If its cranking good but not starting, your crankshaft and camshaft sensors maybe on its way out?

If its not cranking or weak, you might have a strong parasitic drain. If thats the case, you need to start looking at all your electrical. From door locks, mirrors, windows, lights, etc. If something is not working, fix it and see if that fixes the drain. Good luck.

Put a multimeter on your battery posts at idle and see how much the alternator is putting out.

Did you mentioned P0420. If you have a clogged CAT, thats another possibility causing your hard starting? Thats bank 1 -firewall side CAT.

 

Was the 12.1 volts after your daughter was trying to start the car for a long time? I don't know that the strong fuel smell is conclusive about anything just yet (e.g. injector) since an engine can get flooded with continuous cranking. You "playing with the pedal" probably put it in clear flood mode.

You may want to charge the battery and let it sit overnight and check voltage at the terminals first thing in the morning. If it's unusually low then it may be a good idea to do a parasitic draw test as suggested above. If there's any aftermarket electrical stuff installed then those would be the first suspects.

Are there some conditions that are shared with each of these incidents that you can think of (e.g. outside temp, after raining/snowing, after filling up with gas, anything...)

 

Was the 12.1 volts after your daughter was trying to start the car for a long time? I don't know that the strong fuel smell is conclusive about anything just yet (e.g. injector) since an engine can get flooded with continuous cranking. You "playing with the pedal" probablyoff put it in clear flood mode.

You may want to charge the battery and let it sit overnight and check voltage at the terminals first thing in the morning. If it's unusually low then it may be a good idea to do a parasitic draw test as suggested above. If there's any aftermarket electrical stuff installed then those would be the first suspects.

Are there some conditions that are shared with each of these incidents that you can think of (e.g. outside temp, after raining/snowing, after filling up with gas, anything...)

She made 3 attempts to start last night and I figured it flooded.
I thought about a parasitic draw. I can check that.

12.5V right the charger with multimeter

This is right off the charger with battery tester. I'm not liking the 79% but agrees with the state of charge chart above. More doubt on the load tester I have?
Battery charger is brand new. It was in the maintain mode after charging all night.

12.3 V with multimeter after headlights on and off for 10 seconds

It was 15 degrees or so, not a whole lot different than previous days.
No aftermarket equipment that I can see. There looks like there was a trailer light package installed but the wire is disconnected at the positive terminal.

 

Charge it until 100%, it may take longer than just overnight when charging at a lower rate if it's very discharged.

15 degrees definitely affects things. Temps that low will compound battery issues if it's not fully charged...

Other than the low SOC, the other info from your battery tester looks healthy. It's also possible the low SOC is due to the low temps...

 

After about an hour on the charger, it reads 12.7V and 100% charged and was in maintain mode. I'll leave it on.

I was thinking about parasitic draw. She does have a phone charger that was plugged in. I unplugged that. I'll let it charge for a while and attempt the parasitic drain check later.

 

Disconnect the charger and put your multimeter on the battery post. See if you get the same voltage. Then start the car and see what voltage your alternator is putting out-at idle. Then, turn on everything electrical. headlights, ac-full blast, radio, rear defrost. Check your multimeter again at battery post. Let us know what you get.

If all checks out with the alternator, I would leave the batter disconnected from the charger. Get the charge reading. Check it again in the morning. If it drops 12.6 v, you have a drain or a bad battery. Where did you get that new one?

 

Multimeter 12.3v after removing charger
Multimeter 14.6v after starting unloaded
Multimeter 14.7v loaded up

 

The charging system in the Murano will reduce voltage if it senses the battery is well charged. I recommend that immediately after starting the car (when you know the battery was used to start) you check voltage across the battery terminals. It should be slightly above 14V. Vehicles normally run at 14V, but that's not widely understood.

 

Multimeter 14.6v after starting unloaded
Multimeter 14.7v loaded up
Back on the charger, it says 87% charged and 12v, not sure how accurate this is. The charger was in the maintain mode.
Charger output 15.5v at battery

 

All of that looks great.

 

Your battery is not good for a new one. Low reading 12.3 v after charger disconnection. That is probably why the alternator is putting out 14.6-7 v. Usually it does not go passed 14.5v with good battery. At least ,the alternator seems to be doing its job. Although I don't like seeing it passed 14.5 v. I would get another battery. Should be free replacement.

Did you have trouble starting the car? One click? Cranking good? Car does not sound like its choking?

 

Your battery is not good for a new one. Low reading 12.3 v after charger disconnection. That is probably why the alternator is putting out 14.6-7 v. Usually it does not go passed 14.5v with good battery. At least ,the alternator seems to be doing its job. Although I don't like seeing it passed 14.5 v. I would get another battery. Should be free replacement.

Did you have trouble starting the car? One click? Cranking good? Car does not sound like its choking?

Its an Interstate battery from Costco mfg'd 11/2021. Put it 2 days ago. Car really hasn't been driven since.

 

Costco is hassle free return. Only hassle is the actual removal, return and reinstallation. I would do it.

Here is a good read for troubleshooting battery drain once you get a really good one. Find a DEC made one. Diagnosing A Car Battery That Runs Down

 

Anyways, he could start doing the battery drain test with the same battery. Leave it over night without the charger on. If it drops more the next day or so, then he'll know there is a drain somewhere.

 

Update:
My daughter needs her car tonight so I'll have to do the draw test this weekend. Just pulled off the charger after 8 hours or so.
100% charged per battery charger, 12.7V with multimeter.

 

Are you charging the battery in a warmer environment, or during the 15-25 degree nights?

If you're charging it when very cold, that could explain the lower than expected for a brand new battery voltage... The 12.7 reading right after charging looks just like I would expect for a brand new battery. It's also warm just after charging. If it's then left in the 15-25 cold temps for several hours overnight, that may explain your lower voltage readings. It's equally possible parasitic drain is occurring simultaneously with the cold to reduce the voltage...

 

I have been charging outside in the cold.
Just got my daughters car. today Multimeter read 12.54v after sitting 2 hours at 32 degrees. She drives about an hour a day. I guess in not happy with the 85% result but that's the reading of my battery tester which I have doubts about. Is voltage a better indication?

 

I have been charging outside in the cold.
Just got my daughters car. today Multimeter read 12.54v after sitting 2 hours at 32 degrees. She drives about an hour a day. I guess in not happy with the 85% result but that's the reading of my battery tester which I have doubts about. Is voltage a better indication?

The 85% state of charge reading is roughly approximate to the 12.5 volts on the tool, but what concerns me is why the voltage is dropping more than 4 volts when the engine is turning over. At this point, I think you need to do voltage drop testing on each of the positive and negative sides of the starter circuit (see my post #24 earlier).