Some corrections:
arnis said:
Older Leaf (charger in the trunk) had this algorithm for 12V charging:
Always charging while vehicle is ON.
I'll assume you actually mean READY in Nissan's terminology. Not so. The LEAF only charges for a few seconds and then spends the rest of the time at a float voltage of 13.1V. The exception is that the vehicle actually charges the battery at about 14.5V whenenever the windshield wipers are on.
arnis said:
Always charging if vehicle is charging HV battery.
Not so. As above, it normally charges for only a few seconds and then drops to a float voltage of 13.1V for the rest of the time. The exception here is that it
sometimes charges during the ful charging period. It appears this happens during very cold temperatures, but perhaps it also happens occasionally at other times.
arnis said:
Always charging if vehicle is preheating/precooling.
While I haven't measure it, I strongly suspect this case is similar to the charging case listed above.
arnis said:
Automatic charge after 120 hours of nothing happening (5 days) for 5 minutes.
Unfortunately, this has very little effect on the SOC of the battery since five minutes is not enough time to do much of anything with a 12V lead-acid battery.
arnis said:
Nissan most likely noticed a big problem with that and new Leaf (charger under the hood) works that way:
Always charging while vehicle is on.
Always charging if vehicle is charging HV battery.
Always charging if vehicle is preheating/precooling.
From what I have read, the MY2013 and later use exactly the same algorithm as listed above for the MY2011-2012. The difference seems to be that those later LEAFs appear to also have a programming defect which
occasionally leaves a load on when the car is turned off which drains the battery, just adding to the problem of keeping the 12V battery alive.
arnis said:
Automatic charge after 24 hours of nothing happening (1 day) for 4 minutes.
Thanks, I didn't know about this change. It's better than nothing, but, again, 5 minutes is hardly worth the effort, IMO.
arnis said:
This solved the problem in most scenarios.
I don't think so. It seems the MY2013 and later LEAFs have at least as many problems with the 12V battery as the earlier models, if not more.
arnis said:
For those who own older Leaf, ran out of warranty and plan to keep the Leaf for longer period I would STRONGLY recommend
to replace 12V battery with AGM 12V battery next time. It costs more but it offers more reliability, especially in this
lousy situation: Leaf draining battery for 5 days and then charging it only for 5 minutes
AGM battery is capable to survive deeper discharges with less sulfation happening.
Sorry, but I do not agree with the advice of switching to an AGM battery. Unfortunately, 13.1V is a DISCHARGE voltage for many new AGM batteries. I have one that is several years old now that sits around at 13.25V for MONTHS at a time. As you can see, the LEAF will actually DISCHARGE an AGM battery in normal operations. Additionally, my experience is that AGMs tend to sulfate FASTER than flooded batteries. I am currently trying to recover several 400 Ah AGMs which were 75% sulfated after only about three years of use. I have read of other similar experiences with AGMs.
arnis said:
AGM battery is capable to absorb charge faster than regular flooded battery, especially in cold temperatures.
This is true. What is perhaps more important for those who live in very cold climates is that AGMs freeze at a MUCH lower temperature when they are mostly discharged. Unfortunately, a flooded lead-acid battery will freeze at about 17F if fully discharged. In my experience, freezing often ruins the battery.
arnis said:
Therefore it is able to absorb more during 5 minute period.
Perhaps, but it is still not nearly long enough.
