Is there a legitimate use for charge mode in the Prime?

I think it’s better to put in in hybrid mode on the highway before you reach the city, and estimate how much ev you will need to get to your destination. I do this, last time I got home with 2 % soc which was just right. Even at the end of two days, save the ev. Or do use the charging mode on the highway which also is useful for gaining battery for upcoming grades.

 

I have not done exhaustive testing, but these are numbers based on my tests:

Charge from 0% to 80% in HV Charge mode at 65mph flat highway:
- 150 minutes 160 miles at 20mpg less than HV mode, uses roughly 2.8 gallons extra
- cost 50 gas miles to get 40 EV miles.
So from the costs Charge mode is not efficient but if I haven’t used any gas in 3 months, I start to feel pressure to burn some and HV Charge mode burns it off faster…

 

Not sure about that. HV mode will use some EV mode capacity, but I have not heard anyone test if it will actually drain it to 0%

 

Using charge mode at a time when the gas efficiency penalty is at its best to have EV for when gas efficiency would be worse is about the only time it makes sense. Assuming simply saving grid charge until then wouldn't have been as effective. Another reason is for places with ICE exclusion zones.

Otherwise, it is like EV mode on the hybrid. There are some niche uses for it, but it can be easily overused to the point of hurting overall efficiency.

 

I prefer to run my 4th gen in EV mode around the city and in rush hour traffic. The car is much more responsive; but you can also switch to performance mode. I would probably forget to switch it back to Eco mode. I haven't been in a 5th gen yet; larger motor & battery - but on a long trip like that. I'd probably force a regen about 100 miles outside of Atlanta. That should get you 50% EV battery and the ability to zip through city traffic. That's usually what I do when I need to drive into San Francisco; 2 hour trip one way. I rarely use the regen function; but it does come in handy when a plug isn't available.

 

For such a trip, I'd use EV mode on surface streets, and then switch to hybrid mode when on highways and interstates.

When cruising at a set speed, using charge mode could push the engine out of the light load and into a heavier load where it is more thermally efficient. The fuel efficiency during that segment will drop, but the gasoline is doing more work per unit burned. Combined with the future gas free EV miles gained, overall efficiency might come out ahead. Knowing when doing so just takes more knowledge of the systems to pull that off.

For most, the effort simply won't be worth that effort.

 

One reviewer I remember vaguely mentioning that you could use charge mode to charge the battery to use the outlets for camping or tailgating. Similar to having a gas generator. Seems to be the only situation that makes any real sens to me.

 

I could imagine there are situations you want to charge a little bit before parking so you can remote activate the hvac system on battery before coming back - e.g. especially in cases where you dont want to use the ICE or are not allowed to.

There are limits though of what the car allows without automatically starting the ICE - so probably not a realistic case.

 

Starting a long trip in EV mode at 11 F will warm the traction pack quickly, put the poor heat pump will struggle to warm the cabin. At 11 F I'd start in HV 1; to complete warmup mode as soon as possible at the slowest speed possible and take car of that first. Get the cabin up to a comfortable temp for the trip and watch how many times the engine truns off and the Prime uses only EV while in Denver. If you see more than 20% EV range used up before you hit the hwy, switch to charge mode and take it back up to 80% SOC while still at a slower speed. Best is below 40 mph as you can see the charge rate clearly using DrPrius..... but I doubt you'll use much EV range while in HV mode at 11 F. ( ymmv - and usually does ).
I'd just leave the car in HV mode for the entire trip. The only way I believe the car will use up all EV range on 2 500 mile trips is if you forget to switch from EV mode to HV mode at the beginning of either trip.

Several 800 mile trips in vastly different temps in our Gen 4 all in HV mode, except when I or my co driver forgot to switch to HV mode after stopping.

 

Please, what was your MPG in HV Mode?
The 40 EV miles are included in the 160 miles?
2.8 gallons to produce 40 EV miles would be a generator with a FE of 14,3 MPG, it sounds too poorly efficient.

Whether is convenient or not, it depends on the gas price and electricity price, so is region and time-dependent.
That's the reason why i'm trying to get just the FE comparison, but for time being, to not avail.

 

One interesting use of Charge mode I saw was to use it for a few hours while driving around on initial delivery to speed up and keep control over the break-in oil change that many car people highly encourage folks to do. Sure the manual says every 10k, once a year, but I've read and seen enough from people much smarter than me to make me think that - at the very least - a break in oil change is still a smart thing to do. No amount of engineering can change the fact that the first thousand or so miles on an engine are the ones with the most wear and highest volume of oil contamination.

Motor Oil Geek on youtube did analysis on his daugther's 2023 hybrid toyota oil and there was a significant drop off in contaminants after that initial break in. Now, is it a practical concern in 2024 in the same way it would have been 30 or 40 years ago in older engines? Maybe not. But its an inexpensive simple preventive maintenance so if the charge mode ensures you have more control over that process early in the car's life, it does have a purpose.

 

MPG in HV: 45.9 actual
The 40 EV miles are not in the 160.

I haven’t a clue how I came to the conclusion, and I am certain it is wrong.

 

Do you mean that in HV mode (no charge) you've got 45.9 MPG at 65 mph and using the Charge mode you were getting 25,9 MPG @ 65 mph? Seems way to high.

I think it's easy to evaluate the charge mode on a flat highway at constant speed, just stabilize first the speed & FE for some 15 min, zeroing the trip computer when the speed is constant, reading the FE in Pure HV, and then charge mode for some 15 min and record the kWh achieved and the extra-fuel.

 

In my use of charge mode in the' Gen 4 Prime the sweet spot for me was 35 mph 0 - 80% SOC in half an hour and I didn't commit the mpg to memory, but I do remember in gerneral 39 - 40ish mpg typically in the 35 to 45 mph range. At 70 mph in traffic it's a lot harder to monitor and remember even a subset of the stats. And I've only done it once or twice.

 

In another thread I noted that CHARGE mode has it's uses.

First is the ability to add a quick charge to a depleted battery pack so that you can do demonstrations of the technology to prospective buyers, family and friends.

Second is to enable stealth mode when approaching a noise sensitive area such as a recording studio or my mom's driveway when I came in too late.

Third is to satisfy the requirement to drive on battery only in some geofenced areas.

Fourth is to top off the battery before going into camping mode to minimize the ICE kicking on while grabbing 40 winks.

I'm sure that there are more uses.

 

And if using charge mode while idling in place mpg might be 0. One thing about the plugins is that the higher the mpg gets while driving ( 999.9 mpg in some trims ) the faster that mpg number drops as soon as the ICE fires up. Not as fast in a Gen 5 as it does in a Gen 3 after using up all the EV range, but fast enough to raise an eyebrow or two.

 

Yes, stealth mode is a must-have for all drivers who don't want theirr relatives or neighbors to know they got home late at night