LeafDD - Dash Display for Leaf

[DaveinOlyWA]

Last April (month 26 of ownership) my leaf showed 279 gids after allowing it to cell balance to 100% SOC for 2 days. Now 4 months later it only gets 255.

Keep in mind that unless you have the P3227 update GID counts in cool weather are likely too high and GID counts in warm weather are likely too low.

But still - letting it balance for 2 days? No one recommends leaving it at 100% for more than 4 hours for balancing purposes and it's always best for battery longevity to minimize time spent at high SOC.

Let me clarify, I let the car charge to 100% for two consecutive days allowing for balancing at night. It was driven between so it wasn't sitting around at a high state of charge for 48hours.

cool rainy morning here in Oly. how was your weather? problem is a night or even a day or TWO days is barely enough to cool the pack. remember the hot weather charging experiment i did last Summer? I was able to "artificially" lower my full charge GID count by 20?

I had strong anecdotal evidence that it takes a few days for the pack to cool off from high temps. Now, i started using the LEAF Batt App on Friday. I did not charge Friday night and only for a short period Sat. and did not use LEAF on Sunday so my battery temps were down to the high 60's low 70's.

a Full charge yesterday brought them to 73-75º and 242 GIDs. I did 73 miles of driving yesterday with a 14 min QC that brought batt temps from 76ish to 85-86º

parked car in garage (warm day yesterday) and charged a few hours stopping at 5 PM with batt temps essentially unchanged. Now last night was not as cool as I hoped it would be but batt temps are between 78.2 and 79.5º so not much cooling and garage temp is 65 AND i still have 6 TBs...

 

[GregH]

Let me clarify, I let the car charge to 100% for two consecutive days allowing for balancing at night. It was driven between so it wasn't sitting around at a high state of charge for 48hours.

Yup. When you first turn on the car after a "full" charge, try pressing the LeafDD button twice to get to the voltages page. If the BMS has selected cells to be balanced you'll see it turn on the shunts from left to right over a few seconds... Ignore the first second though as that might be old data in LeafDD from last time you were on the voltage page and not fresh data.. but within a second or two you'll see the fresh shunt data roll in as dots on the bottom. As the shunts turn on you can see the voltages dip accordingly. This would seem to indicate to me that the car does NO balancing when turned off. I don't know who started the "4 hours at full charge" idea but it seems to be false. Other than the 15 minutes after full while all 3 blue lights are on, my guess is that balancing turns off when the car shuts down. But, it turns back on again in the prescribed order whenever the car is on.. be it at 95% SOC or 20% SOC.. be it driving or charging.. The LBM likely prescribes a certain amount of time (perhaps an hour or two) that the various shunts need to stay on (regardless of SOC) in order to withdraw a few mAh of charge from some cells and they turn on whenever the car is on or charging. The occasional dancing of a few odd shunts on an off however.. I have no explanation for that...

 

[GregH]

I'm still loving this device. I do have two very simple suggestions to improve the user interface, though, and will post here for any discussion. Sorry if this has been covered before.

When you hold the button for a second to change the units, it would be an improvement for the digits to start blinking at the one second mark prior to having to release the button first. That way you know the mode has changed and the button can be released. Secondly, while the digits are blinking with your finger off the button, you should be able to ignore the unit and a timer should expire after a few seconds and stop the blinking automatically, returning the unit to normal mode of operation.

That's all. These simple changes would make the device simpler and easier to use. Still a wonderful instrument. Thanks again, Greg!

Thanks! It's funny the mechanism in the software for the short vs long button press goes back several hardware iterations back to old code the EDrive plug in Prius display used. Here at AC Propulsion they have the buttons set up as you suggest.. hold until you see action. That is a better solution and I'll dig into it on the next software iteration. Also the timeout makes sense as well.. Good suggestions!

 

[DaveEV]

If the BMS has selected cells to be balanced you'll see it turn on the shunts from left to right over a few seconds... Ignore the first second though as that might be old data in LeafDD from last time you were on the voltage page and not fresh data.. but within a second or two you'll see the fresh shunt data roll in as dots on the bottom. As the shunts turn on you can see the voltages dip accordingly. This would seem to indicate to me that the car does NO balancing when turned off. I don't know who started the "4 hours at full charge" idea but it seems to be false. Other than the 15 minutes after full while all 3 blue lights are on, my guess is that balancing turns off when the car shuts down.

I believe that Phil/Ingineer has said that the car can balance the pack at any time. I'm pretty sure Tony Williams was one of the first to come up with the "4 hour" balancing recommendation. One would probably need to directly instrument individual modules to determine this for sure. I think it may be more effective if one could do a 120V/6A charge from 80%-100% - say overnight - then for sure you'd know that the BMS is active and balancing as necessary. Would need an EVSE that can charge at that low a rate, though (EVSE Upgrade or Open EVSE? Maybe Volt L1 cord which is selectable between 8-12A or iMiEV L1 cord which is 8A?)

