Tip: How to Recharge the 12-volt Battery

Marktm said:

A lead acid battery that drops below 10 volts or so - usually under an extremely heavy load (doubt you have that) is likely a dead battery - I'd guess you know that!

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Hello Marktm,
Yes, I understand what you are saying. However the battery is now up and will hold the 12v for some time. It is not acting like what I have seen before for a dead cell. I will publish more data later when I get it.

Thanks,
Dan

LA batteries don't always "die" when the voltage drops below 11 volts for relatively brief periods. They are damaged, but often still will function.

Danl said:

OK, Today I went out and the 12v would not boot up the car. Here is what data I caught.



The car had completed an 80% charge two days ago and was not driven on Aug2nd. The OBDII was pluged in all the time and Leaf spy had been left on on my phone all day and night on Aug 2nd. But it only caught data for 2 minutes in the morning I added the blank area in the chart to show that I have a day with no data.

The car would not respond to any attempt to charge or turn it on. I had to put a 12v charger on it to get any response. It started at 8v and dropped to 6v with 7 amps going from the 12v charger into the battery. It would not recognize the key fob at one point and would not connect to Leafspy with the car off. Kept trying to turn the car on with a little wait for the 12v charger to bring up the 12v a little.

More later.....

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Thanks for being patient with me telling this story between my other daily tasks.

When I first got the car to go into accessory mode and connect to LeafSpy, the cabin fan was on. I turned that off and realized that the car had not completely booted up and I had a red triangle. I tried it again several times and it would not boot and the voltage showed between 6v and as high as 11v on LeafSpy during these try's. This is all in the data. When the car was off between try's LeafSpy did stay connected. The voltage slowly climbed when the car was off and slowly dropped when the car went into accessory mode. I realized that I had a significant power draw on the 12v system in accessory mode. More than the 7 amps the 12v charger said it was supplying.

So at this point I realized I needed to clear all the codes. It took me a while to do this. First I had to experiment to get the code reader up on LeafSpy. I had not done it for a while, and it was not intuitive for me. The car had lots and lots of codes. I did not record these codes because I know most of them were not meaningful. I am sure that most of the codes were caused by the failed boot process rather than by the problem that drained the 12v battery. LeafSpy would not clear them all at one time. After about the 3 sets of clearing codes the car seemed to act better. At this piont the car center display started doing things and then the car would boot up all the way. I finally got all the codes clear and then everything on the car worked properly. I was able to remove the 12v charger and the 12v battery held its charge voltage.

At that point I plugged in the L2 charger and let the traction battery charge to 100%. the 12v went to 14v and stayed there for much longer than it normally does. I then did a drove the car a while with a one hour stop in the middle of the drive. All is fine. the 12v has held all of that time.

Thanks,
Dan

You need to change your behavior with the car. First, don't use Accessory Mode for anything - ever. Use Ready mode. Second, top off that 12 volt battery with the external charger once a week. The 12 volt battery is now damaged, and has less capacity than it had. It may still work for years - or not - but it can't provide as much power now.

Danl said:

Marktm said:

A lead acid battery that drops below 10 volts or so - usually under an extremely heavy load (doubt you have that) is likely a dead battery - I'd guess you know that!

Click to expand...

Hello Marktm,
Yes, I understand what you are saying. However the battery is now up and will hold the 12v for some time. It is not acting like what I have seen before for a dead cell. I will publish more data later when I get it.

Thanks,
Dan

Click to expand...

My experience is based mostly on AGM style batteries (literally dozens and dozens of them). I've been optimistic that I could recover ANY that were in the 10 to 11 volt range and been essentially 100% disappointed as they all failed within a few cycles of usage. I experimented with re-hydration and lengthy desulphating - all to essentially no reasonable success. These were the small, inexpensive ones used in UPSs. The larger telcom style with catalytic gas recovery as well as the flooded lead acid may be different - I'm skeptical. BTW, the ability to hold well over 12 volts (12.6 to 12.8) is very common with bad batteries - until a significant load is applies and then the voltage will drop quickly.

I am interested in the data - Thanks

Could the ODB-II somehow "wakes" ECU constantly and draing the 12v?
I hope to plug a ODB-II and monitor the vitals. However, short circuit and battery drain are my concerns, when leaving the dongle attached unattended.
Any light ?

soldcake said:

Could the ODB-II somehow "wakes" ECU constantly and draing the 12v?
I hope to plug a ODB-II and monitor the vitals. However, short circuit and battery drain are my concerns, when leaving the dongle attached unattended.
Any light ?

