2016 Leaf SV 12V battery draining

[RegGuheert]

What we need in the LEAF is a mode which engages the high-voltage battery WITHOUT also engaging the electric drive system.

Two presses of the Start button with no foot on the brake pedal will do exactly this, IIRC, but the 12 volt battery won't be properly charged. It's still better than accessory mode.

No, that mode does not engage the high-voltage battery until the 12V battery is almost completely dead. I just tried it and my battery was sitting at 12.05V.

 

[Marktm]

Here's a whole thread http://www.mynissanleaf.com/viewtopic.php?f=37&t=11999 on it; I still have this exact battery installed today 3+ years). Most people stop at the price, but there are other/similar alternatives; it's important that you get one with some sort of cell-balancing built-in (the "cheap" ones don't have it). You shouldn't need voltage protection since the Leaf doesn't go above 14.4v.

Thanks Stanton;
With the price of LiFePO4 dropping continuously, it will be my choice - if I am still driving this Leaf WHEN the battery goes out (I believe it is fairly new). I've had this technology (with excellent BMS) in my dirt bike for over a year and it always works - even if I don't ride for 2 months. From the descriptions of the DC/DC converter and charging logic (5 day), it seems to be a good/economical choice.

I do wonder what the proper amp-hour sizing would be for a well designed Li tech 12 volt battery for use in a Leaf?

 

[DaveinOlyWA]

things to keep in mind; NEVER NEVER NEVER use accessory mode in your LEAF. There are no known cases of death from inhaling electrons, so no reason whatsoever to use this mode. This mode does not maintain the 12 volt system....only drains it.

...except when you don't want someone to drive off with your car! I'm amazed at the activity these 12v threads get. Just last week I was "showing off" my car after delivering an EV presentation, and folks wanted to see what the dash/console looked like...and I didn't want them driving my car off by accident, so I put it in accessory mode. I've listened to baseball games on the driveway plenty of times in the same mode with no issues; after all, the car is designed to "top off" the 12v when needed (just not from the dead).

E-brake would fix that...

If Nissan was using a good charging profile OR if someone told them that lead acid and Lithium based batteries are different then sure its ok to occasionally add some more drain to the battery since it would be draining from the top but what you are essentially doing is trying to organize a blood drive using patients in the ICU

 

[Stanton]

Thanks Stanton;
With the price of LiFePO4 dropping continuously, it will be my choice - if I am still driving this Leaf WHEN the battery goes out (I believe it is fairly new). I've had this technology (with excellent BMS) in my dirt bike for over a year and it always works - even if I don't ride for 2 months. From the descriptions of the DC/DC converter and charging logic (5 day), it seems to be a good/economical choice.

I do wonder what the proper amp-hour sizing would be for a well designed Li tech 12 volt battery for use in a Leaf?

I don't know about "proper", but my 20A LiFePO4 starter battery works just fine. I've run a 9A battery (that's not a typo) for a couple of weeks in my Leaf, but it wasn't mechanically stable (just too small). Obviously, it doesn't take much to "start" a Leaf.

 

[Marktm]

Out of curiosity, I checked the battery voltage - after driving an hour or so ago with nothing on (except a new ELM 327 OBDII). Voltage was 12.25. Now I'm worried as this would be a "settled" voltage of about 40-50% SOC. Needless to say, I've put it on a trickle charger as will monitor it closely over the next few days. If the battery stays at this level of SOC, it will sulfate rapidly.

I may be looking for a Li technology replacement.

 

[LeftieBiker]

Out of curiosity, I checked the battery voltage - after driving an hour or so ago with nothing on (except a new ELM 327 OBDII). Voltage was 12.25. Now I'm worried as this would be a "settled" voltage of about 40-50% SOC. Needless to say, I've put it on a trickle charger as will monitor it closely over the next few days. If the battery stays at this level of SOC, it will sulfate rapidly.

I may be looking for a Li technology replacement.

An AGM SLA battery would be less expensive and would tolerate the lower SOC much better than the OEM starting battery. If you got one with a 40 or greater AH capacity I don't think you'd have trouble with it. Going by the anecdotal evidence here, and my own observations of my car, it seems like longer trips with low or modest accessory drains will bring the 12 volt battery up to near 100% charge. It's the shorter trips with lots of accessory drains that run it down. And, of course, leaving the car plugged in but not charging is the worst scenario.

