It's a great model, Martin. One attribute I've been trying to identify is Kona regen efficiency, which is very impractical to measure accurately on the road, nearly impossible. I was trying to simulate this with your model by driving up, then down the same slope and noting the total power requirements.

It indicates a regen efficiency of effectively 100%, based on a typical scenario outlined below.

At a constant 40 km/h:

78.89 kW up 15% grade

then -59.95 kW down 15% grade

or 9.46 kW on the flat

So, if I drive for 1 hour uphill at 40 km/h I use 78.89 kWh, then 1 hour downhill at 40 km/h I recover 59.95 kWh, net usage 18.94 kWh.

If I drive for the same 2 hours on the flat at 40 km/h I use 2 x 9.46 = 18.94 kWh. So regen efficiency according to the model is 100%.

Breaking down the components, what I'm seeing is that transmission, DC/AC and battery losses do not increase as expected when there is a higher current. It seems that this is where the actual losses would reside in the climbing and descending situation, making regen efficiency less than 100%.

I am not sure how you are making that calculation but it is virtually impossible to get figures accurate enough to do it like you are saying.

The total conversion of gravitational energy of a 2 tonne car at 40km/h down a 15% grade is around 30kW. So you'd have to be going

*at least* 80km/h or down a 30% grade to get 60kW.

If you were to require 9.46kW to run at a steady 40km/h that would mean your mi/kWh (sorry, I have to fall back into our imperial units to get a feel for this) is 2.6mi/kWh at a steady 25mph, which is way out.

You also need to define what you mean by 'efficiency'. Are you trying to get an estimate of the round trip efficiency of electrical energy into kinetic and gravitational energy and then back again, or simply from those (which you need, so you might be double counting otherwise) back into electrical energy?

You can bank on around 90% conversion of electrical energy from the battery to mechanical power, then the same back again with a further 85% efficiency stuffing that back into the battery. With other variables thrown in, temperature, the particular trajectory of motion through the efficiency map, etc, regen is around 60% 'efficient'.

As an absolute measure of energy, it become much less, and also less efficient, at slow speeds. It adds so little to regen below 10mph I wish they'd blend out regen to zero by 5mph so one can get a smooth stop. It is really clutching at straws to try to get electromagnetic deceleration down to 0mph and I have yet to drive an EV that does this perfectly, the best so far, by a good margin, was the Fluence. Everything else clonks, strains, lurches, changes the decel rate suddenly, or a combination of any or all of those.

If anyone who actually calibrates these things is reading, please blend brakes to 100% and regen to 0% by 5mph or less, thanks!!....