LeafDD - Dash Display for Leaf

GregH said:

Not sure what to make of the temperature discrepancy.. I should hope I could handle 32+1.8x!!
Page 1 shows the max, but also graphs the relative temps of all 4 relative to max. Page 2 shows all 4 temps in Celsius.. Also note the LeafDD shows temps down to 0.1 degrees Celsius. If the android app is just taking the raw data from the car it's only 1 degree Celsius resolution.. That probably accounts for the difference. LeafDD interpolates tenths of a degree based on the raw thermistor A/D values.

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If the android app was just taking raw data so that there was one degree Celsius resolution, the temperatures would always change in steps of 1.8 degrees F. In fact, the app changes in increments of 0.2 degrees F. Must be something else to explain the difference. We will have to get Turbo3 to chime in here.

PS Love the LeafDD!!! Thanks for making it available.

GregH said:

I'd recommend starting with raw Gids.. We know LBW is 50->49 and VLBW is 25->24.. I wouldn't count on having anything under 5 Gids but YMMV. Honestly if you're under 25 Gids you're probably better off watching the little battery voltage dot.. As long as its not pegged on the right (330V) you've still got a little juice left. I get nervous when I get down to 345V. The true SOC is fun to watch but I don't know really where the bottom is.. Same for Ah*SOC. None of the energy display options on LeafDD will get down to zero... In all cases the car will be dead before then. When you get down to single digits on Gids you might even be better off on the 3rd page where you can see the lowest cell voltage..

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I used your methodology and found it helpful:
1) I start w/SOC (for some reason I just like watching it go up and down)
2) I kept an eye on the voltage "dot" and checked actual value on Pg2 once I hit LBW
3) I flipped to Pg3 to check the lowest cell voltage(s) when I got really low

Stoaty said:

GregH said:

Not sure what to make of the temperature discrepancy.. I should hope I could handle 32+1.8x!!
Page 1 shows the max, but also graphs the relative temps of all 4 relative to max. Page 2 shows all 4 temps in Celsius.. Also note the LeafDD shows temps down to 0.1 degrees Celsius. If the android app is just taking the raw data from the car it's only 1 degree Celsius resolution.. That probably accounts for the difference. LeafDD interpolates tenths of a degree based on the raw thermistor A/D values.

Click to expand...

If the android app was just taking raw data so that there was one degree Celsius resolution, the temperatures would always change in steps of 1.8 degrees F. In fact, the app changes in increments of 0.2 degrees F. Must be something else to explain the difference. We will have to get Turbo3 to chime in here.

PS Love the LeafDD!!! Thanks for making it available.

Click to expand...

Thanks! As for the temperature software... As I get more data points I've been refining it to make sure when LeafDD rolls over from say 21.9 to 22.0 or from 17.0 to 16.9 that the non decimal component matches what the car is reporting. I've been updating the original post in the thread:
http://www.mynissanleaf.com/viewtopic.php?f=44&t=11676
As I get new data.. If the non decimal component of the LeafDD's value does not match the car's then on Page 2 it'll have a little + or - next to the temperature... holding the button down reveals the raw thermistor values. So for example if the LeafDD is calculating 45.9C but the car is reporting 46C then page 1 will still say 45.9, but on page 2 it'll say 45.9+. If you see a + or - please let me know the raw values so I can update the software! I think it's accurate to within 0.1 degrees from about 12 to 44 degrees or so. After that it's probably off no more than 0.1 or 0.2 degrees Celsius.

Received my Leaf DD today.
I decided to mount it over the console and made a mount for it that is Velcroed to the dash. Thought about using metal but figured it would get too hot so I used cardboard instead: white on the front and black on the back for better viewing contrast:

The idea is for it to act as a sunshade for the device as well as a holder and viewing backdrop.


(The unevenness of the display brightness is an artifact of the display/camera interaction.)

I was disappointed, but not surprised, to find my battery "health" at 93.39. I've known that my range was reduced since last winter. (Sure would be nice if there were public charge stations around here. Oh well.)

Sure is nice to be able to track battery temperature and the energy needed for various trips. I found that a trip from town to the top of my mesa takes 33 GID at 77-80ºF temperatures; I'll be interested to see what it is at 20ºF.

