12V Battery Questions

Our Leaf had been driven on Saturday, plugged in Saturday night. Not used and now, Monday evening I started up LeafSpy Pro, and saw that the 12V battery was at 11.96V.

Q 1. That sound reasonable?

Q 2. How much SOC will I lose per day of non-operation?

Q 3. What's the highest SOC at which you would consider topping off?

Q 4. Let's say the Leaf is left plugged in, and the SOC begins dropping. At what point will it top off on its own (if ever)?

Thanks!

Based on what I've read here over the last two years, that reading is somewhat expected. It can be affected by other factors.

Did you leave the bluetooth OBD adapter turned on?

Did the vehicle do a charge cycle anytime from when it was plugged in Saturday until you checked it on Monday?

Do you have the charge or climate timers activated?

Have you checked the cells on the 12 volt battery to see if they need topped off (use only distilled water)?

Is it cold where you are (near freezing or below)?

Is the vehicle parked in a garage or outside?

SOC is generally used to refer to the charge level of the traction battery, not the 12 volt battery. If the vehicle is sitting parked, the SOC of the traction battery should change very little under normal conditions. There is a heater that will kick in if the traction battery gets too cold, and it will charge up the 12 volt battery if the voltage level gets too low. The Leaf will not automatically charge the traction battery, unless the charging timer is active.

I would try to avoid letting the SOC of the traction battery fall below 20%. How often you charge it should depend on how often you drive it. Don't let it sit at 100% for more than a few hours, if at all possible, especially in high heat conditions. I've had to make changes to my charging patterns as my battery has degraded (now 3 bars down). Currently, the charge timer runs every morning at 2am, to 100% on weekdays and 80% on weekends.

Thanks.

>Did you leave the bluetooth OBD adapter turned on?
No, I switch it off.

>Did the vehicle do a charge cycle anytime from when it was plugged in Saturday until you checked it on Monday?
No.

>Do you have the charge or climate timers activated?
No

>Have you checked the cells on the 12 volt battery to see if they need topped off (use only distilled water)?
No

>Is it cold where you are (near freezing or below)?
No. Around 45 degrees F.

>Is the vehicle parked in a garage or outside?
Inside.

The 12 volt battery is charged whenever the traction battery is charged. It also kicks in when the windshield wipers are turned on. There are some minor loads that never turn off, like the radio memory and clocks. I would periodically check the cell levels, and top off as needed. Otherwise, don't worry over it until you start getting odd behaviors or the car won't turn on.

It is warm enough that the battery heater should not be turning on. You should see little or no change in the SOC of the traction battery if it sits for several days without being charged or driven.

2016 year Leaf doesn't have problems with 12V battery. Don't worry.
If it goes bad it goes bad. That happens with all cars.
I'm not sure about "switching OBD dongle off". Just remove it.

arnis said:

Don't worry.
If it goes bad it goes bad. That happens with all cars.
I'm not sure about "switching OBD dongle off". Just remove it.

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Or, you could get a CTEK charger and help the battery live longer without worrying about removing the OBD dongle every night. In my opinion it is a great charger, much better than the Battery Tender which I used to use back when I rode a Honda Rebel 250,

I have the CTEK 0.8, which is $51 at Amazon, or they have the MUS 4.3 for $69, which does everything the CTEK 0.8 does but can also be switched to charge at 4.3 amps instead of the 0.8 amps. In looking back, I think I would have spent the bit extra to get the MUS 4.3. A few other people on the forum here use the CTEK charger too.

One detail though, which the experts can hopefully correct if I'm wrong or confirm if I'm right, is that when charging the 12V battery hook up the + (Positive) lead of the charger to the + (Positive) of the 12V battery, but hook up the - (Negative) lead of the charger to the bolt where the Negative cable from the 12V battery is attached to the inverter and do not use the - (Negative) terminal of the 12V battery itself. I'm not really sure why attaching to the - (Negative) terminal of the 12V battery is so bad, especially if the LEAF is off, but as I understand it the experts do not want it hooked up that way, only to the bolt.

You pay for the charger and pay for parasitic electricity.
And whatever you try to do lead acid battery will still fail.
It will take longer. Most likely with trickle charging you will never break even.

Like I said, I would recommend somebody to try to disconnect current sensor at
negative terminal. I'm pretty sure that will result in 14.4V fixed mode on older Leafs.

PianoAl said:

Our Leaf had been driven on Saturday, plugged in Saturday night. Not used and now, Monday evening I started up LeafSpy Pro, and saw that the 12V battery was at 11.96V

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This seems a bit low and may lead to premature battery failure. I charge on L1 for several hours (instead of L2 for only a couple). During that time, my lead acid battery is being charged. Also, I periodically top it up with a CTEK trickle charger. I typically see about 12.6-12.8 V when checked. The CTEK charges it up to about 13.6 V. This is with the original 2011 battery, now almost 6 yr old. I typically get 7 years out of lead acid battery in this area. I'm hoping that this constant charging and topping up will keep the battery running for another couple years. So far so good, knock on wood.

