Range Drop after Range Charge

[dhrivnak]

Has anyone had a drop in STD range or their CAC after range charging? I do a range charge about once a month and never have noticed a drop in the past. But this summer I needed maximum range a few times and afterward I had a drop in range of about 2 miles. Maybe it is random chance or possibly range charging puts more stress on a 5+ year old pack. Has anyone else seen something like this?

 

[djp]

How far did you drive after the Range charge? A full discharge (to <20% SOC) gives the algorithm an opportunity to measure the end points of the battery capacity and recalibrate the CAC. It's typical for the CAC to hold a constant level or drift higher on shallow charge cycles, and be reset to the correct level on the next long drive.

 

[dhrivnak]

I did drive from nearly full to nearly empty both times. So yes I could be seeing a recalibration. If I look at my car while on the low side of other owners it appears I am in "normal" limits, just low normal and battery loss is part of having an EV.

 

[djp]

I saw the same on my last road trip. My CAC has been hovering around 155-156 for the past four years, and dropped to 153.5 after driving to Vermont and back. I'm not too worried about it, it's less degradation than I expected when buying the car.

 

[hcsharp]

How far did you drive after the Range charge? A full discharge (to <20% SOC) gives the algorithm an opportunity to measure the end points of the battery capacity and recalibrate the CAC. It's typical for the CAC to hold a constant level or drift higher on shallow charge cycles, and be reset to the correct level on the next long drive.

This.

Cac rarely drops slowly. It moves in steps whenever it gets re-calibrated.

 

[tomsax]

Here's a chart of our Roadster's CAC history (upper line) along with a graph of our daily miles driven (lower spikes). As noted by others, the CAC tends to drift when lightly used then correct when driven through full charge cycles.

The first giant dip (Sep-Nov 2010) was after our pack had three sheets fail the bleed test, which resulted in a full pack replacement. After the battery swap, it took several months for the car to get to know the new battery pack. After that you can see a number of rapid changes (mostly dips) generally associated with road trips.