12v battery drain due to inadequate DC-DC charging - 2013 Nissan Leaf SL

2013 Nissan Leave SL: Phantom 12 battery drain.
This car loves to eat 12v batteries every 6-12 months and their death is usually due to inadequate 12v charging and maintenance, especially while idle.
I finally put a battery monitor on it the other day and noticed a pattern: A brief 5 minute charge each 24 hour period, inadequate to keep the battery topped off. It also charges at quite frankly, an inadequate voltage.
Is this just a "known issue"? Any way to fix the retarded behavior of the DC-DC charger?
Are there any software updates to help this?

It is a know issue, although Nissan hasn't acknowledged it. Depending on how big the vampire drain is, using an AGM type battery may "solve" it, because they accept charge faster, and are more tolerant of being at a lower State Of Charge. If the drain is too big, you have to find it. It's often one of the various relays in the motor compartment staying on. Another bandaid is to run the front wipers a few times while driving; just one 'blip' will raise the DC system voltage to about 14 volts, for about 1 minute per blip. I'm headed out, but others will link the numerous topics here on the subject.

As Leftie said, it's a known issue. It appears that later model years do a better job of keeping the 12V battery charged but even then, it isn't great and I haven't heard of any available firmware updates to improve it. There have been some 'hacks' used, including things like removing the voltage sense line to make the DC-DC charger run continuously and some folks have installed wires so the 12V battery can be easily charged using an off-board charger but that's about it AFAIK.

People have done a lot with CAN bus spoofing and programming so if you are into coding, you might be able to change how the DC-DC converter operates but I don't know of anyone who has done that to date.

My 2013 LEAF never caused me grief from the 12v. I swapped them out preventatively every 3-ish years; and as recommended above, most recently put in an AGM.

One thing to avoid if possible: plugged in but not charging will drain the 12v.

There have been some 'hacks' used, including things like removing the voltage sense line to make the DC-DC charger run continuously

Click to expand...

That's the current sensor on the Negative battery terminal. Upside: the 12 volt battery stays charged. Downside: you have to worry about the 12 volt battery getting 'cooked' on long trips and/or during Hot weather. That hasn't been reported, though, AFAIK.

I'm one of the ones who ran a DC cable with an SAE plug from the battery, through the motor compartment, to terminate in the charge port compartment. That works ok - just plug the cable in to a battery maintainer when the car will be sitting a long time, or when you know it will be plugged in but not charging. Note: there isn't much point in plugging in a maintainer for the same period of time in which the car will be charging, as the higher voltage from the DC-DC converter will fool the maintainer into thinking that the accessory battery is already full.

The phantom drain could be caused by the TCU. There is a procedure to disable it. The one on the 2013 is pretty useless now, as the cell radio is obsolete.

https://www.mynissanleaf.com/viewtopic.php?t=25949

Edit: found the TSB...

https://static.nhtsa.gov/odi/tsbs/2017/MC-10120572-9999.pdf

pc500 said:

2013 Nissan Leave SL: Phantom 12 battery drain.
This car loves to eat 12v batteries every 6-12 months and their death is usually due to inadequate 12v charging and maintenance, especially while idle.
I finally put a battery monitor on it the other day and noticed a pattern: A brief 5 minute charge each 24 hour period, inadequate to keep the battery topped off. It also charges at quite frankly, an inadequate voltage.
Is this just a "known issue"? Any way to fix the retarded behavior of the DC-DC charger?
Are there any software updates to help this?

Click to expand...

Has been an issue since Day One on EVERY model year. I had hoped that by Gen Two, the issue would be resolved but still see multiple reports of 12 v battery issues. Sure some undoubtedly user error but unlikely to be all of them.

One thing you can do is force charge the battery by running the windshield wipers. I am more concerned about the battery in Winter and that jives nicely with the weather I get but even if its not raining or barely raining, I will put it on the slowest intermittent speed for a bit a few times a week.

I did some random experiments to see if my habits could make it better but to no avail. I did talk with someone who did the same and it does appear that when the car is off and charging, the 12 VDC system takes over essentially giving the 12 volt a rest and that does NOT appear to affect the timing of the boosts soooo....

https://daveinolywa.blogspot.com/2021/04/charge-your-leaf-every-day.html

Sadly, I'm about to just put a solar panel battery charger. Thanks for confirming.

However, charging it (EVSE charger) does not help for me.

There is a trend towards "more sophisticated" charging to save energy and have longer battery life. My son in law's 2022 Jeep does the same thing. Most of the time the alternator is not charging.

I've never had a problem with my Leaf. With other cars, if I have a discharged 12 volt battery, I connect my 12 volt charger. I don't replace the battery unless I am sure that that's where the fault is. Unfortunately, the more sophisticated charging would make it harder to diagnose.