bitflung
Posts: 20
Joined: Wed May 27, 2015 11:27 am
Delivery Date: 26 May 2015
Leaf Number: 023791
Location: Boston, MA

2012 SL battery performance questions/issues with DTCs and leafspy data

Thu Mar 31, 2016 7:43 am

[EDIT: odd... the bbcodes for lists and images didnt' work for me. sorry for the broken formatting, not sure what went wrong exactly
edit2: need list=1 not list= to start the first list, then list=2 for the second list]

Discussion started here: viewtopic.php?f=31&t=4295&start=430#p456845
(sorry, should have started a new thread for this from the start)

Short summary:
  1. 2012 SL bought used in May 2015; ~21k miles on it now; 12 bars
  2. SOH=~84%
  3. Hx=~70.43%
  4. max GIDs = ~225 (seems to differ a bit every day)
  5. zero QC sessions recorded prior to purchase; leaf didn't record the first ~3 QC sessions i performed but did start recording them when i ran leaf spy during a QC session (now up to 9 QC's total reported)
  6. took the leaf for its first "long trip" (beyond a single charge range)
  7. made calculated assumptions about range
  8. observed range appeared significantly less than calculated assumptions
  9. now trying to dig into technical details to see WHY: was it my mistake or is the battery behaving poorly? any chance the battery was reset by the dealer prior to purchase?

As mentioned in the range chart thread (above link):
  1. I observed range only until LBW (or shortly beneath it); i had a toddler in the back seat and knew DCQC sations were ~20 miles apart so was not comfortable driving below LBW
  2. metrics:
  3. ~40F
  4. driving style: ~60mph highway + ~30mph backroads, approx 70/30 split favoring highway; light acceleration and deceleration (i'm accustomed to hypermiling in a Honda Insight)
  5. cabin heater was OFF 100% of the time; steering and seat heaters used ~50% of the time
  6. light occupancy (1 adult @175lbs, 1 toddler @ 30 lbs, otherwise empty)
  7. tires at 40psi (cold)
  8. carwings tells me i got 3.6 mi/kwh over 234 miles (round trip, driving time=7.2hrs) on that day (march 6th, boston area)
  9. SOC ~100% to LBW @ ~37 miles (full overnight charge via L1 evse)
  10. SOC ~80% to LBW @ ~25 miles (SOC was max from DCQC)
  11. sadly I didn't have leaf spy running on the trip (bluetooth fouled up as i was leaving home) and my notes are rough (the above is all i've got)

I was asked to take screenshots of leafspy so I've done that. shots taken this morning after a full charge on L1 evse. car was fully charged for at least ~5 hours while still plugged in.
Images are also shared in google photos here: https://goo.gl/photos/QZKdafKZirzQxssV6

edit: mod notes on pics for further discussion and clarity while figuring out tags.

https://goo.gl/photos/oyF3pFX4yyhbfhLu6 leafspy screen 1, the important view
https://goo.gl/photos/fF42SofvAqhDcAPU9 leafspy screen 2a, nothing of import here
https://goo.gl/photos/6za4Eb1UsgqDiX7z6 leafspy screen 2b, temp data
https://goo.gl/photos/685wy4n4iyRoUpzeA leafspy screen 3, not the screen to discuss battery health
https://goo.gl/photos/yeuM272gbrxt91GG6 leafspy screen 4, the second most important screen
https://goo.gl/photos/SkaAjvBJtxoWA8b97 DTCs reported! ABS low voltage, BCM low voltage

dhanson865
Moderator
Posts: 1492
Joined: Wed May 25, 2011 7:12 am
Leaf Number: 16156
Location: Tennessee

Re: 2012 SL battery performance questions/issues

Thu Mar 31, 2016 3:28 pm

sorry, can't see the pics from here, work proxy doesn't allow some sites. I'll be busy watching the Tesla reveal tonight but I'll try to edit your tags when I get home and take a look at the data.

It'd also be good if you updated your profile with a city, st. I think it is Boston, MA? Should be plenty of data from your post for us to dig into.


