Is it worse to keep battery full overnight or empty overnight?

The good news is, unless you're doing something you shouldn't be doing, the HV battery is never discharged, the ~25 mile EV range lives between 82-15% SOC. So when you get below 15% your display will show 0% and the ICE starts and at which point the car becomes a regular Prius. The Prime in HV mode the battery will stay between 11-15% (unless you have a lot of hills to go down, which will allow you to re-enter EV mode. I lot of this is has been repeated a lot but there is a lot of stuff to speculate about the Prime, how it works. Some people have said that there are 3 batteries in the Prime (there's only 2, HV battery and 12 V aux battery....key fob doesn't count).

The doing something wrong part, don't use neutral in a Prius unless there is a legitimate reason to do so. Shifting in neutral prevents the Motors from recharging the HV battery. The other thing is driving without gas in the tank. The ICE can start at any time even in EV mode under certain conditions. No gas in the tank is very bad for the fuel pump. The gasoline actually lubricates the fuel pump, run it out of gas and the pump sucks air can burn the pump out and replacing it is pretty expensive.

Yes the HV system cannot start without a 12 V battery. So if your Pirus starts acting weird could be very well to do with the 12 V battery and not something wrong with the HV system.

 

It doesn't take much to jump start a Prius.
All you need do is get the computer running and from there all the grunt work is done by the HV battery.
This assumes the HV battery is not dead.
A pair of lantern batteries in series is enough.
They do still make lantern batteries don't they?
8 D cells in series would do the trick as well.
Point is you don't need a huge battery to jump an otherwise
operating Prius.

 

I read this in the Owners manual and thought that the statement above was near useless unless you define “long period of time.” Is it a year, a season, a month, a week, a day, or overnight? I have heard of people leaving their vehicle for all those time periods, and for longer periods of time they take some precautions. So if you are leaving your Prius and you are planing to turn off SKS, disconnect the 12v battery, drain fluids, and/or put it up on blocks, then you should plan to run down the traction battery as well.

I think ambient temperature is a more important factor of battery longevity than sitting traction battery levels.

 

Thank you for reply!

 

@Chazz8 Yeah that does leave a lot of room for interpretation. I don't think there's any problem leaving the car charged up overnight at all. I also agree that temperatures will speed up degradation and probably outshines battery cycles since we're not fully cycling the battery in a charge cycle. While I did get the car in September from the little bit I observed, it takes a lot to get the Prime battery hot unlike the regular NiMH Prius, even after sitting in a parking lot in the sun the battery wasn't as hot as I expected...most temps stayed below 90F while the cabin was sweltering. So, it won't be until next summer before I can really track it and just just how hot it gets because September just doesn't get as hot.

As far as charging goes, If you're leaving for a week and want to have it charged and not have to worry about this whole thing, set up a schedule for the occasion. Me, I found it slightly annoying because most of the time I want it charged up immediately.

 

agree that it is ambiguous, and we all make our own interpretation based on our limited knowledge of lithium batteries in general, and toyota chemistry in particular.

however, my response was to the last sentence of the post above me by ed which reads: 'i believe that toyota recommends keeping the battery fully charged at all times.'

that kind of misinformation could be detrimental to readers looking for advice on the subject

 

48k miles? How many EV miles?

 

The worst thing to a Lion battery is empty, fully empty, for prolonged period. That kills the battery.

The next to it is to keep battery at full, 100%, for long period. That reduces capacity.

For Prime, after fully charged, it is actually close to 85%. That is limited and good for battery. I won't consider it harmful, but you want to avoid that for days. So when I take vacation, I would keep it charge about 50%. But for daily use, I just charged it as soon as I arrive at home.

 

The main reason I bought my 2017 Prius Prime was so I could store and use the excess KW's that my solar panels produce. Therefore I have been charging my Prime during daylight hours. My electric company is a cooperative and they only pay me wholesale for power I send to the grid, while I have to pay the retail price (about double) for power I take from the grid, so I do not want to charge it at night. I do not charge the battery when I do not plan to drive it the following day. However I very often charge it in the afternoon and it sits at full charge overnight from about 5 PM- 9 AM, 16 hours. Will that really shorten the life of the battery?

 

Due to change of plans I've left my Prime sitting for some days (3 to 4) with the battery fully charged. This happened two weeks in a row. Yesterday after the night charge I've noticed the calculated range dropped from 65 km to 61 km. Is it just a coincidence? The ambient temperature dropped also by around 4 deg. Celsius, still not really cold yet (12 C).

 

coincidence. we're talking long term damage, years and years.

 

I bought mine in March of 2017. It is my primary car, but I don't use it as much as most of you seem to. It has 7521 miles on it. We often cruise (on a cruise ship) for a long period of time. A few months ago we went on a long cruise and I left it fully charged before we left. I found that before I left it had a certain number of miles showing on the HUD (maybe 25), and when I returned the same number were available. I posted that because I thought it was showing me that the battery doesn't change much over time and was told that I should not leave it sitting for awhile fully charged. I just came back from a 60 day cruise and I left it depleted. Just hooked it up to the charger so it will be ready to go in the morning. I expect that it will be just fine, no different than before, and of all the things that I should worry about, the life of by EV battery is not one of them. It will probably live much longer than me. I will be 79 in a few weeks, so that works for me if not for you.

 

I found out what the Owner’s Manual thinks a long time is (2 - 3 months) in Lee Jay’s post; Regular Battery Charging | PriusChat

 

So this morning I jump into my fully-charged Prime and I see that my EV range is down to 26 miles. Wth? Now I'm getting worried. I've owned this car for 20 months now and never changed how I drive it or charge it and now I get this sudden, drastic drop. Last winter, it never dropped below 28 miles.

If it drops a few more miles, it actually won't be worth even plugging it in. It's not worth paying $1.50 for 24-25 miles of EV when I get >54 miles for $2.60 worth of gas. I'll end up driving it like a regular Prius at that point.

 

What is your per kWh price there?

 

stop looking at the dash, and try a measured run with full battery until ice fires

or measure your kwh charge

 

Cold is the issue and with me its also the Bizzack WS80's. I am down to 16 Miles of EV.
Gas millage down to 45 MPG due to the temp and snow tires.

Not worried at all.

Gas in Grand Rapids MI was down to $2.16 a gallon Sunday. May burn some for heat.

 

If I think I might use my Prime later in the day, I will top off the charge since I have solar power. Otherwise, I'll let it recharge overnight. If I'm using the a/c in the house, I might not recharge during the day since my solar system can't keep up with the load of running the a/c and charging the Prime simultaneously. My power costs when buying from the power company are a lot higher during the day than overnight.

 

I realize this is the Prime part of the forum but doesn't the standard Prius have the same chemistry battery but just not as many cells?
When you park a regular Prius the amount of charge for the battery pack is just what it is and with no thought about it.
The difference is you have a choice with your Prime if you want to charge it or not except when it doesn't need it.