12v Battery

GerryAZ said:

lorenfb said:

Given all the hysteria on the Leaf's 12V battery, you'd think there would be answer to this one:

LeftieBiker wrote:
The problem with the above is that the car makes no effort to FULLY charge the 12 volt battery even under optimum conditions. It either charges for a fixed amount of time or to a too-low voltage. As a result the 12 volt battery in a pre 2014 will be chronically undercharged unless you use an external charger once or twice a week...

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lorenfb wrote:
So the 2014+ Leafs have an improved charging algorithm? Haven't heard of this before, is it posted somewhere?
If so, are the pre-2014 Leaf's capable of having the ECU, e.g. the BMS, responsible for 12 battery charging re-flashed?
My 2013 has never had any 12 volt battery issues and I don't use a maintainer, although my SL with a PV cell
does supply about 50ma in moderate sunlight over the standby battery drain of about 30ma.

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Waiting.

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It may depend upon usage patterns, but my 2011 kept its 12-volt battery charged and my 2015 has been keeping its original Nissan 12-volt battery charged. The original battery in the 2011 lasted at least as long as typical OEM batteries last in my climate. The original battery in the 2015 is still OK so it is doing better than normal. I NEVER used an external 12-volt charger on either LEAF, but did have to jump start 2011 and 2015 one time each (left Bluetooth unit plugged in to OBDII port of 2011 while parked for extended time and upgraded telematics unit kept systems awake on 2015 while parked for a few days).

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Thanks for the feedback on your Leaf, i.e. numerous factors affect a necessity to externally charge the 12V
battery. Given that you are/were somewhat technically involved with your present/past Leafs, have you
heard of Nissan changing the 12V battery charging algorithm in later Leafs?

lorenfb said:

GerryAZ said:

lorenfb said:

Given all the hysteria on the Leaf's 12V battery, you'd think there would be answer to this one:





Waiting.

Click to expand...

It may depend upon usage patterns, but my 2011 kept its 12-volt battery charged and my 2015 has been keeping its original Nissan 12-volt battery charged. The original battery in the 2011 lasted at least as long as typical OEM batteries last in my climate. The original battery in the 2015 is still OK so it is doing better than normal. I NEVER used an external 12-volt charger on either LEAF, but did have to jump start 2011 and 2015 one time each (left Bluetooth unit plugged in to OBDII port of 2011 while parked for extended time and upgraded telematics unit kept systems awake on 2015 while parked for a few days).

Click to expand...

Thanks for the feedback on your Leaf, i.e. numerous factors affect a necessity to externally charge the 12V
battery. Given that you are/were somewhat technically involved with your present/past Leafs, have you
heard of Nissan changing the 12V battery charging algorithm in later Leafs?

Click to expand...

The charging algorithm on the 2015 is different than the 2011. Both cars charge at about 14 volts until the current into the battery (measured by the sensor at the negative terminal) drops below a threshold and then they float charge at about 13 volts (varies slightly depending upon ambient temperature). It is difficult to accurately measure the threshold current, but the 2015 is significantly lower than the 2011 was so the 2015 should get the battery to a slightly higher SOC before switching to float mode. The 2011 and 2012 models turn on the DC-DC converter for 5 minutes every 5 days when parked to charge the 12V battery. Later models monitor the 12V battery while parked and turn on the DC-DC converter to charge whenever necessary. This is probably why the 12V battery in the 2015 did not get discharged when I inadvertently left the Bluetooth module plugged in to the OBDII port while parked at the airport for 2 weeks recently.

As noted previously, the charging algorithms for both cars are (or were) appropriate for my usage patterns so I never need to use an external charger.

GerryAZ said:

lorenfb said:

GerryAZ said:

It may depend upon usage patterns, but my 2011 kept its 12-volt battery charged and my 2015 has been keeping its original Nissan 12-volt battery charged. The original battery in the 2011 lasted at least as long as typical OEM batteries last in my climate. The original battery in the 2015 is still OK so it is doing better than normal. I NEVER used an external 12-volt charger on either LEAF, but did have to jump start 2011 and 2015 one time each (left Bluetooth unit plugged in to OBDII port of 2011 while parked for extended time and upgraded telematics unit kept systems awake on 2015 while parked for a few days).

Click to expand...

Thanks for the feedback on your Leaf, i.e. numerous factors affect a necessity to externally charge the 12V
battery. Given that you are/were somewhat technically involved with your present/past Leafs, have you
heard of Nissan changing the 12V battery charging algorithm in later Leafs?

Click to expand...

The charging algorithm on the 2015 is different than the 2011. Both cars charge at about 14 volts until the current into the battery (measured by the sensor at the negative terminal) drops below a threshold and then they float charge at about 13 volts (varies slightly depending upon ambient temperature). It is difficult to accurately measure the threshold current, but the 2015 is significantly lower than the 2011 was so the 2015 should get the battery to a slightly higher SOC before switching to float mode. The 2011 and 2012 models turn on the DC-DC converter for 5 minutes every 5 days when parked to charge the 12V battery. Later models monitor the 12V battery while parked and turn on the DC-DC converter to charge whenever necessary. This is probably why the 12V battery in the 2015 did not get discharged when I inadvertently left the Bluetooth module plugged in to the OBDII port while parked at the airport for 2 weeks recently.

As noted previously, the charging algorithms for both cars are (or were) appropriate for my usage patterns so I never need to use an external charger.

Click to expand...

So it wasn't until the 2015 model that the algorithm changed, i.e. 2011 - 2014 models the same, right?

I don't know when change was made, but assume it was 2013, 2014, or 2015. I just know that 2011 and 2012 were made in Japan and are essentially the same except for cold weather package on late 2011 and all 2012 models. Change to drive train happened for 2013 (at least in USA).

It didn't change in 2013 - those cars seem to be the worst at keeping the accessory battery charged. So either 2014 or 2015.

Bumping this so some new folks can find it.

This thread contains good information on this subject, but fails to show up if using the forum search feature. 12V battery failure seems to be very common on this forum, and is a very serious issue for an EV.

Service Life:
To get a long service life, a lead acid battery must be kept fully charged all the time. As the battery is used or discharged, sulphur comes out of the electrolyte to form a lead sulphate coating on the internal plates. During charging this coated is removed and the sulphur goes back into the sulphuric acid. A buildup of sulfate over time will weaken the battery and shorten it's useful life.

Troubleshooting current drain:
A clamp-on current probe/meter is useful to find out which circuit is causing an abnormal drain on the battery. Connect it around the cable coming off the negative terminal and read the "off" current flow (key and lights off and doors closed). It should normally be low, such as 20 to 50 mA.

If it is higher than that, then something is on and pulling current which is draining the battery. To find out what it is, you will need to pull fuses one-by-one until the current drops. This will help narrow down which circuit has the load and how much current it is drawing. From here you can look at the wiring diagram for that circuit to find the component loads.