Max charge % will always be below 100%. If you get 90% or 92% at full or whatever when charge is done that is not abnormal. My post about ahr isn't related to % SOC in any way.

OK, I've seen the Pics, 90.7% SOC is where you stopped charging at "full" because of temperature and because of the minor cell imbalance) some change in charging habits could balance the pack more but it isn't worth focusing on. It may reblance properly when you deal with the issues below.

The DTCs are worrisome. I'd start with checking the 12v battery disconnected from the car. You could go a couple of routes.

1. Just buy a new 12v and swap and recycle the old 12v never looking back even if it isn't the root cause
2. Buy a new 12v and spend the time and effort testing the old 12v to confirm
3. Test the old 12v (tieing up the car for some time where it can't be used) and then replace if necessary.

Decent chance the 12v battery needs lots of love from a 4 amp CTEK smart desulfating charger if it is still salvageable or that it is so far gone that you just need to replace it.

Insanely Proper testing of the 12v requires a DMM you trust, a CTEK or equivalent smart charger you trust, charging to full outside the car for a couple of days, letting it rest outside the car for an extended period (maybe 12 hours or 24 hours), testing the voltage at rest over time to see how bad the self discharge is, then testing voltage under load to get a better idea of how it holds up in use.

Possible that there is something else going on but you have to rule out 12v issues before you can take the DTCs at face value.

From the looks of the SOH% and AHr it looks like your battery is in considerably better shape than my 2012 that has lived further south than yours. I'm at 77% SOH and 50.73 AHr per leafspy screen 1. Bottom line I'm not concerned about your pack health or any dealer hanky panky like resetting bars.

I'd confirm your tire pressures manually just to confirm all the TPMS data is accurate (the TPMS units are likely more accurate than your handheld gauge but with a low 12v I'd check them), it looks like one is lower than the other 3. In winter I run mine such that they are at sidewall max around 40F so that they aren't any less than 2 PSI lower if the car sits in below freezing air for half the day in my parking lot at work. Winter air lowers the PSI as the tires cool and increases the resistance of both the tires on the ground and the car going through the air. Assuming there are no plugs, patches, tire damage I don't worry about going over sidewall max as I drive but if you want to avoid it you still have room to increase your tire pressure. The F/R weight ratio on the leaf is near 1:1 enough that I only try for 1/2 PSI difference between front and rear tires.

You may lose a slight bit of range if the car is pumping 2+ amps into a dying 12v the whole way. It can get up to several hundred watts during the bulk charge phase near the start of a trip and it will continue to pump more than a healthy battery would require even at the end of a trip if the 12v is unhealthy. Still the range loss would be minor compared to the temperature issues you were dealing with.

Oh and your comment about 0 Chademo sessions when you got it is par for the course. My 2012 didn't have any logged on it back in May 2013 and I QCed 3 times on the drive home from the dealer. I've never QCed since. My current count is 3062 L1/L2 and 3 QC after 47,000 miles.
Blue 2012 Leaf 195/65/15 tires, 15" Rims
Silver 2012 Leaf 16" stock wheels
wiki/index.php?title=Real_World_Battery_Capacity_Loss
(efficiency 3.x KW vs 6.x KW)
please join Truedelta.com and input your repairs.

dhanson865
Moderator
Posts: 1492
Joined: Wed May 25, 2011 7:12 am
Leaf Number: 16156
Location: Tennessee

Re: 2012 SL battery performance questions/issues with DTCs and leafspy data

Thu Mar 31, 2016 11:03 pm

As to driving range I tend to leave the "miles to" block in leafspy screen 4 set to "rsrv" on a long trip and I have reserve set to 0.5 kwh in the settings. That gives you a truer to turtle level range estimate assuming you have the miles per kWh in the right range. Turtle happens based on cell voltage not % SOC but it will be very close to 0.5 kWh remaining. It also has the advantage of being a fixed target instead of relative (SOC% varies as your battery degrades, SOC% is nice for quick math but it isn't apples to apples for a car whose battery degrades as fast as a leaf does). I might cycle through to check how far to LBW and VLBW but I'm not afraid to drive beyond VLBW if I'm in a urban area with options to charge within 10 miles.

