Wasn't sure whether to post it here or the Technical Discussion but a quick search of PriusChat seems to show most people post EV Auto questions in the FE & EV Range forum. So far, We've figured out that EV Auto will start in EV Mode until the range runs out and then starts the engine, almost similar to EV mode. I have also noted in one run on the highway that EV Auto started the engine at 30ish % SOC left and then stayed in EV mode until the charge was depleted. The other day, my destination was 31km away (one-way). I wouldn't make it there and back on a charge because it was mostly highway. I also remembered the last time I went EV Mode on the highway, I ran out of charge in 30ish km (but this was when the car was new back in January). Thus, I decided since I have to run the engine, I might as well try out EV Auto since Toyota states it's the mode to best reduce overall energy consumption (fuel or electricity) The weather cool with temps near 15-17°C (low 60s) with on and off rain and the car was fully charged. I recall that when the engine comes on at highway mode to do a warm up, it can be a bit jerky so I thought I'd pre-warm the engine and switched to HV mode to fire up the engine, then switched to EV Auto after 1-2km. The engine continued to run until the warm-up cycle was done. From then on, I was in EV mode through the 80-100km/h section (50-62mph). If you recall from the manual, Toyota says EV Auto will kick in the engine under heavy load such as mountain driving or passing. Up til the other day, my experience is that it hasn't and has stayed in EV mode. However, that day, when I did two passes, accelerating to 110km/h (68mph), it kicked the engine on. When I settled back in the right lane and back to 100km/h (62), it ran the engine for maybe another 20 secs then shut off and went back into EV mode. About 3/4 into the trip, there are two hills to climb and both times, it kicked the engine on for the climb, as the manual stated EV Auto would do. Finally, at my destination, I arrived with 34% charge remaining (about 14-15km). It's low because of the high speed which put a dent into the kWh/100km). I forgot to check what my mpg was for that trip. (If you're curious, I drove the rest of the day in HV after depleting the rest of the charge. 112.8km later, the diary says 1.5L/100km or 156.8mpg. It included 1 full charge in the morning and 1 half charge to top up the battery before the 31km trip midday). TL;DR: It appears that if you want to use EV Auto as the manual states, you may have to run the engine in HV mode and let it do its pre-warm cycle. If you don't, it'll stay in EV mode more readily. I'll be interested to hear what others have to say. It's unfortunate the timing is such that it's the end of road trip season and other instances such as temperature will force the engine on but perhaps those like @Salamander_King who have commutes or trips that will require the engine to run in the winter can try this method of EV Auto and see if it helps reduce their overall consumption (both battery and fuel)
So if I understand you correctly if I am going to take a trip that involves some highway driving I should precondition the ICE by running in HV mode briefly to start a warmup cycle and then run in EV AUTO from then on?
I have not used EV Auto much except for the first few months after purchasing the car for trying out different modes. But for during the small samples of my trials, under my normal driving conditions, what you wrote was true. I don't have any highway segment on my commute. The top speed limit is 45 mph. I may get up to 60 mph on the down hill portion, but never accelerating at that speed on my daily commute. Some uphills may benefit from HV, but under normal conditions with EV AUTO, it did not fire ICE. This summer, I have been manually switching HV/EV to manipulate more HV on steep uphills, but this usually result in less overall mpg for return of increased miles/kWh.
My commute is 38 miles one way and 95% of that is at freeway speeds (when not stuck in traffic). To get to the on ramp, I leave the car in EV mode. Once the light is about to turn green, I push the HV/EV button to fire the ICE and have it “preconditioned” for 2 large hills I have to traverse to work. Once up to 65 mph and moving with traffic, I push the EV button (which puts it in EV Auto) and ride that out until the first hill. At the first hill, HV/EV is pushed and I use the ICE to climb that hill. Once at the top, EV button is pushed and back into EV Auto until hill #2 and repeat. I usually end up with 32 miles of EV driving for my 38 mile one way, so not too bad.
Any comparison to the number if you drove all EV until it runs out then switch to HV (or if it does not run out then 100% EV). Also, comparison on MPG difference in between those two cases? In my case, I have 36miles (18miles one way) daily commute. During summer time, I can drive most of 36 miles on EV mode. Sometimes I can make back to home completely in EV, but most often EV range runs out a few miles to few hundred feet before reaching home. If I do not switch HV/EV, I usually ends up with 199.9mpg (even with a short HV run included) but can only get 4.6-5.2miles/kWh on EV. If I use HV/EV switch to drive HV on steep uphills, I end up with 160-199mpg, but can get 7.4-8.7miles/kWh. With switching HV/EV, I use more gas and have some EV range left when I get home.
