Third light blinking means 12V battery is charging -- true, or false?

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brenton

Active member
Joined
Sep 17, 2017
Messages
25
Someone on the internet is claiming that if you ever see the 3rd charging indicator light b\nking while not plugged in that this means the car is topping off the 12V battery. The claim is that this information is in the manual.

I highly doubt this as it would mean the car has to 1. be monitoring the voltage of the 12V battery, which it clearly doesn't, and then 2. AUTONOMOUSLY PHYSICALLY CONNECT THE TRACTION BATTERY in order to run the DC-DC charger. That seems to go against the whole point of physically disconnecting the traction battery when off. What if you were working on the car and it suddenly does this?
 
brenton said:
Someone on the internet is claiming that if you ever see the 3rd charging indicator light b\nking while not plugged in that this means the car is topping off the 12V battery. The claim is that this information is in the manual.
Yes, it can be a reason it alone blinks.

See page CH-35 of https://owners.nissanusa.com/content/techpub/ManualsAndGuides/NissanLEAF/2013/2013-NissanLEAF-owner-manual.pdf (page 84 of the PDF). It refers back to page 24 of the manual. Notice no interval is specified.

And, yes, I've seen it on my former '13 Leaf SV w/premium when the car was unplugged and the battery warmer wasn't running (my area doesn't get near cold enough to trigger it) and when I wasn't pre-cooling/pre-heating the car.

https://www.nissan-techinfo.com/refgh0v/og/leaf/2011-nissan-leaf.pdf on page 80 also discussed it. Page 28 describes the interval and some conditions.

Just because that light blinks to charge the 12 volt doesn't mean the car does a very good job of it. And, if the 12-volt is a kaput, no amount of charging will help.
 
brenton said:
Someone on the internet is claiming that if you ever see the 3rd charging indicator light b\nking while not plugged in that this means the car is topping off the 12V battery. The claim is that this information is in the manual.

I highly doubt this as it would mean the car has to 1. be monitoring the voltage of the 12V battery, which it clearly doesn't, and then 2. AUTONOMOUSLY PHYSICALLY CONNECT THE TRACTION BATTERY in order to run the DC-DC charger.
Initiation of the automatic 12V battery charge is time-based when the vehicle is off.
That seems to go against the whole point of physically disconnecting the traction battery when off. What if you were working on the car and it suddenly does this?
Any work on the high-voltage side includes precautions like pulling the battery disconnect. There are multiple other cases where the car can autonomously close the high-voltage contacts, such as charge timers and climate control timers.
 
Yeef. :shock: I hope it can't happen with the 12V battery completely disconnected. What if it had happened at some critical time (say unplugging or reconnecting the side-curtain airbag) while I was installing my seat-heater yesterday?
 
hbquikcomjamesl said:
Yeef. :shock: I hope it can't happen with the 12V battery completely disconnected. What if it had happened at some critical time (say unplugging or reconnecting the side-curtain airbag) while I was installing my seat-heater yesterday?

The computer that decides this is run by the 12V, so if it is disconnected, nothing will be alive to cycle the charging. ;)

As far as I remember, 10.5V is when the battery is cycled to re-charge if it happens to do a reading and catches it. All other times, as others have said, kind of random.
 
Also from service manual:

When Vehicle is Not Used for A Long Time
VCM measures the time of no operation using its internal timer. If the time of no operation reaches 24 hours,
VCM performs automatic charge for 4 minutes.
VCM resets the no operation status continuous time when the vehicle satisfies one of the following conditions.
• READY continues for more than 4 minutes.
• Normal charge continues for more than 4 minutes.
• Quick charge continues for more than 4 minutes.
• Climate Ctrl. Timer or remote climate control continues for more than 4 minutes.
• When the charge current of 12V battery is 1.5A or less after start of automatic charge.
NOTE:
• During automatic 12V battery charge, the charging status indicator blinks.
• The automatic 12V battery charge control does not start within approximately one hour when the power
switch is turned ON/OFF
 
Thanks for posting that LearJet. This seems like a topic that should be in a sticky section somewhere. Eventually we'll all have to replace our 12V batteries if the car is owned for long enough and it is easy to forget about these precautions.
 
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