Gid Vs SOC and Cell Balance Issue

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.

Vaggeto

Member
Joined
Mar 2, 2013
Messages
14
Hi,

I started a longer than normal commute home today. I'm a comfortable LeafSpy pro user and have a good feel for what miles/kwh I can get. I decided to try to make it home by driving very conservatively but half way into the drive things were not going as planned.

I started with (per the dashboard) 46% SOC on my 2015 Nissan Leaf.
I needed to go 40 miles. It was about 100* outside and the leaf was parked out in the sun. (it normally isn't)
I pulled up Leafspy Pro and it determined I needed to do 4.7miles/kwh before hitting VLBW.
As I had 22/40 miles left in my drive, LeafSpy was now saying I needed well over 5m/kwh to get evne 20 miles but the dashboard efficency which I reset at the start of the drive said I was at 4.6m/kwh.

I decided I would need to stop to charge and got to a Nissan dealership. By the time I got there it said 10% left on the dashboard. Shortly after working with the dealership to get to a charging port, I started the car again and it was only 6%!
As I stopped I was at 6% dashboard SOC (dashes), 29.1 miles driven at 4.6m/kwh economy.



According to my math, I shouldn't have run out of power so quickly. I seem to have some inbalance in my cells and also have a large difference between %SOC and % GIDS at 6.3% GIDs and 21% SOC as you can see in these screenshots of Leafspy Pro. http://imgur.com/a/xgVBK

Is there anything else I can provide to help understand if there is an issue?

Thanks in advance for any advice/help!
 
After charging for 75 minutes at ~5200 watts I'm now at 46.7% GIDS and 52.7% SOC and up from 1.4 kWh to 10.4kWh. This doesn't seem possible based on the math of 5200 watts for 1.25 hours - 100watt aux usage while charging.

Cell balance looks a bit better as well although not perfect, but I'm not familiar with what it should look like. Updated screenshots attached:
http://imgur.com/a/xgVBK
 
My new pack had a couple of weak(er) cells from day 1, while at lower SOC they are clearly outliers, hopefully the situation will not get progressively worse at those cells and the whole pack will degrade more or less uniformly, but the fact they are located in the hottest spot (literally) is somewhat disconcerting.

Screenshot_2016-07-15-19-03-34.png
 
Vaggeto said:
I seem to have some inbalance in my cells and also have a large difference between %SOC and % GIDS at 6.3% GIDs and 21% SOC as you can see in these screenshots of Leafspy Pro. http://imgur.com/a/xgVBK

Do you ever charge to 100% to let the BMS equalize the cells? IMO, you should try that a few days in a row and see if that improves those weak cells. Even one weak cell will really hurt your range, because the BMS will not allow that weak cell to drop below some preset voltage, even if the rest are fine.
 
Interesting, thanks for the feedback!

I charge to 100% every night via an L2 charger at home. I typically end up around 25-40% left each day, sometimes in the teens when I go somewhere after work.

I'll take another look after it's at 100%.

Before today I have been very confident to use LeafSpy Pro along with my guess at m/kWh economy but this has me second guessing that.
 
I find that my 2012 Leaf gives much rosier efficiency than LSPro. Let's say I take a 30 mile drive, the car will say I went an avg of 4.6m/kwh; but with LS, it will give an efficiency of 3.2.

I don't understand the discrepency. I suggest people compare the LS readings and the car's readings, then use your judgement on how far you can go.
 
Vaggeto said:
Interesting, thanks for the feedback!

I charge to 100% every night via an L2 charger at home. I typically end up around 25-40% left each day, sometimes in the teens when I go somewhere after work.

I'll take another look after it's at 100%.

Before today I have been very confident to use LeafSpy Pro along with my guess at m/kWh economy but this has me second guessing that.

your charging profile is near perfect to maintain a balanced pack. it looks like you have bad cells. the voltage delta increases as the SOC drops. mine are typically under 10 mV at full charge but no more than 15 mV at 70% SOC. I am guessing yours is probably a lot higher.

the erratic changes in your estimated ranges are due to the very low voltages that will cause an early pack shutdown. problem with weak cells is while under very low load (like sitting at a red light) the voltage delta is likely to be small but when load applies, the weak cells drop much farther than the rest of the pack meaning that weak cells take on the greatest amount of the load so will wear out faster and discharge faster
 
You need to see a dealer and request a CVLI test, Which you can read about here: http://www.mynissanleaf.com/viewtopic.php?f=31&t=19076&start=10#p411119

But there are other similar threads. They may only replace the bad cells, not the whole pack, but you want to stress that they're causing loss of range. As Dave suggested, they'll only get worse. Save your LeafSpy shots to show them, but they won't go by that, they have to do the official test.
 
Thanks!