Just the difference on LBW to VLBW is something like 10 miles at moderate speeds and LBW to reserve is close to 15 miles (further if you hypermile stretching to reach a charging station). If you are trying to do a 70 mile leg that could be enough to pass up a charging stop and do the charge at the end of the trip instead of the middle.

With a 3.6KW charger a 10 mile L2 stop costs you what an hour in the cold if you leave the car and go inside somewhere? If it is cold enough that you run any heat during the charging that slows down the rate of charging the battery and it can take more than an hour.

You did say you hit turtle once, that I've never done. 215 miles or so I drove from NC to TN over the mountains to my house and the year driving since I've never seen the turtle come on. I came close, I think the lowest I came to on the miles remaining in leafspy was around 2 miles to reserve but I'm not sure what I had reserve set to back then. I probably had more because I set reserve too high.

Good news is you made the trip OK, as things warm up your effective range improves in Spring, Summer, and Fall. You just have to be ready for reduced range in the winter time and adjust.
Blue 2012 Leaf 195/65/15 tires, 15" Rims
Silver 2012 Leaf 16" stock wheels
wiki/index.php?title=Real_World_Battery_Capacity_Loss
(efficiency 3.x KW vs 6.x KW)
please join Truedelta.com and input your repairs.

bitflung
Posts: 20
Joined: Wed May 27, 2015 11:27 am
Delivery Date: 26 May 2015
Leaf Number: 023791
Location: Boston, MA

Re: 2012 SL battery performance questions/issues

Fri Apr 01, 2016 9:18 am

dhanson865 wrote:sorry, can't see the pics from here, work proxy doesn't allow some sites. I'll be busy watching the Tesla reveal tonight but I'll try to edit your tags when I get home and take a look at the data.

I actually plunked down the $1k to reserve a model 3. i might cancel between now and when it ships (nice that there is a no-risk refund policy) but figured if i do want the model 3 i'll want my best crack at getting it before the subsidies run out

It'd also be good if you updated your profile with a city, st. I think it is Boston, MA? Should be plenty of data from your post for us to dig into.

done; yes Boston MA.

Max charge % will always be below 100%. If you get 90% or 92% at full or whatever when charge is done that is not abnormal. My post about ahr isn't related to % SOC in any way.

ok, thanks. so the full Ahr rating from leafspy is ~55Ahr so i've got ~5Ahr left before i expect to lose my first bar?

OK, I've seen the Pics, 90.7% SOC is where you stopped charging at "full" because of temperature and because of the minor cell imbalance) some change in charging habits could balance the pack more but it isn't worth focusing on. It may reblance properly when you deal with the issues below.

i'd like to know more about charging the charging habits you mention.

i generally plug in every day (at least in the winter), but at the end of every day my SOC is generally ~60% or less (with ~22 miles driven each day starting from a full charge, again in winter time). aside from rare trips i exclusively use the L1 charger that came with my leaf. i was under the impression that this was "good" charging behavior?

the overnight charge prior to capturing the screenshots provided the car with 4-5 hours of being "full charged" and still plugged in. i though that was supposed to provide opportunity to balance the cells well?

The DTCs are worrisome. I'd start with checking the 12v battery disconnected from the car. You could go a couple of routes.
[...]

the 12 volt failed shortly after i bought the car. using a simply multimeter i measure the battery at less than 8v. the dealership replaced it with a new battery last summer/fall. if this new battery has already failed i would be concerned that the DC-DC converter is somehow damaging the battery...

as you can see on most leafspy screens the 12v is reported as 13.04volts (screen 3 appends this with 1.85amps... leafspy documentation doesn't seem to state what this is supposed to tell me, so i wonder if it is discharging at 1.85a or pulling 1.85a from the DC-DC converter?)

