PP 2017 battery degradation?

there is no way, it's a factory defect toyota refuses to address

 

Reading through this thread, I may have missed seeing where you mentioned if you use scheduled charging to end just before you are ready to leave. If you are not, I would try that, it sure seemed that another person observed some energy storage recovery over time by no longer leaving a full charge overnight.

The next is less evidence driven, but I'd think to try limiting charge current along with that. I know the driving discharge current is way more than an L2 charge current, but anything to "baby" the battery, I'd go for. For my L1 charging, I may limit charging to 8A. What the heck? Nothing to lose that I can see: Car still charged in the morning, ready for EV driving.

In the manual, I read something to the effect of, "Although the battery range may decrease over time, this does not indicate a problem. The car is still operating as intended." That last bit meaning "expected by Toyota," but not "expected by the customer." So here again, they're covering their large, corporate tuchus.

 

yup. and all ev's have a 'degradation' clause, to protect the mfg

 

I could see the unscrupulous at heart trying to come up with an untraceable way of "eighty-sixing" the battery after range loss gets too annoying. Or just before the 10 year / 150k mile warranty runs out. Not that I would actually consider such.

"He's Dead, Jim!"

 

6.8 kWh? I get about 6.2 kWh and mine is brand-new.

 

Do you use L2 EVSE? With OEM L1 EVSE, my average is 6.4-6.5kWh for a full charge, but it can get as high as 6.8kWh if HV portion of battery was low before plugging in, or battery heater or cooler or climate condition is used during charging.

 

According to the manual, the charge current would be limited for the following:

"In the following situations, charging time may become longer than normal:
●In very hot or very cold temperatures.
●<...>
●When the “Traction Battery Heater” operates.
●When the “Traction Battery Cooler” is operated before charging. (P. 136)
●<...>"

Under normal conditions Toyota must not see the need to limit current lower for their expectations of battery performance. But, Toyota likely accepts lower battery performance than we'd want to see as "normal."

Perhaps (and a very "perhapsy-perhaps") limiting charge current can help to promote battery longevity for a > 6.5 kW capacity that we'd want for the battery. (A hypothesis that would need to be tested.)

I'm guessing I want to limit battery charging current more than what Toyota accepts, in general. It really is a guess. Stop those lithium dendrites from creeping outward ...

 

"Also — kW is not a capacity, it's power or rate of energy flow. Capacity is kWh."

Yes, of course. I sit corrected, thank you.

It is possible they modulate the lower and upper bounds of battery capacity. It would be for temperature concerns, or any other reason that a lower battery life would otherwise be predicted.

Perhaps if doing so, they reduce the incidence of hard-failures - which they absolutely don't want to pay for.

 

From the manual:

"The hybrid battery (traction battery) capacity (the ability to hold a charge) reduces with time and use in the same way as other rechargeable batteries. The extent at which capacity reduces changes drastically depending on the environment (ambient temperature, etc.) and usage conditions, such as how the vehicle is driven and how the hybrid battery (traction battery) is charged.

This is a natural characteristic of lithium-ion batteries, and is not a malfunction. Also, even though the distance that can be driven in EV mode decreases when the hybrid battery (traction battery) capacity reduces, vehicle performance does not significantly become worse.

In order to reduce the possibility of the capacity reducing, follow the directions listed on P. 143, “Capacity reduction of the hybrid battery (traction battery)”.

p. 143:

"
Capacity reduction of the hybrid battery (traction battery)

The capacity of the hybrid battery (traction battery) will decline gradually when the hybrid battery (traction battery) is in use. The rate at which it declines will differ in accordance with environmental conditions and the way in which the vehicle is used. Observing the following can help suppress battery capacity decline.

●Avoid parking the vehicle in areas with a high temperature under direct sunlight when the hybrid battery (traction battery) is fully charged.
●Avoid accelerating and decelerating frequently and suddenly when EV driving.
●Avoid frequent driving near the top speed for EV driving. (P. 95)
●Leave a low level of charge in the hybrid battery (traction battery) when leaving the vehicle undriven for a long period of time. After confirming that EV mode has switched to HV mode, turn the power switch off.
●Use the charging timer function as much as possible in order to fully charge the hybrid battery (traction battery) immediately before starting off. (P. 157)

Also, if the hybrid battery (traction battery) capacity reduces, the distance that can be driven in EV mode decreases. However, vehicle performance does not significantly become worse.

