Question-2025 Prius in EV Mode: Reply quickly!

The Prius phev 2023, switches on the ice, in Ev mode, when you ask for more than 75% of the power.
You can easily see this on the energy meter. There are 4 energy consumption blocks, 25% eco, +25% eco, then 25% power, this always goes electrically, but if you start the last block of 25%, the Ice always starts.

Once the Ice starts spinning, it will continue to do so for at least 5 minutes.

 

You got too excited and accidentally hit the HV or EV-Auto button? I have done that.

It could also be a high-battery-temperature issue as the manual says.

 

I am not familiar with the Gen 5 display (darn, it is small and cramped!), but no, that cannot be. As discussed here, in the BEV mode (not in the BEV/HEV auto mode), the engine would not kick in no matter how much you press the accelerator as long as you are under 84 mph, except perhaps in unusual circumstances such as an overheated or too cold traction battery.

 

I do like how all the info was put together in that small display though.

The Arene software platform (available in the Gen 6 RAV4 and probably also the Gen 6 Prius) will revolutionize these displays, as they will become highly customizable.

 

The maximum power you can ask for in EV mode is 75%. Try it.

Power demand is limited to 75% even if the engine is running!

That never happens in EV mode. Full pedal travel won't enter the last block of 25%.

Any engine start will be due to some other condition, such as the system feeling the battery can't currently supply the full 75%.

 

Well, Gen 3 PHEV didn't really have a decent BEV mode. Gen 4 PHEV and Gen 5 PHEV are very similar.

The other poster who claims the engine kicks in at high throttle is confusing the EV mode with the EV-Auto mode.

All that said, in the owner's manual, Toyota doesn't recommend using the EV mode on the highway. They recommend the HEV mode for highway, which is usually cheaper at high speeds and prolongs the traction-battery lifespan, and the EV mode for city, which is cheaper at low speeds and not hard on the traction battery.

 

Both high traction-battery currents and high traction-battery mileage will reduce the life of the traction battery.

Don’t forget that the traction-battery life is based on the number of charge cycles. For a 13.6-kWh PHEV battery, you will get 1/4 of the mileage life of what you would get with a 54-kWh BEV battery. So, if a BEV-battery life is 400,000 miles, you might end up only getting 100,000 miles of BEV driving with a 13.6-kWh PHEV battery.

@bwilson4web only got 150,000 miles out of his Tesla Model 3 BEV battery, but his 2170 cells probably had the short-cycle-life NCA cathode unlike the Prius PHEV’s NMC cathode and he probably used fast charging a lot, which is also not available in the Prius PHEV.

Battery life of 2019 Tesla Model 3 Std Rng Plus—Fuel Economy, Hypermiling, EcoModding News and Forum—EcoModder.com

 

the trouble with these studies is that manufacturers use different lithium chemistries, and differen types and levels of battery protections.

 

There is something called cycle life, which is well-studied for different batteries.

As far as aging due to time, the best practice is to never store the battery at high SOCs, which means that you should charge the car only immediately before you drive. The ideal storage SOC is about 25%. You should never store at over 70%, and even that is too high for longer than overnight. Also, avoid charging immediately after you drive when the battery is hot.

 

I just want to point out that overly prioritizing HV battery health could lead to behavior that negatively impacts ICE health.

If you're doing everything possible to drive ONLY in EV, you're letting all the thin 0W-16 oil drain down from the cylinder walls and bearing surfaces. After enough time, you're going to lose seal around your pistons, letting fuel leak down into the oil when the engine finally does start. And letting the bearing surfaces "dry" out means increased wear during engine start. Now, it only takes the engine about a half second to build oil pressure, but it's still not good for the lifespan of the engine to repeatedly let it start dry.

It's also not great practice to let the fuel always sit at around 1/4 tank just to reduce weight. The fuel pump needs to be immersed in fuel to help keep it cool while operating. It can handle occasionally running down to a 1/4 tank(and the 1gal buffer after "empty" certainly helps), but always operating at low fuel is a good way to reduce the lifespan of the fuel pump. And these aren't cheap pumps any more.

Personally, I'd run the engine at least once a week to keep everything lubricated properly if I had a Prime. And I'd never go longer than two weeks without running the engine.

 

Well, even SAE 0W-8 is thick when it is cold.

I think the Prius Prime/Prius PHEV has a failsafe that periodically turns on the engine to maintain it even if you only use the BEV mode.

I use the BEV mode only for city driving.

 

The safe mode is a lot longer interval than you'd think. I think it's on the order of multiple months. And all oil will eventually drain away from from cylinder walls and other wear surfaces. It's why dedicated engine rebuild shops use assembly lube while ordinary mechanics shops can use motor oil for the same thing. Motor oil works fine if the completed engine is only going to sit around a day or three before being installed and started. But dedicated engine shops don't know how long their finished engines will sit around waiting for the rest of the project to be completed. It could be a week or a year. So they use the much, much thicker assembly lube that will stay clinging to the wear surfaces and still give initial startup lubrication.


For a humorous thought, you could put iRun's and Mendel's behaviors together to see how quickly you could destroy an engine. iRun wants to try never using his ICE, so every time it actually does start, it dumps lots of fuel past the rings and into the oil. And then Mendel's behavior of "well, I'm not putting many miles on, so I can go a year or more between oil changes" would just mean the oil getting more and more contaminated with fuel. I wonder how long that poor engine would last. lol

 

Well, if I drive with the engine (in the HEV mode), I make sure that I drive for at least fifteen miles so that the fuel is completely cleared from the oil.

See, that is the nice thing about the Prius Prime/Prius PHEV. You can completely avoid short trips, which reduce the engine life significantly, by using the BEV mode for short trips. You can’t do that with a Prius HEV. That’s one reason I wouldn’t want to buy an HEV instead of PHEV, the former compounding the problem over an engine-only vehicle by slowing the warm-up for short trips. Moreover, if you make short trips only, then the best choice by far is a BEV.