 

[Marktm]

Going by the anecdotal evidence here, and my own observations of my car, it seems like longer trips with low or modest accessory drains will bring the 12 volt battery up to near 100% charge. It's the shorter trips with lots of accessory drains that run it down. And, of course, leaving the car plugged in but not charging is the worst scenario.

With my limited knowledge of the converter charging algorithm, it does seem there are better alternatives to a "CCA" based ICE battery (if that is what is actually OEM in the Leaf) that include AGMs, FLA deep cycle, and LiFePO4 technology (with good BMS). As the solar guys know, you do need to "float" as much as possible at the end of the day, equalize every so often, and do not leave at low SOCs for extended periods if you want good life out of flooded lead acid batteries (and to much extent AGM/GELs). The overall energy consumption from the traction battery would not be much different to do so and "surprise" deaths of the 12 volt system might be reduced significantly??

http://www.mynissanleaf.com/viewtopic.php?f=30&t=12959

Wonder if anyone has detailed the "logic" that is used by the Leaf's 12 volt charging system?

 

[LeftieBiker]

Wonder if anyone has detailed the "logic" that is used by the Leaf's 12 volt charging system?

Not that I know of, but the charging pattern has been observed. It starts out at about 14.1 volts, IIRC, when you plug the car in, but then quickly switches to a float charge of maybe 13 volts? The end result is that the 12 volt battery is charged too little and too slowly, especially for L-2 charging. It has been suggested that the quick switch to float charge is because the OEM starting battery is too small, and the voltage rises too quickly for a longer bulk charge to be sustained.

 

[Marktm]

Those voltages all seem quite low for FLA application - you would think Nissan would have always kept the battery above bulk charge (~ 70% SOC) to ensure it was always in the constant voltage charge. That would require 13.5 to 13.8 volts. And even the 14.1 seems a little low to "equalize" or "boil" the acid to prevent stratification. Maybe the Leaf's suspension takes care of that one!

Probably over-thinking this one, but I am going to monitor the battery more closely - especially trying to get the OBDII dongle working. (Appears I've fallen victim to the "cheap Chinese" ELM327).

 

[RegGuheert]

Out of curiosity, I checked the battery voltage - after driving an hour or so ago with nothing on (except a new ELM 327 OBDII). Voltage was 12.25. Now I'm worried as this would be a "settled" voltage of about 40-50% SOC. Needless to say, I've put it on a trickle charger as will monitor it closely over the next few days. If the battery stays at this level of SOC, it will sulfate rapidly.

That is precisely what happens at that SOC. In fact, it likely has already happened unless the battery is very new.

This is the normal result we see with the 12-V battery charging algorithm used by the Nissan LEAF. Here is a plot I made in 2012 with our LEAF over a three-week period (I only took readings intermittently at the points where you see a dot):

Note how the battery started in a fully-charged state, but within a few weeks of normal use it was down to about 50% to 60% SOC. Your voltages are a bit lower than those seen here, the difference being that you have the ELM327 installed. Now that I have that installed, I often see the 12.25V level that you are reporting.

Here's another plot I made using data from poster 69800 that gives a bit more detail on what happens in the LEAF:

The above plot used a five-minute sampling interval. This was with a brand-new SLA battery. Note how the voltage following a "charge" in the LEAF is no higher than it was just before that "charge" occurred.

Wonder if anyone has detailed the "logic" that is used by the Leaf's 12 volt charging system?

Yes, we know in quite some detail what happens:
1) When the car is charged or placed into "READY" mode, the battery is initially charged at 14.50V. The key word here is "initially". Normally this voltage is maintained for less than 60 seconds.
2) After the initial charge at 14.50V, the voltage drops down to a 13.1V float voltage and remains there until the car is turned "OFF" or the charging of the traction battery ends.
3) There are exceptions which occasionally cause the 14.50V value to be maintained longer than normal. They are:
a) When the windshield wipers are turned on (even on intermittent), the voltage is raised to 14.5V and stays there until about 1 minute after the wipers are turned off.
b) Sometimes during a charge cycle, the 14.5V charging voltage is maintained during the entire charging period. This happens frequently (always?) when the temperature is below about 30F. It also happens occasionally at other times. I don't think we know what triggers this real charging cycle to occur. Perhaps it happens every so many charge cycles. Frankly, I think it's a good idea, but it should be done every fifth (or perhaps 10th) cycle, but instead it happens less frequently than Elvis sightings.
4) If the car sits for five days with no activity, the DC/DC converter is engaged for a period to charge the 12V battery. You can see the result of this after day 19 in my first plot above. As you can see, while it DID charge the battery, it did NOT charge the battery fully.

