12 volt battery dead?

My Leaf was not used for approximately 4 weeks.

When we went to use it today, the traction motor would not start... in fact the whole car was dead, even though the car was hooked up to the 240volt charging system. I remembered reading somewhere that the 12 volt battery under the hood controls the initial startup, so I jumped the 12 volt battery.... and within a few minutes the traction motor came alive, and the instrument panel indicated that the traction motor had a full charge for a 98 mile driving range. I drove to my Nissan dealer, who checked out the car and found that the 12 volt battery was indeed in a discharged condition, but tested ok as to its ability to take a charge. We talked a little on how the 12 volt battery could discharge if the traction motor battery was fully charged and the 240 volt charging system was hooked up and fully functional. Apparently, the battery that supplies the traction motor does not charge the 12 volt battery while the car is tethered to the 240 volt charging system. The 12 volt battery is charged up when the car is actually running after being disconnected from the 240 volt charging system (or so the explanation went).

Has anyone else experienced the same problem with a dead 12 volt battery after the car set unused for a period of time? If the explanation I received from the service technician is correct, it seems that if the car is going to be unused for a while, the 12 volt battery should be connected to a trickle charger. Do any of you do this?

(When we got home from the dealer, I connected the 12 volt battery to my battery charger, and 12 hours later the charger is indicating that the battery is successfully taking a charge and should be fully charged very soon.... so all is well, apparently.)

Known issue, widely reported. If you are going to be away for a week or more, do not leave the Leaf connected to EVSE. If longer than a couple of weeks, putting the 12 volt battery on a trickle charger is a good idea.

Cant the solar panel maintain it a bit?

Stoaty said:

Known issue, widely reported. If you are going to be away for a week or more, do not leave the Leaf connected to EVSE. If longer than a couple of weeks, putting the 12 volt battery on a trickle charger is a good idea.

Click to expand...

Not if it is plugged in. The 12 volt power consumption rises substantially when the car is left plugged in (a bug in most people's opinion) and the solar panel can not handle the extra load in most cases. It only puts out a few watts...

kieranmullen said:

Cant the solar panel maintain it a bit?

Click to expand...

Yes I am aware of that as it was just said. However it was mentioned to put it on a trickle charger when unplugged.

Again I am asking about how it was been for people to leave unplugged solely with the the panel for multiple weeks.

TomT said:

Not if it is plugged in. The 12 volt power consumption rises substantially when the car is left plugged in (a bug in most people's opinion) and the solar panel can not handle the extra load in most cases. It only puts out a few watts...

kieranmullen said:

Cant the solar panel maintain it a bit?

Click to expand...

Click to expand...

kieranmullen said:

Again I am asking about how it was been for people to leave unplugged solely with the the panel for multiple weeks.

Click to expand...

In theory consumption drops enough that the solar panel should be able to maintain the charge, however it's a good policy to put a trickle charger on any vehicle battery that will be unused for more than a couple of weeks.

I've done it many times for up to a month and never had an issue, even when parked completely in the shade or indoors. However, after 14 days, the telematics shuts down so you will loss communication with the car until it is next turned on.

kieranmullen said:

Again I am asking about how it was been for people to leave unplugged solely with the the panel for multiple weeks.

Click to expand...

On my 2011 LEAF the 12V battery is charged when the main battery is being charged so setting a charge timer for a short duration to charge the traction battery during the 4 weeks will also charge the 12V battery. If you needed 4 hours or 240 minutes of charging then setting charging schedule for 35 minutes during each week would keep the 12V battery charged while incrementally charging the main traction battery.

kieranmullen said:

Yes I am aware of that as it was just said. However it was mentioned to put it on a trickle charger when unplugged.

Again I am asking about how it was been for people to leave unplugged solely with the the panel for multiple weeks.

Click to expand...

The solar panel output will depend on the weather. IIrc, it puts out a max of about 5 watts at noon in full sun. So not sure what that comes out to for the battery over the course of a day? Maybe an amp-hour or so? Might be enough if the weather holds. and you park in full sun.

Then again, parking for weeks in full sun will take its toll on paint and interior, not to mention higher temperatures for the traction battery. I think parked in shade with a trickle charger would be more beneficial. Also, you can simply disconnect the 12V battery and as long as it's relatively healthy and fully-charged it should be good for at least a month.

Went to Hawaii for 7 days, left the main battery un-plugged and at 50% charged, connected the Battery Tender Plus (021-0128) 12V Battery Charger which I got from Amazon. Kept the 12v battery fully charged. It's one of the best tips I got from this site.

As for the Solar Panel, I keep my Leaf inside the garage away from the elements so that wouldn't help me at all.

Fred