Solutions to 12 Volt Batteries and Chargers Posted Here

[69800]

To get an accurate reading you need to disconnect it from everything and let is sit for a few hours. Voltage reading are pretty close but not perfect. The one thing you can tell though is if you charge the battery up then drive it for a week and take a voltage reading each day after the car has been parked for a few hours, You will see that each day that battery voltage will go lower and lower because it is never getting a full charge while driving.

 

[QueenBee]

To get an accurate reading you need to disconnect it from everything and let is sit for a few hours. Voltage reading are pretty close but not perfect. The one thing you can tell though is if you charge the battery up then drive it for a week and take a voltage reading each day after the car has been parked for a few hours, You will see that each day that battery voltage will go lower and lower because it is never getting a full charge while driving.

But that trend doesn't continue or else you'd eventually no longer be able to start the car. It may not be charging to 100% but it's clearly keeping it charged otherwise my battery would not have lasted nearly 4 years. As long as it's not going below an actual (measured disconnected or using specific gravity) SOC of 70% I don't think there is any harm in this, is there?

 

[Nubo]

Is there any value in measuring the voltage of any lead battery when it's still connected to the car? It's my understanding that those data points don't really mean anything. You need to measure the specific gravity or disconnect it and let it actually rest unloaded to get a meaningful SOC.

I'd be hard-pressed to measure the SG on mine without causing some serious damage; it's an AGM deep-cycle battery.

Load test is the most informative, but the resting voltage is useful and correlates to state of charge. You just need to measure at a time that is several hours after the battery has been charging. As far as it still being connected, the "dark current" being drawn by the car is low enough so that voltage sag shouldn't be skewing your measurement.

 

[TimLee]

...As long as it's not going below an actual (measured disconnected or using specific gravity) SOC of 70% I don't think there is any harm in this, is there?

Yes, a lot of harm in a standard lead acid battery.
Allows sulphation to occur.
A lead acid battery treated that way will have a substantially shorter service life than if it was kept fully charged.
I don't have a good data source that quantifies the service life reduction.
But guessing somewhere in the 50% to 65% range.

 

[QueenBee]

...As long as it's not going below an actual (measured disconnected or using specific gravity) SOC of 70% I don't think there is any harm in this, is there?

Yes, a lot of harm in a standard lead acid battery.
Allows sulphation to occur.
A lead acid battery treated that way will have a substantially shorter service life than if it was kept fully charged.
I don't have a good data source that quantifies the service life reduction.
But guessing somewhere in the 50% to 65% range.

I'd like a source for that. I've always been under the impression long term storage is fine as long as it stays above 70% SOC.

 

[dhanson865]

...As long as it's not going below an actual (measured disconnected or using specific gravity) SOC of 70% I don't think there is any harm in this, is there?

Yes, a lot of harm in a standard lead acid battery.
Allows sulphation to occur.
A lead acid battery treated that way will have a substantially shorter service life than if it was kept fully charged.
I don't have a good data source that quantifies the service life reduction.
But guessing somewhere in the 50% to 65% range.

I'd like a source for that. I've always been under the impression long term storage is fine as long as it stays above 70% SOC.

we aren't talking about long term storage, we are talking about charging and discharging with load on a daily basis where the charging isn't enough to keep the car charged.

For those of us with short commutes (I used to drive less than 2 miles one way to work) it literally won't start the car if you do it enough days in a row. And every time you put a load on a battery that has that low of a state of charge you degrade the battery. And all the loads you put on it as it's getting near to that point are degrading the battery as well.

I'm up to a 15 mile commute now but I still charge my 12v battery with a ctek 3300 about 3 times a year (plus anytime I forget and leaf something on). When I do I try to keep it on the charger for more than 24 hours to get a full charge because even a decent smart charger like that won't charge it to full in any reasonable length of time. Maybe it would charge faster if it were removed from the car, I do it with the CTEK (56-263) Comfort Connect Cig Plug so the battery charging is trying to overpower the minimal car off load/drain from the electronics of the SKS and such.

