If you have warmed up the ICE but finish your trip by driving slow (in EV 'sub-mode' of HV) and end at the lowest possible remaining charge (only 3 bars, two bars turns on the ICE), should you charge your car a little bit immediately? I see two conflicting principles here: 1) Let your battery rest after use, charge after giving the battery a break, and 2) Do not ever leave the battery at it's lowest state of charge. (I'm leaning towards thinking that Toyota would foresee someone discharging the car to 3 bars in HV and ensure that that charge level is OK until the next charge).
I think the dire warnings about not leaving the car in a mostly discharged state is for the situation where you won't be using the car for some extended period of time. Like for at least a month or two. If I were to encounter such a situation (3 HV battery bars, long trip coming, just got home), I might be inclined to plug the car in for an hour or so to get a partial charge into it, but not necessarily a full one. In a likelihood, I'd just park the car and leave it. I have only managed to run the HV battery indicator down to 4 bars, and that took some work. Most of the time it bounces between 6 and 8. In my 2005 Prius, I would regularly bounce between 2 and 7 bars. I have a hill that I have to climb up every day I go to work. I have been up this same hill over a thousand times. Sometimes when I would get to the top of the hill, I would be at 2 or 3 battery bars. And other times it would be at 5 or 6. I could never figure out why since this happened in all sorts of different weather conditions. Nowadays when I go up that hill, I'm either in EV mode with ICE blending, or I deliberately put it into HV mode for the climb. Depends upon my mood. I suspect the dire warnings about not leaving the car discharged for a long time won't apply to normal day to day use of the car. Rather they are for those rare outlier situations that most of us will never encounter.
It seems like Toyota would have been wise to have protected us users from either harmful situation: Making it idiot-proof such that you could do either: 1) Charge the car immediately after driving 2) Turn the car off when it is at the lowest possible charge level (3 bars). (But I did charge my car just a little, about an hour after I did this, just in case... )
Where did you see Toyota recommending principle #1? I think the two relevant points from the Owner's Manual pg. 93 are: I believe the first point applies to leaving the car undriven for a few days. The second indicates the car should be charged just before driving, not not charged after driving.
I used to think the same as iRun.. in fact, I'm sure I've said it here a few times (when discussing my charging "strategy" and how I wanted to let the battery "rest"). I do believe it was based on the interpretation of the two points you highlighted from page 93. I do also recall someone mentioning something about not charging a hot or warm battery or something to that effect. Put those all together and the idea of letting a battery rest came to be (or at least thats how I see it). HOWEVER.. I was driving down a relatively steep hill a few days ago. I had used HV to "climb" the hill and at the top, switched over to EV. On the way down the hill (took maybe a minute or so at 50-55MPH), I picked up 2 miles of EV range from regeneration. Now, that got me thinking about the "battery resting" thing.. with regen, you're constantly charging up your battery. And you're doing it at a rate that is much faster than even charging on a Level 2 charger. So I agree with Joseph. I think the idea that has been tossed around that the battery needs to rest is incorrect.
I think I saw it in someone's post on PriusChat. I got the feeling that it was from the online version of the owner's manual, but maybe that is not the case. I have not seen it in the printed version of the manual that cane with my PiP. I can't imagine it could be that bad to recharge soon after driving because the car could just have easily went down a hill right before that time and recharged at a FASTER rate than what the charger could perform. If recharging after driving was so bad, I think they would have put limits on the regeneration process that can recharge the battery quickly while driving. (Oops! I didn't read Tracksyde's post before I replied. In any case, I agree with what he said).
With lead-acid, you would never want to wait before putting it on a charger. Lithium batteries are much happier if kept at 40%-50% SoC in general, so they would perhaps prefer that you follow the guidelines from P. 93. It has nothing to do with a rest period. I don't know that Toyota engineers necessarily foresaw the use pattern of racking up significant EV miles with regen.
I think they designed it that way. The terrific regen rate may be a larger benefit than the plug-in charge!
I think it makes for a super HV system, far superior to the standard (non-LI) battery HV. It sure beats the HV mileage of 2005 (Gen #2) Prius!
I charge immediately if I know or suspect I will be going out again soon. If not, I set the timer and let the car get charged just before next commute. I get the EV range down to under 1.0 on both legs of commute so I have a lot of full discharge/delayed timer recharges such that I don't worry about battery health, even though the nights and weekends have a lot of partial discharge/recharge cycles. I will say, however that having a 150k warranty on such new tech is reassuring!
If you get to 150k miles and your battery only has a 5 mile maximum capacity because you have driven >100k of those miles on EV, your battery will not get replaced for free. There is an expected level of battery degradation with use. I doubt very few people will get their battery replaced unless it clearly shows a problem other than the loss of capacity from charge/discharge cycles. I fully expect the car keeps track of the number of EV miles driven and number of charge/discharge cycles (one that can not be reset with the 'trip' button).
Oh Andy my friend . Unless you are coming off Donner Pass, just plug it in and deplete those EV miles to zero, then drive it like a normal Prius. High rate charging i.e. sustained regen is detrimental to battery life, particularly when the state of charge is already high. And as far as I can tell, the people who are playing HV/EV games to add back in EV miles with regen are getting lower fuel economy and they could be causing pack damage in the long run.
TY Seilerts. I will defer to your overall Prius knowledge and yes I do come back from Reno several times a year.
