Hill Climb in EV

I was wondering what the ioniq EV was like on hill climbs, thanks for the info. Very interesting.

Remember that, if you can connect to the OBD port, you can read Cumulative Energy Charged (CEC) and Cumulative Energy Discharged (CED). From the change in CEC you can know how much energy was regenerated. On a given trip, consumption is CED-CEC.

Maybe you got one of those which don't work well with the Ioniq? I lost some time too.

Everybody recommends the chinese Konnway kw902. I figured that the kw904, being more modern, would be at least just as good... But no, it's all crap. That's good engineering for you...

An older one, also crappy, is now working for me. It's good to read battery temperature. It's a pity that coolant temperature is not available.

chui said:

From the above I conclude that speed has more of a detrimental effect on range than climbing hills.

Click to expand...

The (static) energy needed to move the car is friction resistance plus air resistance (and these 2 don't depend on the inclination), plus gravitational potential energy from the inclination (and this doesn't depend on the speed), so the one with the most "weight" is variable ;-)

So no matter how fast you're going, you'll need 6,19kWh to climb 1520m with 1495kg (on my previous Leaf, that would represent 33% of the total capacity), and this is just the gravitational component of the total energy, you still need to add the "movement" part...

What varies a lot in mountain climbing (and that's why most people get huge consumptions in this situation) is dynamic power. When driving straight you accelerate to a given speed (dynamic power + static power) and after that you just maintain the speed (only static power). When you're mountain climbing, especially with lots of curves, you're often accelerating and decelerating, accelerating again, ... Depending on how "sporty" this driving is, you can spend a lot of additional energy in it.
You probably did it steady and smoothly, which would explain why you feel climbing is not such a big deal.

At a first moment, it appeared to me that there wasn't enough data to estimate how much energy you recovered, in particular how much of what you could have recovered. I was probably looking for something in particular.

Of course, there is enough data here for an estimate. Perhaps not the best one, but a first estimate is better than nothing.

• Distance: 88.5km
• Energy going up: 13.72kWh
• Energy going down: 2.52kWh
• Height: 1750m - 230m = 1520m
• Weight: 1650kg assumed
• Work of gravity: 1650×1520×9.8 = 24.5784MJ (megajoule) = 6.827kWh

Now, the extra energy that you had to spend for the climb was at least that, but should be a bit more because the car isn't 100% efficient. Could we use the number you quote as a typical number for similar speeds, 5.5 miles/kWh? No, that's 11.3kWh/100km and for 88.5km it would be exactly 10kWh. If you had spent that much, you'd have to have spent only 3.72kWh=13.72-10 in the climb, and that's impossible. We have to imagine that the road had a lot of curves and you spent a lot less than you usually do near sea level.

So, we have to take 6.83kWh as the extra energy you spent for climbing. We could inflate this number a little bit and arbitrarily.

In that case, you spent almost exactly half the energy in the climb, 13.72kWh - 6.83kWh = 6.89kWh. So, how much was the bonus when going down? Assuming consumption would be 6.89kWh if it was level, then it was 6.89kWh - 2.52kWh = 4.37kWh.

That's 64% of the energy you could have recovered. This is a maximum, unless, of course, you had less weight.

If we think the car is about 95% efficient converting electricity out of the battery to tractive energy, then you spent 105% that amount (6.83kWh) going up (= 7.17kWh) and recovered only 59% going down (= 4.03kWh).

This could be a round number to keep in memory. We recover 60%. It's not just better than nothing, it's a lot better.

That also means that if we go up 1000, down 500, up 500, down 500, up 500, down 1000, for instance... it is equivalent to going up 900m and not returning, 900m = (1000 + 500 + 500)×105% - (500 + 500 + 1000)×60%.

PS: The CEC counter, however, would have told us how much was the bonus directly, apart from a few strange effects.

I can be accurate about the weight in that it was 2 adult @ 155Kg total plus the weight of the car (from the V5 registration document) @ 1523Kg = total 1678Kg.

The road itself was not a continuous climb, there were some descents along the way but these were reversed on the return as I took exactly the same route. The road was very twisty with lots of hairpins and hardly any straight sections, hence the low average speed though again the total time up and down are very close so again balance out.

Thanks @migle for taking the time to annalise my results. I might try in the future to find a section of road that offers a continuous ascent and note the up/down energy use on that.

There isn't much point in getting too accurate about this. Also, a continuous climb is not necessary if we're logging CEC and CED, since energy charged and discharged are accounted separately, all energy charged while the car is moving comes from regeneration.

The numbers can't be completely right, because even if you spent only 6.83kWh on elevation, that leaves 6.89kWh for remaining tractive energy in 88.5km, meaning an average of 7.78kWh/100km if the terrain was level, which is a bit low. So, it's possible that we can recover more than 60%.

But we can never go beyond a rough rule of thumb, because there are things that are not linear at all. The battery won't start immediately accepting charge, if I understand correctly. At least if I can understand anything about the battery hysteresis effect... (talked about on other post). I don't know much about batteries and only the basic principles of electricity.

I will re-run that same route sometime and see what results I get. Of course, due to the bends, the speed was very low and never exceeded 50 Kph, and I also used eco driving style and slow acceleration and never braked hard enough to activate the mechanical brakes.