Miles/Kwh degradation?

[doggyworld]

So.. when we first got our Kona back in 2019, I think we were getting a consistent 4.1m/kwh during our regular driving, but it seemed after 36k miles, it went down to closer to 3.8m/kwh. It didn't really bother me too much as I thought maybe it was just our driving changed during Covid maybe.

But now, after getting our battery swap with a fresh battery, I'm seeing 4.1m/kwh again. This leads me to wonder if the battery becomes less efficient over time. Or is there some weird calculation perhaps with the battery degradation that affects the efficiency calculations.

Anyone else notice this?

 

[Esprit1st]

I personally haven't seen any change over the 2.5 years I've been driving my Kona.

Also, if there was a change in m/kWh that would mean that your motor or reduction gearbox would be less efficient.

If it is the battery degrading you would only get less total miles because your battery capacity degrades.

The only thing I can imagine is possibly different atmospheric conditions, meaning more use of AC or heat.

 

[KiwiME]

This leads me to wonder if the battery becomes less efficient over time.

Based on the cell data sheet the cycle efficiency certainly would drop slightly as time goes on and that would increase the energy input required per energy output. But it seems reasonable to assume (but not proven) that the dash reading is based only on energy output, not caring what losses were incurred to get that energy into the battery.

Or is there some weird calculation perhaps with the battery degradation that affects the efficiency calculations.

As above we can only assume that it's measuring voltage and current in real time, then integrating that over the distance covered. It's unlikely to care where the power came from.

As with some ICE cars that have very high MPG ratings fuel economy can seem more variable than those that are less-efficient. EVs are much the same, speed and temperature in particular.

 

[mikeselectricstuff]

The figure depends on a number of factors, mostly temperature and driving style, but also heat/AC use etc., and a variation between 4.1 and 3.8 is well within normal day-to-day variations

 

[Genevamech]

Is this the trip average or the long-term average? I'm wondering if it's possible that during the first 36K miles you had some low efficiency drives that brought the long-term average down a bit, and some counters were reset as part of the battery swap process?