Dead 12V battery question

[Stanton]

So long thread, skimmed through, I will be leaving my car parked for 8 weeks in a driveway where I can't keep a trickle charger hooked up. Should I expect a dead 12V battery when I return? It's possible the car could be driven once every few weeks by the people there but if I wasn't to count on that, should I expect a dead 12V battery?

With a lead-acid battery, you never know. I have left my Leaf for > 1 week (not connected to EVSE) with no problems, but I replaced the lead-acid battery with LiFePO4 one a couple of years ago. I like being able to "ping" my Leaf for a status, but that requires leaving the 12v cable connected.

 

[RegGuheert]

So long thread, skimmed through, I will be leaving my car parked for 8 weeks in a driveway where I can't keep a trickle charger hooked up. Should I expect a dead 12V battery when I return? It's possible the car could be driven once every few weeks by the people there but if I wasn't to count on that, should I expect a dead 12V battery?

If you have not had issues with 12-volt battery before, it should be fine. Try to park with 60 % to 70% SOC on the traction battery (6 to 8 bars), make sure there is nothing plugged in to the OBDII port, and make sure the car is completely powered off. The car will turn on the DC-DC converter periodically to charge the 12-volt battery. I have parked the 2011 and 2015 at the airport or my office numerous times (longest so far has been 3 weeks) with no problems.

Gerry

+1 on Gerry's suggestions. I also recommend that you fully trickle-charge the 12V battery (use a high-quality charger that puts out 2A or less) just before AND after the 8-week trip. My testing tells me that your 12V battery will be at about 60% SOC after sitting for that long.

 

[Nubo]

So long thread, skimmed through, I will be leaving my car parked for 8 weeks in a driveway where I can't keep a trickle charger hooked up. Should I expect a dead 12V battery when I return? It's possible the car could be driven once every few weeks by the people there but if I wasn't to count on that, should I expect a dead 12V battery?

The vehicle is supposed to charge the 12V every five days, but that is disabled if the car is plugged in to the EVSE. So definitely leave it unplugged or you WILL come back to a dead 12V battery after 8 weeks.

Still, the simplest way to be sure is to disconnect the 12V battery. Only takes a few seconds and you don't lose much. May need to re-select your charge timer if you have one programmed, and maybe the auto-up behavior of the driver's window if you've enabled that. Have your fob at hand and be prepared to turn off the alarm when reconnecting. If you have the vehicle locked when disconnecting the battery, the alarm may sound upon re-connect.

 

[JRoque]

Hi. I've had two, 12V battery die offs in 3 months. Nothing external connected and plenty of charge on the main pack. Charger was not connected in either case.

I'm starting to think there are power up/down sequencing issues with these cars - or at least mine. Quite often, if I try to start the car took quickly - that is, press pedal and push the power button too quickly - the car will not start properly. Several other combinations result in a variety of anomalies. I've read on several forum where people have to "reboot" their cars to get them to initialize properly. There's a chance that the same sequencing issue is happening on shutdown and something running off the 12V battery is left on.

Separately, the last "jump" needed was done with a small 7Ahr connected with a minigrabber jumpers. Charging the car battery and powering whatever is needed to get the car started had to be <3A, I estimate. It took a quick second of that and the car initialized without a problem. Big jumper cables and another car to jump from are not needed.

Regards,
JR

 

[Levenkay]

Hi. I've had two, 12V battery die offs in 3 months. Nothing external connected and plenty of charge on the main pack. Charger was not connected in either case.

Just in hopes of fueling my own private urban myth, could you confirm that your LEAF did not have an illuminated solar panel?

 

[TomT]

Based on measurements I made years ago, the solar panel should be sufficient to keep the battery trickle charged when the car is parked outdoors...

Just in hopes of fueling my own private urban myth, could you confirm that your LEAF did not have an illuminated solar panel?[/quote]

 

[RegGuheert]

Hi. I've had two, 12V battery die offs in 3 months. Nothing external connected and plenty of charge on the main pack. Charger was not connected in either case.

I find it hard to believe that two batteries would die completely within 3 months. Even if it got completely discharged, it would likely be fine after a full charge.

