PIP EV range falloff

correct. we're talking about ev range comparison over the years with everything off.

 

And at same temperature.

 

As I posted earlier here, by measuring the energy into the battery by kWh meter I have on the line, the reduction in my battery capacity is around 3.3-3.5% per year (11-12% in 3.5 years).

I have also in my database actual EV range I get in various temperatures for a trip I am taking about twice a week. It is 21.4 km return trip all city drive and light traffic at the times I drive. No climate control. Extreme cases (rain, heavy traffic etc.) where not included.
Here is a chart of my results until now:



Numbers just above x axis are odometer in km x 1000.
Lately, @~13C temp, I had to park the car about 400 m from destination in order to complete a return trip.

Chart shows about 2.3 to 2.8% per year (depending on temp) which is lower than my kWh measurements. Improved driving practice in time? maybe, but my feeling is that I am trying harder lately (even incautiously) to make the trip EV, which may mean change in driving style.

I trust kWh measurements more, no personal bias.

 

how many ev miles do you have?

 

About 27500 km.

 

almost as much as me, 32,000 miles. we don't get much participation from pip owners, but there must be a correlation between ev miles only, and degradation.

 

No doubt.
In my case, temperature could also be a significant factor - many days of around 100F max in the summer.

 

For charging, we have the added complications of the chemicals within changing. Does aging alter internal resistance?

For driving, we know vehicle break I improves efficiency. So, a small amount of battery loss is offset by that gain.

It's extremely difficult to measure so many influences, especially when you take several 80 mph trips like me. My lifetime average is 71 now at 89,000 miles.

 

Drove a route the other day that I used to drive when the car was brand new. Based on this anecdotal performance evidence (taking into account temperature and other variables) and confirming what I already guessed was true: I believe I have around 65% (+ or - 5%) battery capacity of what I had when the car was new. The car is almost 4 years old. That would be around a 8-10% degradation rate per year. Probably not quite as good as I had hoped, but it could be much worse I suppose.

 

gallde I am curious what type of charging you usually do? 120V or higher voltage (quicker charging)

 

8-10% per year seems very high, do you plan an appointment with a dealer for battery checking and possible warranty claim?

 

Method of measure?

On Friday, my commute was a balmy 27°F (quite comfortable here in Minnesota), so no need for the heater. That meant an opportunity to measure. I went the full 9.2 miles of hilly suburb EV driving before running out of sub-62 mph road. At that point, the remaining EV was indicated to be 0.4 miles. Being able to drive 9.6 miles of EV in those conditions (hilly & sub-freezing) for a Prius PHV just 1 month shy of 5 years sounds right on par for aging expectations.

Right now, I'm at the coffeeshop blogging. The temperature for the drive was 32°F. The route 7.6 miles of all flat suburb (45, 50, 55 mph limit roads). The entire drive was EV. The remaining capacity was stated to be 2.7 miles. The SOC was 39.6%, which confirms accuracy of the estimate. That gives me a total of 10.3 miles of EV driving, which is right on too. There was only 1 stop along the way. Both lights were green and the 3 roundabouts you only have to slow down for. Again, that seems quite reasonable for almost 5 years of use.

Note that during the work week, I recharge twice. At home with 120 and at work with 240. Both include long cold-soaks (many hours). For random full charging, I always wait a minimum of 90 minutes. When stopping at the grocery store, the quick 10-minute top-off is immediate. The battery-pack rarely ever saw extreme heat. It simply never gets that warm this far north.

In other words, my aged battery-pack is working great still.

Can we get some fresh accounts from others, using a format like that above to describe their own experiences?

 

i can still do 10.3 miles at 32 degrees, but it was more like 12 at one time.

 

Simple math would seem to indicate your pack is just fine still.

85% - 23.5% = usable EV capacity available is 61.5 %

61.5% of 4.4 kWh = EV capacity calculates to 2.7 kWh

2.7 kWh / ( 29 kWh / 100 miles ) = EV range is 9.3 miles

That doesn't take into account hills or regen, of course. It's just a basic measure of potential using the EPA measure of efficiency for Prius PHV. Nonetheless, seeing 10.3 miles years later looks good.