Possible that there is something else going on but you have to rule out 12v issues before you can take the DTCs at face value.

i am thinking the dealership service tech likely forgot to clear the DTCs after replacing the 12v battery. they also likely failed to READ the DTCs back then too, since prior to replacing the battery they actually replaced the head unit (stereo/nav) as it was behaving oddly on a failed 12v battery (screen kept opening and closing, over and over, any time the car was off. i stopped it by half-inserting a CD).

i've now used leafspy to reset all DTCs and will monitor from time to time to see if any return.

From the looks of the SOH% and AHr it looks like your battery is in considerably better shape than my 2012 that has lived further south than yours. I'm at 77% SOH and 50.73 AHr per leafspy screen 1. Bottom line I'm not concerned about your pack health or any dealer hanky panky like resetting bars.

that's great news - thanks for the insight.

I'd confirm your tire pressures manually just to confirm all the TPMS data is accurate (the TPMS units are likely more accurate than your handheld gauge but with a low 12v I'd check them), it looks like one is lower than the other 3. [...]

i use a digital guage at home, built into a compressor. i top off to 40lbs every other month or so. it does seem that one tire is losing pressure faster than the others, it may have a small leak (we've had a lot of work done on the house lately, could be a nail in there somewhere).

prior to the trip in question i topped off within minutes of departure. generally i'm very confident that the tires are well maintained at ~40lbs.

You may lose a slight bit of range if the car is pumping 2+ amps into a dying 12v the whole way. It can get up to several hundred watts during the bulk charge phase near the start of a trip and it will continue to pump more than a healthy battery would require even at the end of a trip if the 12v is unhealthy. Still the range loss would be minor compared to the temperature issues you were dealing with.

when the dead 12v battery was replaced i saw an immediate improvement in range. reacll i've had the car for less than a year, so prior to the battery replacement last summer/fall i was struggling to differentiate between perceived range issue (noobie range anxiety) and real issue (failing components). i didn't yet have a working ODBC module back then, so i wasn't using leafspy yet, but prior to replacing the 12v i couldn't comfortably drive 2 days in a row without charging overnight; after replacing the 12v i was able to drive two days in a row very easily (22 miles round trip each day, all backroads at max 30mph). i still don't think i could make 3 days in a row without charging (66 total miles all at <30mph on easy, mostly level backroads).

i'm hopeful that by using leafspy and monitoring the DTE to 0.5kwh this will change and i'll be able to push to 3 days between charges (if only for the sake of knowing i can do it - with a toddler in the backseat i don't plan to actually push so close to the limit very often)

Oh and your comment about 0 Chademo sessions when you got it is par for the course. My 2012 didn't have any logged on it back in May 2013 and I QCed 3 times on the drive home from the dealer. I've never QCed since. My current count is 3062 L1/L2 and 3 QC after 47,000 miles.
wow, really? never QC'd again after that? are there no QC's in your area or do you just find that you don't need them?

there are actually a good number of QC's around here, though in my recent experience the QCs at ~50% of Nissan dealerships are dead/non-functional. (small sample size: only went to 6 dealerships on that journey, 3 had nonfunctinal QCs). the most reliable QCs i've found are also the most expensive: eVgo chargers were 100% operational on my journey (i think i hit 3-4 of those) but i also spent ~$50 charging on them (yeah, grossly outweighing what i would have spent on fuel on the same trip if i had driven my wife's subarau outback).

bitflung
Posts: 20
Joined: Wed May 27, 2015 11:27 am
Delivery Date: 26 May 2015
Leaf Number: 023791
Location: Boston, MA

Re: 2012 SL battery performance questions/issues with DTCs and leafspy data

Fri Apr 01, 2016 9:32 am

dhanson865 wrote:As to driving range I tend to leave the "miles to" block in leafspy screen 4 set to "rsrv" on a long trip and I have reserve set to 0.5 kwh in the settings. That gives you a truer to turtle level range estimate assuming you have the miles per kWh in the right range.
[...]
Just the difference on LBW to VLBW is something like 10 miles at moderate speeds and LBW to reserve is close to 15 miles (further if you hypermile stretching to reach a charging station). If you are trying to do a 70 mile leg that could be enough to pass up a charging stop and do the charge at the end of the trip instead of the middle.

leafspy currently shows me DTE=39.9mi to LBW, 47.5mi to VLBW, and 52.6mi to 0.5kwh (all with mi/kwh set to 4.0, which is a reasonable upper-limit estimate for my average daily commute)

With a 3.6KW charger a 10 mile L2 stop costs you what an hour in the cold if you leave the car and go inside somewhere?

you mean 1 hour to get an additional 10 miles of range? on a long trip, for me, that MIGHT get me to the next charging station....