I'm starting to think there are power up/down sequencing issues with these cars - or at least mine. Quite often, if I try to start the car took quickly - that is, press pedal and push the power button too quickly - the car will not start properly. Several other combinations result in a variety of anomalies. I've read on several forum where people have to "reboot" their cars to get them to initialize properly. There's a chance that the same sequencing issue is happening on shutdown and something running off the 12V battery is left on.

Yes, starting with the MY2013 LEAFs, there have been many reports of something remaining on in certain situations and draining the battery. It's a bit frustrating that Nissan has not yet isolated this situation and fixed it with a firmware update.

 

[JRoque]

Hi and thanks for the reply.

Let me restate what I mean with "die offs". The same factory battery suddenly discharging to ~2.4V (by the time I notice). Quickly "jumping" the car and starting it charges the battery and all is back to normal. My 2013 SV car does not have a solar panel.

I don't use the car everyday so I don't charge it everyday. Perhaps this is not more prevalent as most will likely use and charge the car daily - not enough time to drain the 12V battery if something is left running. The solar panel on some cars further masquerades the issue.

It wouldn't be terribly hard to add something to the 12V battery that monitors the voltage and disconnects it when it drops below a certain level. I wonder if someone already make a device like that. Then again, rather than band-aids with gimmicky stuff, Nissan should get on the ball and fix their on/off sequencing issue since it's pretty obvious there are issues with that. At the very least, they can use the 12V monitor the car already has and send an alert when needed.

Regards,
JR

 

[TimLee]

...
Let me restate what I mean with "die offs". The same factory battery suddenly discharging to ~2.4V (by the time I notice). Quickly "jumping" the car and starting it charges the battery and all is back to normal. ...

I agree the car has a problem that Nissan needs to correct.

But just because you jumped the car and got it to start, you have not returned the 12V to fully charged.

When the 12V has been badly discharged it is very unlikely the LEAF will get it charged back up fully.

In that situation it definitely needs 12 to 24 hours connected to a good quality trickle charger.

 

[RegGuheert]

But just because you jumped the car and got it to start, you have not returned the 12V to fully charged.

When the 12V has been badly discharged it is very unlikely the LEAF will get it charged back up fully.

In that situation it definitely needs 12 to 24 hours connected to a good quality trickle charger.

Absolutely!

 

[JRoque]

When the 12V has been badly discharged it is very unlikely the LEAF will get it charged back up fully.

In that situation it definitely needs 12 to 24 hours connected to a good quality trickle charger.

Hi and thanks for the comments.

Correct, the 12V battery does not instantly charge after a jump start. My point was that big jumper cables and another vehicle, as it is typically done with ICE, are not needed. As long as the 12V rail is somewhere near that, the vehicle will initialize and the DC-DC takes over. Yes, you have to run the car and/or charge it to get the 12V fully charged.

You might have suggested disconnecting the 12V battery and running it on a 12V trickle charger. That would be ideal but I'm not sure it's required. The car's own 120V "trickle" charger would likely be sufficient since it being a slow charger gives the DC-DC more time to charge the 12V battery. Using the car for a couple of charge cycles will also restore the 12V battery.

Regards,
JR

 

[LeftieBiker]

The car's own 120V "trickle" charger would likely be sufficient since it being a slow charger gives the DC-DC more time to charge the 12V battery. Using the car for a couple of charge cycles will also restore the 12V battery.

You'd think so, but it doesn't usually work that way. To get a fully charged 12 volt battery, you need an external charger of some sort. And if the car is left plugged in after charging finishes, it will proceed to slowly but surely drain the accessory battery...

 

[TimLee]

... Correct, the 12V battery does not instantly charge after a jump start. My point was that big jumper cables and another vehicle, as it is typically done with ICE, are not needed. As long as the 12V rail is somewhere near that, the vehicle will initialize and the DC-DC takes over. Yes, you have to run the car and/or charge it to get the 12V fully charged.
...

But the LEAF 12V charging protocol will leave it not fully charged to the fully charged state that a good quality 12V trickle charger will.

