[Solved] Start Problem--2012 SL with 45k miles

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nlspace

Well-known member
Joined
Jun 6, 2017
Messages
749
[Edit: Replaced the 12-volt battery to solve this]

Need some advice--for a 2012 SL with 45k miles and 8 capacity bars, here's my troubleshooting notes and observations:

The car has been garage-kept until August 2019. Then the owner left it outside fully charged for several weeks, and then it wouldn't start. Called tow service and they came and jump-started it showing 19 miles range. Then towed it to the dealer service.

Dealer checked the 12-Volt aux battery reading 435 CCA of 500 on the label and declared it good. Chargged the pack overnight and in the morning started it and showed 19 miles range, and declared the HV pack as bad. Towed the car back to the owner and that's when i was given the car for troubleshooting.

Used LeafSpy: showed 42.8 Ahr and the pack was at 401 with all cells within 10mV, but dash only showed 7 chargge bars and 19 miles. Drove it 20 miles to home and it dropped to 4 bars with 21 miles Range Remaining. Spy showed the Aux battery at 14 V after starting with taper down to 13 V, 2.5 A while driving.

The 12-Volt battery had been replaced at the dealer in march 2017 and it was reading about 12.5 OCV with -0.3A draw, so i chargged it out of the car overnight at 3A. Added some distilled water to cell #1 and chargged again at 1A. Measured with a 100A tester and it showed as good at just below the 600 CCA mark. Specific gravity measurement read weak at 1.12, so trickle chargged at 1A till it hit 14 V.

Chargged the pack using L2 to 12 bars 55 miles, and drove it 40 miles, then repeated and next day drove it 50 miles with 9 RR. On the third day it would not go to READY, the RR and bars were blank, with yellow PS and ! errors lit up. Jump start failed. Aux reading 12.6 OCV.

Removed the aux to measure OCV and trickle it. Then shorted the positive and negative cable lugs together before putting Aux back in. Cars started to READY showing 11 bars and 44 RR, so i drove it 40 miles down to 3 bars. Chargged L2 overnight and same failure to start the next morning, quickly unbolted aux cables and shorted them together, and re-install. Started to READY showing 7 bars and 41 RR, drove it 42 miles and showing 2 bars and 12 RR... What is goin' on with this thang?

The 12V has about 0.25 A draw all the time, so in 4 hours it pulls 1 A-Hr out of the aux battery. This is a Nissan 51R battery, 500 CCA, any idea what is the capacity?

It seems that shorting the lugs somehow resets an error condition--any ideas if this is really a thing or just coincidence?

Spy was showing 12.0V, -7 A draw while the car was just sitting in ACCY mode. Is this normal draw? How much does it draw during the start transient to go to READY mode?

Tonight when i plugged in L2, the voltage on the aux went up to ~14.2, +11 Amps, then it slower tapered down to about 13.13 V and +1.5 to 2 Amps.

i know that a weak, old or worn out aux battery can cause a multitude of issues on EVs.

Earlier in the week i took the 12-Volt battery to the dealer with the invoice to see about getting a replacement under the 84-month warranty, but they said it had to be in the car, and the car had to be brought to the service dept and tested there to determine if good or bad. At the time i couldn't get the car started, so kinda hard to drive it in. Seems like he said the warranty would only discount about $25 off a new one, so maybe i'll just buy one elsewhere and forget about the Nissan warranty.
 
You are a braver person than I, shorting the battery cables together. AFAIK, just removing and replacing one battery cable will reset most (but not all) error codes.
 
With a voltmeter i measured ~2.75 VDC across the terminal lugs when removed from the aux battery, then as the sun came up the voltage on the lugs varying between 1.7 and 4.5. When i covered the solar panel with a dark mat the voltage dropped to 1.2 and began bleeding off.

i pulled a 15A fuse from the front box labelled "capacitor", no idea what it is or does, but it had no effect.

This morning the car wouldn't start again, so i disconnected the terminals and shorted the lugs together, replaced the terminals; then it started showing 11 chargge bars and 57 miles RR.

The aux battery was measuring 12.3 to 12.6 this morning depending upon current draw, and this was after an overnight L2 session that should have topped it up. When i put it on a trickle the voltage went up to 14. in just a very short time (10-15 minutes). This is a good indication that the 12-volt battery is defective.
 
The aux battery was measuring 12.3 to 12.6 this morning depending upon current draw, and this was after an overnight L2 session that should have topped it up. When i put it on a trickle the voltage went up to 14. in just a very short time (10-15 minutes). This is a good indication that the 12-volt battery is defective.


The older Leafs do a poor job of charging the 12 volt battery while charging the pack. I wouldn't take those results to mean that you have a bad 12 volt battery, as I would expect the rest voltage in that case to be below 12.1 volts.
 
Forget about all of the "miles remaining" stuff. That's just the fevered dreams of the "guess-o-meter". The one concern is the 250mA "dark current", which seems too high. The battery when new is probably around 40AH capacity.

When testing dark current, make sure all doors are closed and locked and all lights are off. Also the hatch -- I find it's easy to close the hatch and think it is fully closed when it isn't. The hatch light can drain the battery.

Dark current should be 50mA or less. There are normal functions which may raise it temporarily. Wait 30 minutes with the car completely off and re-measure. If it's still well above 50mA then you may need to find the culprit by pulling fuses.

Have you had the "telematics upgrade"?
 
Don't know anything about the telematics, hope it's not drawing current and draining the aux battery.

i had not waited 30 minutes after the car was off to measure the current draw, so i'll check the dark current in the morning before anything is active.

i put a new 12-Volt battery in it today, then found that there is a 12V Battery thread discussion about the issues and concerns of underchargging in these cars-- i wish someone had pointed that thread out to me. Who knew that it is a good idea to put a trickle chargger on these cars every week? The forum search ignores the word 'battery', so the thread can't be found by searching here.

i went out and checked after dark and don't see any lights on in the trunk or elsewhere.
 
