2018 Prius Prime EV battery problem

This is not necessarily a problem. The range indicator (Guess-o-meter) is extremely inaccurate, and should not be relied upon. Better for your sanity to change it to display the percent instead. I had similar experiences with my Leaf years ago. Hopefully, the estimates will improve in newer models.

If you still believe something is wrong and wish to debug the battery, you can use a device to measure how much energy (kWh) is added to the battery when charging from 0 to 100%.

 

I’ll let folks with a Prime chime in here, but temperature changes (which you described) will affect EV range as well as mpg. If you use the cabin heater, there’s a big draw on your battery, and the vehicle might be anticipating that in its calculations.

Was your capacity back up there during the more recent summer months?

 

• Low temperatures will reduce range.
• High temperatures will reduce range.
• Low tire pressure will reduce range.
• Wet roads will reduce range.
• Hard stops will reduce range.
• Dragging brakes will reduce range.
• High speeds will reduce range.
• Running the heat will reduce range.
• Low AC temperature settings will reduce range.
• Bad alignment will reduce range.
• Dying 12V battery will reduce range.
• Driving in PWR rather than ECO will reduce range.
• Any combination of the above will reduce range even more.

Did I miss anything?

 

New tires will reduce range
Hills will reduce range
New driving routes will reduce range
New drivers will reduce range

 

New tires will reduce MPG if they have higher rolling resistance. They will appear to lower MPG due to a larger circumference than the worn previous tires (fewer revolutions/mile).

JeffD

 

I wouldn’t describe it as chilly, but we did go from a mini heat wave around 90 to 59 one morning and high seventies.
I don’t think that is your problem, my range didn’t change.
Try an experiment. Charge up and go for a drive on local streets until you run out of ev.
Then disconnect the 12v negative and do it again, see how they compare

 

The sudden change (usually a drop) in GOM displayed EV range is not uncommon. Upward change in GOM takes more effort (and some luck) so it is harder to increase the GOM indicated EV range following sudden drop. The causes of the drop in GOM indicated EV range are listed in @jerrymildred comment above.

Similarly, a sudden drop in the ACTUAL EV range can also happen for various reasons listed in @jerrymildred comment above. I also add bad tires or new tires, increased cargo, or people riding on Jerry's list. But when this sudden drop in the ACTUAL EV range happens in absence of any common causes listed and persists even after eliminating all the factors that usually cause the reduction of the EV range, then there may be some other issues. I have read a few reports of others experiencing such a drop in the ACTUAL EV range, but most without very clear documentation of the problem, so it is hard to say what the cause is. Unfortunately, a dealer is even less helpful, and escalating such an issue with Toyota HQ is most likely to end up wasting your time.

The most obvious cause would be a degradation of the traction battery but without a clear MIL code, the warranty will not cover it. Even though the traction battery is covered by 10yr/150K miles in your case, the Toyota warranty clearly states that reduction of lithium-ion battery capacity is NOT covered under warranty (emphasis not mine but by TOYOTA). You have a lost case even if you can show that the reduction in EV range is due to capacity reduction of the traction battery.

 

In my case,
My wife reduces the range.

 

you can call toyota customer service (number in your manual) and file a complaint, but they are going to tell you it is not covered by warranty.
still worth a try, that might have a dealer run a few checks if you're lucky.

thy can test all the battery cells under load, check the hybrid system and charger. brakes, etc., but if they don't find anything, they'll probably tell you that you have to pay a diagnostic fee.

 

Have you checked your daily eco log to see how your miles/kWh has changed? If it started 4 weeks ago, there should be close to all the daily logs still left how the daily miles/kWh and distance you drove over last month. Then You still have 24 month period of monthly logs to compare. If your recent drives are showing lower miles/kWh than used to be, then that is consistent with the shorter EV range. But it does not point to anything that is wrong with your car. It just eliminates one possibility of the traction battery somehow has lost capacity suddenly. Also, if you are using OEM L1 EVSE, you can try Kill-a-watt meter to check what amount kWh of electricity is going into the battery for a full charge session. It is one time $30 investment for the meter, but it is well worth it. The only thing is that you have no record of what the charge session kWh use to be, so this can't be a direct comparison. But if your traction battery is somehow taking less than 5.7kWh for a full charge, then you know something is wrong... either traction battery itself or charger or control unit.

If it turns out the problem is an efficiency issue, rather than a capacity issue, then you can try increasing the efficiency. But most likely the dealer nor Toyota will do anything to fix the problem unless you can pinpoint a faulty mechanical issue that is causing low efficiency.

