12 volt Battery dying while charging leaf

So, here is a strange follow up. The dealer had the car for a week. They replaced the 12 V battery again at no charge, and I did not have to ask, so I give them credit. They drove it some every day and had no problems. As I picked it up I asked them if their meter had shown any voltage drop on the battery over the week, and the answer was that I did not ask them to check that, so they didn't. I was surprised because I had assumed that they had the car to see if they could diagnose the cause of the problem rather than treat the symptom. They repeated that they would have been happy to check the battery daily if only I had asked them to. So I ask you, am I out of line to think that they should have checked it? I'm willing to be wrong, but I do find it odd. As it is, I have the car back and can set up my own testing regime.
Thanks, by the way, for the help.

Your not out of line to ask, but they are likely just cookie cutter mechanics and do what they do with every other car. Unless they can see something broken they don't know how to fix it. I gave up on working with the dealers.

Anyway I got the tray and tie down on Amazon or was it ebay? Just search the part number 24428-56L00 for the tray and 244204M800 for the battery hold down.

And again I know I might jinx myself, but I have had great luck so far with the shunt on the negative terminal of the 12v battery disconnected causing the Leaf to keep the 12v battery at 13.8v which keeps that battery full and in better shape to handle some random stuck on / intermittent load.

BrockWI said:

We need a momentary emergency "push to jump" button from the traction battery

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I've read that EV1 had this feature.

Nubo said:

BrockWI said:

We need a momentary emergency "push to jump" button from the traction battery

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I've read that EV1 had this feature.

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I think the Ioniq EV also has one, although it may not work with a dead 12 volt battery.

BrockWI said:

I disconnected the shunt or sensor on the 12v battery itself, this causes the car to keep the 12v battery at 13.9v in my case, which charges the 12v battery more than it would otherwise. So far (knocking on wood) we have not had to jump it

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That's very interesting, Brock. I would guess that Nissan reduced the charge voltage to avoid over-charging and boil-off of water. But that might be overcome by checking the electrolyte level monthly.

(I'm reminded of the radio ads for the AutoLite "Stay Full" auto battery, which proclaimed that you only needed to add water once per day)

Yes I agree, most ICE's sit about 14v with the battery so really it is about the same as an ice. I honestly think they did it to reduce load, keeping it floating at 14v vs floating at 12.6v is probably 10-20 watt load and what do you gain? I say a fully charged 12v battery, but if done correctly that is essentially turned in to heat for no reason, if the 12v was truly full. I have watched the levels in the 12v battery and have not seen any reduction in acid levels yet...

DanDietrich said:

Well, They still have the car. They charged the battery and it has been running perfectly for them. They can find nothing wrong. So I will go tomorrow or Friday to pick it up. My 84 F250 has bounced out enough of my teeth for now. I want my car back.
Now for the ethical problem. I want to sell the car privately. I will put a larger new battery in it, and I guess I will tell the buyer to check the charge every couple of weeks. I'll have to take a bit off the price, but I cannot in good conscience sell the car without disclosing this.
I think I will by a used ICE car to run for two years or so, because I am not thrilled with any of the electric cars on the road right now, and keep hearing promises of new models.
I am really bummed about this. I love having an electric car to go with my solar panels.

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It is refreshing to see others with a sense of ethics. Kudos to you on that.

If this were my car, i would do one remaining thing to rule it out. The 3G telematics is known to randomly drain the battery and cause problems. While I'm not saying that's the issue with the car, I would try disconnecting the TCU entirely, unless you use carwings. The process is quite simple and I posted it here:
https://www.mynissanleaf.com/viewtopic.php?t=25949

It took me about 15 minutes and is only low voltage cables.

I understand you may be fully done with the car, and if so, that's more than reasonable. This must be infurating. However, given the TCU has a known fault (although yours has the updated firmware to *supposedly* fix that defect), that would be something good to check. I don't know that the TCU can cause a 2A drain, however...

I can say that while battery issues are common with the Leaf and well-documented, I haven't had any problems with my 2011 except when I went on vacation for 4 weeks and left the HV charger connected. The battery was dead when I got back home. Battery looks pretty old too--it's definitely not AGM. I've checked it with an external charger a few times and it's always topped off, and I haven't done any shunting of the negative terminal or anything.

I've been reading and waiting, and is sounds like TSB NTB18-045 is a real fix to my TCU hanging problem. Since I've replaced my battery with AGM, I've never been left for dead, however my TCU regularly hangs up and doesn't respond to the app, requiring me to pull the fuse. Coming from someone that has never reported the issue, and regularly pull the fuses to recover, I have a couple questions that I'm hoping someone here can help me with:

1. Knowing that I've never reported this issue, what do I need to do to prep my Nissan dealership service organization of the appropriate action for repair?

2. Will I be expected to pay for this if I had my TCU replaced August of last year?

3. Any other advice?

Thanks in advance!

They just looked up the TSB for mine and reprogrammed it. I'm hoping that helps with my problems. They did not charge me.

I have a mid-year 2013 Nissan Leaf SL, with nearly 33,000 miles. Still running with the original factory 12V battery. I just did some 12V battery maintenance to get ready for the winter.

1. Removed 12V battery from vehicle.
2. Measured approx., 4 volts of voltage between positive post and plastic cover of battery!!!
3. Removed covers, cleaned plastic covers and battery top with baking soda.
4. Noticed that several cells had slightly low acid level, so added distilled water into those cells.
5. Cleaned the battery posts and terminals.

Texas heat kills car batteries far more than the cold weather up north! The heat causes the acid levels to drop and if neglected will expose the plates to air instead of staying submerged in acid. Down here during the summer, everyday, there are at least 5 cars sitting in the Autozone parking lot waiting to have batteries tested and replaced. On average, most car batteries only last 3 years.

It's been a couple of weeks since I got my car back. I have to say it has been running perfectly. I have my LeafSpyPro hooked up and I can see it charging the 12 volt as needed. It is entirely possibe that the three updates they did actually fixed my problems. I have ony one warning light showing up after home charging, and it goes away if I restart the car. I don't like that it appears, but right now it doesn't seem to be affecting anything. I wish that I could figure out why it is appearing, but I wonder if it is because I use a JuiceBox at home and not a different brand of EVSE. I also wish the spreadsheet generated by LeafSpyPro would give me 12 volt battery info, but so it goes.