12v battery dies repeatedly

jlv-Yes I've had the TCU updated.

If something happens such that the updated TCU does not communicate through the cellular system to the Nissan servers, it may keep CAN bus communications active so that some of the modules (including the TCU) fail to go into low power sleep mode. This may also prevent the automatic (periodic) charging of the 12-volt battery from the traction battery while the car is parked. There is no issue if the car is driven frequently, but a dead 12-volt battery when it is parked too long. Look at the threads on telematics upgrades for more information.

Will check that out. Thank you.

dcarleaf said:

Will check that out. Thank you.

Click to expand...

Look in this thread, starting near the end (page 68 or so): http://www.mynissanleaf.com/viewtopic.php?f=31&t=21573&start=660

I had this same problem, and I'm noticing a lot of people are based on just this first page of threads. My battery kept draining. I don't recall where I read this, or how I even figured it out, but at one point I was doing the suggested battery tender every day and charging the 12 v. I bought an AGM battery as well hoping it would make it better. But it didn't the battery kept draining.

Then I finally figured it out. The problem was, when I'd park the car, I opened the door before fully turning off the vehicle. Apparently that leaves something "on". Since then, I make sure to turn the car off before I open the door!! Crazy... since doing this, I haven't battery tended the 12v - not even once. It's been mooooonths since figuring it out. Hope that helps!

I always turn my Leaf off before opening the door, and while my experience with 12 volt battery drain wasn't extreme, it did almost kill the battery after just a year. I don't believe that the door issue is the only problem.

hmmm, I will have to pay attention to the door issue. We regularly have the kids in the car and they often hop out as soon as the car stops moving and is in park (unlocks the doors) but before the car is off. Often becasue I am resetting the trip odometer or resetting some other setting.

Hi all,

I understand there's a different thread on this topic but that one's already way too long.

About 2 weeks ago, I woke up to a dead car. I "jumped" it for a few mins and it worked fine for the day. A few days later, same thing. Again, jump and go. Starting this Saturday, the darn car has drained the 12V battery all but one day. On Sunday, I purchased a new 12V battery - manufactured in May - and installed it. The next day the car was out again, and 3 more consecutive days after that.

I just put a voltmeter on the 12V battery and got this:

- While EV charging to 100% = 14.2V
- At rest, 10 mins after charge completed = 12.132V, already too low
- Removed the 12V neg terminal, inserted an ammeter = after an initial spike of 2.7A when first reconnected, it settled to 165mA draw.
- Disconnected the 12V battery completely and after 10 mins, it had sprung back up to 12.6V

I'm not sure what is normal in this car but 165mA seems high to me and it would kill the 12V battery in no time unless the DC-DC converter recharges it - which evidently does not happen. I have the battery on a separate charge now and will charge it for 12 hours to try again. BTW, the original battery I removed from the car recharged fine and it rests at ~12.8V.

I have only had 12V battery issues when stupid Carwings doesn't work and it hasn't worked for me solidly since June 1st. I have a call into Nissan for a related but different issue (plugged and charging status not showing in app/website) and have told them several folks here have complained about the same. I'm sure they jotted that down on their block of ice so they don't forget. Two weeks after reporting my issue to Nissan, the status has always been "escalated, no news from L2 support".

JR

Hi all,

Update to my previous post.

I charged the 12V battery to 13.5V overnight, installed it this morning, drove a few miles, no issues. A few minutes ago, I hit the 'refresh' button on the Carwings webpage and it loaded the EV battery percent charged. This had not happened in over a week.

To confuse matters, the Carwings webpage failed the first time I tried to load it with a "sorry, under maintenance" type of message. For this reason, I don't know if the status updated because my 12V battery was fully charged overnight - as some have suggested that is needed - or if it did because Nissan fixed something with their site.

BTW, the plugged-in / charging status is still not updating so that remains an issue. I suspect something is wrong with my record in Nissan's database that prevents that status from showing on the site or phone app. All else, including command to start charging the car or turn climate control on, works fine.

JR

If you want to measure battery at rest you have to disconnect terminal and wait an hour.

165mA load is expected as vehicle is not in sleep mode.
Any door/OBD device/pedal/button action will wake vehicle up again. It takes few minutes until it falls asleep.

If the 2G --> 3G telematics upgrade was done, it's the culprit.

Cross-post here:
http://www.mynissanleaf.com/viewtopic.php?f=30&t=12448&p=497352#p497352

Executive summary = Nissan (manufacturer not dealer) flew over their telematics engineers to look at my car, and promptly confirmed that it was the problem.

Best,
Tal

Hello Tal and thank you.

I've been thinking that all of these issues started after the 3G modem upgrade. I had no issues at all with the 2G modem and everything worked with it.

With my limited information on the issue, I see two possible causes:

1) The 3G modem hangs because it tries incessantly to connect to Nissan's Carwings backend - but the back end is down - and it doesn't enter sleep mode until it does. Seeing that Carwings has had so many issues since the start of the year, that is a possibility. However, I have checked with 3 other Leaf owners and no one else had seen Carwings issues while I was.

2) The 3G modem hangs because the 12V battery drops below a certain voltage level. If there were something broken with the 3G modem, it would always stay on and always drain the 12V battery, but it doesn't. As I had mentioned above, I replaced my 12V battery with a new one straight from the store. That new battery got drained a number of times until I took it out and charged it separately with a proper charger. After it worked for a few days, I left the car alone without starting it for 5 days straight. No issues and Carwings worked every day. This gives credence to the guys claiming that the Leaf is not properly charging the 12V battery.

Yes, it does sound like a chicken<>egg thing. Does it drain the battery because Carwings backend is not available and the modem keeps awake trying or does the 3G modem hang and doesn't enter sleep mode because the 12V battery is below expected voltage?

BTW, my car started throwing all kinds of strange errors in the dash and DTC codes when the battery was below nominal voltage. All of those went away after charging the battery.

Regards,
JR

PS: happy Father's day!

Did you ever figure out what the underlying issue was?

I haven't figured it out on ours, still happens to us every month or so. I have noticed that when I have it set tot charge to 100% it is way less likely to have a dead 12v for us. I am guessing this is just becasue the 12v has a longer time to charge, including the tapering at the end of the 100% charge. on 80% it might be charging an hour a day and at 100% it might be charging 3 hours a day.

This doesn't help figure out what is causing the problem, but since I believe it tops off the 12v battery it can handle the phantom drain. Still annoying, and my wife know how to "jump" the 12v with a small 12v lead acid I keep in the car...