I suppose if I stepped up to the 7002 it'd get done in half the time and my over 24 hour habit would become an over 12 hour habit.

If I were willing to pull the battery out of the car it'd charge quicker as well, but that is too much work considering I'm more likely to charge it in the winter when I'm using more lights, heated seat cushion, and the battery is exposed to lower temps. Not to mention the resetting the radio and power down driver window after disconnecting the battery.

 

[QueenBee]

we aren't talking about long term storage, we are talking about charging and discharging with load on a daily basis where the charging isn't enough to keep the car charged.

Yes, clearly I realize we aren't talking about long term storage. So are you are saying that long term storage is fine as long as it says above 70% but charging and discharging on a daily basis while keeping it above 70% during short term storage between uses is not fine?

In any case something is clearly wrong if the battery only lasts 2 years like the OPs or goes dead even though the car is being driven daily.

 

[Bob]

What do you use to log battery voltage?
Where do you connect the logger?
Is it acceptable to log voltage from the dashboard 12V outlet?
Where do you connect a Battery Tender Plus?
Is it acceptable to connect a 1.5A Battery Tender Plus to the dashboard 12V outlet?
Can you explain the battery charging algorithm that the Leaf uses to keep the 12V battery up while driving?
Can you explain the battery top-off algorithm that the Leaf uses when turned off?

Please forgive me for so many naive questions.

I found a really cool stand-alone temperature logging device, Elitech RC-5. It costs under $20 and can be programmed to log temperature at any selected interval for many months, until the internal coin cell discharges or the internal memory fills. I have one running in my garage logging car external temperature. I'm looking for a similar device for battery voltage logging. No luck yet. I may have to make my own.

Bob

 

[dhanson865]

Yes, clearly I realize we aren't talking about long term storage. So are you are saying that long term storage is fine as long as it says above 70% but charging and discharging on a daily basis while keeping it above 70% during short term storage between uses is not fine?

In any case something is clearly wrong if the battery only lasts 2 years like the OPs or goes dead even though the car is being driven daily.

I don't have a source for long term storage, you provided that number, I'll take your word on it being accurate.

I'm going to say that if you drive short enough trips then the car won't keep the battery above 70%. I'm saying the car doesn't care what the state of charge of the 12v battery is. The engineers picked a charging pattern and it works OK for some and isn't good enough for the rest of us.

Prius, Leaf, you name it if you drive short trips the car isn't going charge enough to keep ahead of the drain.

The something that is clearly wrong is the charging algorithm chosen at the mothership in Japan. If you can't see that you need to stop focusing on the number 70 and start thinking about the result of a large number of transactions where +x and -y don't equal 0.

Imagine a battery is fully charged at 13.0 and useless for starting the car at 11.0 just for round numbers, now imagine that every time you drive to the car it charges +0.1 and drains -0.2. The net change per trip would be -0.1 and it would take 20 trips to hit the one where you couldn't start the car. Obviously not happening that quickly but it's very close to what happens for some drivers.

 

[AndyH]

...As long as it's not going below an actual (measured disconnected or using specific gravity) SOC of 70% I don't think there is any harm in this, is there?

Yes, a lot of harm in a standard lead acid battery.
Allows sulphation to occur.
A lead acid battery treated that way will have a substantially shorter service life than if it was kept fully charged.
I don't have a good data source that quantifies the service life reduction.
But guessing somewhere in the 50% to 65% range.

I'd like a source for that. I've always been under the impression long term storage is fine as long as it stays above 70% SOC.

That info can be sourced from any manufacturer of lead acid batteries on the planet.