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The ODB-II current is trivial. I have had it plugged in with no use of the car for several days before with no problems.

When my 12v battery went down the current draw was several amps. It was obvious that something else was drawing a lot of power. Also this current draw did not stop until codes were cleared. So the power draw was tied into something having an error that just rebooting the car did not correct.

It has now been 3 nights and 2 days with no further problem.

Also the ODB wakes up and sends data for about two minutes when I plug in the L2 charger. Then it seems to turn itself off.

Thanks,
Dan

Marktm said:

csites said:

Thanks. I just purchased an LELink bluetooth OBDII adapter on eBay for $20, per Turbo3's iOS-related May 16th post near the end of the thread you mentioned.

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Has the adapter worked as expected? Can you leave it in place without draining the 12 volt battery? Does it restart seamlessly each time you start your Leaf? Still holding out for consistent good results with iOS bluetooth LE.

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Yes, yes, and yes!

I put LeafSpy on an old unused iPhone 4s which I leave in the car 24x7. The LElink bluetooth OBDII adaper is plugged in 24x7 as well. Now every time the car comes home, it automatically connects to my WiFi and uploads the data to DropBox which I can then view from my computer or my personal phone.

So LeafSpy and the LElink are working great, however there is an unfortunate limitation which I believe is caused by the car, not LeafSpy. I only get data when the car is turned on or charging - despite continuous power to the LElink.

So back to my 12v battery dying overnight every six months problem. If the problem is due to a parasitic draw that occurs every six months at night, the LeafSpy/LElink won't really help me. On the other hand, if the problem is due to the DC-DC converter failing every six months - unnoticed by me during the day before the battery dies overnight, then the LeafSpy/LElink should confirm this.

Next I may install a low battery voltage alarm with an extra-loud alarm so I can catch a parasitic draw in the act and maybe start pulling fuses to see what stops it - at 3:00am. But of course, I have around 5 months to find one and get it installed since it just died about a month ago.

BTW, I've been working with Nissan Aftersales and 3 different dealer techs on this for years. The most recent development is that Nissan is sending their own Leaf tech to my dealer to meet me about a month from now. That's after they decided not to buy back the vehicle. They did give me a free Gold 48-month warranty extension, which covers everything but the drive battery, so if I can ever figure this out myself, I should be able to get them to fix it.

And now to make matters worse, my drive battery capacity seems to be dropping exponentially instead of logarithmically as it's supposed to - and I'm at 58k miles - but that's for another thread.

I believe I'm in the Tesla Model 3 queue around 100,000.

csites said:

I put LeafSpy on an old unused iPhone 4s which I leave in the car 24x7. The LElink bluetooth OBDII adaper is plugged in 24x7 as well. Now every time the car comes home, it automatically connects to my WiFi and uploads the data to DropBox which I can then view from my computer or my personal phone.

So LeafSpy and the LElink are working great, however there is an unfortunate limitation which I believe is caused by the car, not LeafSpy. I only get data when the car is turned on or charging - despite continuous power to the LElink.

So back to my 12v battery dying overnight every six months problem. If the problem is due to a parasitic draw that occurs every six months at night, the LeafSpy/LElink won't really help me. On the other hand, if the problem is due to the DC-DC converter failing every six months - unnoticed by me during the day before the battery dies overnight, then the LeafSpy/LElink should confirm this.

.

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Thanks for the confirmation - $20 is a bargain for the LELink - I'm going to track that down and order one.

What is your set up for auto download of the (assuming) LeafSpy data via wifi? Sounds very useful.

Your 12 volt battery issue is very puzzling! The most common FLA battery failure problems are related to bad/weak/shorted cells in the pack - simply have to replace it. Loss of capacity is usually a result of sulfation of the plates - eventually having to replace! Such lengthy durations between "dying" is difficult to explain without continuous voltage data around the 12 volt system. However, the Leaf's normal charging profile does seem to promote sulfation and gradual loss of capacity. I recently "load tested" my battery (original) with a 100 watt inverter to a 60 watt bulb and estimated about 20-25 amp-hours capacity - a significant loss assuming they are about 40 AH original capacity. I keep it charged regularly with a 1.5 amp desulfating/charger

Marktm said:

Thanks for the confirmation - $20 is a bargain for the LELink - I'm going to track that down and order one.

