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

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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.

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

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?

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.

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.

@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??

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.

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

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?

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?