PianoAl said:

Our Leaf had been driven on Saturday, plugged in Saturday night. Not used and now, Monday evening I started up LeafSpy Pro, and saw that the 12V battery was at 11.96V.

Q 1. That sound reasonable?

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Reasonable? No. Typical for a LEAF? Yes. But I will say that you must have opened the doors to turn on LEAFSpy, so you likely awakened the car's electronics before your measurement. A better way to measure the 12V battery is to pop the hood when you park it and raise the hood and measure with a quality meter at a later time. Since the number you got is so low, I recommend you make such a measurement soon to ensure you do not get stranded somewhere.

PianoAl said:

Q 2. How much SOC will I lose per day of non-operation?

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Unplugged: about 3% of 12V battery is lost.

PianoAl said:

Q 3. What's the highest SOC at which you would consider topping off?

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For the 12V battery? They NEED to be topped off frequently. If you use a quality trickle charger, then anytime is fine.

PianoAl said:

Q 4. Let's say the Leaf is left plugged in, and the SOC begins dropping. At what point will it top off on its own (if ever)?

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Arnis has reported this happens daily on the 2016s and newer and does a decent job of charging the 12V battery. In earlier versions, it was every five days and the charging did not actually "top off" the 12V battery.

That CTEK charger may be good, but overpriced at $60.. I got my several battery tenders at Costco for $29 each..

Also, either hard wire the quick connect pigtails directly to the battery terminals or put clamps right onto the battery terminals. That stuff about not connecting to the battery is nonsense. the charger needs to measure the voltage right from the battery...

powersurge said:

Also, either hard wire the quick connect pigtails directly to the battery terminals or put clamps right onto the battery terminals. That stuff about not connecting to the battery is nonsense. the charger needs to measure the voltage right from the battery...

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I'm not a LEAF expert, nor an electronics expert, nor a PbA battery expert, but it seems in my opinion that Phil (Ingineer) is, and I am going by what he has recommended many times, " Also, heed my warning about NEVER connecting ANYTHING directly to the LEAF's negative battery post EVER!" In my opinion "ANYTHING" includes the negative connection for a battery charger.

It is so unfortunate, Stoaty asked the exact question about proper battery charger connections, even down to the CTEK charger, asking for "very simple and specific terms," and Phil (Ingineer) replied "See this post," http://www.mynissanleaf.com/viewtopic.php?p=148133#p148133, where once again he adamantly implores people to never connect to the LEAF's negative battery post, but that reply is in the topic about "Jumping another vehicle" with a LEAF, not about a trickle battery charger. I'm thinking though by him linking to that post, his warning holds true for the trickle battery charger negative connection and not to connect it to the negative battery terminal.

In the CTEK 0.8 manual, http://smartercharger.com/wp-content/uploads/2010/11/US-800_us.pdf , page 5, Step 16, steps to follow when battery is installed in a vehicle, negative grounded, Substep 2, "Connect negative charger clip (black) to a good metal engine ground away from the battery." It is my understanding the major reason for this recommendation is the remote possibility of a spark and subsequent explosion of the 12V battery. But I'm going to follow their recommended procedure.

Phil takes this risk very seriously, and as evidence I can speak of an incident where I witnessed a guy blow up a 12V battery at night. It was like a bomb went off, with a huge flash of light, and there was nothing left of that battery. At first I hadn't realized what happened, as I wasn't focused on the guy, and I was a bit far away. I then heard him screaming in pain, and quickly went to him. A few other people had gathered, but I was right by him, and told somebody to go in the store and get distilled water. They must have been looking for a specific brand and waiting in line to pay, as it took forever. I was starting to panic, as I was about 21 years-old or so, when an older guy said he had some vinegar which should be poured on to "neutralize the acid." As a chemistry major, I just knew that was wrong, always being taught use only distilled water, but I was starting to lose any ability to think and was actually considering it, and the irony of course is that vinegar is acidic too. The guy finally came back from the store, and I started pouring the water all over the injured guy's face, and trying to get him to relax his muscles so a bit of water could wash his eyes, as I knew too that I shouldn't touch him. Thankfully the ambulance pulled up and they took over, I think he was OK because he had a large cut above his eye but I think his eyes were OK.

The proper course of action would be baking soda, regarding acid burns.

Durandal said:

The proper course of action would be baking soda, regarding acid burns.

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That would be a definite "NO," at least according to essentially every safety agency's recommendation and everything multitudes of chemistry students have been taught for generations. I believe water is the ONLY allowed method for such a chemical burn such as sulfuric acid to the eye.

http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/sulfuric_acid.html

https://www.cdc.gov/niosh/npg/firstaid.html

Quoting from the CDC site: "If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. "

The Canadian site recommends continuing flushing with water for 30 minutes.

WebMD recommends a "mild, soapy solution if the burns are not severe." They continue, "but it is better to flush the area and not leave the acid on the skin."

The ONLY time I have seen baking soda recommended was the site WebMD, and that was ONLY for Hydrofluoric Acid. And even then, they give the specific warning, "Do not flush the eye with a baking soda solution."

Sorry, I somehow missed the part about eyes, I was thinking skin. You are correct, the action for eyes is just water.