On 05/22/2017 07:47 AM, paul dove via EV wrote:
Still sounds like a hold over from lead batteries. I can't imagine the voltage of an unbalanced pack being more than 10 volts loss in voltage. This would not be noticeable.
I agree, it seems inappropriate to talk about "stiffness" from balancing a lithium pack. Though, I think Bruce was quoting someone else. Maybe Bill Dube will chime in here, but if all cells are well top balanced and charged to maximum voltage, that amount above "normal" voltage represents a tiny amount of energy and is gone in the first few seconds of discharge. Of course, lithium packs will sag when approaching discharge rating limits. But there is very little sag associated with SOC.
Which brings to mind the old "top balance"/"bottom balance" arguments. Is anyone out there still having good luck with bottom balancing?
Bruce mentioned "guessometer" in a Tesla context. It is my understanding that Tesla arrives at an estimated range by applying a constant, linear scale factor to the estimated remaining energy. For normal use, that scale factor is about 285 wh/m. The driver is properly left to make allowances for wind, speed, elevation, weather, etc. The imiev does apply some guessing based on past data. They do a fair job of such guessing. Leaf, OTHO, does such a terrible job that it is nearly useless. I remember my wife calling me on her way home from picking up the new Leaf: "This thing has lost 15 miles of range in the first 5 miles traveled. At this rate, I won't be able to get home. Are you prepared to come get me?" We, of course, learned to mostly ignore the really crappy instrumentation.
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