Great advice on the initial steep hill. Follow-up question:
Along the highway, there's a 1-2mi lower gradient hill, is it better to put the car into HOLD here and run the ICE for 5minutes or to let the battery deplete and run on ICE for the last 5 minutes of the drive?
Just trying to figure out if 5min of HOLD is more less efficient then running purely on ICE after I get off the highway. In both case, I'm running ICE for about 5minutes.
I realize I'm nitpicking, but I'm just trying to get a good understanding of this powertrain.
(Btw: I noticed on Friday morning that the estimated battery range was in the 60s when I started the car (full charge overnight). Thought it would only display up to 53. I'm guessing that it bases that number off previous full charge drives.
It's both more complicated and simpler than that.
Let's start with Charge Sustain (cs) mode. That's what the car does when it's "out of battery". It's not really out but it's down around (I think) 20% charged. There's a small window there that we can call
csLow and
csHigh. The difference between those is about (from behavior and for Gen 1, since I don't have a Gen 2) 0.5 kwh. So 3-4% of the battery's real capacity. When the charge gets below
csLow, the ICE turns on, and does what it's gonna do until the battery is charged up to
csHigh, at which the ICE turns off. The generator running off the ICE can fill that in about two minutes if nothing else is going on, but there's almost always something going. There's power going to lights and computers, and motors pushing the car along unless you're stopped someplace. If the load is low enough, it'll catch up and the ICE shuts off and you're driving along in a "phantom EV mode" until you use up from csHigh to csLow. If you're going down a hill at the time, that might several miles. If you're going up or driving fast, it won't be long at all.
Now, as part of the "it's more complicated", the ICE running isn't ALWAY generating a lot of power. The first 40 seconds or so, it's warming up and making sure the fluids are all moving properly, so it doesn't generate more than about 6kw. (It's also drinking a comparative lot of fuel at this point because fuel = heat and we want to get up to operating temp as soon as possible.) After that, it'll generate up to about 50kw, plus power splitting to help drive the wheels if conditions are right. How much power it generates is determined by the rate that power is being used, and how far below
csLow things have gotten in the time between "Turn on ICE" and the "warmed up and ready" state. So the most typical pattern you'll seen when tooling down the highway and you "run out" of battery is the engine comes on, thrums along quietly for a while, then revves up (maybe a lot) for a couple of minutes, then settles down to a rate someplace between the two, varying by things like hills, wind, drafts behind other traffic, and all mostly delayed by anywhere between 5-15 seconds from what people expect, because the ICE is actually chasing the power drain between those two
csLow and
csHigh points instead of reacting to the road conditions as they are Right Then. And this includes turning off for a long while if you're stopped at a light, or going down a hill steep enough that most of the power you need to maintain speed comes from the slope itself.
And that's basically all the complicated. Here's where it gets simple: Hold mode just temporarily sets a new (I think)
hmHigh right at whatever the current sate of the battery is and a new
hmLow at the appropriate window below the
hmHigh. Mountain Mode sets a new
mmHigh at a Generation-specific point and a corresponding
mmLow. Gen 1 it's about 40% on the meter, and 20% on the Gen 2. And then the ICE generator does what it needs to get there, whether that's use up the power that's above
mmHigh driving or roaring through a quart or two of gas to get the battery up from "empty". (Gen 2 gets less because the gas engine is little more powerful than the one in Gen 1, AND it can power split and supply motive force under more conditions, so the overall need for pure electric power is less. Gen 1 can't power split at low speeds so it depends on its reserve more.)