What is your set up for auto download of the (assuming) LeafSpy data via wifi? Sounds very useful.

Your 12 volt battery issue is very puzzling! The most common FLA battery failure problems are related to bad/weak/shorted cells in the pack - simply have to replace it. Loss of capacity is usually a result of sulfation of the plates - eventually having to replace! Such lengthy durations between "dying" is difficult to explain without continuous voltage data around the 12 volt system. However, the Leaf's normal charging profile does seem to promote sulfation and gradual loss of capacity. I recently "load tested" my battery (original) with a 100 watt inverter to a 60 watt bulb and estimated about 20-25 amp-hours capacity - a significant loss assuming they are about 40 AH original capacity. I keep it charged regularly with a 1.5 amp desulfating/charger

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LeafSpy has a logging option which will automatically send the logs to DropBox. Easy setup - it will ask you for your ID/PW after you enable logging. (Also to supplement the phone battery, I daisy-chained a USB battery between the phone and 12v cigarette lighter style power adapter)

To attempt to fix my problem, the Nissan dealer replaced my 12v battery after 1yr/16k miles, then again 6 months later at 24k miles, saying there had been a bad batch of 12v batteries. The problem continued every 6 months so I doubt that. Every 6 months I brought it to them and from there on out they said my 12v battery checked out fine. So my current 12v battery is 2 years old, but it died recently and they checked it again and said it was fine.

I suspect the reason it took 12 months to fail the first time instead of 6 months is that I was using the level 1 trickle charger for the first 6 months. Since the level 1 charger takes all night long to recharge, the car's built in battery maintainer (DC-DC converter) was working all night long as well. Maybe if I went back to level 1 charging at night, I'd never have the problem again. (or if just got a separate battery maintainer/charger like everyone else)

Also wonder if I had the 3.3 kW onboard charger of the original car design instead of the later 6.6 kW charger, I might also not have this problem - again since the charging would take longer, leaving the built-in 12v battery maintainer on longer.

csites said:

LeafSpy has a logging option which will automatically send the logs to DropBox. Easy setup - it will ask you for your ID/PW after you enable logging. (Also to supplement the phone battery, I daisy-chained a USB battery between the phone and 12v cigarette lighter style power adapter)

Also wonder if I had the 3.3 kW onboard charger of the original car design instead of the later 6.6 kW charger, I might also not have this problem - again since the charging would take longer, leaving the built-in 12v battery maintainer on longer.

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I'll definitely use that feature when I get set up with LeafSpy - thanks

I've had the 2012 3.3kw charger operating with the original battery now for about 8 months. I consistently charge level 2 when ever the battery is depleted below 20-30 miles remaining range - just so I have enough range to take a trip into Houston if needed. My Leaf is a 9 bar with limited range, so that compounds the need to keep charge near 100%. I've been monitoring the 12 volt "system" and know that it is often in the 12.1 to 12.4 volt range which is not good for the battery (SOC is below 60% much of the time). That combined with an "old" battery has prompted me to use the battery "tender" is often as I remember to hook it up. I keep a connector that is easily attached for convenience.

Your issue seems to indicate an intermittent "parasitic" type load OR a charge profile that is even worse than the "norm" and the battery is being continually but slowly drained (which could also be a very small continuous "parasitic" load?). Either way, if you can continuously monitor the battery voltage, it might tell the story. There are many posts about this issue and some have charted battery voltages that show the apparent "poor" charging profiles. It is hard to believe that many "bad" batteries!

Keep us informed.

Danl said:

... I said I did not get data in that timeframe. I assume it went down sometime during the Aug 2nd time that LeafSpy did not get data.

Thanks,
Dan

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That is the problem in attempting to use LEAF Spy Pro to analyze a vampire power loss.
You do not get any data when you need the data.
So as you clearly explained the graphs pretty much useless.

As a 5.6 year LEAF driver, the correct answer is to hook up a low amp CTEK or Battery minder all the time the LEAF is in the garage and always unplug the EVSE when charging is finished.

While the car is charging the CTEK or Battery Minder does not do much as the DC to DC on the LEAF is holding 13V.
But the rest of the time it will keep the 12V in good condition.

The Nissan DC to DC is a very powerful 100 amp capable 12V charger.
But the Nissan programming of it does a pathethic job of keeping the 12V fully charged.

