Is there a way to check the effectiveness of battery?

I bought my car used last month.

It would say 10.1 miles on a full charge.

Last week, it went up to 10.2.

Today, it is 10.4.

So it is slowly going up for me.

I wish I knew what it would show if it was brand new.


iPhone ?

 

after 3 1/2 years, 25,000 miles of ev, and 13,000 hv, i haven't seen any noticeable deterioration since the first year, when i felt like i lost a mile or so.

the battery icon is almost useless. the only way to track battery efficiency is to set up a course and drive a predetermined speed from a full charge until the engine kicks on. do this with the hvac off.
try to repeat every 3-4 months in similar weather, and record your miles.
the dealer can't do anything to test the battery, other than put the computer on it, tell you it's fine, and that all batteries deteriorate over time, and charge you $100.+

for funsies, you can disconnect your 12v negative for a minute, and that will reset the icon to 13.1 default miles. but it won't change your battery health or actual ev miles.

 

A calibrated test drive sounds like a meaningful test although a bit difficult to do accurately. Even wind direction makes a difference Perhaps the amount of kWh it takes to charge the battery over a large known state of charge range would be a good measure. Of course even that will be effected by the ambient temperature.

 

Sanjath, we purchased our PiP's at about the same time in the Bay Area and we even drive on the same highways.

The way I check the status of my battery is simple. When it was new, I drove out of my garage at 5 AM and noted where I ran out of EV. I made sure the engine never comes on. I did this over the course of the first few months and then randomly throughout the year and noticed the engine turned on at the Mowry exit on 880 plus or minus 1 mile. In other words, I get 8-10 EV miles. There was no rhyme or reason to the 2 mile swing that I can tell. I drove in the right lane at 55 mph. Very few cars out at that time, so traffic is similar. I only note the distance while dry.

I've since stopped tracking this as my motive was to set a baseline to determine efficiency and figure out where I could improve. But with 20% fluctuations in distance in as controlled an environment as I can get tells me I have no control. As best as I can determine, I have no control over the 3 red lights it takes to get to the freeway. Also while I can keep a constant speed, I cannot consistently keep a constant rate of acceleration everyday which is compounded by the red lights. And then there's temperature, wind direction, and so on.

TL;DR, with 2 miles discrepancy in my tests when new, I think what you're seeing is normal variation. This winter is also abnormally colder than the previous 4. My EV guessometer rarely goes single digits. (Even though going to work is single digit EV, coming home with traffic and a full charge, I hit 15-20 EV miles. I get an average for the day and thus it will always be wrong.) The past 5 consecutive days it's been displaying 9.7 EV miles. This is the lowest it's ever been consistently. But I also know, it's raining and it's been colder than it's ever been in the last 3 years.

 

I "measure" by using the Chargepoint chargers at work maybe once a week on days when I arrive at work after having consumed all of my EV range. Its not entirely accurate, but its the easiest way to do some kind of measurements. There's also about 6-7 other PiPs here at work which I occasionally compare numbers with. From that, I do believe my car takes less juice than when it was new (and less than cars that are newer than mine).

From my CP history, on August 28, a brand new PiP took 3.076 kWh (I plugged him in since he didnt have a CP card yet). On Sept 2, my car took 2.658 kWh. A week later, on Sept 10, my car took 2.743 kWh. And more recently, on Dec 16, my car only took 2.61 kWh. So like I said, not entirely accurate, but you can definitely see there is a difference (new vs old). With enough charges and time, you can draw some kind of conclusion/trend.

But like Bisco, I think the majority of "capacity loss" probably happened earlier. I dont have much data from before to quantify that though.

 

This may only work with your own car because SoC when you charge will be different. I turtle my car the mile or so from the freeway to my home and work so I am down to 2 or 3 bars when I plug it in.

 

I have used a similar method over the almost 3 years of ownership. However, I take into account the SOC before and after the full charge. From that I calculate an assumed total capacity of the battery. Its not important that the assumed efficiency hence capacity be accurate only how it changes over time. Since the results aren't entirely consistent I expect there is a temperature component. However, it pretty clearly shows a 10% reduction in capacity. I average about 1.1 charges per day, not all are full charges.

 

This 2.5% degradation per year is consistent with what we found in the thread:

Electric battery degradation | Page 4 | PriusChat

 

The ChargePoint history for my 2012 PiP (March 2012) shows a similar trend. Roughly 3.05 kWh at the start down to about 2.65 kWh now. When I charge, I typically have dropped to HV and see one or two empty bars on the display.