If it is cold enough that you run any heat during the charging that slows down the rate of charging the battery and it can take more than an hour.

yeah on the journey in question (specifically on the return trip, after business hours) i did run the heat while charging. i also brought my kid up the the front seat and we watched curious george on my phone. with all the frustrations of that drive if it weren't for good data connectivity and netflix/pbs-kids on my phone i doubt my son would have handled it well enough to push through for the rest of the drive.

key take-away: if you've got young kids, an EV, and plan to drive beyond your range then you absolutely need something to entertain the kids. a LOT of something to entertain the kids. i burned through 2GB of data by playing curious george while charging....

You did say you hit turtle once, that I've never done.

it was back when i had the failed 12v battery though, so i'm not sure it counts for much.

215 miles or so I drove from NC to TN over the mountains to my house and the year driving since I've never seen the turtle come on. I came close, I think the lowest I came to on the miles remaining in leafspy was around 2 miles to reserve but I'm not sure what I had reserve set to back then. I probably had more because I set reserve too high.

WOW. 215 miles?!? my ~230 mile round trip took about 12 hours of driving and charging time, all with very little elevation change. do you recall how long it took you to make your drive?

Good news is you made the trip OK, as things warm up your effective range improves in Spring, Summer, and Fall. You just have to be ready for reduced range in the winter time and adjust.

yeah. it took a bit to convince my wife (who stayed home at ~7 months pregnant) that we would be ok taking my car. after the negative experience of that trip i don't think i'll ever win her over again. no matter what improvements the spring/summer hold for range, i don't think she'll be ok with me taking our son on a long trip with the leaf ever again.

that's the saddest part of the whole experience. she sat at home, watching google+ location tracker so she knew we were making progress, the whole time hating that i drove my leaf beyond ~40 miles. and so that's the end of it for the leaf: she will never be ok with it taking a long journey again. i can't blame her.

i might try a trip to the cape by myself sometime, but with a 2nd kid on the way (end of april) it's unlikely i'll have the opportunity any time soon.

dhanson865
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Joined: Wed May 25, 2011 7:12 am
Leaf Number: 16156
Location: Tennessee

Re: 2012 SL battery performance questions/issues

Fri Apr 01, 2016 3:06 pm

bitflung wrote:ok, thanks. so the full Ahr rating from leafspy is ~55Ahr so i've got ~5Ahr left before i expect to lose my first bar?


No, you'll lose that bar in the next few weeks. Any day now. Your 55 Ahr is below 56 so you could drop it the next warm day you see or might hold out for a little bit longer. You definitely won't make it below 54 AHr without losing the bar.

Loss of bar 12 - between 53.75 AHr and 56 AHr.

as you can see on most leafspy screens the 12v is reported as 13.04volts (screen 3 appends this with 1.85amps... leafspy documentation doesn't seem to state what this is supposed to tell me, so i wonder if it is discharging at 1.85a or pulling 1.85a from the DC-DC converter?)


positive amps is going from the HV battery pack / inverter to the motor or to the 12v bus (to charge the 12v battery). negative amps is charging the HV pack. 13 volts is float charge level meaning it isn't doing much to help if the battery is low. The leaf has a complex charge routine for the 12v so you can't easily watch leafspy and see what is happening, you need to test the 12v with a smartcharger + DMM.

generally i'm very confident that the tires are well maintained at ~40lbs.


yes, but 40 PSI at what temp? are you checking in a heated garage? In a cool but not cold garage? In a parking lot in the day? At night? You need 40 PSI at the coldest temp you'll drive at to get decent range in the harsh sub freezing wintertime. You should be setting it such that if your car sits outside in the cold for 24 hours the PSI don't go below 40 even at the coldest point during that day.

wow, really? never QC'd again after that? are there no QC's in your area or do you just find that you don't need them?


