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

[ulf]

Hi,

I have a Nissan Leaf 62 kwh from 2019. I've been having a 12V battery drain issue for a few months, and I have some information that might be of value for others.

To diagnose the issue I created a battery logger using raspberry pi zero, an ADC chip and a power bank. With that I logged the battery voltage every 5 s, which produced the following 3-day graph:


You can clearly see that the battery voltage is gradually decreasing and that it ends with dead battery (< 5 V). Zooming in you see more interesting stuff:


Every 14 min, there is a significant voltage drop, obviously due to some load. Using a current clamp I could measure the peak to 3.6 A. After that, the current is decreased in steps until it reaches low levels (< 100 mA, but probably lower, not enough accuracy on the clamp to know for sure)

I presented this to an authorized car mechanic and they informed me that a few days before (around 2024-05-30) Nissan had put out a statement that many cars have shown a battery drain issue, and a temporary fix is to disable the connection to Nissan Connect. They did that on my car, and this is the result (1 night of logging):


No more issue!

I don't know the details of what the car mechanic did, but my guess is that disabling Nissan Connect in the car will have the exact same effect.

They first wanted me to pay for diagnosing the issue, but I claimed it's Nissans responsibility, since it most likely was introduced with a software update (there was no issue a few months ago). They will make a case against Nissan, and we'll see where it ends. My car is 4 years old, so the 3-year regular warranty has passed.

Disabling Nissan Connect is of course only a temporary fix, and Nissan apparently has not yet figured out a long term solution. When they have, my car mechanic will let me know and most likely fix it without charge.

This has troubled me for quite some time, so with this I hope to help anyone else with the same issue! If you don't have a battery logger, you can simple open the hood and listen. If you hear a relay go off every 14 min, you most likely have the same problem as I had.

 

[nlspace]

That is an excellent data capture with your logger, thanks for sharing. Looks like you found the culprit.

It appears that your 12V battery is old, weak or worn out since it was below 12 from the beginning. Maybe an external charging could bring it back up and desulfate the plates somewhat.

Do you suppose it is only one relay, or are the main contactors being engaged also?

 

[ulf]

The battery is new, I exchanged it when the issues started. I also got it load tested the day after the first graph, and it checked out fine. It starts low presumably because my regular driving of 30 min per day is not enough to keep the voltage high.

Using my ODB2 scanner I can see the battery was charged with high current to start with (around 20 A) but then decreasing to a few amps after 15 min, when I still had the issue.

That said, it's probably not in perfect shape, since it has been discharge to < 5 V several times...

 

[knightmb]

I agree, good troubleshooting with data the Nissan tech can't argue with. The default FLA 12V battery that Nissan installs is rated for 43AH or in lead battery speak, 25.8 watts an hour for 20 hours. It was asked earlier if the 3.6 amp draw was the traction battery engaging, but probably not. It takes +15 amps to do this, it would be very visible on the data logger.

Over a 3 day period, I can see this killing a new FLA easily. It's odd that the telematics are cycling on and off every 15 minutes, that basically prevents the Leaf from entering deep sleep where it sips less than 0.158 watts of power. Something is up with the Nissan Connect.

The first thing I would try is to turn Nissan Connect back on and reset back to factory defaults, delete all it's data, account, etc. See if the same thing happens with no account connected to it. If that fixes the "can't sleep" issue, you can try to re-create your telematics account and then see if the problem returns. If so, that would leave me to believe Nissan is the issue as it's constantly "waking" up the Leaf to poll it for some odd reason.

Might be a bigger issue that affects all of us if Nissan is polling across the whole network for some reason other to wake up the Leaf and waste power for 15 minutes.

 

[Jerther]

This is far fetched, but having recently sold my 2018, this could happen: the previous owner of a leaf could keep the car set up in his or her Nissan connect account, provided the new owner has not claimed the vehicle at Nissan. Then, the previous owner could have a Nissan connect gateway such as this and is polling the car every 15 minutes. There are warnings in these software not to poll the car too frequently so not to drain the 12v battery.

In any case, make sure the car is yours at Nissan. And it should be if your car is in your own Nissan connect account. It would make sens that Nissan denies access to a car that had its ownership changed, but I personally cannot verify this...

Again I think this is far fetched but I'm a software developer and, you know, Murphy's been part of my life for decades

 

[FrancoVecchi]

I read somewhere that the remote communication system in the Leaf doesn't work if the battery voltage drops a little. I experienced this once I left the car stationary for 15 days, and I went abroad by plane. The first 10 days I could see my Leaf's data, then the system stopped working. When I returned the car started normally. Therefore I suspect that you have some problem that is not causing the communication system to go into standby. I have no idea what could be the cause of this problem.

