baustin wrote:The charge cycle has to completely finish for the cells to be balanced...
I keep seeing this posted here, and it does not make sense. Look at first leafspy page. All those red lines are cells being bled off via balancing resistors in BMS. It happens all the time, regardless of the SOC. I think you are perpetuating the myth that you need to charge to full in order for balancing to occur.
balancing happens all the time but there is a benefit to top end balancing and that is more range.
The issue we have is that even slight amount of overcharging will degrade your cells MUCH faster so the charging profile insures that does not happen but cutting off charging when the fullest cell hits a certain voltage. in a perfect world, all the cells would be at that same voltage but no... not happening. Some will get left behind. this is why the charge cycle will kick back on for 3-4 short charge cycles after the main charging has been completed.
there is also a factor on the discharge curve because Li likes to give its all until its nearly exhausted which means SOC tends to fall off a cliff at a certain point. this means weaker cells get weaker at a faster rate. This explains why voltage delta is so small when SOC is high but grows considerably as SOC drops
so what happens when you to top end balance? You will have the cells that fell behind will potentially continue to fall behind. they won't get that far behind because they will be in a perpetual state of 24/7 trickle charge. (ok not quite that bad!) so is this bad? not really if
1) you don't spend a lot of time at real low SOC (if you are then you need to tell me why you are not charging to full...)
2) you don't need that extra few miles of range
so top end balancing is important... if you need it.
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 13,705 mi, 93.41% SOH
My Blog; http://daveinolywa.blogspot.com
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