Std vs. ext charge vs. charging cycles vs. battery life

[Kohler Controller]

My testing just completed 50k simulated miles. The cells have retained ~92% of original capacity, on average.

Pretty darn good. I'm at 25,000 real miles now, with about 6% loss.

My results show about ~5% loss after 25k miles. Since your's are actual miles driven, I'm happy with a +/-1% difference!

 

[Kohler Controller]

After simulating 50k miles, what does that equate to in terms of number of charging cycles?

I'm running 4 different scenarios. The number of charging cycles after 50k miles is roughly:

Standard charge discharging 60 miles worth (60% DOD) = 800 charging cycles
Standard charge discharging 95 miles worth (85% DOD, down to first Low Battery Warning symbol) = 530 charging cycles
Extended charge discharging 60 miles worth (45% DOD) = 800 charging cycles
Extended charge discharging 115 miles worth (85% DOD, down to first Low Battery Warning symbol) = 430 charging cycles

 

[Dsinned]

My testing just completed 50k simulated miles. The cells have retained ~92% of original capacity, on average.

Pretty darn good. I'm at 25,000 real miles now, with about 6% loss.

My results show about ~5% loss after 25k miles. Since your's are actual miles driven, I'm happy with a +/-1% difference!

I assume Kohler's tests are being done at a constant room temperature, which may tend to explain the 1% difference. Also, I believe Kohler's test results show that degradation is non-linear; more loss occurs initially, then slowly tapers off with additional cycles. But, the really interesting thing from Kohler's preliminary results, so far, the difference in degradation comparing standard vs. extended charging is actually quite minimal. Maybe, after many more charging cycles, that difference will become much more significant. Stay tuned . . .

 

[Dsinned]

After simulating 50k miles, what does that equate to in terms of number of charging cycles?

I'm running 4 different scenarios. The number of charging cycles after 50k miles is roughly:

Standard charge discharging 60 miles worth (60% DOD) = 800 charging cycles
Standard charge discharging 95 miles worth (85% DOD, down to first Low Battery Warning symbol) = 530 charging cycles
Extended charge discharging 60 miles worth (45% DOD) = 800 charging cycles
Extended charge discharging 115 miles worth (85% DOD, down to first Low Battery Warning symbol) = 430 charging cycles

In my car's case, I'm pretty close to scenario #1, which I assume your test resulted in the least degradation comparing all four scenarios. I usually only recharge my car once per week after ~60 to 70 miles driven on the last standard charge. Thus, I have done about 50 standard charges since my car was brand new. I may have done extended mode charges maybe 4 or 5 times all together. The car has been driven ~4200 miles since last November. I always charge early in the morning between midnight and 9am (including both bulk + balancing/topping charge), when OAT is generally around 55F +/-15F year round. Between my wife and mine driving styles, the car is averaging about 3.1mi/kWh with an indicated range of about 95 +/-10 miles on the GoM after each standard charge, with no noticeable degradation, at least not that I can tell so far.

 

[TonyWilliams]

Could you do a "torture cell" test... 50C temp at 100% (4.1v?) continuously?

 

[Kohler Controller]

Could you do a "torture cell" test... 50C temp at 100% (4.1v?) continuously?

I will check to see if I have a thermal chamber available to do it.
"100%" would be charging up to 4.15V.
How far down do you want me to discharge?

2.9v

A simple ice chest with a 100 watt light bulb might work for the thermal chamber.

 

[jzj]

This is not a reply per se, I just want to post a question and see if anyone tracking this topic has a suggestion. (Honestly, I find this message board hard to use.)

Lately, when using extended charge, the GOM is not increasing. Typically, a regular charge would result in a range of about 100 miles, and an extended charge would result in a range of about 118. Now, despite that the time of charge and amount of charge seems to indicate that is in indeed getting an extended charge, the GOM remains at 100. Of course, the SOC gauge is no help, because it reads full when completing the charge either with regular or with extended. Anyone have any thoughts?

Thanks.

jzj

 

[Dsinned]

First, the obvious . . . it's Winter time and generally much colder outside, and with more frequent use of the climate control heating system, and a driving style that is NOT as efficient (avg miles per kWh of only 2.9 or less), your battery capacity as indicated on the GoM will generally be reduced as compared to warmer weather, less (or no use) of the climate control heating system, driving more efficiently (avg miles per kWh of 3.0 or greater). Of these conditions, I believe the most reliable in predicting changes in battery capacity after a full charge is your center console's displayed average of miles per kWh.