Thanks Tim most appreciated.
Is it OK to have the CTEK conditioner attached to the 12v while the Leaf is charging?
I thought it was better to keep the car connected to the wall charger even after it is charged?

Please delete.

TimLee said:

The Nissan DC to DC is a very powerful 100 amp capable 12V charger.
But the Nissan programming of it does a pathethic job of keeping the 12V fully charged.

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Hi Tim,
I have not had any more events since Aug 2nd. However, I am thinking that the problem is really that the "brains" in the car, or in the NissanConnect system are, on occasion, turning something on. I have had 3 or 4 events between April and August where I went out to the car in the morning with the climate control doing something even though all pre-conditioning timers are off. I live in a area where 2g phones are flakey and I am thinking that NissanConnect may have tried to communicate but confused the data link. In a case like that anything can happen.

So I agree that LeafSpy logged data does not catch events when the car is off and not charging, but the purpose of looking at logged data is to see the SOC of the 12v when the DC to DC is not holding the 12v up to 13 or 14v. If I see a droop below 12v then that is an "almost fail" event.

I expect Nissan will never find this bug. When they get complaints about it I expect they spend all their time trying to prove that the dc-dc programing is really ok rather than looking for the real root cause, which may be a poor NissanConnect system.

Thanks,
Dan

Danl said:

I live in a area where 2g phones are flakey and I am thinking that NissanConnect may have tried to communicate but confused the data link. In a case like that anything can happen.
...
I expect Nissan will never find this bug. When they get complaints about it I expect they spend all their time trying to prove that the dc-dc programing is really ok rather than looking for the real root cause, which may be a poor NissanConnect system.
Dan

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Wow, I've been wondering all along whether NissanConnect might be related. With the every 6-months or so dead battery that I get, I wondered whether that was the interval at which AT&T was doing some overnight testing or resetting or something.

And so I wonder if the 3g upgrade cards we're supposed to be offered before the end of the year might avoid the problem (or if it might get worse if I don't upgrade and 2g gets turned off)

All speculation on my part though. I've never had anything concrete to link the problem to NissanConnect.

I am with Dan on this except I have an S with no 2g (that I know of) so I am ruling that out. But I do believe it is the car doing something that either doesn't shut off by accident or tries to do that runs the 12v way down and once it realizes the 12v is low the car tries to close the high voltage contactors to recharge the 12v battery which really run the 12v dead.

In any case I agree that it is to random for Nissan to track down and I doubt even if one of us did, that Nissan would make a change anyway.

Henryv said:

...
Is it OK to have the CTEK conditioner attached to the 12v while the Leaf is charging?
I thought it was better to keep the car connected to the wall charger even after it is charged?

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It is OK and what I do.
But while the DC to DC is holding 13V on the battery the CTEK isn't doing much.

It is bad to leave the EVSE hooked to the LEAF for any significant period of time after charging completes.
As long as it is hooked up the LEAF has much higher 12V loads and also Nissan's programming is messed up and the DC to DC isn't available to charge the 12V.
Numerous people have come back from a 10 day vacation where the EVSE was plugged up to the LEAF and found the 12V battery dead in the water.
And the LEAF dead in the wayer till jumped off with a good 12V source.

TimLee said:

Henryv said:

...
Is it OK to have the CTEK conditioner attached to the 12v while the Leaf is charging?
I thought it was better to keep the car connected to the wall charger even after it is charged?

Click to expand...

It is OK and what I do.
But while the DC to DC is holding 13V on the battery the CTEK isn't doing much.

It is bad to leave the EVSE hooked to the LEAF for any significsnt period of time after charging completes.
As long as it is hooked up the LEAF has much higher 12V loads and also Nissan's programming is messed up and the DC to DC isn't available to charge the 12V.
Numerous people have come back from a 10 day vacation where the EVSE was plugged up to the LEAF and found the 12V battery dead in the water.
And the LEAF dead in the wayer till jumped off with a good 12V source.

Click to expand...

Excellent Tim!!
It all makes perfect sense!


Thank you.


Henry.

Here's an update to my original post which started this thread:

Nissan Aftersales arranged for a service technician from Nissan (not from the dealer) to meet me at my local dealer. The Nissan service technician installed two software updates. The work order reads, "Reprogrammed PDM and EV control units".

Now I wait for 6-9 months and hope for the best.