Dr Prius and the Gen4 Prime (bad news)

I worked on a 2017 Prius plugin once and the basic data from Dr. Prius app worked fine... Never tried the life expectancy test with it though because there's better ways to monitor battery health than paying extra for that feature. Keep in mind a plugin Prius battery lifespan is alot different than a standard hybrid battery lifespan, especially when the vehicle is only a 1/2 dozen years old.

 

PriusCamper, are you able to describe the ways in which the 2017 traction battery lifespan is a lot different than a standard hybrid battery lifespan? I’m interested in this issue.

 

It's a way bigger battery with way more modules... Using the engine & inverter to discharge & recharge a standard 1.3 kilowatt-hour battery pack is easy. But when you boost that number up to 8.8 kilowatt-hours you aren't going to get much meaningful data using the engine & inverter on the pack without driving it a significant distance and Jack avoids making any major changes to his app now that it works so well.

 

So are you saying that the assessment of the two batteries is different or the actual longevity?

 

Yes, both... Also the method used to test a 1.3KW battery is not going to be very accurate for an 8.8KW pack.

 

Keeping track of MPG is a good way... But the main number on Dr. Prius app that matters is "Voltage Diff." As the battery gets older and loses capacity and balance that number goes up. The high that number goes the shorter your packs lifespan. Though that's more specific to NiMH chemistry than Lithium chemistry.

 

I was able to get the life expectancy test completed once, but it's not something I'd do again unless I needed to explain exactly how it can be completed to someone else. It's results are what they are because of how the test must "currently" be done to complete the test, as Jack mentioned in the DrPrius support email.

Basically, it's a very customized set of it's own chicken dance. It only measures the very bottom of the traction pack and when figured out it only takes a few minutes to complete instead of the 10 minutes or more for supported models. Plus the Prime shoots and error message to the MID about the foot on the Go Pedal and Brake Pedal at the same time in the middle while charging the battery for the test. The Prime also limits the engine rev range while the Go Pedal in to the floor and foot is on the brake.

1
Run the traction pack down to 1 or 2 miles of EV range left before starting the test.
2
Start the test.
3
Run in EV mode until it runs out.
4
To complete the charge section of the test "I've had to switch to charge mode" and the test finishes this section within a few minutes.
5
The discharge part of the test is where the error message shows on the MID
Put your feet on the Brake and Go Pedals, floor the Go Pedal and watch the DrPrius app to get the dial indicator into the green area with the needle at 12 O clock high or even 1 PM if possible.
I also needed to turn on everything I could think of, to get the indicator steadily in the green.
One I had the indicator in the green it only took a another few minutes to complete to test and give me the results for the part of the traction p;ack the test actually test ran on. My results were 56%, be that what it may.

To run the DrPrius Full Battery Test the pack temps need to be above 77 F / 25 C I've only started the test a few times over the years, but every time I try the test my pack has never been warm enough and the DrPrius app errors out of the test.
When my pack is 25 C or above, I've always wanted to use as much of the pack as efficiently as I know how to bring my Estimated EV miles as high as I can get it, because the other driver of the car brings it down every time. lol

 

Unless you figured out a way to get the test to measure anything besides the bottom ( 5% "guessing") of the pack capacity, ir looks to me like the bottom of your pack is in pretty good condition. What's the internal resistance look like when your down below 10 or even 5% SOC?
For sure, the test isn't looking at the Primes full pack. so there's nothing really to trust or mistrust, the test isn't made to evaluate the Prime pack, it might work on a Gen 4 Prius, but that eval will probably be off too.

see the stats at the bottom of the screenshot above.

 

0.0244 voltage difference seem oddly low for the highest number. I'm doubting the accuracy of that particular data point. It should be higher than that?

 

Lol... Why use mv? That's not a standard on here, nor anywhere else when it comes to HV batteries.

Additionally, I don't associate with proprietary Microsoft files... I'd be happy to take a look if you make it available on Google spreadsheet or Dr. Prius app screenshot?

And maybe tell me again why Dr. Prius screenshots of "voltage diff" aren't available to you? Seems like an easy request to fullfill?

 

speed is kmh? The graph looks ok to me, after I zoomin far enough to read the scales and see the color bleed. But I don't really care if the readings the app show or the readings the cars gauges show are dead on balls accurate. I get a base line of data that I use to compare.. I keep track of the highs and lows. As I become more familiar with the range I start to fill in between the highs and lows.
The reason I say the graph looks OK to me, is I'm extrapolating from the DrPrius screenshots I've posted to different threads here in the past. AndI realize that internal resistance on a well maintained Prime pack can stay at a very minimal state most of the time, and when it starts to go vonkie and the graph scatters around there is usually a good reason for it. That is what I look for. ie; What was going on when the interenal resistance graph started to deviate from it's normal state.

Just to be clear, posting what is seen as internal resistance at a different time than when you ran the test, will not reveal much about the internal resistance at the time the test was run. It (internal resistance) at the time ofthe test could be that same, somewhat or wildly different at another time, It might not matter, but we would not know for sure.

 

My point is typical max voltage difference in a healthy Prius is in 1/10th to 1/100th of volts, not 1/1000th range. Thus, those numbers are wrong and tell you nothing.

The primary screen on Dr. Prius app can give you "voltage diff" numbers in real time as you drive in real life and if you want to know the lifespan on your pack, pay attention to that, not your proprietary MS spreadsheet.