The bottom line is that the 12V charging system in the LEAF RARELY achieves a 100% charge on the 12V battery with the result that the lead sulfate hardens and capacity is steadily lost.

Like you, I connect a high-quality trickle charger to occasionally top off the 12V battery in an effort to prevent premature failure due to sulfation.

 

[LeftieBiker]

I have my charging lead hardwired to the battery and run into the charging port compartment. This lets me plug in the maintainer whenever convenient, and also whenever I think the car may sit plugged in but not charging for any length of time above 10 minutes. The only upside to this inconvenience, aside from not getting a dead accessory battery, is that I also don't have to worry about plugging the car in to charge later, or to stop charging hours before I unplug it. If you have a setup like this, even a 0.75 amp Battery Tender Jr. Will work fine, as long as you use it at least several times a week. For more intermittent use I suggest a 2 amp or more charger/maintainer. I had a DieHard 2 amp unit used for this, but it proved to be misnamed: it died early and easily.

 

[Marktm]

RegGuheert;

From the perspective of an off-grid solar enthusiast using FLA deep cycle batteries (my golf cart and a spare set), the charging profiles you have documented would likely ruin any lead acid battery bank in less than a year of daily use - AND have very limited capacity (SOCs in the 70 to 30 % range!). I realize the service is very different, but the sulfation at continually low SOCs IS DESTRUCTIVE.

I took the battery voltage reading after a nights level II charge - 12.15 volts (~30% SOC). I'm going to fully charge the battery and do an actual load test. My guess is that my battery is on the verge of failure.

I've attached a typical FLA charging profile. If I did my math correctly (grosso-moddo numbers!), the 13.1 volt charging voltage corresponds approx. to 90% at the C/40 line. (C=20 AH rating typical of deep cycles). As an example, a 40 AH battery would be charging at ~1 amp. It would take 10 hours to charge from 80 to 90%. Of course at ~60% SOC, the charge profile is ~ C/20 or 2 amps and would take 5 hours to charge from ~50 to 60%. I guess the point is that constant voltage charging at 13.1 volts is much too low to keep the SOCs in the 90%+ range. Compound this with the use of a "CCA" (cold cranking amp) designed battery - designed to fail prematurely?

http://mynissanleaf.com/download/file.php?mode=view&id=2290

 

[RegGuheert]

Thanks for the chart, Marktm! I don't recall seeing one like that before.

I've attached a typical FLA charging profile. If I did my math correctly (grosso-moddo numbers!), the 13.1 volt charging voltage corresponds approx. to 90% at the C/40 line. (C=20 AH rating typical of deep cycles). As an example, a 40 AH battery would be charging at ~1 amp. It would take 10 hours to charge from 80 to 90%. Of course at ~60% SOC, the charge profile is ~ C/20 or 2 amps and would take 5 hours to charge from ~50 to 60%. I guess the point is that constant voltage charging at 13.1 volts is much too low to keep the SOCs in the 90%+ range.

Agreed on all of the above. This is why LEAF 12V batteries tend to live around 50% SOC and not any lower or higher typically leaving 1/2 of the battery's capacity to sulfation.

While some LEAF 12V batteries DO fail at one year, anecdotal evidence tells me that they typically last between 2 and three years. There are two main reasons that they tend to last a bit longer:

1) It takes very little in the way of capacity and CCA to start a LEAF.
2) Those periods when the charging system DOES stay at 14.5V do help. I suspect those who live in rainy climates may get better 12V battery life.

Since our LEAF was assembled in June 2011, our 12V battery was likely over five years old. I occasionally use a desulfating charger on it and have been able to recover nearly all sulfation in the past. Currently the battery appears to be about 15% sulfated and I am hoping to bring it back close to new. It also has retained almost 100% of the water that came with the battery. My expectation is that I will get 10 to 12 years from this battery by continuing to provide the care that should be provided by the built-in charging system.