It is also nice to see regen adding charge to the battery and watch the SOC% going up. One concern is that one of my battery cells, #48, is consistently lower in voltage than the others.

dgpcolorado said:

Received my Leaf DD today.

I decided to mount it over the console and made a mount for it that is Velcroed to the dash. Thought about using metal but figured it would get too hot so I used cardboard instead: white on the front and black on the back for better viewing contrast

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You beat me to it: I ended mounting mine about the same spot, except I placed the velcro directly on the bottom of the LeafDD case and the top (chrome) plastic of the console. It's so light it stays put. However, it will probably spend most of it's time stored away inside the steering wheel to protect it from heat and theft (see earlier post).

I looked at my 13's steering wheel column, and only have a hole the size of a dime or so there. Did you make that hole bigger, or did they change it in the 2013MY?

lion said:

I looked at my 13's steering wheel column, and only have a hole the size of a dime or so there. Did you make that hole bigger, or did they change it in the 2013MY?

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They must have changed the 2013's, because I definitely didn't make that "hole" bigger! It's larger than a silver dollar

So last night I took my car down to 8 Gids just to see how things looked on LeafDD.. The last 10 Gids or so was burned off in the garage with the heater on. I probably should have taken it down to turtle but I was getting impatient and maybe a little nervous.

Here's how it stacked up down at 13 Gids.. At this point the Voltage dot on page 1 was bumping up against the right edge of the display (334V).
Note SOC 8.5371% and Vcell delta (3.558-3.343) = 215mV



And down even lower at 8 Gids.. At this point the Voltage dot was pinned (pack voltage 322V!!)
Note SOC 6.3168% and Vcell delta (3.462-3.164) = 298mV!!



It probably could have gone a bit lower, but at this point the voltages are dropping like rocks and the spread Vmin to Vmax was getting crazy.
Pretty consistently now my lowest cell at low SOCs is cell#1.. the module right next to the BMS.. The BMS that gets warm during cell balancing.. hmmm.

Looks like your cell #1 might qualify for replacement, or at least
an evaluation, if the cells are well balanced at the top end.

Perhaps some auto-scaling of the wide-range cell voltages would be helpful?

Splendid that you are doing so much with that compact device.

I think I've mentioned it before but my cell-pair 48 is consistently low. Yesterday I noticed that it got even lower in voltage than the others when I neared LBW. This picture was taken this morning at 67 Gid, but it was much the same at the low of 54 Gid (I charged a few minutes to get the battery back over 20%):

Cell-pair 48 was fluctuating between about 3.799 and 3.794 Volts, well below the others.

My concern is that if I get down in the VLBW range the low cell-pair might trigger a turtle or early shutdown because of the low voltage. Might be time to take the car to the dealer, but it seems likely that the LEAF tech there probably hasn't dropped or split any battery packs. (As of January they had sold about a half dozen LEAFs, so it isn't a high volume dealer like so many of you have.)

Any ideas about whether this is something to be worried about?

By the way, anyone know where cell-pair 48 is located? I presume that if they replace it they would just do the whole can with four cells in it, right?

dgpcolorado said:

Any ideas about whether this is something to be worried about?

By the way, anyone know where cell-pair 48 is located? I presume that if they replace it they would just do the whole can with four cells in it, right?

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Definitely; I've never seen this sort of behavior (isn't LeafDD great?). I would schedule a dealer visit ASAP & let us know what they do.

dgpcolorado said:

By the way, anyone know where cell-pair 48 is located? I presume that if they replace it they would just do the whole can with four cells in it, right?

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Interesting.. Yes.. the 4 cells are actually two in series and two in parallel so cell pair 47 and 48 are in module 24.
Module 24 is the last one in the back stack so looking at the back of your car it's on the absolute far right side.
In my car cell #1 (on the far left side, right next to the BMS) is the lowest at VLBW.. Not quite as bad as your 48 but close..
I wondered if my cell #1 was losing capacity because it was being heated by the BMS which no doubt gets warm when all those battery balancing shunts are turned off.. They are a bunch of resistors (one per cell pair) all in one box that bleed off energy from the cells as needed.. noted by a dot on the bottom on page 2 of LeafDD.
In your case it seems suspicious that your weak cell is the absolute far right side... Does the rear right corner of your car get abnormally warm? I'm not sure what could cause this but the location seems odd.

