Help me figure out lower than expected range (factoring in battery SOH)

[jakealake18]

I bought a used 2024 GT in November and am still trying to figure out what I can expect from it for real world range. Today, it has 17,000 miles and the battery state of health is 93.5%. I assume this means that I should have about 85 kWh of usable battery capacity (91kWh usable when new * 93.5% SOH).

Last weekend I followed the process to reset the state of charge meter so I started my week with a 100% charge. After about 5 days I had gone 203.1 miles, averaged 3.1 miles per kWh, and had 13% battery left.

203.1 miles at 3.1 miles per kWh should have used 65.5 kWh. That would be equal to 77% of the usable battery (at 93.5% SOH), meaning I should have 23% left, not 13%.

This is a pretty big discrepancy (10% SOC less than where it should be, or 30 miles of range) and is a pretty big factor for some planned road trips this summer.

Anyone know what’s causing this discrepancy? Getting a ~230 mile range in real world driving is pretty disappointing when the data says I should get ~265.

(Clearly they installed the wrong battery at the factory, right? )

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[JohnFoxeSheets]

When it comes to batteries, state of charge, battery health, and pretty much everything else are part science, part engineering, and part art. There are so many factors that it is pretty much impossible to get exactly accurate assessments of all of this. It is generally recommended to charge the car frequently, and enjoy it. I personally charge when the car is at less than 70% and have the charging target set to 85%. If I have a roadtrip planned the next day, I charge to 100%. I totally get the urge to try to get everything to be exact and make the calcs all foot properly (I'm a bit OCD), but I've learned that it's much more fun to just charge frequently and enjoy the car. On roadtrips, I also charge often, though I usually let it go down to the 20-30% range before charging. I try to never go below 20% as it stresses the battery some. That said, I'll go below 20% if it saves me a charging stop on the home leg of the journey.

Enjoy your awesome car!

 

[Mach-Lee]

The 91 kWh includes the buffer below 0% indicated. If you exclude that and start with about 88 kWh, your expected capacity is about 82 kWh. But that’s only if the battery is 25°C. If it’s a little cold, that might drop the capacity by another 5-10%. Now you’re down to about 76 kWh, which is close to what you are getting. The efficiency meter may not be accurate across multiple drive cycles FYI.

If you had any idling (such as remote start or sitting in traffic) that will also throw off your result.

You can find my topic on battery calibration, but I would do a few 5-100% charges in a row to update the BMS. Make sure you let it sit long enough at both ends, and use a single uninterrupted level 2 charger (no departure times or remote starts) to charge fully to 100% in one session.

For road trips, plan stops about every 200 miles. That’s about what mine does when you are driving 75 MPH.

 

[Maquis]

There are too many uncontrolled variables (battery temp being the big one) to calculate with much precision, what you are trying to calculate.

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