 

[Marktm]

I occasionally use a desulfating charger on it and have been able to recover nearly all sulfation in the past. Currently the battery appears to be about 15% sulfated and I am hoping to bring it back close to new. It also has retained almost 100% of the water that came with the battery. My expectation is that I will get 10 to 12 years from this battery by continuing to provide the care that should be provided by the built-in charging system.

Between LeftieBiker and your suggestions, I hopefully can recover this battery and/or determine it's too far gone and replace it, and not take any chances getting stranded. I too use desulfating type chargers - not too sure how effective mine is, but it's worth a try.

Is there a code on these Japanese batteries that give the manufacture date? Since I've only had this 2012 for 5 months, I'm not sure if it's original?

Kudos to this forum for pragmatic solutions, helpful and educational.

 

[LeftieBiker]

I just dropped my 2013 SV off for annual "service." I asked them to check the capacity of the 12 volt battery because it's still under warranty, and they just called me back to quote a $105 "diagnostic fee." I told the service salesman (because that's what they are - salespeople) that because the car is under warranty and I'm asking them to investigate a failing part that is covered under warranty, there is no fee. He seemed to agree, but...we'll see.

 

[RegGuheert]

I too use desulfating type chargers - not too sure how effective mine is, but it's worth a try.

I think mine works for batteries this size, but it does take time to break up the sulfate. I've had the best results with this battery by leaving it on the charger for a couple of weeks while on vacation. Just don't expect a battery to become desulfated overnight.

Is there a code on these Japanese batteries that give the manufacture date? Since I've only had this 2012 for 5 months, I'm not sure if it's original?

If it's translucent with Japanese markings on it, then it is almost certainly the original battery, since I would expect dealers in the U.S. to replace it with a U.S.-manufactured battery. I looked for the manufacturing date on mine before I posted this morning, but I could not find it.

FWIW, I really like this battery BECAUSE it is translucent. I can easily verify the water level without ever opening the covers by simply shining light through it from a stubby flashlight. I also feel it is very well manufactured.

I asked them to check the capacity of the 12 volt battery because it's still under warranty, and they just called me back to quote a $105 "diagnostic fee."

To me it is entirely ridiculous to charge $105 to diagnose a part which can be bought at Costco for about $75. I guess many people must pay these fees, however.

 

[knightmb]

No lead acid technology will do well spending it's life at 50% to 60% SOC. Seems so short sighted of Nissan to NOT design a decent DC/DC converter for the battery technology they selected. The gentle use requirement (low temp/low discharge) should give 5+ years of a deep cycle FLA or AGM battery. Replacement with LiFePO4 is a definite consideration for me.

Anyone have extended experience/recommendation with the the lithium technology?

Been running lithium replacement for over a year and a half, flawless operation in all cold or hot temperatures since changing over.

Alchemy - Turning Lead into Lithium - 12 Volt Battery Mod

 

[LeftieBiker]

Been running lithium replacement for over a year and a half, flawless operation in all cold or hot temperatures since changing over.

How cold does it get where you live?

 

[jjeff]

With all this talk about 12v batteries failing prematurely mainly due to low 12v SOC, has it been shown that the batteries in the SL models(with the tiny solar panel that only charges the 12v battery) last longer than S or even SV models? If that solar panel does any good you'd think, at least in sunny climates, SL 12v batteries would last a fair amount longer before failing.....I occasionally(couple times/month) hook up my desulfating trickle charger to both my S and SL models but am wondering if I need bother with the SL as it has the solar panel and is parked outside......
Also lots of talk about using a Li battery as a 12v replacement but would a AGM gel type battery be any better? Not necessarily this one but one like it in the correct size?
http://www.amazon.com/Optima-Batteries-8171-767-DS46B24R-YellowTop/dp/B006VFEJJQ/ref=sr_1_1?s=automotive&ie=UTF8&qid=1463489758&sr=1-1&keywords=12v+prius+battery
I used this as a replacement in my Prius and it's been working trouble free for several years.

 

[DaveinOlyWA]

Out of curiosity, I checked the battery voltage - after driving an hour or so ago with nothing on (except a new ELM 327 OBDII). Voltage was 12.25. Now I'm worried as this would be a "settled" voltage of about 40-50% SOC. Needless to say, I've put it on a trickle charger as will monitor it closely over the next few days. If the battery stays at this level of SOC, it will sulfate rapidly.

I may be looking for a Li technology replacement.

make sure that ELM turns off if disconnected from LEAF Spy. if not, you will have battery issues soon