Here are the screenshots from LeafSpy Pro at full charge the next morning just after starting the car:

http://imgur.com/a/wkriC

Overall they do look more balanced but if they go down quickly once the battery isn't full that seems like a big problem.

I got the car last year in April. I had to have my Power Distribution Module completely replaced (which took a month due to waiting on the part) only a month after owning it. I haven't had any tests/maintenance done since. Might that be a problem with getting this resolved without any obstacles?

Thanks,
John
 
The dealer will insist on performing the annual battery test--the first two are free so there should be no cost to you. It is unlikely that the dealer and/or Nissan would try to deny warranty coverage due to lack of that one test. More likely, they will say everything is normal and you will have to keep accumulating miles until it gets worse. If that happens, make sure you get the second battery test on time next April and complain when useable range drops.

Gerry
 
DaveinOlyWA said:
run it down to around 80% and post a screen shot

Alright... you can find a new series of screenshots at the link below.

http://imgur.com/a/O70cG

I started at ~75% and then another at about 45% and then took some others as I got lower all the way until I turtled.

The variance looked until half full but then it really started to grow. I also got one at exactly 3.712.

Do these provide any other insight? it's interesting that at about 11.7% it highlights the weak cells but at 3.9% turtle it says all cells are okay.

Do these provide any other insight?

Thanks again for your time and knowledge. It's appreciated!
 
It is normal for Leaf Spy to indicate all cells normal when the battery gets really low (turtle or shutdown). It looks like 24 and 44 are somewhat weak. The other cell pairs listed as weak are not far out of line, but 24 and 44 are likely limiting the allowable depth of discharge. My concern about cell pairs 24 and 44 is that they are consistently the lowest in all of your screen shots with the battery not at full charge. The max/min difference of 297 millivolts is a little high, but not too far out of line for when the battery level gets down to turtle or shutdown. I noticed your tires are at 36 psi--look at the wear patterns. If the edges show more wear than the middle of the tread, you might try increasing the cold pressure to at least 40 psi for improved tire wear, handling, wet stopping distance, and range.

Gerry
 
GerryAZ said:
It is normal for Leaf Spy to indicate all cells normal when the battery gets really low (turtle or shutdown). It looks like 24 and 44 are somewhat weak. The other cell pairs listed as weak are not far out of line, but 24 and 44 are likely limiting the allowable depth of discharge. My concern about cell pairs 24 and 44 is that they are consistently the lowest in all of your screen shots with the battery not at full charge. The max/min difference of 297 millivolts is a little high, but not too far out of line for when the battery level gets down to turtle or shutdown. I noticed your tires are at 36 psi--look at the wear patterns. If the edges show more wear than the middle of the tread, you might try increasing the cold pressure to at least 40 psi for improved tire wear, handling, wet stopping distance, and range.

Gerry

Great, thanks!

I noticed the same thing with that pair being consistently lower than the rest both a few days ago when I had the range loss and also yesterday. It looks like once the battery gets to around 50% they start to stand out. The max/min diff today once fully charged from turtle was only 7mv but I'll look again once I'm closer to 50%. I did notice the mv max/min difference vary. At some times it was closer to 450.

regarding the tire pressure: I kept my tires at that based on the car manual. I'm all for those benefits though so will increase it soon. In the Texas heat and highway driving though, it typically goes up a bit.

Thanks,
John
 
Vaggeto said:
Interesting, thanks for the feedback!

I charge to 100% every night via an L2 charger at home. I typically end up around 25-40% left each day, sometimes in the teens when I go somewhere after work.

I'll take another look after it's at 100%.

Before today I have been very confident to use LeafSpy Pro along with my guess at m/kWh economy but this has me second guessing that.

Do you use an end-timer? I'm not sure if that allows a full cell-balance, especially if you use the car shortly after the end-time. Maybe someone else can clarify.
 
I use a start and end time for 8PM-5AM since that is when my power is free. I'm usually done charging by around 11PM.
 
Nubo said:
Do you use an end-timer? I'm not sure if that allows a full cell-balance, especially if you use the car shortly after the end-time. Maybe someone else can clarify.

That is a good point and basically true: if you really want to give the pack a chance to balance, you need to charge to 100% without a timer and sit for several hours (I think as many as 6).
 
Stanton said:
Nubo said:
Do you use an end-timer? I'm not sure if that allows a full cell-balance, especially if you use the car shortly after the end-time. Maybe someone else can clarify.

That is a good point and basically true: if you really want to give the pack a chance to balance, you need to charge to 100% without a timer and sit for several hours (I think as many as 6).

Does this apply even though I use both a start and end time? My Leaf always charges instantly at 8PM and never waits to finish charging by a specific end time. It usually sits around 8-9 hours at a full charge before being driven.

Thanks,
John
 
Back
Top