Are you sure that you can actually see CP voltages drop when balancing shunts are turned on? Given the low current and the low internal resistance of the cells I would imagine that you wouldn't see the voltages sag any noticable amount - unless there is a significant amount of precision in the CP voltage readings or perhaps because the CP voltage readings are taken at the end of a longish small gauge wire.

 

[Stanton]

parked car in garage (warm day yesterday) and charged a few hours stopping at 5 PM with batt temps essentially unchanged. Now last night was not as cool as I hoped it would be but batt temps are between 78.2 and 79.5º so not much cooling and garage temp is 65 AND i still have 6 TBs...

Talk about a different perspective: once we hit June here I NEVER see battery temps much below 90 degrees F regardless of whether it's day/night or my car is inside/outside!

 

[HighDesertDriver]

...clip... This would seem to indicate to me that the car does NO balancing when turned off. I don't know who started the "4 hours at full charge" idea but it seems to be false. Other than the 15 minutes after full while all 3 blue lights are on, my guess is that balancing turns off when the car shuts down.

I believe that Phil/Ingineer has said that the car can balance the pack at any time. I'm pretty sure Tony Williams was one of the first to come up with the "4 hour" balancing recommendation. ...clip...

Many of us with the means to record from-the-wall timelines first noticed the "4-hour" sequence 12-18 months ago. After charging to 100%, everything would shut down for approximately 4 hours and then sometimes restart, tapering back to zero amps after 20 minutes or so. There was then no insight to individual cell voltages, but some thought it might be the "second act" of charging after balancing. While much more is known today, battery balancing protocols still seem to a subject of much conjecture -- except perhaps to folks with Nissan NDAs. ;-)

 

[GregH]

I believe that Phil/Ingineer has said that the car can balance the pack at any time. I'm pretty sure Tony Williams was one of the first to come up with the "4 hour" balancing recommendation.

"Any time" the car is on (as compared to not just in the hours directly after a charge).. I'm guessing the LBM goes to super low power sleep like the rest of the vehicle when completely off and not charging. Once a determination is made that you want to take out X mAh from a cell it really doesn't matter when you do it.. When I did BMSs for the Prius I would do the balancing in the hours after the end of charge (as Tony suggests) but this doesn't seem to be how the Leaf does it.

Are you sure that you can actually see CP voltages drop when balancing shunts are turned on?

Yes. Here's a video I posted somewhere else on MNL a month ago.. Note due to polling the cell voltages and shunt info separately sometimes it may look like the voltage dips before the shunt turns on..
[youtube]http://www.youtube.com/watch?v=ek98u2SBdzc[/youtube]

 

[DaveinOlyWA]

...clip... This would seem to indicate to me that the car does NO balancing when turned off. I don't know who started the "4 hours at full charge" idea but it seems to be false. Other than the 15 minutes after full while all 3 blue lights are on, my guess is that balancing turns off when the car shuts down.

I believe that Phil/Ingineer has said that the car can balance the pack at any time. I'm pretty sure Tony Williams was one of the first to come up with the "4 hour" balancing recommendation. ...clip...

Many of us with the means to record from-the-wall timelines first noticed the "4-hour" sequence 12-18 months ago. After charging to 100%, everything would shut down for approximately 4 hours and then sometimes restart, tapering back to zero amps after 20 minutes or so. There was then no insight to individual cell voltages, but some thought it might be the "second act" of charging after balancing. While much more is known today, battery balancing protocols still seem to a subject of much conjecture -- except perhaps to folks with Nissan NDAs. ;-)

actually we with NDAs know nothing either. when we asked about it, they stated no knowledge of the phenomena either in real life or any talk of it here...

i believe the balancing goes on anytime the car is plugged in or turned on but who knows. with the ELM app, its apparent that whenever balancing goes on, it does a pretty good job of it

 

[bowthom]

Hello,
I've been watching to see if the balancing would take care of my #16 cell. Once it looked like it had come up in voltage but alas that was only one day and it's back in the low pole position. It's interesting that cell #16 is also the low one in the video above.


Aug 10th


Aug 28th


Sept 1


Oct 3 After the P32270 reprogram. #16 looks perfect and it's showing more gids @ 80%. The GOM was goofy for a bit but settled down

 

[dgpcolorado]

Hello,
I've been watching to see if the balancing would take care of my #16 cell. Once it looked like it had come up in voltage but alas that was only one day and it's back in the low pole position.

My cell-pair #48 has always been low since I started tracking it in mid June: usually about 10-30 mV below average. Nissan won't fix it unless it sets an error code.

 

[DaveinOlyWA]

Is it possible that we are mistaking anything less than the stellar balance between the other cells as being bad?

 

[GregH]

I've been watching to see if the balancing would take care of my #16 cell.

Aug 28th


Sept 1

Wow.. what does #16 look like when you're down around VLBW (20-30Gids?)

 

[dgpcolorado]

Is it possible that we are mistaking anything less than the stellar balance between the other cells as being bad?

