Dead 12V battery question

[DougSchwartze]

Completely normal and if the lowest you are seeing is 12.25 volts, your battery is in pretty good shape relatively speaking. I see much lower and have never had a starting issue. The weather is "finally" expected to turn (at least for a few days) at the end of this week which means 12 volt monitoring will be stepped up.

One likely load is the monitoring of the inverter. It heats up and once I heard the water pump run for about 2 mins after the car was unplugged (this only happens on AC charging) so naturally, had to load up LEAF Spy. It did appear the fan was running of system power and not the battery though.

https://daveinolywa.blogspot.com/2021/04/charge-your-leaf-every-day.html
[/quote]

Thank You Dave. These are all good clues.

On the subject of the "Dead 12 volt battery" issue it is known that
Sulfation of lead acid batteries is a major cause of early life failures.
Sulfation is crystallization which slowly shorts out a cell and happens quicker when a battery is left sitting at a voltage
of 12.4 volts or below.
https://www.power-sonic.com/blog/what-is-a-sulfated-battery-and-how-do-you-prevent-it/

Leftiebiker notes that this 15 minute period happens during the traction batteries cell equalization process. I believe here should be no drain put on the 12 volt battery at this time. Software and hardware should stop any large load from being applied to the battery.

If I disrupt the equalization by removing the EVSE cord from the car just before, or just when the 3rd light comes on solid then I do not see a load put on the 12 volt battery and it rests nicely at 12.6 volts.

My contention is that this repeated discharging of the 12 volt lead acid battery leaving it sit below the required 12.4 volt limit may be causing sulfation of the cells. Leaving your car sit at 85 degrees F. will also increases the discharge rate by 50%. There are many possible other causes working against us as well.

I am focusing on this one deficiency (in my opinion). It appears that either my car is different than others (for example it has a bad anti-drainback diode in the DC/ DC convertor output), or there may be
room for an engineering improvement which could improve everyones' 12 volt battery charging function forever.

I believe that Nissan owes us Faithful Customers old and new, the best Service Support possible.
There is a lot of competition out there these days.

All the nerds I know appreciate good continued Engineering and Service support, and show it through their EV buying Dollars.

Nissan Leafs are great cars with awesome engineering. Many of us plan on keeping our old ones forever and hope to buy new ones as they improve as well. It would be a mistake to not give it all you've got with open support before you lose what you had to start with... Customers.

Peace, and Happy Charging !!!
-Doug...

 

[LeftieBiker]

Completely normal and if the lowest you are seeing is 12.25 volts, your battery is in pretty good shape relatively speaking. I see much lower and have never had a starting issue.

That sounds like 'Granny smoked like a chimney until she died at 95, so I don't see a problem with smoking.' It's widely considered a bad idea to let a 12 volt battery get down to 12.1 volts or lower. It won't kill the battery on the spot, but it weakens it. Granny could have lived to be 105 or 110, had she avoided the cigs...

 

[DaveinOlyWA]

Completely normal and if the lowest you are seeing is 12.25 volts, your battery is in pretty good shape relatively speaking. I see much lower and have never had a starting issue.

That sounds like 'Granny smoked like a chimney until she died at 95, so I don't see a problem with smoking.' It's widely considered a bad idea to let a 12 volt battery get down to 12.1 volts or lower. It won't kill the battery on the spot, but it weakens it. Granny could have lived to be 105 or 110, had she avoided the cigs...

"relatively" speaking, it could be looked at many different ways but the reality is Nissan 12 volt management is a train wreck and has improved very little if at all in the past decade. Many factors are involved namely temperature. Last night coming home from work, it was in the mid 40's which is perfectly normal for this time of year with a high in the low 70's which is not normal. So I will be seeing 12.1ish until Winter truly hits where it will hover around 12.0.

The one thing I have noticed is the manual boosting by windshield wipers might contribute to my not being stranded but it does not change the fact that the battery is has lost the war starting from day one.

I will soon (next week) move into new territory having owned a LEAF for longer than 3 years (this one has already beaten the previous record for longevity) and beyond, likely much beyond. Its all a matter of time and my hopes is to last 5 years. We shall see.

 

[GerryAZ]

I respectfully disagree with all of the negative comments about the LEAF 12V charging algorithms. The OEM batteries in my LEAFs survived longer than average for OEM batteries in my climate. The Nissan OEM batteries lasted between 2 and 2-1/2 years while OEM batteries in other vehicles I have owned started showing weakness in as little as 12 months and required replacement in 18 months or so. I had replacement batteries fail in as little as 6 months in other vehicles before I started purchasing only AGM batteries over 25 years ago. I have never connected an external 12V charger to any of my LEAFs and the first replacement batteries in the 2011 and 2015 were still going strong when the cars were replaced. I hope to keep driving my 2019 long enough to find out how long the Optima deep cycle AGM battery group size 51R lasts (again the first replacement battery and identical to the ones I put in the 2011 and 2015). It is still going strong with no sign of weakness (resting voltage after sitting overnight was 12.66 this morning). It was 12.87 volts when I unplugged the car 1-1/2 hours after completion of traction battery charging yesterday morning.

The charging algorithm has changed over the years. The charging voltage drops from absorption charging voltage of 14.0-14.5 (depending upon ambient temperature) to float charging voltage of 13.0-13.4 when absorption charging current drops below a threshold. The absorption current threshold was highest on the 2011 (probably 8-10 amperes), significantly lower on the 2015 (probably 5-6 amperes), and lowest on the 2019 (2-3 amperes). Therefore, the 2019 gets the 12V battery to a slightly higher state of charge before dropping to float voltage.