 

EPA 29kWh/100 is calculated from wall and, if I am not mistaken - on a nice spring day.
taking 15% charging efficiency gives 24.7 kWh/100 in the battery or EV range of ~11 miles.
The 12 lower temp. miles reported by bisco (in the past), just shows he is beating EPA and his average speed is low.
But agree, his battery looks fairly good.

 

Running those same calculations on Prius Prime is interesting:

85% - 23.5% = assumed usable EV capacity available is 61.5 %

61.5% of 8.8 kWh = EV capacity calculates to 5.4 kWh

5.4 kWh / ( 25 kWh / 100 miles ) = EV range is 21.6 miles

Anyone know the actual usable value? There was speculation that deeper discharging with the new chemistry was realistic, especially since GM decided to expand usable capacity for gen-2 Volt. I haven't heard actual numbers though... and I don't have my Prime yet. Based on the calculation result, it's easy to see where the original EPA stated range was 22 miles. I have found a mention of 6.18 kWh usable. In that case:

6.18 kWh / ( 25 kWh / 100 miles ) = EV range is 24.7 miles

Note that using the 133 MPGe rating (to be more precise), we get 25.3 kWh / 100 miles. That's 33.7 kWh per gallon of gas / 133 MPGe. Values reported for EPA are truncated, rounded, and adjusted. So, be careful of trying to get too precise. And of course, YMMV.

 

@bwilson4web reported 6.3-6.4 kWh from wall for zero to full. This confirms EPA calculation of 6.33kWh from wall (33.7*25/133). Usable capacity will depend on charging losses, 15% gives 5.4kWh or 62% of 8.8kWh.

 

Over 100k miles already.

 

On another thread here I posted a link a few weeks ago to the Idaho National Labs battery test results for several Prius Plug-ins driven just over 100,000 miles. I think these test cars are typically made available to parcel delivery services around Phoenix, Arizona and aren't necessarily charged more than once a day. I vaguely recall the results showed around 10% capacity loss. Similarly tested Volts showed roughly the same loss, maybe even slightly more. I remember being impressed at the results.

My own Volt seemed to show maybe a 10% loss after 6 years and 143,000 miles in a moderate SF Bay Area climate when I sold it recently and switched over to a Bolt EV. That loss is an impression based on perceived range loss and measuring the energy needed for a full charge when new versus recent months. On the other hand, I switched to different and somewhat less efficient tires so it's not an exact comparison to the original vehicle.

I did not obsessively keep exact written records and was too lazy to measure the full charging energy right before selling it. I used to drive it carefully to work 45 miles from home on the freeway at 55 mph and when it was new it would routinely have 4-5 miles estimated remaining and sometimes more. Towards the end it was just barely making it to the charger at work before starting the engine and sometimes wasn't quite making it.

Another consideration is that battery output power also degrades quite substantially over time. In a blended PHEV car like the Prius Plug-in that had limited battery-only HP to start with, this degraded power limit should cause the engine to become more likely to start (power output capability also drops as the battery SOC goes down while driving). This could result in a greater perceived loss of capacity even though the battery might still be capable of additional output if it had been driven more gently.

This is less of a problem with the Volt since the much bigger battery starts off with a lot more power output capability than it needs for normal driving and because the EREV strategy of not blending may tend to hide any output power degradation since it does not trigger engine startup in the same way. The Volt pulls as much as 120 kW from the battery but that much is almost never needed in daily moderate driving and the same cells were presumably used in the 2016 Cadillac ELR which was allowed to pull up to 160 kW (~215 HP).

My Bolt EV is sort of following the same strategy -- it is starting with a relatively long EV range, energy capacity, and generous power output capability so it should age gracefully since the large pack is under minimal daily stress and initially exceeds the range and power I need for daily driving. I intend to keep it for at least 6-8 years and 125,000+ miles.

Well there's your problem! You just need to floor the accelerator a few times to blow the dust out of your overly pampered battery.

 

However, a blended PHEV has the engine to assist so at high power demands it may be less perceived power loss. The G3 Prius PHV battery power limit is ~37kW so at high power demand battery power degradation is a small factor of the combined power.

And yes, I saw these accelerated tests, thanks for sharing.