To achieve the 'standard' cycle life for lead acid, they must be recharged to 100% daily - through the absorption phase from 80% to 100% - all the way to float. Otherwise, battery life is less.

http://rollsbattery.com/public/docs/user_manual/Rolls_Battery_Manual.pdf
http://support.rollsbattery.com/sup...f-charge-charging-flooded-lead-acid-batteries
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

Lead acid batteries must always be stored in a charged state. A topping charge should be applied every six months to prevent the voltage from dropping below 2.10V/cell. With AGM, these requirements can be somewhat relaxed.

 

[AndyH]

Is there any value in measuring the voltage of any lead battery when it's still connected to the car? It's my understanding that those data points don't really mean anything. You need to measure the specific gravity or disconnect it and let it actually rest unloaded to get a meaningful SOC.

FWIW my 2011 will be 4 years in June and havent he any problems yet. It's been a long time since I've tested it on a digital load tester though.

Yeah, it's already been reported as being open-circuit. That was my first question.

Maybe I missed something but how do you measure the open circuit voltage while th battery is being charged/connected to the car like all the graphs in the original posts?

The charts are not generated during the moments the open-circuit voltage is measured.

 

[AndyH]

we aren't talking about long term storage, we are talking about charging and discharging with load on a daily basis where the charging isn't enough to keep the car charged.

For those of us with short commutes (I used to drive less than 2 miles one way to work) it literally won't start the car if you do it enough days in a row. And every time you put a load on a battery that has that low of a state of charge you degrade the battery. And all the loads you put on it as it's getting near to that point are degrading the battery as well.

This seems to be a fairly 'universal' problem in EV land. The smart owners manual makes it clear that the 12V accessory battery is likely to be undercharged if the car is used for routinely short trips (I suspect the Leaf manual still has a similar maintenance note)...which pretty much describes the 'standard' life of an EV.

To add insult to injury, the least expensive battery type - lead acid - will only give a long life when it's kept at 100%. Like lithium, the absorption phase of charging from 80% to 100% is a very slow process. Off grid batteries (which is a closer type of service to an EV than the life of a starting battery) are cycled very shallowly - often using only the top 20% of charge - specifically so that the battery has a chance of being brought back to 100% each day.

Compare with a lithium - any lithium - that gives the longest life with the lowest rate of degradation when kept at 50% charge/state of charge. Though expensive relative to a single lead acid battery, and not likely to be worth it for a leased car, anyone keeping their EV for the long haul has a very high probability of being money ahead if they dump the lead as soon as the car's delivered. Follow Porsche's lead - though thankfully the prices have come down dramatically since 2009.

http://press.porsche.com/news/release.php?id=510

ATLANTA, Nov. 23, 2009 – Dr. Ing. h.c. F. Porsche AG, Stuttgart, is the first car maker in the world to offer a starter battery with lithium-ion technology. Weighing less than 13 lb or 6 kg, the new battery is more than 22 lb or 10 kg lighter than a conventional 60 Ah lead battery.

The new lithium-ion battery will be available as an option as of January 2010 for the 911 GT3, 911 GT3 RS, and Boxster Spyder and is delivered with the car. It is priced at $1,700.

 

[QueenBee]

Yes, clearly I realize we aren't talking about long term storage. So are you are saying that long term storage is fine as long as it says above 70% but charging and discharging on a daily basis while keeping it above 70% during short term storage between uses is not fine?

In any case something is clearly wrong if the battery only lasts 2 years like the OPs or goes dead even though the car is being driven daily.

I don't have a source for long term storage, you provided that number, I'll take your word on it being accurate.

I'm going to say that if you drive short enough trips then the car won't keep the battery above 70%. I'm saying the car doesn't care what the state of charge of the 12v battery is. The engineers picked a charging pattern and it works OK for some and isn't good enough for the rest of us.

Prius, Leaf, you name it if you drive short trips the car isn't going charge enough to keep ahead of the drain.

The something that is clearly wrong is the charging algorithm chosen at the mothership in Japan. If you can't see that you need to stop focusing on the number 70 and start thinking about the result of a large number of transactions where +x and -y don't equal 0.