 

[hradek]

I agree, good troubleshooting with data the Nissan tech can't argue with. The default FLA 12V battery that Nissan installs is rated for 43AH or in lead battery speak, 25.8 watts an hour for 20 hours. It was asked earlier if the 3.6 amp draw was the traction battery engaging, but probably not. It takes +15 amps to do this, it would be very visible on the data logger.

Over a 3 day period, I can see this killing a new FLA easily. It's odd that the telematics are cycling on and off every 15 minutes, that basically prevents the Leaf from entering deep sleep where it sips less than 0.158 watts of power. Something is up with the Nissan Connect.

The first thing I would try is to turn Nissan Connect back on and reset back to factory defaults, delete all it's data, account, etc. See if the same thing happens with no account connected to it. If that fixes the "can't sleep" issue, you can try to re-create your telematics account and then see if the problem returns. If so, that would leave me to believe Nissan is the issue as it's constantly "waking" up the Leaf to poll it for some odd reason.

Might be a bigger issue that affects all of us if Nissan is polling across the whole network for some reason other to wake up the Leaf and waste power for 15 minutes.

Do you have an active paid account for Nissan Connect?

 

[ulf]

I have a working Nissan Connect account, which I got activated after contacting support. For some reason I did not need to pay for it.

It was not active when I bought the car, and it worked fine until the fix, so I don't think it has anything to do with a previous owner's account.

 

[DavidMW]

This almost certainly explains what happened to me a few weeks ago. After standing unused for about 36 hours the 12v battery had dropped to about 3v. I called out the AA who gave the battery a quick boost. The battery had been replaced a year earlier following a similar incident and the AA engineer confirmed it was in good condition. At least I now know that if it happens again I can use a battery charger to get me going.
Given that this has only occurred twice in over a year, maybe there is some other variable involved as well, Perhaps I'll wait and see if Nissan come up with a solution? 3.6A seems a heavy drain for Nissan Connect - is it perhaps enabling something like climate control while the car is otherwise off?

 

[ulf]

Could be the same issue, although for me it's not sporadic, it was constantly there. I'll post here as soon as I get any more info.

No, the AC does not go on, but 3.6 A seems to be the general current draw (for a short while of course, around 1 minute). After that it stays at 1.6 A for around a minute, then 0.5 A also for a minute, ending with very low < 100 mA.

I measured roughly the same when triggering Nissan Connect manually (refreshing battery level in the app).

 

[Stanton]

Great data! Nissan Connect/CarWings/etc. have always presented a parasitic drain (via the TCU) since the beginning.
Luckily, in Gen1 Leafs you can avoid the problem by replacing the TCU with OVMS; development for Gen2 Leafs is ongoing.

 

[Malcky]

This is an excellent thread, so thanks for this.

I need to ask a couple of really stupid question though.......

How or when do you know if the 12v battery is draining?
Is there any obvious tell tale signs in the cars behaviour to suspect a 12v battery drain issue?

Or @ulf were you looking at leaf spy and happened to notice the 12v being low?

 

[ulf]

How or when do you know if the 12v battery is draining?

In my case I noticed when I could not start the car, or even open the doors with the remote. Then you can measure with a multimeter over the battery of you have one. When completely dead, my battery was around 4 V, but it seems from 11 volts and below your car will not start.

I also used leafspy, but it is needs the 12 V battery to work so I can only measure down to 11 V or so.

 

[ulf]

Luckily, in Gen1 Leafs you can avoid the problem by replacing the TCU with OVMS

Sounds interesting! It's the first time I hear of OVMS. But it seems it connects to the ODB2-socket. Doesn't that require the system to be woken up every time it measures, basically causing the same problem? Or are you saying a piece of hardware is replaced?

 

[nlspace]

The default FLA 12V battery that Nissan installs is rated for 43AH or in lead battery speak, 25.8 watts an hour for 20 hours.

Over a 3 day period, I can see this killing a new FLA easily.

Spot on.

i checked it also using quick and dirty calculatus, it looks like 8-9 Watts per hour drain, which is about a third of the default. So 60 hours and it's used up and the battery is empty.

How to do the back-of-the-envelope calc? The current spikes look like little inverted Right Triangles, so the area of the RT [one half Base x Height] times 4 pulses per hour gives you a good total hourly current draw. Multiply by the average voltage to get the power draw per hour. [edit: technically the base x height gives you the amount of charge drawn since current = charge/time].

