Not Charging all the way

Winter can definitely be the reason for a drop like that. Even my new 2022 only makes it 15-20 miles on a charge due to temperature, snowy roads, hills, cabin heating, snow tires, extra passengers... The number on the dash is also just an estimate. You may find after a few days of really cold driving that number has dropped even further but when it gets warmer out again you should exceed the estimated range.

But the battery should be under a 8yr/100k warranty so you can certainly have the dealer check in on it but those numbers do seem typical. I think they even allow for a certain amount of battery degradation over time before they would consider it a problem.

Do you happen to know how much electricity it's taking to recharge every day? If you're recharging from 0 it should be using about 6-7kwh to recharge. If you don't have a meter on your home charger, most public chargers will tell you how much you've used in a season.

 

the dealer will likely charge you to look at it, and they won't do anything if there are no trouble lights on. in fact, they'll probably tell you that up front.
no lights, no warranty.
it is definitely because of winter, no matter what you remember, everyone experiences this, completely normal.
if it doesn't go back up this spring/summer, you can start worrying.

 

toyota recommends not leaving it plugged in (full battery). that will reduce battery life, and you may be experiencing it if that has been your practice for 3 years.

 

As @bisco said, this is a pretty bad practice. For one thing, the traction battery lasts longer if it's not at a high state of charge all the time. Charge it before you use it. Also, while it's plugged in, the computer in the car is communicating with your charging cable and running down the 12V battery.

It sounds like you're still in good shape.

PS. "North America" is pretty vague for a location. You could be having daytime highs anywhere from 80º or -25º. You can get way better help if you at least give the state if not the city. While you're at it, it's helpful if you can put "2018 Prius Prime" in your vehicle information rather than "Other Non-Hybrid." That'll make it much easier for people to help you with future questions where the answer might depend on your location. For example, if you're in Montana, your range is totally normal for this time of year. If you're in Florida that's not such a good range.

 

is it ok to plug it in when the battery is not full?
I schedule as "leaving" at 7am since I leave the house around 7:30. I always plug it it when I get home like 5pm.
Thanks

 

You can plug in as often as you want as long as you don't leave the car fully charged and parked for a long time. Since you are using a daily schedule to manage the charging time, you don't have to worry about leaving the plug earlier than the actual timing of charging.

 

Is there a consensus on what constitutes a “long time”?

During one particularly cold stretch a few weeks ago (3 days of -20C or colder highs and -30C or colder lows) I left it plugged in for about 80 hours to keep the battery warmer working. Obviously I don’t do that all the time but it’s unclear from the manual if what I did is bad or good for the battery.

 

there isn't, and toyota does not quantify. i don't think 80 hours is going to hurt it.

 

yes, it's fine. and my wording was a bit misleading. you don't want to leave the battery full for long periods of time.
as for leaving it plugged in for long periods of time, toyota warns that that can drain the 12 volt. but what you are doing is fine, and what the car was designed to do.

 

see post #11

 

As @bisco pointed out, there is no consensus on how long is too long. I don't think Toyota even knows the exact length of time that will affect the longevity of the traction battery. Certainly, I would not sweat on 3 days of -20C to -30C. I would be more concerned if it was a fully charged traction battery in 30-40C temp under the sun.

The ambiguous information Toyota gives about the traction battery heater function does not help us, consumers, what we should do during cold days. The manual certainly tries to tell us that the traction battery heater function is useful feature, but it fails to explain how it works and how we should use the feature. Nowhere in the manual does it say to keep the charging cable plugged in during cold days. The simple fact that the traction battery heater function is operator switchable tells me that is it not an essential part of the battery management system to protect the integrity of the traction battery. If it is, Toyota would have certainly fool-proofed it by not allowing an owner to tinker with the setting, I hope. For that reason, I had switched OFF the traction battery heater option in the setting menu as an experiment. So far, I am not seeing any noticeable difference in the way the car behaves after being cold-soaked for a prolonged time.