Imagine a battery is fully charged at 13.0 and useless for starting the car at 11.0 just for round numbers, now imagine that every time you drive to the car it charges +0.1 and drains -0.2. The net change per trip would be -0.1 and it would take 20 trips to hit the one where you couldn't start the car. Obviously not happening that quickly but it's very close to what happens for some drivers.

You are describing a different problem than what I understand the OPs is describing and what I am concerned with. It's clear that my usage pattern falls within what Nissan designed for considering I have not had a dead battery. From what I understood the OP is claiming that the charging profile of the LEAF is not adequate at all, as in its not at all charging a 12 volt battery like a 12v battery should be charged. If this is the case I find this more interesting it means it is impacting my 12v and it's something I can do something about.

The problem you are describing is certainly related but different. There are clearly usage patterns which were not properly considered or tested when they designed the scheduling aspects of the 12 volt charging. As in your example of short drives and short charging allowing the battery to go dead or the leaving the car plugged in for weeks and the battery going dead, etc. AFAIC that shouldn't happen

 

[QueenBee]

That info can be sourced from any manufacturer of lead acid batteries on the planet.

To achieve the 'standard' cycle life for lead acid, they must be recharged to 100% daily - through the absorption phase from 80% to 100% - all the way to float. Otherwise, battery life is less.

http://rollsbattery.com/public/docs/user_manual/Rolls_Battery_Manual.pdf
http://support.rollsbattery.com/sup...f-charge-charging-flooded-lead-acid-batteries
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

Lead acid batteries must always be stored in a charged state. A topping charge should be applied every six months to prevent the voltage from dropping below 2.10V/cell. With AGM, these requirements can be somewhat relaxed.

Looks like I picked up that percent from deep cycle batteries. Big difference. So 90% in standard lead acids... That's going to be a harder target to maintain if Nissan isn't charging properly.
http://www.trojanbattery.com/BatteryMaintenance/Storage.aspx" onclick="window.open(this.href);return false;
"Batteries in storage should be given a boost charge when they show a 70% charge or less."

 

[dhanson865]

You are describing a different problem than what I understand the OPs is describing and what I am concerned with.

No really I'm not. The car isn't charging the battery fully. What I did was describe the underlying cause and you somehow thought that made it a different issue.

The charging system detects the voltage of the battery and decides if it needs to

A. Leave the battery alone
B. Charge slightly
C. Charge it a lot

The problem is that most of the time the cars system chooses A it was incorrect and should have chosen B and the same for the car choosing B way more than C when it should be using C some of the time it is using B.

The engineers designing the charging algorithm chose a "safer" profile to reduce off gassing, reduce the need for adding water, reduce the chance of a 12v battery fire. This makes the liability lawyers happy but leave us consumers with a less useful product.

All in all for people that drive a lot of miles or just leave the car in ready mode for hours at a time it leaves the cars 12v battery undercharged, for people drive short trips it leaves it dramatically undercharged.

It is one cause, multiple levels of symptoms.

No matter what you do if you want your 12v battery to last longer you'll have to plug up an external 120v smart charger from time to time. How often will depend on your usage patterns and your willingness to deal with the inconvenience.

It's clear that my usage pattern falls within what Nissan designed for considering I have not had a dead battery

That's like saying you have no battery degradation on your HV battery without using a gidmeter, leafspy, or even the dash to tell you how many bars you have left.

If you aren't testing your 12v battery and aren't charging it outside the cars built in charging I guarantee you it is below optimal. You just don't know it yet. Unlike an ICE vehicle the with starter drag there is no in the face of the user kind of warning that your battery is low. Your car may not start one day or the electronics might go and do random things but you won't know what it is for sure until you test the 12v battery.

