Car won't start after dead 12V battery was recharged

My 12V battery was dead on Friday morning. (This happens in my Leaf. No, I didn't leave it plugged in not charging or sitting for days.)

I have a smart battery tender/charger so I plugged it in and let it bring the battery back up. It's still charging now (about 40 hours later) but close to 100%.

Plugging in a L1 charger, the car beeps once and there are some clicking sounds from under the hood, but it does not start charging.

The car acts like it has full 12V power. Can put it in accessory mode and use everything. But if I try to turn the car on to drive it, it shows the little animation telling me to put my foot on the brake pedal (which I am doing), the steering wheel shakes very slightly once, and it goes into accessory mode with several yellow warning lights:

Brake system warning light (Exclamation in a circle)
Power steering warning light ("PS")
EV System warning light (Exclamation in a car)
Vehicle Dynamic Control warning light (Car with skid marks)

None of these were an issue before the 12V went out. The car is at 33% charge and I don't want to let it sit that low for too much longer. I've heard that 12V systems cause all sorts of false alarms. I'm going to take the car in to the dealer to get the 12V replaced (it's still under warranty) but I just want to get the car running so I can drive it in instead of towing.

^^^
Once your car is in that bad state, what is the voltage of the 12 volt battery as measured across its terminals with no tender hooked up and the car totally off?

I wouldn't be surprised if it's way low at that point.

If you've got LeafSpy and an ODB2 dongle, you can reset any DTCs - they are probably what's preventing the car from starting.

Otherwise, if you have another car, you could try hooking up jumper cables to its battery while starting the LEAF. That should rule out a 12V under-voltage issue.

Some 12 volt batteries will come back from being completely dead (usually with much less capacity) but most need to be replaced. You can often get them to read 12.x volts by charging them, but they have no capacity left, not even enough to engage the Leaf's relays.

Agree, 12V battery could be damaged, particularly after a full drain. Suggest replacing it.

I tried connecting to another car and it made no difference.

I don't think the battery is dead since all accessories work normally--radio, doors, horn, etc. Just won't go to drive mode.

OBDII adapter is being overnighted right now. Will resetting the codes cause any potential problems with the dealerships ability to diagnose?

Have you tried disconnecting the 12v battery for a minute or so, and then hooking it back up? It's possible that might clear your faults also.

brenton said:

I don't think the battery is dead since all accessories work normally--radio, doors, horn, etc. Just won't go to drive mode.

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Bad assumption. Please measure the 12 volt battery voltage while in this state w/the car off.

If the car will not go into READY mode (green car with arrows appearing on dash), this is a classic symptom of a dead or bad 12 volt. If it's too low or the voltage sag is too great when trying to go into ready, that'll cause this symptom.

brenton said:

OBDII adapter is being overnighted right now. Will resetting the codes cause any potential problems with the dealerships ability to diagnose?

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Maybe but if the problem is real, the code will likely eventually be triggered again.

What Cwerdna is saying about a "bad assumption" is that a weak 12 volt battery can still power accessories, but at a voltage too low for the car's drive electronics to tolerate.

I agree -- replace the 12v battery.
No reason to be shafted by the dealership, just go to Walmart or equivalent and buy a battery replacement. The install takes all of a couple of minutes.

I replaced my 12v last month with one from Walmart. Piece of cake. I found it most convenient to walk into the store with the old battery and hand it over when I bought the new one.

Replacement was with the MAXX 51R, $107.22 + tax
The replacement worked fine and measured 12.6 v but I put a battery minder on it overnight anyway. After a month of car use it reports 12.5 v

jjeff said:

Have you tried disconnecting the 12v battery for a minute or so, and then hooking it back up? It's possible that might clear your faults also.

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I just did this and the car seems to be working normally again.

However, in the process of disconnecting and reconnecting the battery, a series of VERY STRANGE events occurred!