Also I should have mentioned that some OBD2 dongles can be battery-drainers, particularly ones that use WiFi
 
Great news, all is working this morning. Replacing the 12-volt battery solved this problem.

Full charge to 12 bars and the dark current was only 50mA as you said.

i use a scantool OBDlink LX blueteeth dongle and never leave it plugged in.
 
Great news, all is working this morning. Replacing the 12-volt battery solved this problem.


I strongly suggest you monitor the rest voltage of the new 12 volt battery for a few weeks. If it drops below 12.6 volts then a regular external charge would be wise. And don't of course, leave the car plugged in for long after or before charging.
 
LeftieBiker said:
You are a braver person than I, shorting the battery cables together.
.
Truly.

This sounds like a case of 'if the person is alive after pulling that stunt, the 12v is defective.'
 
SageBrush said:
LeftieBiker said:
You are a braver person than I, shorting the battery cables together.
.
Truly.

This sounds like a case of 'if the person is alive after pulling that stunt, the 12v is defective.'

Not sure if you understood that he meant: "shorting the terminal leads together NOT connected to the battery." It's a common trick on some ICE cars and often fixes diagnostic codes and other weird electrical gremlins.

It should NOT be done on a Leaf for two reasons:
1) The Leaf uses electronics in the battery terminals and it might damage them for the same reason that you should never attach a charger to the negative terminal on the battery while it's connected to the Leaf.

2) The Leaf has a DC-DC converter from the main battery pack. If the converter was on when you did this, you could blow the fuse in the DC-DC converter, or worse, as you said: 'if the person is alive after pulling this stunt'
 
Not sure if you understood that he meant: "shorting the terminal leads together NOT connected to the battery." It's a common trick on some ICE cars and often fixes diagnostic codes and other weird electrical gremlins.


I understood the procedure, but thought it was a bad idea. Apparently it is.
 
Lothsahn said:
Not sure if you understood that he meant: "shorting the terminal leads together NOT connected to the battery." It's a common trick on some ICE cars and often fixes diagnostic codes and other weird electrical gremlins.

It should NOT be done on a Leaf for two reasons:
1) The Leaf uses electronics in the battery terminals and it might damage them for the same reason that you should never attach a charger to the negative terminal on the battery while it's connected to the Leaf.

2) The Leaf has a DC-DC converter from the main battery pack. If the converter was on when you did this, you could blow the fuse in the DC-DC converter, or worse, as you said: 'if the person is alive after pulling this stunt'

i fail to see how your two reasons indicate any problems with this procedure:

1) The only electronics is a current sensor that surrounds the wire just before it reaches the negative terminal. Currents normally flow in both directions thru this wire/sensor, sometimes very high currents, and it is designed to handle these. Attaching a chargger to the negative terminal actually by-passes this sensor altogether, so how could it be damaged with no current flowing thru it? The positive terminal has large in-line fuses but no electronics.

The admonition against connecting a chargger lead to the negative terminal is due to the potential of sparking and possible ignition if there is excessive hydrogen gas venting nearby.


2) How is it that you think the DC-DC converter could turn ON when the 12-volt battery is disconnected? What current source would drive the relays and main contactors necessary to connect the main pack to the converter?
 
nlspace said:
i fail to see how your two reasons indicate any problems with this procedure:

1) The only electronics is a current sensor that surrounds the wire just before it reaches the negative terminal. Currents normally flow in both directions thru this wire/sensor, sometimes very high currents, and it is designed to handle these. Attaching a chargger to the negative terminal actually by-passes this sensor altogether, so how could it be damaged with no current flowing thru it? The positive terminal has large in-line fuses but no electronics.

The admonition against connecting a chargger lead to the negative terminal is due to the potential of sparking and possible ignition if there is excessive hydrogen gas venting nearby.

This explains why from the person who made the rule "Phil's Law". See his two posts in the same thread:
https://www.mynissanleaf.com/viewtopic.php?f=30&t=8588&p=191318&hilit=current+sensor#p191318
https://www.mynissanleaf.com/viewtopic.php?f=30&t=8588&p=191318&hilit=current+sensor#p191304

In addition to draining the battery and sulfating it, or possibly sending reverse current through the 12v current sensor, there's one other issue. It's also been found that in certain cases leakage to ground can cause the car to throw diagnostic codes thinking that there is an HV battery fault to ground, which can only be cleared by a Nissan Dealer (not LeafSpy).


nlspace said:
2) How is it that you think the DC-DC converter could turn ON when the 12-volt battery is disconnected? What current source would drive the relays and main contactors necessary to connect the main pack to the converter?

I don't think it could turn on while it was disconnected. But if it was on prior to disconnecting the battery, and it was still supplying power when you pressed the two leads together, it would get exciting, to say the least.

While I assume the DC-DC converter would recognize the open circuit and shut off, I don't know how quickly the DC-DC converter does so. It's probably pretty fast. But I don't know anywhere that it's documented as such, and I sure don't want to prove that hypothesis wrong.

An ICE, while off, has no electrical power to the 12V system other than the battery and some capacitors. That is not true of an EV.
 
Lothsahn said:
An ICE, while off, has no electrical power to the 12V system other than the battery and some capacitors. That is not true of an EV.

I was a bit skeptical at first too until I realized this point.

It is probably a safe thing to and something I have often done on ICE cars before working around airbags, etc but I don't think I'll do this to my Leaf.
 
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