estomax
Posts: 81
Joined: Fri Jan 20, 2017 9:23 pm
Delivery Date: 21 Jan 2017
Location: Seattle

D mode stays on even while on B mode

Thu Jun 08, 2017 10:45 am

Hey Guys,

i noticed this the last couple of times i drove my Leaf, but when i start with a full charge, then even in B mode it never actually goes to B mode once a little bit of battery wears off to allow more regen. i can switch between D and B and there is no regen difference at say 40 mph (while usually there should be a large difference). power cycling the car seems to fix this , but i was wondering if anyone else has noticed this?

cheers,
Marko

edit: bringing more info to the first post. First, this happens at various SOC levels, it is normal for the car to not regen during high SOC, but this happens even at 30% SOC, when regen should function fully. i also once noticed that even though the B mode functioned correctly, the brake pedal regen did't work (pressing the brake didnt increase regen). All these symptoms are intermittent and happen once or twice during a long drive, so not very easy to reproduce. One more symptom to the list is that cruise control disengages on its own, randomly, has happened 3 times in the last week where i use it maybe once per day when traffic allows. The battery voltage at rest is 12.6V so unlikely that the aux battery is going bad.

here are the latest errors:
Image
Last edited by estomax on Sun Jun 18, 2017 3:23 pm, edited 4 times in total.
2013 Leaf SL Premium
27k, 93% SoH, 2/17
32k, 96% SoH, 6/17
37k, 92% SoH, 9/17

alozzy
Posts: 601
Joined: Fri Jan 20, 2017 4:25 pm
Delivery Date: 18 Jan 2017
Location: Vancouver, BC
Contact: Website

Re: D mode stays on even while on B mode

Thu Jun 08, 2017 11:15 am

Can't say I've noticed it as I seldom charge to 100%, but it makes logical sense since regen is charging the battery pack at a rate of up to 30kW.

If regen was permitted when there's a high state of charge already, then individual cells could end up being over voltage - not good. I'm no expert with LION batteries, but I suspect this is a prudent measure to avoid damage to the battery.
Vancouver, CA owner of a 2013 Ocean Blue SV + QC, purchased 01/2017 in WA
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magico13
Posts: 55
Joined: Thu Dec 22, 2016 12:39 pm
Location: Cleveland, OH

Re: D mode stays on even while on B mode

Thu Jun 08, 2017 12:25 pm

Max regen is reduced at high states of charge. I don't know what the limit is, but at 99%+ I can only get one dot of regen, at 98% I can start to get two dots, and after that I'm usually on the highway so I haven't gotten to test any others. I think by 90% it's back to full regen available. Unfortunately that makes braking at high states of charge really weird in comparison to braking at other charge states, so I have to remember to drive differently in the morning than in the evening.
2015 SV w/ QC

alozzy
Posts: 601
Joined: Fri Jan 20, 2017 4:25 pm
Delivery Date: 18 Jan 2017
Location: Vancouver, BC
Contact: Website

Re: D mode stays on even while on B mode

Thu Jun 08, 2017 2:07 pm

At full regen rate (30 kw), 1 min of braking at that rate would add 0.5 kWh of energy to the pack battery.

So, 0.5 kWh / 21 kWh is about 2.4% of pack charge added per minute of MAX regen.

Given that max rate, one would have to be doing a lot of braking to significantly charge the pack.

So, I don't get why Nissan chose to be so conservative with limiting regen at low 90% SOC. I guess they just wanted to be sure no individual cells would be over voltage...
Vancouver, CA owner of a 2013 Ocean Blue SV + QC, purchased 01/2017 in WA
Zencar 12/20/24/30A L1/L2 portable EVSE
1-1/4" Curt #11396 hitch
After market, DIY LED DRLs
LeafSpy Pro + Konnwei KW902 ELM327 BT OBDII dongle
Loving my first BEV :D

jjeff
Posts: 1387
Joined: Wed Jan 13, 2016 9:10 am
Delivery Date: 13 Jul 2014
Leaf Number: 422121
Location: MSP MN