I watched the current flow to very discharged 12V on the LEAF the other day.
Was down around 9.6V, just barely enough to start the LEAF.
And the LEAF DC to DC does initially put 100 amps into the 12V for a long time.
But once it drops back to 13V float, it then periodically sees that float current is too high, and bumps back up to 14.6 V periodically with current into the 12V at 15 amps to 20 amps range.
But after spending 5 hours charging the high voltage pack to 100%, when you put an external 12V trickle charger on it will take at least six hours for the 12V to show fully charged.

The LEAF protocol does not fully charge the 12V.

If you don't have a current drain problem like you and BrovkWI do, and you drive the LEAF frequently a 12V might last five years.
But if you do have current drain problem and don't drive frequently and do not use an external 12V trickle charger, then you will rapidly destroy the 12V which is what you have been doing.

I agree the LEAF DC to DC should be able to fully charge the 12V.
But in your situation it does not.

 

[BrockWI]

JR is your by chance a 2013 and charge to 80%

I can run a 1000w load with and inverter with the car in the "ready" mode with no problem, the DC-DC converter handles that nicely. The problem is in truly charging the 12v aux battery, it doesn't bulk, then float it like normal. Now in most of the Leaf's this isn't a problem, but for the few of us that have aload that sticks on, it's not s good.

I have also noticed every time I have had a dead battery was when I have been charging to 80%, my theory is the longer time "eq" the traction battery, the longer time it has to charge the 12v as well, but part of that is luck of the draw, as to when the phantom load might stick on.

I try to charge my 12v battery weekly with a good 3 stage charger and just swapped out my 12v for a larger battery, see

http://www.mynissanleaf.com/viewtopic.php?f=9&t=18129&p=439206#p439206

As my regular disclaimer, I do not believe this is a common problem for all Leaf's or we would see this all across the board. In fact many folks have never had any issue with the 12v setup, but there are enough of us with this problem that something isn't quite right on some cars.

Hope this helps

 

[LeftieBiker]

My 2013 SV doesn't have a phantom load, as I can charge the accessory battery and then leave the car, unplugged, for a week if I want. It does, however, fail to keep that 12 volt battery adequately charged: whenever I plug in the 2 amp maintainer it takes at least 20 minutes, and usually about an hour, to top off the battery. At first I though this only happened with local, short-trip driving, but now I think it's more generally the case. This is plugging it in at least a couple of times a week, and usually more than that; the only time I don't plug the maintainer in with the EVSE is when I know I'll be unplugging the car well before charging is finished.

 

[DaveinOlyWA]

Just disconnect the 12V cable from the battery.

Or you can get a solar powered very low current trickle charger and use that.
I got one I think at Northern Tools or it may have been Amazon.

a LEAF that is working properly should not need to have the battery disconnected. simply DO NOT leave the car plugged in

 

[TimLee]

... a LEAF that is working properly should not need to have the battery disconnected. simply DO NOT leave the car plugged in

But a lot of people have reported on MNL that their LEAFs do not work properly and intermittently leave loads on the 12V battery.

The only certain way to not have a problem after a long trip is to disconnect the 12V battery.

It is up to each individual to choose which approach they believe has the appropriate tolerable risk for them.

 

[ElectricEddy]

I wonder if one of those little generators I used to use on my bicycle front tire for the headlight would work better?

 

[cwerdna]

a LEAF that is working properly should not need to have the battery disconnected. simply DO NOT leave the car plugged in

I agree on the above.

But, FWIW, from my 1st incident so far (posted at http://www.mynissanleaf.com/viewtopic.php?p=440106#p440106) which I the morning of 10/11/15, the car wasn't plugged in. It was last plugged in at free L2 public charging the night before, which I unplugged from (and departed from) at 10:24 pm on 10/10/15.

 

[Dtwhite]

I need to replace the 12V battery of my (2016) Leaf. Is the 12V battery the very same acid type as is used in a standard petrol/diesel car, or a special type? In other words, can I just buy a regular off-the-shelf car battery, or do I need to get something specific? Thanks! The Leaf manual does not really say much about it.