New Battery Observations!! (No, not that one, the "other" one!)

Once again, another report of a dead 12 volt battery on the LEAF.  Why is this happening?  A computer also needs a battery supply to start up. The battery retains basic knowledge about the computer, its hardware and configuration settings so its BIOS can tell the processor how to talk to its various peripherals.

The LEAF battery fills pretty much the same role including a check of the system before it connects the traction battery. So its essential to the operation of the LEAF. Without it, its like having a gasser with a dead 12 volt battery; its simply no go.

With nearly 60,000 LEAF Miles under my belt, I have yet to experience this issue. This includes a time on my 2011 when a door was not closed correctly. I realized the error a few hours later when I went to start up the LEAF to do an errand and noticed the dome light was dimmer than normal. Luckily the car started ok and the dash alerted me to the door ajar issue. My short trip (added a 15 minute cruise around for good measure) was enough to get the battery back on track.

Now this was also about the time when the first reports of people having a dead battery surfaced. Initially, the user was blamed. Left lights on, left car on (ya, this one never made sense) or left door ajar, etc.

Then there was dead batteries after being plugged in while away on extended trips. We found that the 12 volt battery gets a boost every few days if NOT LEFT PLUGGED IN.  So we then decided if gone more than say 3-4 days, charge the LEAF to 50% SOC more or less and leave it unplugged and we should be good right?

Then Casey, A Seattle LEAFer left his car unplugged at 50% SOC for only 2½ days and his  12 volt battery was dead. What the hey!! He did what he was supposed to do and it did not work.  Obviously there was more to this than we realized. This is when I started monitoring my 12 volt battery on the 2011.  What was readily apparent is the car was simply not maintaining a healthy voltage for the battery.

Unlike other battery's chemistry, Lead acid should remain at the upper end of the SOC range as much as possible. extended periods at lower voltages dramatically shortens its life.  So the voltage target should be around 12.7-12.8 volts more or less.  My LEAF's 12 volt battery frequently read in the 12.1-12.3 range.  The longer it sat, the lower it would go. Yes, after a few days, the traction battery would kick in and give it a boost.  How much of a boost, I do not know. I never had an opportunity to monitor this because not driving the LEAF for that long a period was simply not an option and when it was, I was out of town!

Now, all this would make more sense if the issues were uniform but they were not. Some people were seeing dead batteries after a few days, some after overnight periods sandwiched between daily use and others were just fine after several weeks of inactivity.  So the conclusion might have been that Nissan needed to find a better 12 volt battery supplier.  Plus getting them replaced at the dealership was surprising pain free leading me to believe that Nissan had discovered something with the quality of the batteries or their own programming.

Fast forward to now and the recent reports of another battery failure. So it was get the meter back out and start measuring again.  After nearly 10 months and 15,000 miles, I have not had an issue so was not really expecting to get much insight to checking battery voltages but that never stopped me before, so

Like the 2011, my 2013's 12 volt battery seems to settle into a uncomfortably low resting voltage around 12.45 volts give or take.  A bit higher than the 2011 but far from the 12.7ish I would prefer.  I plugged in the car which had an SOC of about 30%, and charged it 90 minutes then checked voltage and it was 12.99 volts.  I unplugged the car, waited 15 minutes, checked voltage, it was 12.65 volts and plugged car back in. Voltage immediate rose to 13.00.

I unplugged car. Let it sit for an hour and voltage dropped back to 12.46 volts.  I plugged car back in and voltage immediately rose to 14.40 volts. So the battery was getting a boost now. So there is a cut in voltage level that initiates a battery boost.

I repeated the process this morning and saw the same results.  So, I did learn a few things about how the LEAF "manages" its 12 volt system but this did not really explain why others still continue to have issues including Tyrel who also has a 2013 and has been DIG (dead in garage) 3 times!

First thought (the fact that they are so easy to blame was a factor!) was Carwings. Carwings uses stone age tech to communicate with Nissan HQ thru the AT&T 2G network. This is a power drain on the 12 volt battery and whether its a little or a lot, its ongoing and also something I do not have.

The other factor is the very nature of wireless communication itself. The stronger the signal, the less power needed to manage it.  We have all been there when you see the roam or the dreaded slashed phone symbol which means you are experiencing poor cellular signals in the area. It could be a blind spot in the network or simply being in the wrong kind of building.  What happens? a MUCH faster than normal declining battery SOC on your phone.  Well, the LEAF system is not a whole lot different.

In a previous life, I pondered over the quality of phones and their ability to function on the network and there were frequently no reasons why they did not do what they were designed to do. The more complicated the phone, the larger the issue.  Environmental factors combined with end users was the general culprit blamed and frequently for lack of a better reason.  But this does make sense. Your phone is a sensitive electronic instrument not unlike your TV or computer, but unlike your TV which spends its life stationary in a climate controlled room, your phone is abused. Its hot, its cold, it takes soda baths, salsa facials, and copes unwanted falls on a regular basis.

So back to the LEAF's failed battery issues. Well, it would seem based on my observations that the 12 volt management system seems ok. It boosts it when its below a certain voltage when you plug it in. So driving and charging regularly would imply a regular boost to the system.  So maybe we need to look at environmental factors here as well.  Cars do go thru rapid and frequent temperature fluctuations and vibration (ya, some of the roads around here really suck!)  and all of that could be a factor as well.

My LEAF does not work correctly in all things. My climate controls are possessed. They change air direction functions on their own. When I first noticed this, I thought it might be a sticky button or something because I noticed a change in air direction (face to foot/windshield is most common)  when doing various things like shifting (ya, do a LOT of that) or even changing radio stations. This got me to paying attention to what I was doing when this "spooky" stuff was happening right? (Halloween is coming so trying to stay in the season!) This is when I noticed it also happened when I was doing nothing at all but steering.  Well, I have a bug. No question about that and one day, I guess I will have it looked into when its convenient and as long as the bug does not have children who might create other issues.

In conclusion, I have no definitive conclusion. I am thinking that further data collection on my 12 volt battery will yield nothing so probably need input from you. If you have a 2013 with Carwings, try some measurements like I did to see what your charging system is doing.  I will probably try to find where the cut in voltage for a battery boost will be. Its apparently above 12.46 volts and below 12.65 volts so we shall see soon enough.

FYI's; I have never used any special charge settings. No 80%, no timers, etc.  when I had Carwings. Now, I did do charge stop, finish alerts, remote A/C on a few dozen times, etc.  Also monitored charge levels a lot on the 2011. So maybe looking at timer settings might be an option as well?