...
Yes, seems like it, from the articles I cited.

http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=30979&id=33558&id=34699 has the 73, 75 and 84 mile figures for the '11, '13, and '14, respectively.
 
No, 80% charge setting existed on '13 in actually 2 places, both the timer and and a new "long life mode" setting. I'm on my 2nd '13 SV.
Click to expand...

OK, I just remember that in January 2013 I learned that the 80% mode was going away in anticipation of the revised chemistry battery. It made for some lively dissusion in Nissan engineering at the time, but after it was implmented (in '14 to your correction), it was a non-event.
 
The 80% charge setting has never been an issue to me because I have always charged to 100% and frequently discharge to LBW or VLBW, but there was no real change in actual driving range between 2011 and 2015 (other than battery deterioration is much less with 2015 so effective range after 2 years is higher).
 
GerryAZ said:
The 80% charge setting has never been an issue to me because I have always charged to 100% and frequently discharge to LBW or VLBW, but there was no real change in actual driving range between 2011 and 2015 (other than battery deterioration is much less with 2015 so effective range after 2 years is higher).
Click to expand...

Many have always thought that climates like Phoenix are edge cases, that is a debate that I don't want to relitagate, but if if after 2 years of heavy duty high mileage usage, and only 2 bars lost Gerry, I'd say that is quite an improvement. I went from 2 bars lost in 32K miles and 2 years to 46K miles 3 years, and no bars lost. And even if I am an outlier as well, the trend of the LEAF batteries are is very positive.
 

Similar threads

S
Charging tips from Nissan
Replies
0
Views
2K
Sweetjan
S
D
Help diagnosing dead 12v (as opposed to some other problem) SOLVED
2
Replies
26
Views
5K
DavidMW
D
N
2013 stuck to public charging station
Replies
12
Views
3K
Flyct
F
C
lots of great free charging as a tourist going from the Bay Area to the LA area
Replies
2
Views
14K
cwerdna
C
G
Official Vinfast VF8 topic
Replies
6
Views
4K
GRA
G

Latest posts

Back
Top