Hey guys nobody is starting any flame wars here, just trying to explain my thoughts and ideas to folks here and you guys can take what you want from them or discard as needed if you disagree.
I'm no chemist but I am an engineer, and I do understand several things though I may not be an expert on everything. We all learn something every day. Your explanation sounds complicated for the average Joe Topher. Let me explain it in my terms and you let me know if you agree or not.
First off, I do understand and know that when you let batteries sit after a drain, the voltage will rise. However, I believe there is a different scenario that causes battery voltage to rise with heat and drop with cold. I don't know the exact chemical explanation for it, but I know about it from my hobbies and have seen it on my Energi. I could leave the car tonight (unplug from charging say at 50% charge and tonight is 40 degrees. Tomorrow the sun comes out and the charge level will be higher, like say 55% for example. I can post specifics later. I have also seen the charge drop from 55% where I left it one day, to 45% the next day when the temp outside was a high of 48 degrees just a couple of days ago. What's your explanation of that (and not counting the relaxation point, that I already know of and agree with).
As far as the supercharging that Gary calls it, here is my explanation of that in simple terms. Assume the Li-ion battery voltage range goes from 3.7v dead to 4.2v at 100% full. You never want to exceed those limits and you really shouldn't use up a Li-ion or Lipo pack below 20% capacity or say 3.73v per cell. Anyways, given this, let's assume Ford decided to limit charge to 90% which is I don't know the figure off the top of my head, say for example 4.1v. The system charges the pack until the cells reach 4.1v at which point it stops charging and it shows 100% full but its really 90% as seen in the SGII.
Now if Gary turns on his AC while charging, that draws some power from the system and will drop the cell voltage to 4v (for example, don't get caught up on exact numbers, just illustrating). The AC pulls about 1.5kwh but the high voltage charger pumps in 3.3kwh, so there is more charge going into the battery while the AC is on. The voltage will rise under load of the AC slowly from 4v up to 4.1v, at which point it shuts charging off and says 100% again, but the AC is still ON. Now Gary turns off the AC and unplugs the charger, and the load is gone, and the cells will bounce up to 4.2v per cell and the car will still show 100% but SGII will also now show 99.9% instead of 90%. By using the AC load on the system, Gary has fooled the charging system into thinking the cells are not up to 4.1v yet and it continues to charge more with the load of the AC until it brings the voltage up to 4.1v with the AC running hence you have "supercharged" the pack or in reality just defeated the safety margin than Ford put in to make room for voltage rise when "fully" charged and soaking in the hot sun in Arizona for example. Lipo or Li-ion packs you never really want to store at full charge, best stored at 60% charge or about 3.95v per cell. Anyway, forget about storage charge, that is for long term storage while not in use and usually shipped in this range, but I believe what I explained above here is easy for the average person to understand.
I was going to ask you guys what you do mean when you use the word recalibration because I didn't think anything was being recalibrated, but I believe you answered my question anyways and agreed that its not.
By the way, I went to Derry NH today and back. Check out my stats below. 65 mph on the highway, 53mph tops using the battery. I didn't follow the higher SOC theory (save battery until the end), but used the battery before, during and after using the gas engine. It worked out really well for me, pretty good stats, and I got a full charge on the HVB at both ends. There was 3% left of the HVB when I got home, disregard the 7 miles you see, I'm charging it now since I got back.
Edited by rbort, 31 May 2014 - 09:40 PM.