 

[ulf]

i checked it also using quick and dirty calculatus

I actually did some more accurate measurements and calculations on that. There are 4 stages of current consumption for every 14 min, as seen here (measured using current clamp, and noting down when the current changed):


The first two stages are clearly visible in the graph, but the third was only clear from the current measurement since the battery voltage recovery makes it indistinguishable from the deep sleep stage.

From that I could calculate the average and days until a fully charged battery dies:
3.6A: 65 s
1.6A: 65 s
0.5A: 65 s
< 0.01A: 12 min
(3.6+1.6+0.5+0*12)/15 = 0.38 A (Average) = 4.6 W
50 Ah / 0.38 A = 132 h = 5.5 days until battery dies

In reality the car would not start well before that, since a 20% charged battery probably will have too low voltage, but it could be considered a max, and it corresponds well to my situation where I have seen that the car is always dead after a week without using it.

 

[nlspace]

Piecewise integration is definitely more accurate.

i think you need to divide by 4 in the final since it happens 4 times per hour?

 

[LeafNissan1]

This almost certainly explains what happened to me a few weeks ago. After standing unused for about 36 hours the 12v battery had dropped to about 3v. I called out the AA who gave the battery a quick boost. The battery had been replaced a year earlier following a similar incident and the AA engineer confirmed it was in good condition. At least I now know that if it happens again I can use a battery charger to get me going.
Given that this has only occurred twice in over a year, maybe there is some other variable involved as well, Perhaps I'll wait and see if Nissan come up with a solution? 3.6A seems a heavy drain for Nissan Connect - is it perhaps enabling something like climate control while the car is otherwise off?

I've had a lifetime of extensive experience, both as an owner and technician with all manner of AC and DC electrical systems, marine, RV and automotive. I've owned 3 gen 2 Leafs, 2 2022's and a 2023. The first 2022 and the 2023 were bought new and the second 2022 was purchased used to replace the first 2022 after it had been totaled in an accident after being hit from the rear. The 2023 was sold to a close friend.

When the first 2022 was less than a year old with only about 1500 miles, the 12v battery went from fully charged to less than 4v overnight. After being deep-charged for 12 hours, this did not reoccur over the next 11 months and 1500 miles at which time the car was totaled in the accident. However I closely monitored the 12v battery and noticed a relatively significant parasitic draw and periodically used my external 15amp charger to fully charge the battery. I was using Nissan Connect with this car and noticed whenever I polled the SOC of the traction battery using the Nissan Connect app, that I could hear a relay activate, at which time there was a 2-4 tenths drop in voltage, i.e. from 12.5vdc down to 12.2vdc for example, but whatever amount of draw that was only lasted for a few seconds before the surface voltage of the 12v battery started to increase. I also notice the relay being activated every time a door is opened when the car has been left sitting in the garage along with the same drop in voltage.

On to the second 2022, I purchased it with 10,500 miles when it was 14 months old. After about 6 months the same thing occurred with it, that is the 12v battery went from a 12.6 volts down to below 4 volts in a period of a few hours. I recharged as before and this hasn't reoccurred in the 5 months since. I have noticed the same parasitic draw on the battery as on the first Leaf and the battery tests good when load tested. This car now has 12,500 miles and Nissan Connect is also being used with the same behaviors as with the first car.

Both of these Leafs were/are lightly driven, only about once a week and 250 miles a month, but I've always kept close track on the 12v battery/dc to dc charging and have noticed that this has been a weak link, not only on the Leafs, but on all of the previous EV's and PHEV's that I've owned, Nissan, Honda and Toyota.

On the 2023 Leaf, which was sold to my friend, it now has approximately 1000 total miles and has the same type of light usage as my Leafs. The Nissan Connect software app has never been used with that car and so far it has not experienced the same problems that I have. So this problem, at least in part, could very well be connected to the use of Nissan Connect.

 

[ulf]

i think you need to divide by 4 in the final since it happens 4 times per hour?

No, I think the calculation is sound. Note that I'm not calculating A/h or W/h. In fact, such a unit doesn't make sense. The units would also be messed up in the end since the energy stored in the battery is in Ah. Dividing by A/h would give h^2.

 

[nlspace]

If it draws 0.38A every 15 minutes, then it is pulling 1.52A in an hour, so 50 A-h/ 1.52A = 32 hrs till drained?