The Chademo's here are Blink network and charge something like $9 a charge. Not a good deal when I can charge at home for $0.10 per kWh or charge at work for free.
Blue 2012 Leaf 195/65/15 tires, 15" Rims
Silver 2012 Leaf 16" stock wheels
wiki/index.php?title=Real_World_Battery_Capacity_Loss
(efficiency 3.x KW vs 6.x KW)
please join Truedelta.com and input your repairs.

dhanson865
Moderator
Posts: 1492
Joined: Wed May 25, 2011 7:12 am
Leaf Number: 16156
Location: Tennessee

Re: 2012 SL battery performance questions/issues with DTCs and leafspy data

Fri Apr 01, 2016 4:47 pm

Hickory, NC, drove to Knoxville, TN. Including the diversions off I-40 to charge it was over 225 miles.

https://evtripplanner.com/planner/2-5/?id=cym3 is roughly what I did (I messed up at one point and used Google maps walking directions instead of car directions and took a slightly different route from black mountain to asheville to waynesville)

the zigzag through asheville was me going to a chademo charge point that I couldn't use, then falling back to another that was further out of the way.

the waynesville detour was to hit another chademo because there wasn't a single DC charger between there and home so I wanted every last drop of range I could get before I had to go through the wastelands of 10 mph L2 charge points.

fwiw I hit VLBW twice on my trip home, with 3 miles range on the GOM in Black Mountain, NC and with --- on the GOM when I pulled into the driveway at home (in fact I drove on --- for several miles).


apparently EV triplanner has purged the old trip plans, so i'd have to recreate the trip plan again manually. I could do it but it probably isn't worth my time.

It took me about 12 hours including charging and meal breaks but I took my time and if I had it to do over again I could cut an hour or two off that trip by not going to chargers that I couldn't charge at, driving faster routes, driving closer to empty or not sitting as long at one of the chargers. On top of that if I did it today I'd have multiple Chademos that didn't exist last year and I could probably cut it down to 8 or 9 hours.
Blue 2012 Leaf 195/65/15 tires, 15" Rims
Silver 2012 Leaf 16" stock wheels
wiki/index.php?title=Real_World_Battery_Capacity_Loss
(efficiency 3.x KW vs 6.x KW)
please join Truedelta.com and input your repairs.

bitflung
Posts: 20
Joined: Wed May 27, 2015 11:27 am
Delivery Date: 26 May 2015
Leaf Number: 023791
Location: Boston, MA

Re: 2012 SL battery performance questions/issues with DTCs and leafspy data

Wed Apr 06, 2016 12:26 pm

dhanson865 wrote:
Hickory, NC, drove to Knoxville, TN. Including the diversions off I-40 to charge it was over 225 miles.
[...]


apparently EV triplanner has purged the old trip plans, so i'd have to recreate the trip plan again manually. I could do it but it probably isn't worth my time.

It took me about 12 hours including charging and meal breaks but I took my time and if I had it to do over again I could cut an hour or two off that trip by not going to chargers that I couldn't charge at, driving faster routes, driving closer to empty or not sitting as long at one of the chargers. On top of that if I did it today I'd have multiple Chademos that didn't exist last year and I could probably cut it down to 8 or 9 hours.

thanks for that - too bad about the evtripplanner maps being purged though.
ok, so my 12 hour 234 mile round trip isn't so far off then.

i was hoping to drive my battery down into sub-LBW territory over the last few days but we had some freak late season snow and i charged up to ensure i could run the heat and defrost the windows.

i'll test down into sub-LBW in the coming week or so though.
for what it is worth: the old DTCs haven't resurfaced. i'm feeling rather confident they were just never cleared out by the nissan tech when they replaced the battery (and, as i mentioned, the stereo. though the stereo likely didn't need to be replaced at all)

dhanson865
Moderator
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Joined: Wed May 25, 2011 7:12 am
Leaf Number: 16156
Location: Tennessee

Re: 2012 SL battery performance questions/issues with DTCs and leafspy data

Wed Apr 06, 2016 1:31 pm

I did my 12 hour trip with a lot of L2 charging on a 3.6KW car

Something to keep in mind on your 100+ mile trips.