GregH said:

...In your case it seems suspicious that your weak cell is the absolute far right side... Does the rear right corner of your car get abnormally warm? I'm not sure what could cause this but the location seems odd.

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No, nothing unusual about that location in my car. My guess is that "bad cells happen". If it was something about that location then cell-pair 47 ought to be bad also. Same with your 1: what about 2? Same can, same temperatures.

It is very hard to get to the dealer in Durango but I guess I should have it checked out. Then they would have to order the battery module and I'd have to make the trek over the three mountain passes (92 miles each way) yet again. And hope that they don't screw it up so I can take my car home rather than get stuck in Durango for a day or two or three.

dgpcolorado said:

GregH said:

...In your case it seems suspicious that your weak cell is the absolute far right side... Does the rear right corner of your car get abnormally warm? I'm not sure what could cause this but the location seems odd.

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No, nothing unusual about that location in my car. My guess is that "bad cells happen". If it was something about that location then cell-pair 47 ought to be bad also. Same with your 1: what about 2? Same can, same temperatures.

It is very hard to get to the dealer in Durango but I guess I should have it checked out. Then they would have to order the battery module and I'd have to make the trek over the three mountain passes (92 miles each way) yet again. And hope that they don't screw it up so I can take my car home rather than get stuck in Durango for a day or two or three.

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I don't know how the two cell pairs are ordered within the module.. Looking at the rear stack on its side it's possible that within module 1, cell 1 is on the far left.. And for that matter cell 48 in module 24 could be on the far right.. If being on the far right or left side of the rear stack turns out to be problematic for any reason, I'm sure we won't be the only ones to have these problems! As we get more date from more cars a trend may emerge...

Should I be concerned that my "H" number has been dropping like a stone? When I first plugged the LeafDD in on Jun 18, it displayed around 94.3. It has been steadily decreasing since and today it reads 91.89. Have I lost 2% of my battery capacity in the last few weeks alone?

Does the H number ever go up?

ampitupco said:

Should I be concerned that my "H" number has been dropping like a stone? When I first plugged the LeafDD in on Jun 18, it displayed around 94.3. It has been steadily decreasing since and today it reads 91.89. Have I lost 2% of my battery capacity in the last few weeks alone?

Does the H number ever go up?

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I hadn't noticed it go up although others tracking Ah CAP and Health have seen them go up and down... Just this afternoon my Health went from 93.77 while charging to 93.74 after charging to 93.78 during the drive home.. Capacity was 62.2609 the whole time.

Sometimes so much precision can be a curse when you don't have nearly as much accuracy... I'd probably truncate to only one digit past the decimal point...

GregH said:

Just this afternoon my Health went from 93.77 while charging to 93.74 after charging to 93.78 during the drive home.. Capacity was 62.2609 the whole time.

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TomT said:

Sometimes so much precision can be a curse when you don't have nearly as much accuracy... I'd probably truncate to only one digit past the decimal point...

GregH said:

Just this afternoon my Health went from 93.77 while charging to 93.74 after charging to 93.78 during the drive home.. Capacity was 62.2609 the whole time.

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Yeah, just noting when the numbers change.. was kinda surprised to see the health change during the drive. Trying to figure out what makes the BMS update the Ahr cap and health. Didn't really address ampitupco's question though.. Not sure what would make the health drop 2.4% in two weeks! Perhaps a well baked battery? Hopefully some of that comes back.

This is purely a guess, but I would expect "health" to include measured variables such as Amp-hour capacity, max and min voltage differences between cells, and perhaps max falloff rates from a standard voltage.

We have missed an opportunity to test for interrelationships by not bringing our Leaf here to Oceanside. I would expect "health" or at least "capacity" to improve with a move from sustained 95-110° temperatures in the desert to 65-75° here at the overcast coast. (I am not yet up for the find-a-DCQC adventure yet. ;-) )

ampitupco said:

Should I be concerned that my "H" number has been dropping like a stone? When I first plugged the LeafDD in on Jun 18, it displayed around 94.3. It has been steadily decreasing since and today it reads 91.89. Have I lost 2% of my battery capacity in the last few weeks alone?

Does the H number ever go up?

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Check the health vs capacity thread. I posted some plots of the roller coaster ride that the health and cap numbers for my 2012. Up and down up and down.