 

[Stanton]

I respectfully disagree with all of the negative comments about the LEAF 12V charging algorithms. The OEM batteries in my LEAFs survived longer than average for OEM batteries in my climate. The Nissan OEM batteries lasted between 2 and 2-1/2 years while OEM batteries in other vehicles I have owned started showing weakness in as little as 12 months and required replacement in 18 months or so

I second that...and add to it: I have now had the same LiFePO4 12v battery in my Leaf for almost 10 years!
I'm still amazed how much air time these 12v discussion get--especially when so many reject better solutions (like Lithium) simply due to cost (which continues to drop).

 

[knightmb]

I respectfully disagree with all of the negative comments about the LEAF 12V charging algorithms. The OEM batteries in my LEAFs survived longer than average for OEM batteries in my climate. The Nissan OEM batteries lasted between 2 and 2-1/2 years while OEM batteries in other vehicles I have owned started showing weakness in as little as 12 months and required replacement in 18 months or so

I second that...and add to it: I have now had the same LiFePO4 12v battery in my Leaf for almost 10 years!
I'm still amazed how much air time these 12v discussion get--especially when so many reject better solutions (like Lithium) simply due to cost (which continues to drop).

I'm one year behind you, mine is almost at 9 years now, transferred from my old 2013 to my 2020 along the way.

 

[LeftieBiker]

Lithium batteries are a solution only in warm climates, because of the danger of charging them when they are below freezing. The best battery to use in a Leaf in a typical North American climate is a genuine AGM.

 

[DaveinOlyWA]

I respectfully disagree with all of the negative comments about the LEAF 12V charging algorithms...

That's fine and we have a lot of ammunition supporting the theory that lead acid probably lasts longer in extreme heat at a lower average SOC but in the North, the reliability remains poor and likely due to the fact that the batteries are not maintained at an optimum SOC and is still responsible for too many current needs when the car's 12 volt DC system is off.

So changes that have been made might have improved the situation but is still far from resolving it. Maybe its time Nissan looked at a "testing facility North" and cater to another area besides Phoenix. :lol:

 

[knightmb]

Lithium batteries are a solution only in warm climates, because of the danger of charging them when they are below freezing. The best battery to use in a Leaf in a typical North American climate is a genuine AGM.

I agree, but now they sell auto style 12v lithium batteries with a built-in heater. For me, that would work for anywhere that stays above -40 F/C and in the areas of extreme cold, AGM would be king.

 

[LeftieBiker]

If you rely on the car, you don't want added complexity in the Chinese branded components. A LiFePo4 starting battery would add a BMS* and a heater, with controls, to the complexity of a 'stone axe' AGM battery.


* Many, if not most lithium battery failures are actually a case of the BMS killing the cells it's supposed to protect.

 

[GerryAZ]

Lithium batteries are a solution only in warm climates, because of the danger of charging them when they are below freezing. The best battery to use in a Leaf in a typical North American climate is a genuine AGM.

Which is why that is all I use. I use genuine AGM batteries in all of my vehicles, as noted in previous posts. They are cost effective and simpler than lithium. I was going to try a lithium in one of my motorcycles, but the battery dealer I buy most of my batteries from quit carrying them because of so many problems. They recently started carrying another brand so I may try one if their customers report good service after a few years.

 

[lorenfb]

I respectfully disagree with all of the negative comments about the LEAF 12V charging algorithms. The OEM batteries in my LEAFs survived longer than average for OEM batteries in my climate. The Nissan OEM batteries lasted between 2 and 2-1/2 years while OEM batteries in other vehicles I have owned started showing weakness in as little as 12 months and required replacement in 18 months or so. I had replacement batteries fail in as little as 6 months in other vehicles before I started purchasing only AGM batteries over 25 years ago. I have never connected an external 12V charger to any of my LEAFs and the first replacement batteries in the 2011 and 2015 were still going strong when the cars were replaced. I hope to keep driving my 2019 long enough to find out how long the Optima deep cycle AGM battery group size 51R lasts (again the first replacement battery and identical to the ones I put in the 2011 and 2015). It is still going strong with no sign of weakness (resting voltage after sitting overnight was 12.66 this morning). It was 12.87 volts when I unplugged the car 1-1/2 hours after completion of traction battery charging yesterday morning.

The charging algorithm has changed over the years. The charging voltage drops from absorption charging voltage of 14.0-14.5 (depending upon ambient temperature) to float charging voltage of 13.0-13.4 when absorption charging current drops below a threshold. The absorption current threshold was highest on the 2011 (probably 8-10 amperes), significantly lower on the 2015 (probably 5-6 amperes), and lowest on the 2019 (2-3 amperes). Therefore, the 2019 gets the 12V battery to a slightly higher state of charge before dropping to float voltage.

Yes, obsessiveness about batteries; https://mynissanleaf.com/viewtopic.php?t=29989&start=40

I totally agree! What's with this continued obsessiveness about replacing the Leaf's battery? It's a waste of money,
my OEM 2013 Leaf battery lasted over 7 years. It's replacement was $110. Most data reported about the need for
a Leaf battery replacement are just anecdotal! Few if any longitudinal data have been reported. Some complain
about the Leaf's low charging voltage, and then recommend an AGM which requires a higher charging voltage than
a typical flooded lead acid battery.