1. The 12V charger/tender has been plugged in since Friday and all day today has been reading 14.4ish volts, I forget the amps. Red is clipped directly on the battery, black is clipped to where the negative terminal cable connects to the big aluminum housing. I unscrewed the car's negative cable and detached it. I expected my smart maintainer to say "no battery" or something to that effect, but it continued showing the exact same volt and amperage--no change whatsoever!! I watched for maybe 8 seconds before I disconnected it because it was freaking me out. The negative battery terminal was definitely air-gapped. There was NO electrical circuit!

2. I then clipped the maintainer's negative directly onto the battery negative. It immediately started ramping down from around 14V to 13.3-ish volts, and within 15 seconds read as "FULL". (This is after 3 full days of nonstop charging.)

3. I reconnected the car's negative cable to the battery. Big spark, then the car alarm system sounded (lights, honks) until I hit the button on the key fob. Car seems in perfect working order at this point--was able to turn it on, put it in drive, turn it off, and plug in my L1 charger it is now charging.

4. I put the 12V charger/tender back onto the 12V battery while L1 charge was in progress to see what it would read. It was reading 14ish volts and 3-4 amps, which is so weird because the battery should be 100% full at this point.

Questions:

* What the heck was going on with #1 above? How is this possible?
* Is it ok to leave the 12V charger connected while L1 charging? Will I fry the car or my 12V charger?
* Is my negative attach point bad? Seems connecting directly to the battery would have given me different results via the charger. I know there are some electrical doo-dads near the negative terminal that are sensitive, but looking at it (photo for reference: https://docs.google.com/drawings/d/1DUHs70HYfY-dwU8u6nibIadIVL8cOpYxjeRzw1jyRh0/edit?usp=sharing) there are two cables directly connected to the negative terminal. The one on the right is copper and goes to the frame and then over to the aluminum casing (where I was clipping). The cable on the left seems to have electronic stuff. What is the difference, electrically, between connecting at A) where the copper cable ends on the casing, B) the other end of that same cable where it is connected to the negative terminal or C) directly to the battery negative terminal.

For those suggesting I replace it:

LeftieBiker said:

Some 12 volt batteries will come back from being completely dead (usually with much less capacity) but most need to be replaced.

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Phatcat73 said:

Agree, 12V battery could be damaged, particularly after a full drain. Suggest replacing it.

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SageBrush said:

I agree -- replace the 12v battery.

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I'm going to the dealership to have it replaced asap. I would replace it myself but the dealer installed it and the battery is still under warranty. Plus, I want them to tell me why this random draining keeps happening.

cwerdna said:

Please measure the 12 volt battery voltage while in this state w/the car off.

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cwerdna said:

Once your car is in that bad state, what is the voltage of the 12 volt battery as measured across its terminals with no tender hooked up and the car totally off?

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Sorry I didn't answer this: I don't have a multimeter. :-(

My 12v was under warranty too, but the list price for a 12v is so outrageous the pro-rated warranty was a joke.
Nissan will be happy to run "diagnostics" on your car. Expect another ... Oh .... $200 to be told everything is fine.

I figure you will walk out with a $400 (or more) bill, and none the better off than had you just followed my advice.

Your money, your time.

SageBrush said:

My 12v was under warranty too, but the list price for a 12v is so outrageous the pro-rated warranty was a joke.
Nissan will be happy to run "diagnostics" on your car. Expect another ... Oh .... $200 to be told everything is fine.

I figure you will walk out with a $400 bill, and none the better off than had you just followed my advice.

Your money, your time.

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Dang, I didn't know they pro-rated the warranty. So dirty. I should have brought it in months ago.

Maybe I won't go to the dealer after all.

My 12 volt was replaced for free long ago on my used '13. At the time, the car hadn't reached the 3 year/36K mark.

jjeff said:

Have you tried disconnecting the 12v battery for a minute or so, and then hooking it back up? It's possible that might clear your faults also.

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As Jeff mentioned, when this has happened to me and it has many times Sometimes I have to disconnect the 12v battery, wait a minute and connect it back up and then everything works. I keep a 10mm wrench and the spare 12 volt 9 amp SLA in the trunk just in case.