12V Battery Drain Issue Problem and Temporary Fix as Instructed by Nissan

[ulf]

More maths nerdness, where 1 Amp = 1 Coulomb/sec

View attachment 4253

Here the drain curve has been inverted and marked to show hashed areas under the curve. When these areas are calculated and added together they represent the amount of electrical charge in Coulombs that has been drained from the 12V battery during the 15 minute period, approx. 395 Coul.
In one hour x4 =~ 1600 Coul; one day ~ 38400 Coul.

The battery of this test started at less than 12V, which indicates it was depleted to begin with, e.g. 11.96V corresponds to about 40% SOC.

The laef uses a 35A-hr (20hr rate) battery which would be about 126,000 Coulombs when full, and 50400 Coul when at 40%. So it was depleted in about 1.3 days.

Water Analogy:
Substitute liters for Coulombs

That's indeed another way to calculate it. My battery is 50Ah and with your numbers that gives a maximum time of 50Ah/(38400C/day)=(50C/s)*3600s/(38400C/day) = 4.7 days. It's a bit lower with your numbers since I calculated 60s instead of 65s to simplify the average calculation and 0 A for the remaining 12 minutes.

 

[lorenfb]

The simple approach:

Battery capacity = 50 Ahrs,
Assumptions; 1/2 Battery capacity (25 Ahrs), Battery drain ~= 50 ma (.050 A)
Time = 25 Ahrs / .05A, Time = 500 hrs ~= 20 days
Typical auto standby/sleep current < 50 ma

 

[nlspace]

Battery drain ~= 50 ma (.050 A)

Thank you for showing us the simple approach and doing that calculation

But how does this apply to the OP's situation?

 

[lorenfb]

Thank you for showing us the simple approach and doing that calculation

But how does this apply to the OP's situation?

Like all automotive ECUs which fail to enter their sleep mode or are defective, it's time for professional and exhaustive troubleshooting.
It's not an effort for those who don't understand automotive electronics. Even dealer techs lose when it comes to this, resulting
in costly needless ECU replacements. The worse situation occurs when the current draw is intermittent.

 

[avg_joe]

2021 62kWh. Same issue. Estonia.
Case no 1: April 2024 - car parked for 20h and after that 12V battery 8.8V
Case no 2: May 2024 - car parked for 16h and after that 12V battery 10.5V - contacted dealership - they proposed to disable Telematics.
Case no 3: June 2024 - car parked for 20h and after that 12V battery 9.6V - seems that I will buy a jump start battery pack, since I want to use App and Nissan has no proper solution.

I have had the car for almost 2 years and have had zero problems till April 2024.

 

[Malcky]

@avg_joe I wonder if the next time you know that your car will be sitting for 20hours or more that you could start your car first so that you can “Decline” the telematics screen that pops up on your radio screen….would be interesting to see if that would stop your 12v battery drain during the time your car is sitting for hours??

 

[ulf]

2021 62kWh. Same issue. Estonia.
Case no 1: April 2024 - car parked for 20h and after that 12V battery 8.8V
Case no 2: May 2024 - car parked for 16h and after that 12V battery 10.5V - contacted dealership - they proposed to disable Telematics.
Case no 3: June 2024 - car parked for 20h and after that 12V battery 9.6V - seems that I will buy a jump start battery pack, since I want to use App and Nissan has no proper solution.

I have had the car for almost 2 years and have had zero problems till April 2024.

Fits very well to my situation. I saw the issue for the first time 8th of April.

I also bought a jump start li-ion battery which has been a life saver.

 

[Don Exon]

2021 62kWh. Same issue. Estonia.
Case no 1: April 2024 - car parked for 20h and after that 12V battery 8.8V
Case no 2: May 2024 - car parked for 16h and after that 12V battery 10.5V - contacted dealership - they proposed to disable Telematics.
Case no 3: June 2024 - car parked for 20h and after that 12V battery 9.6V - seems that I will buy a jump start battery pack, since I want to use App and Nissan has no proper solution.

I have had the car for almost 2 years and have had zero problems till April 2024.

I've had the same problem, going into the garage on Wednesday, hopefully they can fix

 

[DavidMW]

Malcky's suggestion sounds very interesting. I mostly don't hit OK when starting my 2018 Leaf, and have only had a flat 12v on a couple of occasions over the last year. However, I'm always able to check the State of Charge using EV Connect when the car is OFF - not sure how to interpret that in relation to this issue?

 

[MK1]

I've had the same problem, going into the garage on Wednesday, hopefully they can fix

How did it go? Did they offer you a solution?

 

[NoahJ]

I have a 2013 and the TCU will never work again due to being too old for cellular service. Will it harm the vehicles operation if I simply remove the device?

 

[zowland]

Having the same issue with my 12V. The first post in this thread speaks about disabling Nissan Connect. How is that done, and does it make a difference now that my 2012 can't use it anyway, after the last cellular generation update was not supported by a modem upgrade from Nissan.

As an aside, after the latest nearly dead 12V erased all customized settings, I couldn't get the charging timers to set while in the garage. Finally noticed the time display on the radio was blank. Backed out of the garage to get whatever signal is needed to reset the display of time on the radio, and voila, I was able to reset my charging timers..

Does anyone think unplugging the out-of-date TCU will stop the random 12V drains that many of us seem to be experiencing? I purchased the OVMS upgrade, but haven't installed after I read that using the remote climate control feature to pre-heat also quickly drains the 12V.

 

[mcmancuso]

For the pre-2018 cars, you should definitely unplug the TCU, it's not doing anything, and the lack of compatible towers may mean that it's likely constantly using the high power transmitter searching for towers that aren't there. I also recommend (if your car is 2013 or newer, following what I did in the thread here, it has substantially improved the life of my 12v battery) https://mynissanleaf.com/threads/if...age-connector-on-the-negative-terminal.36008/

Having the same issue with my 12V. The first post in this thread speaks about disabling Nissan Connect. How is that done, and does it make a difference now that my 2012 can't use it anyway, after the last cellular generation update was not supported by a modem upgrade from Nissan.

As an aside, after the latest nearly dead 12V erased all customized settings, I couldn't get the charging timers to set while in the garage. Finally noticed the time display on the radio was blank. Backed out of the garage to get whatever signal is needed to reset the display of time on the radio, and voila, I was able to reset my charging timers..

Does anyone think unplugging the out-of-date TCU will stop the random 12V drains that many of us seem to be experiencing? I purchased the OVMS upgrade, but haven't installed after I read that using the remote climate control feature to pre-heat also quickly drains the 12V.

 

[gtleaf]

First, I just want to give kudos to ulf for the Pi project! Awesome job using a pico to log the voltage. I do a lot of tinkering myself with Pis and Arduinos and loved reading this.

I came across this thread because I have the same 2019 62KWh Leaf and I'm getting the error where my car won't turn on. I still have the original battery so I would normally think that the battery just needs to be replaced which could be the issue. However, reading this thread made me remember that I just took my car in for a factory recall about 2 weeks ago and they did a firmware update. Now I'm getting this error and wondering if it's because of the firmware update? Has anyone found if there is a problem with the Leaf and newer firmware?