 

[69800]

I have been working with batteries and charging stuff for 40 years now. Everything from yachts to home power solar stuff. Some of the batteries I have had were 1500 lbs each. I have probably read 1000 articles on the subject over the years. Bottom line is anything under full charge will have some degree of sulphation.(lead acid) My battery ends up spending most of the time at 12.4 volts which is about 75% SOC. But I can assure you that keeping a battery constantly at 75%, It is sulphating the whole time. Over several years (like mine) the plates are really covered. If you had and ICE car that charged exactly the same way this Leaf does you would probably find it would no longer start after about a 1 1/2 years. We are lucky we don't have a starter.(Notice how expensive batteries are getting?) But like I said earlier the problem will not really show itself until you take a two week vacation and come back to a dead battery. Just because everything seems fine.. It's not. Kind of like being just fine until one day you have a heart attack. Doesn't matter to me if you want to let your battery sulphate. Your choice. Some of us are just kind of particular and like to stay on top of our maintenance to get the most life out of our stuff. I have 7 cars and trucks and 2 boats. The all have battery tenders on them. Kind of like cheap insurance. Like I said before, AGM batteries have the plate covered with a material so they can't sulphate. Same with gel cells. The Exide Gel in my tractor is 13 or 14 years old and is still ticking because you cannot sulphate a gel battery.

Someone asked about my data logger. Google USB-500/600 series data logger. Bob also asked.........................................

Please forgive me for so many naive questions.

Where do you connect the logger? on the battery
Is it acceptable to log voltage from the dashboard 12V outlet? no because its off when the car is parked
Where do you connect a Battery Tender Plus? On the battery
Is it acceptable to connect a 1.5A Battery Tender Plus to the dashboard 12V outlet? no because its off when the car is parked
Can you explain the battery charging algorithm that the Leaf uses to keep the 12V battery up while driving? the top off of 14.5 volts is way to short of time period to actually charge the battery
Can you explain the battery top-off algorithm that the Leaf uses when turned off? it only charges a few minutes while the traction battery is being charged. go back to page one of this post. Those little peaks here and there are the only time charging is going on. Not nearly enough

Bob if you search these forums for 12v battery you will find much discussion that will bring you up to speed

Like Andy H said batteryuniversity.com is a very comprehensive web site on batteries

 

[69800]

By the way I put in my new Exide AGM and have put the data logger on today. (Sunday) I am charging it up with the Battery Tender Plus to-nite. The car will be driven Mon-Fri with out any more charges and by Fri nite we will be able so see where the voltage is at the end of the week. I will post the logger results here on Saturday. I do expect the battery will be about 75% charged at the end of the week but at least hopefully with the AGM plates protected the will be no sulphation taking place. I plan to do a supplemental charge once a week with the Tender.

 

[TimLee]

...
Where do you connect the logger? on the battery
...
Where do you connect a Battery Tender Plus? On the battery
...

No.
As Ingineer explained early on you should not be connecting anything directly to the 12V lead acid battery negative post.
There is a current sensor on the connection of the negative post to the vehicle negative ground.
Connections on the negative side should only be to the negative ground.
On the 2011 and 2012 it is a readily accessible easy to spot cable connection on top of the inverter cover.
See http://www.mynissanleaf.com/viewtopic.php?f=8&t=1763&hilit=ingineer&start=30#p182298" onclick="window.open(this.href);return false; for more information.

 

[BrockWI]

If the leaf's current sensor is damaged or confused by a 12v charger charging at 1.25 amps while the vehicle is off or much less a battery data logger we have WAY bigger problems than the charging programming on the Leaf. While I agree any jump starting, backup inverter or any significant load should not be directly on the battery, tiny loads like these shouldn't matter one way or another. Besides that we want to know exactly what the battery is at, not the battery / car ground which could be a bit off because of the current sensor.

 

[69800]

I should correct my over simplified answer to bob. I have my ground on my Battery tender hooked to the bracket that holds the battery in place. I checked it and the ground was very good . 0 ohms...
That being said I question Ingineers statement that the current sensor could be damaged. Nissan must have known that people would be charging and jumping the battery by connecting to the posts. Also with as many people have been doing just that (me included) I have never seen anyone here report a damaged current sensor.