No. If the lowest cell-pair at a given time were to swap around it wouldn't be significant. When it stays like this for months, I think it is fair to say that it is bad:

 

[GregH]

Is it possible that we are mistaking anything less than the stellar balance between the other cells as being bad?

No. If the lowest cell-pair at a given time were to swap around it wouldn't be significant. When it stays like this for months, I think it is fair to say that it is bad:

Wow.. that really stands out doesn't it.. My cell #1 looks like that but only when I'm down well under VLBW.

 

[bowthom]

I've been watching to see if the balancing would take care of my #16 cell.

Aug 28th


Sept 1

Wow.. what does #16 look like when you're down around VLBW (20-30Gids?)

It's down 50mV
Makes me wonder what gids I'd be getting if #16 had the same relative capacity as the others.

 

[bowthom]

Is it possible that we are mistaking anything less than the stellar balance between the other cells as being bad?

No. If the lowest cell-pair at a given time were to swap around it wouldn't be significant. When it stays like this for months, I think it is fair to say that it is bad:

Wow.. that really stands out doesn't it.. My cell #1 looks like that but only when I'm down well under VLBW.

I'd like to see the cell pairs on a Az leaf with a couple capacity bars gone.

 

[JasonA]

Don't know if this really has to do about weird balancing issues, heat, speed of charging, etc.... as I don't know the Leaf's shunting systems as well as the "masters"do on here but watching Greg's XL unit and what happened to my pack last week after the party (2.950v drop) I'll say this...

I used to charge to 261-265 Gids before the party no problem on 240v... after my REALLY BAD pack drain I could only muster 250-256Gids on 100% and 214-218Gids on 80%...

A number of cells were WAAYYY outta balance.. So last night I started them off at 3.800v and used the 120v brick.

Took 16hrs.....

264Gids and I drove 74 miles in the heat around town today with the AC on all day.

Right now.. all cells are sitting pretty.. Does Trickle help?

It does on our CellLab, Hyperion and iChargers.. so why not here? I mean the rate is still nothing close to 1c (that's DCQC speed).. but why can't 240v even keep up?

My $.02

 

[DaveEV]

Don't know if this really has to do about weird balancing issues, heat, speed of charging, etc.... as I don't know the Leaf's shunting systems as well as the "masters"do on here but watching Greg's XL unit and what happened to my pack last week after the party (2.950v drop) I'll say this...

I used to charge to 261-265 Gids before the party no problem on 240v... after my REALLY BAD pack drain I could only muster 250-256Gids on 100% and 214-218Gids on 80%...

A number of cells were WAAYYY outta balance.. So last night I started them off at 3.800v and used the 120v brick.

Took 16hrs.....

264Gids and I drove 74 miles in the heat around town today with the AC on all day.

Right now.. all cells are sitting pretty.. Does Trickle help?

It does on our CellLab, Hyperion and iChargers.. so why not here? I mean the rate is still nothing close to 1c (that's DCQC speed).. but why can't 240v even keep up?

My $.02

It seems that '13 cars spend a lot more time trickling energy into the pack - they will quickly charge up to 95% or so but then taper off the charge current significantly and spend a good hour to charge from 97-100% with just a trickle going into the pack where a '11-12 will quickly taper off in 15 minutes before stopping.

If the LBC stops balancing the pack 15 minutes after charging stops as it has been hypothesized , then it's quite possible that on the '11-12 using L1 to charge allows the LBC to stay active much longer and thus better balance the pack. I wonder at which point would one hit the point of diminishing returns - one could charge as slow as 6-8A on L1 which would give the car a LONG time to balance, even if only charging from 80-100%.

If it weren't summer I'd be more inclined to charge to 100% to test pack balancing theories...

Would be nice if there was an easy way to turn the current down to an arbitrary level while charging - right now you need a recent EVSEupgrade or build an OpenEVSE to do so.

 

[DaveinOlyWA]

Got up this morning to a pack where about 35 cells were balancing with a delta in the 40 mV range. Previous to this the largest difference I had seen was brief touches of 25 mV with the difference normally around 20.

 

[JasonA]

It seems that '13 cars spend a lot more time trickling energy into the pack - they will quickly charge up to 95% or so but then taper off the charge current significantly and spend a good hour to charge from 97-100% with just a trickle going into the pack.

I thought the P upgrade helped with this? I know mine will sit for sometime or a good while trying to balance, but it seems not to do as good as a job maybe right now on 240v and 33+*c pack temps. For the last 2weeks, my pack has not been below this but never above 39*

Would be nice if there was an easy way to turn the current down to an arbitrary level while charging - right now you need a recent EVSEupgrade or build an OpenEVSE to do so.

I do have both but I don't know if its something the Leaf wants to see as a Trickle? (120v input) or just a reduced PILOT sig on a 240v line. It knows the difference..

But again, I'm not the "MASTER" on this side... does the Leaf balance differently or must know the difference on a 6a 240 pilot and a 15a 120 Trickle?

Today & tomorrow is going to be 105*+ here in the valley so I don't think I'll be doing a full test :|