Re: D mode stays on even while on B mode

Thu Jun 08, 2017 2:10 pm

And the worst part is as your battery degrades, it gets much worse :(
Just when you could use the extra regen from a degraded battery pack, you basically get none :x
My '12(missing 2 bars) has zero to little regen, even as low as 30% SOC! My '13(full bars) has more regen at 95% SOC than my '12 at a low SOC!
2012 SL purchased used 2/'16
2013 S w/QC purchased new
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GerryAZ
Gold Member
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Re: D mode stays on even while on B mode

Thu Jun 08, 2017 7:25 pm

Regeneration is limited by maximum allowable cell voltage (or pack voltage if pack is well balanced). This means that high SOC, low battery temperature, and higher internal resistance of deteriorated battery all contribute to reduced regeneration. The lithium battery controller (LBC) limits maximum cell voltage so it limits the regeneration at high SOC to avoid over voltage of the highest cell. If the pack is well balanced, the total pack voltage will be higher before the highest cell reaches the maximum so the LBC allows more regeneration.
Gerry
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015

estomax
Posts: 81
Joined: Fri Jan 20, 2017 9:23 pm
Delivery Date: 21 Jan 2017
Location: Seattle

Re: D mode stays on even while on B mode

Thu Jun 08, 2017 9:00 pm

sorry, i think my post was unclear. At full charge this is expected, but i am noticing this when i am at 30% charge near the end of my trip this morning for example.

maybe i need to plug in with leaf spy and see if i have some unbalanced cells.. but my SOH is very high and i made a 63 mile trip this morning with 23 miles to spare when i got to my destination (80% interstate 60-65mph, albeit with some traffic here and there). just a strange gremlin in the software is what i think.
2013 Leaf SL Premium
27k, 93% SoH, 2/17
32k, 96% SoH, 6/17
37k, 92% SoH, 9/17

jjeff
Posts: 1387
Joined: Wed Jan 13, 2016 9:10 am
Delivery Date: 13 Jul 2014
Leaf Number: 422121
Location: MSP MN

Re: D mode stays on even while on B mode

Fri Jun 09, 2017 3:57 am

Going off what gerryAZ said then, it sounds like you have a few cells that are a much higher SOC%(or voltage) than the rest, limiting your overall regen....not sure why this would be the case, other than if your battery is quite a bit out of balance. Do you regularly or have you lately charged your Leaf up to 100%? Apparently it should be fully charged occasionally to balance the individual cells, sounds like your pack is out of balance.
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a

estomax
Posts: 81
Joined: Fri Jan 20, 2017 9:23 pm
Delivery Date: 21 Jan 2017
Location: Seattle

Re: D mode stays on even while on B mode

Fri Jun 09, 2017 8:08 am

i charge to 100% with L2 almost every day. next time it does this i will have to plug in my obd dongle and leafspy to have a look.

are there any trouble codes that get stored with that?

cheers
Marko
2013 Leaf SL Premium
27k, 93% SoH, 2/17
32k, 96% SoH, 6/17
37k, 92% SoH, 9/17

estomax
Posts: 81
Joined: Fri Jan 20, 2017 9:23 pm
Delivery Date: 21 Jan 2017
Location: Seattle

Re: D mode stays on even while on B mode

Fri Jun 09, 2017 7:37 pm

ok it did it again today, similar to yesterday morning, when my range was around 30 miles on the GOM (today was exactly 31% also, i looked on the % gauge). I was going down a hill and felt the regen fall off and the car would only regen at 10 while coasting down a hill.

i threw leafspy / obd dongle at it when i got to my destination and this is what it showed me before i shut the car off (this B-mode dropout happened half a mile from my destination).

Image
Image

this definitely did not use to happen during the winter when i was driving it to work and back and getting the range below 30 on the GOM.

going to start googling those codes now.

Marko

PS, after completing my visit and getting in the car, i drove home with B mode with no problems, (about 10-15 miles), so powercycling took care of the bug / lockout.
2013 Leaf SL Premium
27k, 93% SoH, 2/17
32k, 96% SoH, 6/17
37k, 92% SoH, 9/17

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