when to charge...

The Prime has the ability to have set “schedules”.

Out here in the great state of California, our “off-peak” time is something like 9PM-6 AM. I set my “leave time” to be just short of the 6 AM mark and it’s ready to go.

If you know the power companies schedule, mirroring that in the Prime is easy.

 

If you want it to be fully charged at 3 AM, it’ll be ready at 3 AM.

If you want it ready at a different scheduled time, you can adjust the schedule to accommodate .

Or just use the “charge now” feature whenever you want.

 

It will estimate when it needs to start, to be ready to go by the departure time. It might start about an hour earlier than it really needs to, but it won't start immediately unless it needs to to finish in time.

I think you can also program a time to start charging, but I can't remember.

Another option would be to get a charging station with scheduling built in, or plug the charger into a timer and don't use the schedule in the car.

 

The car will determine the charge time and then ensure at 6 AM, it is ready for you.

If you select the charge now option, it will charge immediate and be ready still at 6 AM.

What I do at work (since my leave time is variable) is select charge now and it then displays the time it takes to fully charge. Usually around 8-9 hours as I do the 8 amp setting.

Hope that helps.

 

If you are charging daily from empty to full using OEM L1 charge cord and you set your charge schedule for the time you leave say 6 am. The charge will start approximately 12-midnight daily. If you have less than full to charge, then the car will adjust the start time by delaying start time accordingly. You can have your plugged in all that time just waiting for it to be charged by schedule.

If your off-peak time changes frequently, you have to change your schedule accordingly.

 

its not "impossible" to have it charge when you want it to, as several people responded already have said.
using the scheduling option you can tell the car to do one of two things:

• start charging at XX:XX time
• have the car charged and ready at XX:XX time

With the first option you can say "start at 03:00 everyday". When you get home everyday, plug it in, then at 3am everyday it will start charging and keep going until it's 100% full.
The second option you can say "have the car charged by 05:30 everyday". Same thing you come home at the end of the day, plug it in. The car will look at the charge level to determine when to start charging. If your current charge is at 0% it will probably start charging around midnight, if the charge is at 50% it may start around 2am.

Using one of those two options should cover the majority of the use cases for scheduled charging. Will it work for you? Only you can answer that, but from your original post I would say it does. The only issue you might have is on holidays or if the power company changes the schedule, then you will have to change the schedule in the car or temporarily override it.

Far as the comment about the car continually asking if it can use the AC while charging, I would agree always asking is a pain. It would have been pretty simple to give us the option to choose "always use AC/never use AC". For me I ignore it unless I'm using "charge now", by the time my normal scheduled charge starts around 3am the car will have been sitting for 8-10 hours, it's the middle of the night, so it will be cooled down. For you living in arizona, yeah I could see that being a pain in the rear. Have you asked the dealer if they can default it to "always use"? Would be worth asking.

 

The charging times you set can either be “start charging at” times or “complete charging at” times.

Unfortunately, there is no option to “charge to N miles by [time],” nor “charge to N% by [time].” For me, charging to 21-22 GoM miles then stopping would be very useful, because I need that many GoM miles to get to work, where I have quasi-free charging available. (Austin Energy has a “Plug in EVerywhere” program, where you can charge all you want around town for (essentially) $1/week.)

The closest way to approximate that is to, for example, tell it to charge to full about an hour after you plan to leave.

 

See page 147 in the 2017 Prime owners manual.

 

I don't understand why you think it is "impossible" to charge your car when you want using the schedule modes available. What time of day do you want the charging to occur? As @Curlyone pointed out, it is quite easy to schedule the charge session using either "Start" or "Departure" modes if you know in advance when you want the charge to occur as long as the window of time you can charge is relatively wide like ~6 hours on L1 or ~2 hours on L2, and you can finish all charging on a single continuous charge session. However, if your charge schedule requires multiple shorter segments, then it would be impossible to set the timer for that type of schedule.

 

It's not worth asking. There's been extensive discussion in other threads. It is impossible to set the traction battery cooler to default to always run automatically. It's a pretty stupid design.

 

Aside from specialty batteries that cost more, charging Li-ion when the cells are at freezing temps will result in permanent damage to them. That is why the heater is always on auto.

It is silly that the AC on for charging can't be set and forget, but it might be more for creature comfort than battery protection.

 

Know your audience. Toyota does, exceptionally well, as they have proven in the past. For this situation, it is an audience of those new to plugging in who mostly depend upon 120-volt charging. That makes asking the question quite sensible. It raises awareness, providing a subtle reminder of the importance of keeping the battery from getting hot on a regular basis.

The last thing you want in an emerging market is a "set & forget" feature. No amount of arguing will change that. Far too many Prius owners of the past simply ignored the refuel message. Complaints about the battery not being fully charged because the $@%^# cooling system ran in the meantime simply isn't worth it. You must make the choice each time for the non-scheduled charges.

Sorry, but with over 25 years of dealing with users software doing wild things to their computers, I'm in full agreement with Toyota about using the "raise awareness" approach.

 

I thought saying yes to the AC use for charging cooling meant the car would use it if the temperatures reached a certain set point, not that the AC would no matter what while charging? The battery heater doesn't come on every time the car is plugged in. Why would a set and forget ability make the cooling run differently?

 

My interpretation based on what I've observed is as follows:

The car will only display the message if the battery is hot enough to need cooling when you park. That seems to be a little over 95F as reported by Hybrid Assistant. If the battery temperature is marginally hot enough it might not run even if it asked.

If you say Yes to the message and wait to plug in, the cooler will still run if the battery is still hot enough by the time you plug in. It won't run if it has cooled off. I'm not sure if that also happens with a scheduled departure time.

If the battery gets hot while charging, and if the car didn't ask permission when you parked, the AC will NOT run. If the battery gets very hot it might limit the charging rate.

It apparently only has the option of running at the beginning of the charging cycle. If the battery is still hot after that or gets hot while charging, it won't keep running. It seems to lower the battery temperature typically about 7 degrees for me (depending on outside temperature, sun, etc), so it's possible that in direct sun on a hot day the battery could need additional cooling but won't get it.

The cooler cycle always waits 5 minutes to start, then runs for 30 minutes after that.

The good news is that charging doesn't seem to heat the battery up that much, even without cooling. And the car does a fair job of cooling while driving, as long as you're on the highway blasting the AC. At lower speeds it doesn't cool as much to keep fan noise unobtrusive.

So yes, a set and forget option could work the same way, the only downside being as john1701a mentioned people would be confused why their car apparently didn't charge for the first 35 minutes of being plugged in. It seems like a note in the manual would be fine to address this.

 

Are you charging at Level 1 or Level 2? A Level 1 EVSE may not be able to supply enough power for charging and cooling at the same time, so the system alternates between them as needed.

Or have a pop up message on shut off stating the battery cooler may run when the temperatures are hot enough.

 

Even on L2 where the charger could keep up, Chargepoint always shows the power drop to 0 for several minutes in the middle of the cycle. I usually net less than 4% charge in the 35 minute cycle, which is close to nothing. At home on L1 I haven't paid much attention, but I assume it's not doing any better.

I have no idea why it stops charging during the cooler cycle on a L2 charger. I have sat in the car during it, and the AC runs the whole time, although by the end it might be cold enough that the compressor isn't running at full power.