As you know, we have about a 15% top buffer on our HV battery. Many of you, including myself, have reported little if no EV range degradation. My question - No degradation because any degradation is in the top 15% buffer we I don't see? Or no degradation because, well, no degradation?
the buffer just means the battery could be charged more, if the software allowed it. no degradation means no degradation, although proper testing would probably show a slight amount, undetectable in the course of normal use.
The software could be programmed to free up more of the buffer to make up for degradation. Without seeing the code, not sure how to test that.
I've seen what I ( believe could be a bit of degradation ) of about 1 volt , both in the full charge top voltage of 375 volts when it used to be 374 volts and at the bottom which is now 331 volts and used to be 330 volts. DrPrius is not Techstream, although drprius is a lot easier to watch what is happening in general with the traction pack than I'd imagine it would be if I had techstream available to double check reports. 2017 plus trim at 87k miles in the snow belt just east of buffalo and 2 daily drivers. Today at 1:17 PM edit: dr prius is still showing 0.01 cell difference and it's been the same since drprius first worked with the Prime. Internal Resistance reads can play tricks using drprius, especially when the traction pack gets stressed out, but so far it flattens out with enough care and observation.
No degradation because no degradation. I baby it a lot though. One thing I noticed recently is that the tire pressure makes a huge difference in the city BEV range. Going from 34 psi to 43 psi increases the fuel economy from 5.0 mi/kWh to 6.5 mi/kWh or the BEV range from 32 miles to 42 miles. That is because the tire rolling resistance dominates the total drag at low speeds.
@Gokhan I agree with everything said you mention above. The one thing that I'd like to emphasize is that the description of "I baby the car a lot" does not quiet give readers the proper info to work with for them to interpret what babying means to you, much less what anyone else might consider babying their Prius. I've babied our Prime too. Sometimes in a good way, sometimes I've missed the mark through inexperience. I still miss the mark sometimes, since after 6 years of driving, I still don't get all the efficiency techniques the Prime has to offer. Keeping in mind " I'm not the only daily driver of the car and the seasonal differences in ambient temps and the cars many modes to choice from". It's not uncommon here at priuschat that posts will not give needed info to understand what the poster has done, equipment used (for getting data) and many other details specific to easy post, either describing a problem or even simply explaining what they mean when using a vague term in the hope anyone reading will have the same definition of the term used in the post. I have this problem too. I realize it's not easy to fully describe what I'd like to present as a fairly compete description of events that lead to my results / conclusions from a drive session or a lifetime mpg/mpg-e estimate. ( I think I'm down 117 mpge current from 133 mpge a few years ago ) as trip B appears to be the one that has not be reset previously. But, even that one data point really doesn't mean much to anyone else besides me without about 5 pages of how the cars been driven for the last 6 years, with only I have a vague idea of what I've seen in the car while I"m driving it. I try my best to not watch when I'm not driving it, since the driving style of the second driver is nothing like my own.
By babying it a lot, I mean: I don't leave the car charged over 70% for more than a few hours. Typically, I try to keep it below 60% when undriven. I don't drive hard—I accelerate and brake gently. I don't charge it right after the car was driven and when the battery is still hot. I charge it at least once a week. I don't keep at 0% charge for more than a day.
Without going into 4 or 5 pages I will say that one of my initial experiments didn't produce what I was hoping for at the time. The first winter I put a small ceramic heater in the cablin to assist the traction pack heaters. It was nice in that when I got into the Prime, it was like getting into it in the summer, nice and warm, compared to what it would feel like at 0 F. But, when DrPrius started supporting the gen 4 Prime, I realized the heat was not getting back into the battery bay. I'm still trying to understand the difference between Primes traction pack ( minimal resistance heating ) and keeping the pack at a more efficient temp for charge and discharge in sub freezing ambient temps, ( I also realize this might not be relevent to you in your location ). I do admit, you take a lot more steps at babying your Prime and it's traction pack than I do. I'm always plugging in when I get home and charging to 100% SOC and leaving it plugged in until I use the car again. Typically that was the next day, usually early in the morning. I'd try to get through the warmup cycle asap to begin the day, no matter who was going to be driving the car that day.
How does Regen works on the Prius when the temperature is well below freezing? In my Model 3, there is no Regen but 15 minutes later, the battery pack has warmed enough that some Regen is available. How about the Prime?
I am sure there is, but it is probably less powerful than at normal temperatures. There is also a battery heater to increase the battery power at low temperatures. It is also apparently reduced at below-freezing temperatures so that antilock brakes work better on ice.
So right now I got 152k and I'll say this, there's definitely degredation, but it is minor, maybe 1-2 miles and really that's only noticible now that it is winter (winter vs prior winters). That being said the degredation is very minor, other things like putting new tires on, the temps dropping 30 degrees are far more noticable than comparing the car when it was new versus mile 152,000. Not sure what that would be exactly, maybe ~5%. The car can still achieve the 25 mile range, or more...or less. I do think that at this point the battery has done the bulk of its degredation, but only time will tell. I think most people would deny any degreation simply since it is going to be small and changes in EV range can trivial based on speed, terrain and so on.
I think there is some degradation if you cycle the battery enough, especially in hot weather. I estimate I have cycled the battery 2,226 times based off of 800 mpg (not including mpge of EV mode) over 4 yrs/72,200 miles and a guess of 60mpg when in HV mode. This car is parked outside for most of the time while at work 5 times a week in the Inland Empire, CA, which can get over 100 degrees F fairly regularly during the summer. Even with shades covering all of the windows, I have measured the internal temperature of the car at as much as 120 degrees F with a cooking probe thermometer. Based off of Kwh used during chargepoint sessions, I estimate that useable battery capacity has decreased from 6.12 KWh to 5.85 KWh over 4 years, with no appreciable decrease in the last year. The range difference is not really noticeable compared to fluctations from weather and new vs worn tires. I am sure this estimate can be fairly off.
When I got my 2017 with 136k km last July, I ran Dr Prius Life Expectancy test. It came out to... 101% The odometer had (still has) 0.8 L/100 km, which in freedom unit is 294 mpg. I figured my engine consumption averages (without the help of the battery, using Hybrid Assistant to figure this out) at 5.6 L/100 km (42 mpg). So the engine ran about 20k km, so 126k km in EV. Doing avg 40 km per charge, that's 3,150 cycles of the 6.16 kWh or 2,205 cycles of the full 8.8 kWh battery. If that 101% is to be trusted, I'm impressed.