The charging speeds of L2 and chademo in mph are

L2 16a (3.6KW charger in the car) about 11 mph
L2 27.5a (6.6KW charger in the car) about 22 mph
old Chademo about 80 mph
new chademo faster than you care about.

Now think that those speeds are miles per you sitting still for one hour, meaning if you charge at 22 mph, you are sitting still for 4 hours to drive 88 miles (at 60 mph that is 88 minutes). That means your total speed for that leg of a trip is 88/328*60 or 16 miles per hour.

edit: 328 is the number of minutes spent charging and driving if you drive 88 minutes and charge 240 minutes (240 from 88 / 22 assuming charging on L2 with a 6.6KW charger).

If you drove 50 instead of 60 you'd spend less time charging and your average speed would increase.

In fact if you drove 30 mph instead of 60 you'd get there quicker assuming the trip is long enough that you can't make it on a single charge and you have to charge on L2 with a 6.6KW charger.

If you have a Chademo or multiples to use along the way it will be faster to keep up with traffic but if you have to charge at L2 for any reason you are better off slowing down, you'll get there sooner driving slow.

It'd take a lot of math to determine the exact ideal speed because efficiency is best around 12 mph and you likely want to drive 3 to 5 times that fast. The practical option is to drive as slow as you can without causing an accident if you know you have to drive to an L2.
Blue 2012 Leaf 195/65/15 tires, 15" Rims
Silver 2012 Leaf 16" stock wheels
wiki/index.php?title=Real_World_Battery_Capacity_Loss
(efficiency 3.x KW vs 6.x KW)
please join Truedelta.com and input your repairs.

bitflung
Posts: 20
Joined: Wed May 27, 2015 11:27 am
Delivery Date: 26 May 2015
Leaf Number: 023791
Location: Boston, MA

Re: 2012 SL battery performance questions/issues with DTCs and leafspy data

Wed Apr 06, 2016 3:07 pm

dhanson865 wrote:I did my 12 hour trip with a lot of L2 charging on a 3.6KW car

ok, makes sense. in my case i was nearly 100% DCQC (aside from two L2 charges at 3.6kW specifically where the nissan owned infrastructure was dead and i couldn't make it to the next DCQC without some help)

Something to keep in mind on your 100+ mile trips.
The charging speeds of L2 and chademo in mph are

L2 16a (3.6KW charger in the car) about 11 mph
L2 27.5a (6.6KW charger in the car) about 22 mph
old Chademo about 80 mph
new chademo faster than you care about.

the 6.6kW charge times don't affect me (my used leaf is a 2012 SL with only the 3.3kW onboard charger and no way to upgrade)
but wait: "new chademo"?? i didn't know there was such a thing. can you link to an example in plugshare/similar so i can see what to search for?

Now think that those speeds are miles per you sitting still for one hour, meaning if you charge at 22 mph, you are sitting still for 4 hours to drive 88 miles (at 60 mph that is 88 minutes). That means your total speed for that leg of a trip is 88/328*60 or 16 miles per hour.

i'm sorry, but i dont' see where that "328" is coming from?

the numbers you provided seem to use ~25kw as the average for a DCQC session and i've seen similar numbers elsewhere. in fact that's what i used to plan my trip.

