Looking at the graph and doing some rough eyeballing. Looks like at least the top 4 lines are all the same as far as battery degradation when compare total kwh of charging rather than number of times it is charged. For example, the best curve is the 76-65, or in other 10%. Compare that to the 85-25% curve, or in other words 60% per cycle, 6 times the number of kwh run through the battery. Look at the 1000 cycles for the 85-25 and compare to the 6000 cycles for the 75-65 . . . they are both about 93% battery retention (7% degradation).
Are you refering to the graph in post #5?
That graph do not test all SOC regions.
Because of that, you can get fooled to draw the wrong conclusions.
A ”correct” graph or research report should present the cycles in Full Cycle Equivalents(FCE). Then we can see direct in the graph which cycle alternative that gives less degradation per mile driven if we transfer it to an EV.
What we can see is:
Small cycles are better than large cycles.
We can also see that the lower a cycle is placed, the better.
There is only one cycle set with 10% DOD, 75-65% we can not see and compare for example 35-25 or 20-10%.
Batteryuniversity.com use this graph, which is quite missleading.
Recalculated to FCE we will get a complete other view of which cycle alternative that is best of the tested soc ranges (which might blind you from the SOC range that is actually best.
Still, the setup did not test low SOC cycle so it is very incomplete if we should use it to find the best SOC range there is.
That picture is as about as good as how people seem to interpretate Elon Musks soc range answer on Twitter. People took this as the best SOC Charging target is 80% for battery longivety.
Question, how does regen braking play into this? Effectively, every time you brake, you are doing a little mini charge cycle.
Regen makes the depth of discharge lower, which reduces the wear. Smaller cycles cause less degradation.
There might be one thing with high power/high current regen but we saw Tesla increase the limitstions for regen in an update this summer. It was probably done to reduce degradation.
Anyway, extrapolating on this graph, seems like that won't matter since doing 10% cycles performs the same as 60% cycles when measuring total kwh of charging.
The test has a faulty setup, or at least you can not se ”through” these issues.
Hig SOC cycles wear much more. This means that a 80-70% cycle wear about as much as 80-30%, counted per FCE.
Large cycles wear much, but the often used term ”deep cycle” is missleading. The bad part of a large cycle is not at low SOC, it is the high SOC part of that cycle that is bad.
So in the about same SOC range, a smaller cycle wear less than a larger one.
Regen reduces the need for chsrging with about 10-15%, so the DOD is 10-15% smaller. This reduce the degradation.
But 10% cycle is still quite large compared to a single regen braking which is probably only .1% or something.
Yes, its very small cycles, so the wear is low.
I have also been in the habit of varying my charge rate while charging (I have an automatic program managing this) that helps me to peak shave. Not sure if that does anything bad to the battery, I feel like no or I wouldn't do it, but that is just my gut feeling. I vary between 0kw and 5kw charge rate in 1kw increments depending on my other usage.
I dont understand the peak shave term, but any charging below *about* 0.25C or So (about 20kW on a long range) is considered slow charging and do not damage the battery. As AC chsrging is max 11 kW its well below the linit where the chsrging power can cause extra degradation.
At low battery temps this can happen anyway, but Tesla limits the charging speed to cope with the maximum ”safe” charging speed for the actual battery temp.