 

You are seeing the displayed "estimate" adjust to your personal driving route(s) and driving style.

Mike

 

My PIP is now just over 3.5 years old and I've seen a slight decrease in actual driving range on a full charge and in the kwh capacity charged from empty. I have very good records since I use ChargePoint at work everyday. My charge from empty (engine just started while parked showing 0.0 miles) during summer has dropped from ~2.85-2.9 kwh when new to 2.5 - 2.6 kwh this past summer. This is the all EV, everday capacity except for the mandatory 124 mile use of gas.

My actual miles driven has been easier to test. Charge at work, drive home and back to work is just under 12 miles. In winter I could always do this the first 2 years. Last year I could do this almost every day. This year I almost always need to charge up just a mile or so at home to make it back to work, so I do this to be "safe."

So there is definitely some degradation after about 20K miles of EV and 10K miles of HV.

Mike

 

if so, that means that you're seeing a ~10% drop after 20K miles of EV (disregarding HV). IMHO this is pretty bad, especially by Toyota standards – after 100k miles you'll only have half the range? That seems insane.

 

When it comes to fuel economy, it seems the Prius seems to magnify small changes. Just multiply all the numbers he wrote down by 7.

3 kWh x 7 = 21 kWh
This is within a kWh or 2 of the useable capacity of most BEV. Leaf, your MB EV, Focus Energi, etc.

20,000 EV miles x 7 = 140,000 miles
That's the number of miles a BEV would have to travel to get a similar number of charge and discharge cycles as his PiP. Imagine a 10% reduction in range in a BEV after this many miles. A Tesla is estimated to retain only 85% capacity after 100k miles and it has a much larger battery meaning fewer charge/discharge cycles. I don't know the estimates of other BEV. Nissan will only warranty capacity loss of greater than 3 bars out of 12. Which means 25% is acceptable for a Leaf.

And extrapolating to 100,000k miles as you have done to arrive at 50% capacity. Well, I think all of us would be impressively shocked if any BEV still had 50% capacity after 700,000 miles worth of charge and discharge cycles.

TL;DR 10% capacity loss is pretty incredible.

 

it seems to lose most of it in the first year. i still get 12 in mid winter, and 16 in spring, summer and fall.

 

...I don't think we have a single report yet of PiP battery being replaced. Don't recall if anyone has gone past the warranty (100k mile non-CARB or 150k in CARB) yet. A few are getting close.

 

If the 10% is compounded every two years, then the result after 10 years would be 0.9 * 0.9 * 0.9 * 0.9 = ~60%

After 100K EV miles and 50K HV miles that' probably still pretty good.

Mike

 

But this isn't a BEV; it's a plugin, advertised as having a certain range, and being operated under the assumption that you can drive it 100k miles without significant degradation. How many people who bought the car expecting 12-mile range would be happy to know that this will go down to 6 miles at 100k miles?

Leaf bars are non-linear; 16% for the first and 5% for each additional. Note that Nissan had to warranty such ridiculous losses only because they have an equally ridiculous battery cooling system (I.e. None) and high temperatures destroy batteries.

 

Yes, the PiP is not a BEV. There is no expectation on my part that EV range on a PiP would degrade like a BEV. I'm using the BEV comparison to show that if the PiP were a BEV, reported degradation would far exceed expectations for a BEV. Capacity loss is a half to a third what Tesla and Nissan expects for a battery with similar number of charge discharge cycles.

I left the last bit of math open for yourself to calculate as individual usage vary. 3PriusMike posted his expected results above your post.

For myself, I have a 21% EV ratio after 3 years and 90k total miles. I can't track my EV usage better than 10% so I have no noticeable EV range loss. If my EV range suffers a 20% loss over 40k EV miles and 180k total miles over 6 years. I would be ecstatic.

I think the only way to find out that answer would be to wait another 11 years or so and ask them. 1 year / 7000 miles for those that charge/discharge fully twice a day x 100000 miles = 14 years or 28 years if you can only charge once a day. Doubt there will be many PiPs that will be original owners at that point.

 

Capacity loss usually isn't linear. Page 7 has a good breakdown of how most pip batteries will likely degrade.

http://www.nrel.gov/docs/fy13osti/58550.pdf

10 years would correspond to 75+% capacity, and it may be possible to go another 10 years before the actual range is affected. Granted, individual cell replacement may be required, but my guess is that a Prius pack can go ~100k EV miles plus however many HV miles before the entire pack would need to be replaced.