This is not the answer you want to hear, but contacting Toyota HQ is not likely to solve the problem. It will likely just increase your frustration. If the dealer documented that there was nothing wrong with your car, there is very little chance Toyota HQ will do anything about it. And even if it was found to be the traction battery capacity loss, again Toyota clearly states that it is NOT covered by the warranty.

If you still wish to escalate it to Toyota HQ, you can find the contact information easily on your Toyota App or on your warranty booklet or Toyota website.

 

There are lots of threads that explain that the range displayed on the dash or HUD is just a guess as to how many miles you be able to drive based on the recent history (last 4 or 5 days) and the settings such as AC, defrost, etc.

It is NOT a problem. It's just the way it works. If there was a problem the dealer would have found something. Do NOT unplug the 12Volt battery, since all that does is make the car forget your driving habits and lose other settings.

When you drive, the car keeps track (visible in the "diary") of how you drive and adjusts the range estimates based on that. If it's hot or cold you will use the climate control and that will suck up some of the battery power. If you sit at a lot of stop signs/lights with the AC running it will eventually impact your expected range. If you sat in line at the local starbucks drive through in 106 degree heat several times a day that will lower the range today AND it will lower the forecasted range tomorrow. The lowest "range" I got on my PRIME was during the summer when my wife "went shopping" with me but actually stayed in the car the whole time with the AC running.

If you want to see the impact of the climate control, just check the expected range, then turn off the climate control and look at the range again. You will see a jump.

Just in case i was not clear... IT IS NOT A PROBLEM. The expected range display is just badly described.

 

If you have or can borrow an OBDII - Bluetooth adapter you could run the Dr. Prius app to see if one or more of the battery cells are failing. When the SOC is very low, look for a large voltage difference between the highest and lowest cell. Take screen captures, note the date, and watch the low cells to see if they're falling further.

This still won't get you a new battery unless yours absolutely fails but it will improve your credibility with the dealer. He probably has this data from when he had the car for three days, but he doesn't have multiple readings over a period of days or weeks. And it never hurts to have your own copy of the data to challenge him if he says there's nothing wrong.

I've attached a screencap from my car. As you can see, the voltage difference is only 0.01V, but that's at a 21% SOC. You want to do it at a very low SOC to accentuate the voltage difference. No, it isn't charging at 3269 Amps! That appears to be a calibration error in the program that, AFAIK, hasn't been fixed yet.

 

This is VERY good advice.

BTW, I mentioned AC load affecting range. Today I drove to a place about 1-3/4 miles away. The car had been parked outside with about 25% left in the battery. Temperature was over 90ºF. Even though my speed topped out at a brief 45 mph, I only got a little over 3 m/kWh. 35% of the battery use over that 3-1/2 mile round trip went for air conditioning.

 

a real drop from 30 to 20 miles is a major change. i have never seen mine drop by a third in 9 years, not even through the four seasons

 

If the EV range decreased 33% without any changes in the driving condition, I would worry too, especially if it happened suddenly. But, it does not take much to have totally different driving conditions from one day to the next even on the same route. My PP dropped roughly 50% of EV range from the peak during summertime (~36miles) to the lowest in the middle of the winter (~18miles) for exactly the same commuting route. In my case, a 50% drop is almost totally an efficiency loss. And I learned to accept the fact the car loses that much of EV range in the middle of winter.

That's why it is important to distinguish difference between the EV range loss due to the capacity loss and due to efficiency loss. Now, if this happened in the middle of summer as OP has described, I would be worried too.

 

that's amazing. i wonder if the chemistry producing so many ev miles (i've never seen 18) is also less efficient in winter. i currently go from about 14 peak to 11 minimum.

as you know, we don't get anything like summer to winter weather swings in a couple of weeks.
even 95f to 60f doesn't affect my real ev miles much.

 

It must be because the same amount of kWh went into the battery summer or winter. And after getting only 18 miles in winter, as soon as the weather got better, it recovered back to 36miles. So it was not due to capacity loss. A large part of efficiency loss occurs due to heating. But other factors such as snow tires and snow/ice-covered roads also affect winter EV driving efficiency negatively. But, yeah, this did not happen in 4 weeks period in the summertime.

 

yes, heat is probably a big drain, even with the heat pump. snow will definitely reduce my miles further.

i wish the o/p would attempt to fill in more details.