ULYLeaf
Posts: 3
Joined: Tue Jan 28, 2020 6:16 am
Delivery Date: 28 Jan 2020

Key-off battery drain

Tue Jan 28, 2020 10:42 am

I have not seen this topic addressed, but apologies if this is oft-covered ground.

I understand that the Leaf draws current from its 12 volt battery to power lights and accessories--including, I assume, those systems that need constant current during off mode--computer memory, anti-theft monitoring, clocks, etc.

I also understand that the PbAc battery is recharged by the LI battery. What i can't seem to find is just how and when this is done.

EV wisdom says don't leave the car at 100% charge for "very long." But wouldn't the normal PbAc battery drain as I described above reduce the charge level on the LI battery anyway?

goldbrick
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Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Boulder, CO

Re: Key-off battery drain

Tue Jan 28, 2020 11:43 am

The 12V battery is charged by a DC-DC converter inside the car. This only runs under certain circumstances and I don't really know the details.

The 12V capacity and use is very small compared to what the main Li battery stores so it doesn't have any significant effect on the amount of charge in the Li battery, at least in the time frame of hours. Over the course of days, the 12V battery could pull a few % of charge from the main battery (assuming the car charged it....) but there is no good reason that I can think of to do that.

GerryAZ
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Joined: Mon Nov 22, 2010 6:47 pm
Delivery Date: 12 Jun 2011
Location: Phoenix, AZ

Re: Key-off battery drain

Tue Jan 28, 2020 12:17 pm

The car periodically turns on the DC-DC converter to charge the 12-volt battery from the traction battery while parked. The residual current draw on the 12-volt battery is quite low when the car is parked so there is very little drop in SOC (state of charge) level of the traction battery even when parked for a month. I always make sure the traction battery is not over 70% SOC when parking for extended time.
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; traded 8/10/2019 at 82,436 miles
White LEAF 2019 SL Plus purchased 8/10/2019

ULYLeaf
Posts: 3
Joined: Tue Jan 28, 2020 6:16 am
Delivery Date: 28 Jan 2020

Re: Key-off battery drain

Tue Jan 28, 2020 12:31 pm

Thank you!

LeftieBiker
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Location: Upstate New York, US

Re: Key-off battery drain

Tue Jan 28, 2020 1:10 pm

There are actually many topics on the 12 volt battery, and most of them include a description of how the sometimes-inadequate charging algorithm of the Leaf (especially the earlier years) works - and when it doesn't, like when the car is plugged in but not charging.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

henrydehoja
Posts: 83
Joined: Sun Sep 16, 2018 6:40 pm
Delivery Date: 12 Sep 2018
Leaf Number: 317129
Location: Metro Boston, MA

Re: Key-off battery drain

Wed Jan 29, 2020 4:31 pm

ULYLeaf wrote:
Tue Jan 28, 2020 10:42 am
EV wisdom says don't leave the car at 100% charge for "very long." But wouldn't the normal PbAc battery drain as I described above reduce the charge level on the LI battery anyway?
As mentioned, it is a small drop on the Li-ion battery level over a short period.

Here is my experience, as an example:
I went on vacation in August last year and left my Leaf stored in the garage for 21 days, unplugged, w/o 12V-battery trickle charger.
Li-ion battery level as-left: 87%
Li-ion battery level as-found: 77%

So, I was looking at a 10% drop in the Li-ion battery level after 21 days.
2018 Nissan Leaf S w/QC
Placed in action: 9/2018

GerryAZ
Gold Member
Posts: 2593
Joined: Mon Nov 22, 2010 6:47 pm
Delivery Date: 12 Jun 2011
Location: Phoenix, AZ

Re: Key-off battery drain

Wed Jan 29, 2020 10:01 pm

henrydehoja wrote:
Wed Jan 29, 2020 4:31 pm
ULYLeaf wrote:
Tue Jan 28, 2020 10:42 am
EV wisdom says don't leave the car at 100% charge for "very long." But wouldn't the normal PbAc battery drain as I described above reduce the charge level on the LI battery anyway?
As mentioned, it is a small drop on the Li-ion battery level over a short period.

Here is my experience, as an example:
I went on vacation in August last year and left my Leaf stored in the garage for 21 days, unplugged, w/o 12V-battery trickle charger.
Li-ion battery level as-left: 87%
Li-ion battery level as-found: 77%

So, I was looking at a 10% drop in the Li-ion battery level after 21 days.
That is much more loss of charge than I typically have. Did you leave something plugged in to the OBDII port? I typically see either the same SOC or 1% to 3% loss of charge when I return to the car after as much as a month.
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; traded 8/10/2019 at 82,436 miles
White LEAF 2019 SL Plus purchased 8/10/2019

henrydehoja
Posts: 83
Joined: Sun Sep 16, 2018 6:40 pm
Delivery Date: 12 Sep 2018
Leaf Number: 317129
Location: Metro Boston, MA

Re: Key-off battery drain

Thu Jan 30, 2020 8:55 am

GerryAZ wrote:
Wed Jan 29, 2020 10:01 pm
That is much more loss of charge than I typically have. Did you leave something plugged in to the OBDII port? I typically see either the same SOC or 1% to 3% loss of charge when I return to the car after as much as a month.
Nothing was in the OBDII port. Aside from a USB charger (no-light type) left in the power port with just a cable connected to it, nothing that I saw was connected or left ON.
I'm not sure if the summer heat had anything to do with it. There was construction going on in the house during that time, for a kitchen renovation, and the contractor may have used the garage for extra work space.
That was my first time leaving it alone for such a long time.
2018 Nissan Leaf S w/QC
Placed in action: 9/2018

lorenfb
Posts: 2464
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Key-off battery drain

Thu Jan 30, 2020 9:56 am

The typical standby/sleep-mode Leaf 12V battery current drain should be about 50/60 ma (milliamps). This occurs a few minutes after the
Leaf is locked. Using LeafSpy should provide you an insight as to when the 12V battery is being charged, i.e. a voltage greater than 12.5-13.0.
#1 Leaf SL MY 9/13: 76K miles, 47 Ahrs, 5.0 miles/kWh (average), Hx=70, SOH=73, L2 - 100% > 1000, temp < 95F, (DOD) > 20 Ahrs
#2 Leaf SL MY 12/18: 10.3K miles, SOH 109Ahrs/115Ahrs, 5.2 miles/kWh (average), DOD > 20%, temp < 105F

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Nubo
Posts: 5728
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Location: Vallejo, CA

Re: Key-off battery drain

Thu Jan 30, 2020 11:27 am

GerryAZ wrote:
Wed Jan 29, 2020 10:01 pm
...I typically see either the same SOC or 1% to 3% loss of charge when I return to the car after as much as a month.
This is my experience as well.
I noticed you're still working with polymers.

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