If EV Auto is the mode for best overall energy consumption, then that would only be true in the case of a long trip. That is, if your trip will fit entirely into the EV range, then pure-EV mode is definitely more efficient. I haven’t used EV Auto, but I gather the underlying concept behind it is to increase miles-per-charge by kicking in the ICE on operations that would otherwise burn down the battery quickly. I personally would be more interested in the kinda-sorta opposite mode — a mode whose underlying goal is to burn down the battery as needed in order to maximize ICE efficiency. Ordinary hybrid mode, in part: 1. Long-term, strives to hold the battery level roughly where it was when you entered hybrid mode, 2. Where realistic, strives to avoid kicking in the ICE unless it can operate it at close to peak efficiency, and 3. In cases where it’s more efficient for the ICE to just directly drive the wheels, does so. This non-existent-oh-well mode would take #2 above to the max, but not necessarily do #1 and #3. That is, it would run the ICE when and only when it can do so at close to optimal efficiency (only when it’s actually needed, of course), and burn down the battery to “pick up the slack,” so to speak. That, until the battery burns down to the EV-HV threshold, which point it goes to plain ‘old HV mode.
No comparison in other driving methods. I do t like the ICE to kick in when I’m traveling 70 mph and it’s stone cold. The GOM states I have 34.2 miles this morning, and based on the result I probably got 33 miles. Others can experiment while I’ll give my experience as the ICE can be a delicate beast that I don’t want to have any issues with it. I’ll baby it as much as I can .
I understand. In my case, I hate the ICE to kick in only a very short distance before reaching home. Often, it dose not even have a time to complete the warm-up cycle, then I have to shut it down not fully warmed up. With manual HV/EV switch, I usually start HV a few miles before reaching to the bottom of the uphill to complete the warm-up cycle then use ICE to climb up. With EV AUTO, ICE never come on until EV range is exhausted as I stated above, so that mode is useless for me. I also try to keep the ICE warm enough once it completes the warm-up cycle, so that I don't have to do multiple warm-up cycles on a single commuting trip.
If you're cycling with the HV/EV button, then you're toggling between HV and EV mode, not EV Auto. EV Auto is a separate button. Given that scenario, after you pre-condition the ICE (so do the warm-up cycle), what if you just pressed the EV Auto button and left it for the rest of the trip? In theory, it should kick the ICE in to climb one or both of those hills on its own without you having to cycle manually. Same, which is why I kicked the engine in HV mode to do its warm-up cycle on that highway trip so that it's not kicking in stone cold at 62mph.
I've been using EV Auto quite a bit. It always warms up the ICE before using it. I can tell that even though the ice is on, the propelling force comes from the battery for a while. I have the display showing instant mpg/kwh. When the engine kicks on, the display changes to MPG, but the MPGs stay at max until the engine warms up.
At what temps and how do you get the ICE to kick in in EV Auto at the start? (Presumably you're pressing the large "EV Auto" button at the end of the row of buttons and not the HV/EV button)
Between 70 and 100F. It kicks on around 70mph or if I floor it for a while on the on-ramp (starts warming up). Yes, EV Auto.
Is it really bad for the ICE engine when switching from EV to HV in highway speeds (65mph or above)? On my work commute, 51 miles one way, I start EV from home up to the highway (5 miles). Then when my speed is around 65ish, I switched to HV and run it for 5 miles. This 5 miles are pretty much 90% uphill. Then I switch to EV again for the rest of my trip. Sometimes if there are traffic, I can get to work in EV, sometimes it runs out of charge within 1-2 miles to my destination. Thank you.
I really don't think it's bad at all. The car is running almost all on EV while the engine warms up as you can see by the mpg bar next to the speedometer if you have that turned on.
I have noticed that too. If the engine is cold it will run in EV mode until the battery is empty, unless you floor the accelerator. If it is warm it will come on going up hills. I think colder weather and cruise control use make the engine more likely to come on in EV auto, but I can't confirm. I also noticed, with the engine warmed up if I floor it from a stop it will still accelerate in EV mode up to around 45mph, and the engine might kick in after that. I have not tested what it does flooring it with the engine cold, and I don't really want to find out. It's not bad for it. The car controls the engine speed to idle while it's warming up. It might be bad for it if the engine is not warmed up yet and you need to accelerate quickly. Then the engine might get involved before it is fully warmed up. For example if you switch to HV mode just before merging onto the highway, or before going up a hill, or floor it in EV Auto where it supposedly can turn on the engine for additional power. And it's more likely to be a problem in cold weather when the oil is colder and engine takes longer to warm up. In warm weather, even just a few seconds of warm-up is probably enough to prevent excessive wear on the engine.
Probably not since you could do that in HV mode or in a regular Prius. (EV Mode in the Gen 4 is up to 110km/h or 68mph). I’d try to avoid stress and I think what you’re doing is fine.
Where is this display? I'm new to the Prime, and can't find it (the only one I'm able to find so far is on the "history" tab, and I get a bar on the right side. Thanks!