25kW * 1hr = 25kWh; @3.6mi/kWh that gives me a charging rate of 90mph (somewhat optimistic compared to your numbers, but not much and it is based on my actual mi/kwh rating which was spot on with my expected rating when planning the trip)

to travel beyond my battery range i figured on the following formula:
[time spent charging] = [total distance - initial range]/[90mph]
for my troublesome trip each leg was 107 miles so round trip was 214. i estimated my initial range at 64 miles from 100% SOC. so the formula worked out at:

[time spent charging round trip] = [(214mi - 64mi) / 90mph] = 1.67hr
or for the first leg:
[time spent charging first leg] = [(107mi - 64mi) / 90mph] = 0.48hr

clearly i expected to spend more time charging on second half than on the first half of the trip.
[total drive time] = [charge time] + [distance/velocity]

for the first leg i figured that would be: [0.48hr] + [107mi/60mph] = 2.26hr
for the return trip i figured it would be: [1.67hr - 0.48hr] + [107mi/60mph] = 2.97hr

I planned for an additional 30 minutes each way in case my mi/kwh were significantly lower than initially planned, so my "flight plan" included two 30 minutes stops on the first leg and a total trip duration of ~3hrs.

actual chademo charging rates were much slower for me, taking 1hr+ where i expected only ~0.5hr. i also charged more often than planned. this, coupled with hunting for a charger that wasn't out of order (on both legs) put my actual driving time in each direction at ~6hrs.

If you drove 50 instead of 60 you'd spend less time charging and your average speed would increase.

this makes sense too. though the ratio of driving to charging time is less important than the total duration of the trip. taking it to the extreme i could drive ~20mph the whole way and get close to 5mi/kwh to drastically improve my driving:charging ratio... but it would be slower than riding a bicycle (where i never have to stop to charge and would stop to eat/etc about the same frequency).

using the above math:
[initial range scaled by 5.0/3.6] = [64mi] * [(5.0mi/kWh) / (3.6me/kWh)] = 88mi
[25kW*1hr] * [5.0mi/kWh] = 125mph rate of charge.
[time spent charging round trip] = [(214mi - 88mi) / 125mph] = 1.0hr
[time spent charging first leg] = [(107mi - 88mi) / 125mph] = 0.15hr

i would spend less time charging but more time driving:
[total duration] = [1.0hr charge time] + [214mi / 20mph] = 11.7hr

so the net result is the same trip duration, more or less. i'm jot sure i could have found backroads as direct as the highways i was on (so distance may have increased) and surely all the stop lights and city traffic would have lowered my mi/kWh rating (i would have driven right through Boston and surrounding urban areas).

In fact if you drove 30 mph instead of 60 you'd get there quicker assuming the trip is long enough that you can't make it on a single charge and you have to charge on L2 with a 6.6KW charger.

funny that i just wrote out a 20mph equivalent to this comment based on DCQC. i can't charge at 6.6kw so the ratios are different for me but based on the above i doubt my total trip duration would have improved by driving more slowly.

If you have a Chademo or multiples to use along the way it will be faster to keep up with traffic but if you have to charge at L2 for any reason you are better off slowing down, you'll get there sooner driving slow.

thankfully i did find chademos along my route. with a 3.3kW L2 charger i wouldn't have risked the drive at all without knowing before hand that there were a good number of chademos along the route. now if only the chargers at nissan dealerships were dependaly functional and not parked in by dealership owned inventory.... yeah i am still frustrated by that and i'll repeat that Coastal Nissan deserves a cold shoulder from EV drivers and potential buyers. apparently it is quite normal for them to park ICE inventory in the EV spots and if you get there after hours there is no one around to move them out of the way.

It'd take a lot of math to determine the exact ideal speed because efficiency is best around 12 mph and you likely want to drive 3 to 5 times that fast. The practical option is to drive as slow as you can without causing an accident if you know you have to drive to an L2.

the absolute best mi/kWh rating i've gotten over a 10+ mile trip, even driving <20mph on backroads, was 5.2mi/kWh. i can just about hit 5.0mi/kWh if i drive carefully even up to ~30mph, but i have to annoy the folks behind me as i slowly stagger away from stops or cruise to the next stop without using my brakes.

in my experience there doesn't seem to be any gain for driving less than ~20mph and nearly zero difference between 20 and 30mph. above 30 and i do see an immediate drop in mi/kWh. i haven't tracked how the lower end of the ratings scale at speed though since i so rarely drive on highways (and when i do i'm generally on a trip that is more important to me than tracking these things for future reference).

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