Saturday, November 19, 2016

100% or 80%?

In response to an MNL post, I realized that not everything I thought was somewhat common knowledge is not all that well known.

**Now this is "only" my thoughts on the subject, none of which is based in scientific fact. I have only my real observations and suppositions.**

Your longevity is better off cycling thru the upper 3/4th of the SOC range but that leaves a lot of range on the table  and for a short range car like the LEAF, that removes spontaneity and other unexpected joys of life.  not a good thing.  so with that in mind;

What you shouldn't do is leave your car at full charge for excessive periods of time so plan your charging appropriately. what is "excessive?"  well you need to decide that based on your life.  Obviously less is better.

the same goes for low SOC. your car tells you, so listen. Those triple warnings (LBW, VLB,Turtle) are not there to keep you company. it is a notification that "action is required" which means plug it in as soon as you get home.   many people make the mistake of leaving it this way for 3-6 hours waiting for the timer to kick in.  I plug mine in for at least an hour or so. then unplug. its a LOT of work but the extra steps makes my fitbit happy. :)  Due to the additional strain the timer puts on the 12 volt battery, I NEVER use a timer.  Going on my  7th year over 3 LEAFs and zero 12 volt battery issues. Probably just a coincidence. maybe...

My rule of thumb; if you are driving more than 20% of your range one way and parking all day,  before returning home, charge to 100%.  If you are driving more than 30% of your range round trip with short stops like an hour or two for shopping or dinner, charge to 100%.

Background; check my blog for battery stats manipulation. there are a half dozen. It is a well repeated phenomena that driving longer distances, cycling deeper and fast charging increases the range.  I regularly see a 5-8% jump so why is this happening?  Especially when we consider that balancing happens ALL THE TIME so why is top end balancing more effective?

well because unlike balancing at 80% where there is no restrictions on individual cells,  at the top end,  the higher voltage cells are completely cut out of the charging profile.  This allows lower voltage cells to catch up which increases the overall charge in the pack.  At 80%, all cells are receiving a charge because none have reached their max voltage. When the charge cycle stops, the balancing only now has the chance to equalize the cell voltages across the pack.

Finally; a Nissan Engineer stated last year at the European Car Show (or in the area) that you can gain a few miles of range by restarting a completed charge cycle a few times. I tried this by unplugging and plugging in every 10 mins for half an hour.  results varied but did work at least once. I think in my case, my pack was already pretty close to its top end balancing apex.

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