We have a 2015 SEL hybrid (39K miles). Was wondering about what to expect for impact upon the traction battery and overall mpg over time. I understand that the car should function for quite awhile, even as the battery degrades.
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Posted 10 October 2018 - 01:37 PM
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Posted 10 October 2018 - 03:08 PM
See this thread. IMO, when looking at the INL voltage vs Ah HVB capacity curves (see first chart below), I wouldn't expect much, if any, loss in the ability to use the HVB available Ah / kWh capacity in the hybrid HVB over the same range for several 100 k miles. The yellow line is data at 160k miles. Thus, FE should not be affected as the HVB loses "normal" capacity. If you look at the curves, the bulk of the lost capacity is at the far right of the curve or where the knee of the curve is. In the operating voltage range of the HVB about 30% to 70% SOC (about 272 V to 295 V), the voltage of the different mileage curves are virtually the same. In addition, 272V is still rather far away from the knee of the curve. It would take more degradation to reach the knee where I assume the control algorithms would trigger DTCs and not allow the car to start (failed HVB?). We also do not know whether the algorithms might adjust the minimum votage upwards to accommodate degradation.
I also plotted my HVB data at 103k miles from a test run of 57 miles to see how it compared to the INL data (see second chart below). My data seems in line with the INL data.
INL HVB.JPG 32.38KB 0 downloads
MY HVB vs INL.JPG 105.01KB 1 downloads
Edited by Plus 3 Golfer, 10 October 2018 - 05:58 PM.
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Posted 10 October 2018 - 10:08 PM
Good to know.
I would think this would also apply to the Energi as the larger battery degrades and it operates more as the Hybrid (with 800# of additional weight).
Edited by LeoNicholson, 10 October 2018 - 10:19 PM.
Posted 11 October 2018 - 01:02 AM
The Energi HVB has over 5X the energy storage as the Hybrid and the INL data for Energi test vehicles shows around 2X the degradation %. Lastly, the Energi operates over a SOC % range that is about 2X wider. Thus, when the Energi loses capacity, the lost capacity reduces the usable energy available for EV now operation and EV range is reduced.
For example, the Energi 7.6 kWh of capacity operates down to about 20% SOC in EV mode. or down to 1.5 kWh. Then, about 40% of the Hybrid 1.4 kWh or about 0.6 kWh would be reserved for Hybrid operation which leaves about 5.5 kWh for EV range: (5.5 = 7.6 - 1.5 - 0.6). The 5.5 kWh is about what most see on their Energi when new. So, a 10.5% loss in capacity (about a 0.8 kWh loss) would reduce the 5.5 kWh for EV only to 4.7 kWh. EV only range has dropped about 15%. If one was getting 25 miles of range, one would now gets about 20 miles of EV.
Edited by Plus 3 Golfer, 12 October 2018 - 04:36 PM.
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Posted 11 October 2018 - 11:21 AM
From what I have seen with 212k mi. on my CMAX is very little if any loss of MPG's and I think the reason is that normal usage range is between 40-50% SOC so a drop in capacity of HVB would really no effect on MPG's.