Battery starting to deplete more quickly

not at all. you can expect some degradation, especially in the first few years. but there are too many variables to know exactly where you stand. you would have to do some rigorous testing, but then, you have nothing to compare to when new.
one thing you can do is see how many kwh it takes to fill from empty.

your description of less miles at low battery doesn't fit any scientific explanation, and is more likely an anomaly of the guess o' meter.

btw, toyota's description of a failing battery is when it won't start the engine. you will get dash lights, and there will be codes.

 

What is your mile/kwh for those days? If you are carrying anything on the roof, using heat or ac more, etc you'll see a ding on your efficiency. A stuck brake caliper can also add a lot of drag - have you noticed pulling to one side, lots of brake dust or a rubber smell around a wheel?

Could be a few things or a combination of things. The distance display is just a best guess based on your average driving style over time, it's not an exact amount of range. If you deviate from the norm it'll be less accurate.

 

tires too

 

As already said, the key is your m/kWh. To and from work, I get about 30 miles of range with 5.6-5.8 m/kWh. Today, I got about 26 miles with 4.6 m/kWh. Yesterday was even worse.

Even so, some capacity loss is almost guaranteed after five years. I bought mine used with 24k miles, so I don't know what it took to charge it when it was new. But since I started checking 2-1/2 years ago, it has stayed pretty consistent. I did take a substantial and abrupt dip in March, but then mysteriously bounced back. And, obviously, there is some variability in how deep into the HV charge I had gone when I shut it off.

 

There are screens in your dash display with monthly, daily MPG and m/kwh. The car fudges those a little bit but what you're looking for is a change in the numbers. If last week every day was at 5 m/kwh and then this week is down to 2.5 then that might explain the faster "loss" of range - the car is giving you an estimate based on going 5 miles per kwh but instead it's only making it 2.5 miles. If it's still reading 5 and you're not getting as far then you'd want to look into an issue with the battery.

 

Do you mean the screen shot from my spreadsheet in post #5? As the label says, it's kWh, not m/kWh and capacity, not efficiency. It is simply charting how many kWh it takes to fill a depleted EV portion of the battery. I try to remember to check it every few months. Sometimes I check it more often. Just trying to get an idea how much charge it's able to hold as it ages. Because the meter I have installed on my 240V outlet circuit rounds the energy off to whole kilowatts when it reached 10, I have to reset it to zero to get any kind of a precise reading. That means more work later when I gas up and record the kWh to go with that tank.

 

The daily screen stays that consistent for you? Mine's all over the plave because I'm always going different places on different roads at different speeds.

 

You need to check the Eco Diary. Both Daily log and Monthly log.

Where you live, the seasonal miles/kWh fluctuate a lot. If you are maintaining a 5.2miles/kWh average on Drive Monitor 2, that means your summertime EV efficiency is more like 6-7 miles/kWh. Your wintertime EV efficiency is most likely to be 3-4miles/kWh range. Here is my monthly log of miles/kWh.


But what you really want to find out is the daily fluctuation. If it is low, then your GOM will reduce the EV miles displays. If it is high, then it will show a higher guesstimate range. This is an example of my daily log.

 

If your recent days or weeks of miles/kWh are showing normal efficiency for this time of the year, but you are still being able to drive less total EV range, then it's a good indication that some battery degradation has occurred. One another way to check is the battery capacity change as shown by @jerrymildred in comment #5. But for that, you had to have measured the total kWh used to fully charge the traction battery by using a kWh meter. If you don't have any historical data, it may be difficult to prove the battery capacity loss.

But for the short distance remaining on the GOM, I would not worry too much. That is just a guess for the last few miles left from the previous day's trip. I think it is a totally different situation between the last few miles of the trip on EV mode the day before vs the same EV range on the GOM but next morning for a short trip starting from cold.

 

My efficiency is going down due to the increased heat and A/C load. I ran out of battery a half mile from work and again less than a half mile from home.

 

If you have an OBDII adapter, you could use Dr. Prius to check for a bad cell.

 

if you have a 'bad' cell, you'll get a light and trouble code. o/p's description of the problem, while unusual, is not going to find an answer.
the guess o meter behaving badly at low remaining range doesn't tell us anything.

tech stream may have a sophisticated way of measuring battery capacity and kwh usage over those remaining miles vs preceding miles.
if there is a problem, it is more likely a computer glitch than a battery issue.

 

+1 I totally agree.

The GOM sowing the remaining miles is so unreliable, that I would not worry about the problem OP is describing. Even with my 10 mo old PP, on the same route, the remaining last few miles shown on the GOM fluctuate widely from day to day.

The only reliable measure of battery capacity loss is measuring the number of kWh used to charge 100% of the traction battery over time. The second best method is to repeat the same route travel under very similar driving conditions and record the TOTAL EV range you can drive from 100% of the charge. But both methods show very wide variability from day to day such that a one-time comparison has no meaning. It has to be repeated large numbers of times to be statistically significant.

 

Okay, poor phrasing on my part.

Since the OP lists his vehicle as a 2017 PP, it's possible that one or more cells is getting weak. That's a typical scenario for any multi-cell pack. There will always be one or two cells that are weaker than the others. That cell gets repeatedly used to the limits the PP allows while the others don't. The weak cell eventually dominates the pack's life since the computer will report 0% capacity when the weak cell is exhausted. This will show up as a good pack voltage that drops quickly at the end of the discharge. The computer may or may not be able to learn this behaviour and work it into the GOM calculation. This will *NOT* drop any codes because that's just the way that multi-cell battery packs work. Besides, Toyota doesn't warranty a battery for loss of capacity and dropping a code might result in a battery warranty claim. Dr. Prius will show this situation if you take a measurement at a time when the remaining capacity is low, ideally at 0%. You'll see most of the cells with a nice healthy voltage and one or two that are down at the bottom end of the acceptable range. If *ALL* the cells are a similar voltage, regardless of what that voltage is, the pack is healthy.

Ed