lorenfb
Posts: 2487
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Wed Dec 16, 2020 10:30 pm

Some Leaf owners have experienced the condition where the 12V battery was weak preventing
the Leaf from “starting”, requiring a jumper 12V battery. This problematic 12V battery condition
may occur if the Leaf has not been driven or connected to an EVSE for a number of days/weeks,
or when the 12V battery nears its end of life.

Obviously one can always connect an external 12V charger, but occasions may occur where an external
charging source is not available. Typically Leaf1 & Leaf2 charge the 12V battery while in the “run” mode
to 12.9/13.1 volts, which is not very effective when the 12V battery is weak or has prevented the Leaf
from “starting”. Although when the Leaf is initially started, the 12V battery is typically charged to about
14.2 volts for about a minute.

Under a unique condition, i.e. the windshield wipers being on, the Leaf’s 12V battery charges to about 14.2V
as long as the wipers are on. By using the wipers in the intermittent mode with delay being the longest,
the 12V charging voltage will be continuously at about 14.2V. With just one momentary activation
of the wipers, the 12V battery will be charged at about 14.2V for about one minute. So, leaving the
wipers on with longest delay will continuously charge the 12V battery to about 14.2V without
having the wipers fully on. It is unknown whether this Leaf function is documented in any Nissan info,
so some might consider it a software “easter-egg”.

After having posted this on MNL shortly after leasing my 2013 Leaf, I never really thought of a use
until today when 2013 Leaf had not been driven in over a week and the door button unlocking function
appeared to not function. After a few tries, the door unlocked and I was able to "start" the Leaf.
After remembering the feature I had discovered, I decided to leave the wipers in the delayed mode
as I drove for about 30 minutes to assure that the 12V battery received an adequate charge.
#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

GerryAZ
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Location: Phoenix, AZ

Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Wed Dec 16, 2020 11:00 pm

If the 12V battery is low so that it will absorb charging current, then the DC-DC converter will charge at between 14 and 14.5 volts until the current flowing into the battery drops below a threshold (indicating that the battery is fairly well charged) so there is no advantage to running the wipers. The DC-DC converter will charge the 12V battery when the car is in run mode and also when the car is actively charging the traction battery. The 12V is not charged when the car is plugged in but not actually charging.
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

coulomb
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Joined: Thu Oct 09, 2014 5:08 pm
Delivery Date: 07 Mar 2015
Leaf Number: 200445
Location: Brisbane, Australia

Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 7:18 am

GerryAZ wrote:
Wed Dec 16, 2020 11:00 pm
If the 12V battery is low so that it will absorb charging current, then the DC-DC converter will charge at between 14 and 14.5 volts until the current flowing into the battery drops below a threshold (indicating that the battery is fairly well charged) so there is no advantage to running the wipers.
That's definitely not been my experience with a 2012. Either the current threshold is too high, or it just assumes that a few minutes of over-14V charging should fill the auxiliary battery.

My understanding is that later models behave better, but are still not ideal.
2012 Leaf with new battery May 2019. New to me June 2019.

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Stanton
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Leaf Number: 7458
Location: Plano, TX
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Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 7:59 am

I have one of those Antigravity Battery Tracker devices on my 12v...and it shows that the charge level "spikes" to 14v every 15 minutes (or so). You can't expect a (standard) lead acid battery to last in any car, let alone an EV with parasitic drain. Those of you who follow my 12v Lithium thread know that I'm way past 5 years on mine with no issues (and no special treatment).
2011 Blue Ocean SV w/floor mats & window tint
Lithium Pros 12v LiFePO4 battery w/Antigravity Battery Tracker
FIAMM 74100 horns
Wet Okole seat covers
Tor's low-power heater mod
2013 sun visor
Battery Pack replaced (Rev E) @51 months and 41k miles

DaveinOlyWA
Posts: 15447
Joined: Sat Apr 24, 2010 7:43 pm
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Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 8:50 am

Stanton wrote:
Thu Dec 17, 2020 7:59 am
I have one of those Antigravity Battery Tracker devices on my 12v...and it shows that the charge level "spikes" to 14v every 15 minutes (or so). You can't expect a (standard) lead acid battery to last in any car, let alone an EV with parasitic drain. Those of you who follow my 12v Lithium thread know that I'm way past 5 years on mine with no issues (and no special treatment).
Interesting. I am guessing this only happens when car is running? How long do these spikes last?
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 16,686 mi, 91.51% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

lorenfb
Posts: 2487
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 11:00 am

DaveinOlyWA wrote:
Thu Dec 17, 2020 8:50 am
Stanton wrote:
Thu Dec 17, 2020 7:59 am
I have one of those Antigravity Battery Tracker devices on my 12v...and it shows that the charge level "spikes" to 14v every 15 minutes (or so). You can't expect a (standard) lead acid battery to last in any car, let alone an EV with parasitic drain. Those of you who follow my 12v Lithium thread know that I'm way past 5 years on mine with no issues (and no special treatment).
Interesting. I am guessing this only happens when car is running? How long do these spikes last?
That's what's key!
#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

lorenfb
Posts: 2487
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 11:14 am

GerryAZ wrote:
Wed Dec 16, 2020 11:00 pm
If the 12V battery is low so that it will absorb charging current, then the DC-DC converter will charge at between 14 and 14.5 volts until the current flowing into the battery drops below a threshold (indicating that the battery is fairly well charged) so there is no advantage to running the wipers.
Do you know what this actual value is?
GerryAZ wrote:
Wed Dec 16, 2020 11:00 pm
The DC-DC converter will charge the 12V battery when the car is in run mode and also when the car is actively charging the traction battery. The 12V is not charged when the car is plugged in but not actually charging.
Most are aware of this, and it isn't the issue.
#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

GerryAZ
Gold Member
Posts: 2872
Joined: Mon Nov 22, 2010 6:47 pm
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Location: Phoenix, AZ

Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 12:04 pm

The threshold level depends upon the model year, but is less than 10 amperes on 2011 and lower on later models. I have never connected an external charger to any of my LEAFs. I saw sustained charging current of about 80 amperes while driving home from my office after the battery in the 2011 was completely discharged because I left the Bluetooth adapter plugged into the OBDII port and the Android device running Leaf Spy on the passenger seat while parked for 6 days. I used some test leads to "jump start" the Leaf from my office vehicle and drove home without issue.
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

LeftieBiker
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Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 1:09 pm

You can't expect a (standard) lead acid battery to last in any car, let alone an EV with parasitic drain.
Lead acid batteries will last just fine, as long as they don't get and stay discharged too low. They are designed for constant use, albeit in a fairly narrow charge range.
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.

DaveinOlyWA
Posts: 15447
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Re: How to Quickly & Simply Charge a Leaf’s Weak 12 Volt Battery

Thu Dec 17, 2020 3:43 pm

LeftieBiker wrote:
Thu Dec 17, 2020 1:09 pm
You can't expect a (standard) lead acid battery to last in any car, let alone an EV with parasitic drain.
Lead acid batteries will last just fine, as long as they don't get and stay discharged too low. They are designed for constant use, albeit in a fairly narrow charge range.
Well, I thought my Plus had a significantly better charging algorithm but now it appears I simply had bad timing. Checking every morning for almost 2 weeks before charging, I am seeing it dip to ~ 12.15 volts give or take before seeing a boost that lasts 2-3 days. Saw the same this morning 12.12 volts but didn't charge at home since I had errands to run near a charger so took off and was at 14.48 volts for 12 mins before dropping down. I think my garage's ambient rarely dropping below 50ºF is my only advantage.
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 16,686 mi, 91.51% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

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