I think my guess-o-meter has learned a new trick

First, I seem to be noticing the beginnings of a little battery capacity reduction after 60+k miles in this 2017 Prime. I just barely get 25 miles out of it while getting over 5.5 miles/kWh. This was a sudden change from one week to the next. And, the last charge only took 5,835 Wh from 0% to full.

But the new trick showed up last Monday. I had depleted the EV range on the way back from a long errand trip. I stopped for gas and when I started the car back up, it showed 4% SOC on the guess-o-meter. I didn't pay attention to other stuff.

This morning, I paid more attention. I depleted the range Friday on the way back from our trip to St. Augustine. We didn't drive the Prime yesterday. Today, I wanted to check the kWh it took from depleted, so I zeroed my watt meter and readied the car so I could confirm that it was showing double dashes on the SOC meter. Good thing I looked. It showed 5% and an estimated 1.6 miles of range. So, I burned off all but 1% by driving to the grocery store around the corner.

And that lead to the other interesting observation. Even though it said I had 5% SOC and 1.6 miles of range, the car started in hybrid mode and not in EV. I didn't see that until I'd gone several hundred feet. I put it in EV and went to the store. When I started back up at the store, it stayed in EV. When I got home, I charged it with a 1% SOC showing. It took 5,777 Wh, which extrapolates to 5,835 starting from 0%. (My average since starting records two years ago is 6,120.Wh)

It's like battery bounce on a 12V, but it has never happened before on this Prime or on the PiP I had before. Has anyone else seen this happen?

 

I had never even had 1% pop up other than when in the mountains and going down a very long grade.

Agreed. It's really not bad, I guess. I knew it was coming. That average isn't since new; it's over the past two years so it seems kind of abrupt. I'll see what it does over the next few weeks.

I do plan to dig out the HA app and the Android phone for my next drive. If I don't go anywhere tomorrow, the next drive will be 25 miles each way on Tuesday to my part time job. Dr. Prius may be useful, too.

But I suppose it's probably just the natural aging process. Still, it kind of makes me second guess my decision to not get the Ioniq 5 a few weeks ago.

 

Me too. Maybe before the year is out. Right now, I'm kind of broke from new windows and fence. Gotta recharge the savings a bit. That, and about $35,000 has disappeared from my IRA so far this year so I'm avoiding the start of dipping into that for income. With your gas and electric prices, it seems like a no-win situation financially.

I reset the meter again before charging this morning since I used up all my EV yesterday about 23 miles into a 26 mile round trip. Part of that short range was the 12 mph with higher gusts I had to push through on the way out and then the winds changing direction and slowing down on the return. This time the battery only bounced up to 1% SOC. And it only took 5,458 Wh to charge it this time. Interestingly, the guess-o-meter estimates 28.4 miles of EV range. It's been about two weeks since I've been able to go that far. Hence the term "guess-0-meter!"

In thinking more about that SOC bounce, I realized that it may have done it before and I never saw it since I so rarely look at the SOC before starting the charger.

 

We drove it about 19-1/2 miles this afternoon and came home with lots of range left. But, that was due to taking back streets as much as possible and getting 6.8 m/kWh. Monitoring continues.

 

Update:
Capacity has stayed at lower than historic levels. I just checked it again the other day.



But the good part is, on most of my travels, I'm at lower speeds these days which gives me lots of m/kWh. So far, I've only run out of battery once on the 25 mile drive to the part time job. But on a 50 mph road yesterday I barely managed the 22 mile round trip. I only get, at best, 4.9 m/kWh on that road.

 

When I drive to & from work, it's 25.5 miles each way. I usually have about 5 miles left. Because of the sea breeze directions, it's usually into the wind both directions plus using the air conditioner on the way home. But I'm getting 5.8-6.0 miles/kWh on that drive. It seems that after the sudden drop in apparent capacity, it has leveled off and is holding steady.

 

That would be nice, but it's real capacity loss. The energy used it charging has dropped and, if I multiply my miles/kWh by the miles driven when making a trip that uses all the EV range in one continuous stretch, it is lower than it used to be as well. I still do better than EPA figures, though since most of my drives get me close to 6 m/kWh.

I'm still pretty sure my next car will be the Ionic 5 unless something comes along to change my mind.

 

It seems to be coming back. I reset my meter for a charge a few days ago and it took over 6 kWh on that charge from depleted. Along with that, I'm seeing 30-31 miles range at 5.5 miles/kWh where previously I was needing about 5.8 to get that range. Obviously, I'll continue to monitor it. I'll use a full charge again on Sunday and maybe again on Monday. I'll see how much it takes on those days.

 

It's not really surprising. Some capacity loss is to be expected as the car ages. What caught me off guard was the rather abrupt change in how much energy it took to charge it.

 

That seems like a reasonable explanation. I suggest putting the jumper cable in the recycle bin and getting a lithium jump pack. Its never a good idea to jump another car from a Prius. You'll usually be OK, but if you're not OK, you're REALLY not OK.

I got to do two full charges yesterday. I have another hour to go on my charge today, but here's what I got yesterday -- 6,205 Wh and 6,085 Wh. So, it's very close to the old numbers and my range seems to be back to normal. Weird!. I'll do another update after it finishes this charge.

 

Another charge over 6 kWh. In fact, it looks like it's back to what it used to be when I first started checking it over two years ago. I have recently modified the depletion description to just noting the battery SOC indicator relative to the EV/HV dividing marks.