■ When the remaining charge of the hybrid battery (traction battery) is low after charging

In the following situations, the remaining charge of the hybrid battery (traction battery) after charging completes may be less than normal in order to protect the system (the EV driving range after the battery is fully charged may be shorter).*

●Charging is carried out when the outside temperature is low or high
●Charging is carried out immediately after high-load driving or in extreme heat

When none of the above situations apply and there is a drastic drop in the remaining charge of the hybrid battery (traction battery) after charging completes, have the vehicle inspected by your Toyota dealer.

*: When this occurs, even if the remaining charge display of the hybrid battery (traction battery) shows that it is fully charged, the remaining charge rapidly decreases faster than normal.

■When the charging amount sent to the hybrid battery (traction battery) decreases

When the amount of power supplied by the charging equipment is low or operation of the “Traction Battery Heater”, etc., reduces the charging power sent to the hybrid battery (traction battery), the charging amount sent to the hybrid battery (traction battery) may decrease."

 

The very first time I charged it on Level 2, it took exactly 7.00 kWh.

In subsequent charges it took ~ 6.2 - 6.4 kWh from 0%.

 

L2 is more efficient and uses ~10% less kWh to fill. Most reported here use 5.7-6.1kWh for a full charge with L2. I only have OEM L1 EVSE. With L1, the full charge takes anywhere from 6.3-6.8 kWh. It really depends on how deep you go into the HV zone of battery before you plugin and use of heater/cooler/climate control.

 

The hybrid assistant app shows the actual state of charge even in HV mode. It's usually between 10-14% in HV mode. If I'm careful, I can usually just get it to hit 10% by the time I get home. As the SOC drops, the amount of acceleration you can do while staying in EV mode becomes more and more limited. It's usually somewhere around 12kw, but as the SOC approaches 10% it drops to more like 7kw, which is sometimes barely enough to maintain speed on a neighborhood street. The scale on the hybrid system indicator changes, so even though the EV line is always in the same place, the actual amount of acceleration to get to that line varies.

So depending on your driving style and where you live, you're probably parking with more than 10% SOC remaining. That should account for some of the randomness.

Temperature is probably another big factor. I've noticed that the SOC on hybrid assistant sometimes changes notably if I park outside for a day and the temperature changes. For example I've seen it go from 14% to 17% overnight. And one time I took a short trip near my house in the morning and parked with 97% remaining (indicated by the car). When I took a trip later in the afternoon it was down to 92%.

Usually the state of charge indicated by the car doesn't change while parked. I'm pretty sure it fudges the numbers, but I don't have enough information to prove it. That is based on the fact that for identical drive segments the percentage points of charged used can be much different, particularly when the battery is close to empty and it's been a while since I charged.

 

Yes, when I did check SOC using Hybrid Assistant, 0% SOC on the dash can be anywhere from 11%-14% SOC on HA. Accordingly, the full charge after that varies from 6.3kWh to 6.8kWh.

As for the SOC reading on the dash, you are correct that it does not change during the park. The question OP is raising is, is it because there is no phantom draw on the traction battery, or is it simply because the car is not monitoring the SOC during the park. I think both are true. No phantom draw (or at least, undetectable in short overnight park period) and no monitoring of SOC. What I don't know is what happens to SOC of the traction battery after a longer period of inactivity, say a week without driving and charging.

 

Watch what happens when you do a hard acceleration with a cold engine. It will dip down to 9%.

Also, I will continue recommend qualifiers on those "varies" values... since both of our 2017 Prime have always seen 6.0kWh as a maximum with level-2 charging. There is clearly some variable still not identified yet.

 

Yap, I took into the consideration of your reports and stated as follows. I think your case report is the low end of the variation.

 

I got it down to 8% once. I ran out of EV charge just before merging onto the highway and climbing a big hill. The car can shorten the warm-up cycle if it needs to, but in this case it decided not to for some reason. Has anyone seen lower?
Lowest Observed State of Charge | PriusChat

 

I'm pretty sure I saw 8% once as well, but couldn't remember which generation Prius that memory was from.