2018 Prius Prime EV battery problem

nice of him to at least do some research, all the best!

 

Before you do anything, please take photos of the Eco Diary log which is shown in the photo below. From this MID display, if you push the center button on the wheel, you can scroll the dates up and down. Take photos of all 8 screens, (4 days/screen x8=32 days). This will show the changes in the daily miles/kWh for the last 32 days. It saves only the last 32 days, if you wait more days the oldest records get purged. I also attached the manual page that explains how to use the Eco Diary. These data will tell you if your daily miles/kWh is in good agreement with the EV range you have been getting.

 

OBDII (spoken as 'O-B-D two') stands for On Board Diagnostics - Version 2. It's a standardized port that allows anyone to talk to the various computers that are built into the car. AFAIK, all current cars and trucks from all manufacturers have this port. If you look under the dash just to the left of the steering column you'll find the standard OBDII socket. You can buy an OBD reader on Amazon, ebay, local auto parts stores, etc., but they can be expensive and likely won't give you the info you need. You can also buy an OBDII to Bluetooth adapter that allows you to run an app on your phone or computer and talk to the car that way. Price varies, but the cheap ones typically don't support all the necessary functions for newer cars. I use the OBDLink MX adapter, but it's been replaced by the MX+ adapter which is widely available for about US$100. There are other good adapters available, I just happened to pick that one.

Dr. Prius is an app that's available for Android or IOS and provides various capabilities for car owners. AFAIK, it's the only app that shows the voltage of each of the 93 cells in the traction battery.

Your dealer has something similar, but he won't loan it to you. He might give you the info, but he will probably charge you a service fee.

If you search PriusChat, or use Google, you'll find lots of info on OBDII, Dr. Prius, and other apps.

 

Dr Prius

more info

many people use it
even if you do not know how to decipher, you can post screen shots or results here,
and the great folks here can let you know what, if anything, it is showing.

 

It should work, but there are some that are very cheaply made and not going to give the result you want. Read this blog article and decide if you want to take a chance or not.
Hybrid battery diagnostic and repair tool for Toyota and Lexus

It cost a bit more, but OBDLink LX (right ~$60) is extremely well built and very fast. If you want to go cheap, I suggest go with PanLong (left ~$12). Carista (middle ~$30) is another popular OBDII dongle for Prius owners, but I find it to be much slower than LX, and even slower than cheap PanLong.

 

I agree with Salamander. It's a bit of a crap shoot as far as adapters. I tried two cheap ones and neither worked properly on the Prime. One didn't have the necessary features and the other had the features but I don't think it was fast enough to keep up with the data coming from the car. The OBDLink MX seems to be doing the job. The LX should work, but Salamander's link says that there are problems with both the LX and MX. YMMV.

 

Yeah, I think it is app dependant too. Some apps work very well with a particular adaptor but not others. One good thing about the OBDLink adaptors is the company behind does a good job of updating the firmware. Others, no so great. I just tried using my OBDLink and PanLong on my 2021 PP with Dr.Prius app, both worked fine, no issue. On the other hand, I have been having problems using the new version of the Hybrid Assistant with my 2021PP. This seems to be the app problem, not the adaptor, but the Bluetooth connection gets disconnected. This happens with LX, Panlong, and Carista adaptors, and I have tried with three different Android phones, they all disconnect the adaptor as soon as the connect button is touched.

 

it looks good. not sure about the 106% charge though

 

I don't know much about how to interpret this App data. I will leave it to others more knowledgeable. At least, it does not look much different from what mine is showing. And mine is a brand new 2021 model with no deterioration.

I think it is a bug in this app. At 0% SoC on the dash, Dr. Prius shows appropriate 14% SoC, but at a fully charged state, it always shows 105% SoC on mine. This number should be more like 80%. Any SoC in between 0-100% on the dash, the SoC number reading on Dr. Prius is completely linear.

 

So far, so good. The 'voltage diff' is the difference between the highest and lowest cells. 0.01V is what you want to see. The 'state of charge' of 106.50% is a bit harder to interpret. Did you just charge the battery? The high SOC and the rather high temperature could be due to that. Using another app, Hybrid Assistant, I've seen that when the dash is displaying 0% SOC, Hybrid Assistant reports about 14% and when the dash says 100%, HA reports about 80 - 85%. This is just the car being really nice to the batteries and not charging or discharging them too much.

Now you want to discharge the battery down very low - 0%, actually the Prime shows it as --% and take another screenshot. What you're looking for is an increase in the 'voltage diff' reading and seeing that one or more cells have a lower voltage than the others. Other posters have listed various things that could cause an abrupt drop in range. A few, maybe just one, battery cells that are getting weak will hold their voltage as long as possible, but they'll die quicker than the others and the car will react to the drop in the voltage of the pack by reducing the range.

Also, if this test shows that there are no weak cells, then there's no problem with the battery - as far as we can see. The above mentioned 14% minimum SOC shouldn't be an issue because the car won't let you use that energy anyway.

Ed

 

have you checked to make sure the brakes aren't dragging?

 

unfortunately, the display is simply a measure of battery percentage, converted into miles based on past driving.

 

so if the car has a mechanical problem, or your driving route or weather has changed, tires and etc.
thedisplay converts the same battery charge into less potential miles.
we call it a guessometer, but if everything is consistent and working well, it is fairly accurate.