Battery charge / discharge Q

there has always been a buffer at the top and bottom of all toyota hybrid batteries, it keeps them healthy.

not too much charge, not too much discharge.

 

it's probably incorrect, the info toyota gives the user is usually poor. if you can find it someone has gone to a great deal of trouble to analyze the top and bottom percentages.
it's in one of the gen5 threads, but unfortunately, the mods haven't separated them into more defined forums like the other generations, making things a bit harder to find.

how many miles at what average speed are you traveling before the engine comes on?

 

Yes, there is a reserve some of which is for HV mode and some of which is for battery health. We can only know for sure the total specified battery capacity of 13.59 kWh, and we can determine that the portion available for EV mode is around 10.6 kWh. (Drive a bunch of EV only trips, record the trip distance and the reported mi/kWh. Divide each trip miles by the reported trip consumption rate to get approximate kWh used. Divide that number by the delta SOC % - (e.g 100% - 11% = 89% of the available EV mode capacity used) to get the approximate total EV mode capacity. Do this for a bunch of trips of various length and you get an average of 10.6 kWh, min 10.3, max 10.8, stddev 0.2 kWh. 13.59kWh total - 10.6 EV mode = 3 kWh reserve or 22% so the app should either match the car's reported SOC % or it should read 22% when the car shows SOC ----% which would be totally useless information to tell the user.

The app is a mess for the 2023 Prius Prime. I don't know how well it does for other year primes. This app does not reflect well on Toyota in my opinion. They are known for engineering their cars with great thought and research. This app when connected to the 2023 Prius Prime does not tell the same story.

 

Here is proof the app charge value is crazy. I used three different methods to estimate the amount of power put into the battery, and they track pretty close to each other. The app? They are using a wrong delta battery state and multiplying it by 10.3 kWh which I am very sure should be 10.6 kWh.


Oh, and did I mention they disabled the submit button on the "Contact Us" for the App? or that they hung up on me when I called Toyota Connect Services?

 

There's another discussion here, and the concensus is that the app is totally borked. Among other things, it reports 7.2kwh to charge the battery (I wish!) where a commercial charger reads 11.6 for the exact same charge--I've seen at least 3 people verify 11.3-11.6 for a full charge from commercial level 2 chargers. The best guess from the other thread is that the battery size on the back end is incorrect, so everything it reports for numbers is essentially bogus.

The "usable" amount is 11.5kwh (so that's what you use for your cost estimates with charging), leaving roughly 2kwh at the bottom and top for battery health and HV mode use.

 

The short answer is YES what you are seeing is normal.

I believe it should be 30% when empty, but my guess is when you flip over to HV mode, you are regen braking up to 3% charge, so when you go to plug in the reading is actually 33%.

You will notice that in HV mode the car does switch to EV mode if the time is right. This is why the car reserved ~30% of the battery for HV mode use.

There needs to be more consistency in what the app displays and what the car displays, vs what the chargers display. All the numbers are different in the 3 places.

 

Beg to differ slightly on the "usable amount" - 11.3-11.6 kWh from a Level 2 "commercial charger", (EVSE or "charge point" - the charger is under the foam, left rear cargo area), translates to roughly 10.6 kWh into the battery with 92-95% efficiency.

Charging from the provided Level 1 EVSE/CCID at home on a 120v 15A circuit with the car's charge setting at max will pull somewhere in the order of 14.3-14.7 kWh from the wall to put the same 10.6 kWh into the battery with 72-74% efficiency. (Pulls 120v 12A on max, 120v 8A on "8A" setting - I have not tested the at home efficiency at 8A - it may be different.)

The efficiency also depends on the ambient temperature and how much cooling or heating is needed during the charge.

If you want to verify my 10.6 kWh "usable" estimate - Drive in EV mode from 100% to ----% and divide the miles driven by the reported consumption rate (mi/kWh). For example, if you get 44 miles and the consumption rate when you turn it off is 4.1 mi/kWh: 44/4.1 = 10.7 kWh used. If it reports 4.2 mi/kWh then 44/4.2 = 10.5 kWh used. (The car only reports consumption to one decimal place so we have to do the test a number of times and average the "usage")

Cost is per the wall, usage is per the battery. This is one of the problems the app would always have if it was a believable number - It can only measure the power actually put into the battery or estimate it based on delta SOC * known usable capacity, ( I believe the app is using the later, not actually measuring anything!). The app will never be able to tell us how much power we pulled from the charge point or from the wall.

There is a possibility the car is lying to us about the consumption rate. If your estimate of 11.5 kWh usable is indeed correct, the car is low balling us by 8%. The car is repeatedly sampling the current drawn and the battery voltage at that instant. Then multiplying the current * the voltage * sample time interval and adding that value to the prior samples. If the car is driving at a steady speed on constant grade, the measurement will be quite accurate. All other cases will have some error depending on the sample rate. I don't know how to verify the consumption rate the car is reporting so I'm taking it to be close and averaging multiple tests to come up with 10.6 kWh.

 

Just noticed the Toyota App bumped to version 2.1.9 - here's hopin' they done somethin'

 

Can someone explain to me what these items are in the AC charging port? One is a button and the
other is a turn knob in "23 Prius Prime SE.

 

I think the top one is a sensor to detect if the door is closed. The one on the bottom is the spring that pushes the door open when you press it in.

 

Are you talking about the battery SOC in the Toyota app's main page? That number is rubbish, and you should simply entirely ignore it. It is random and has no meaning.

Use the battery SOC on the multifunction display (MFD) instead. That number is accurate, and 0% means that you have depleted the BEV allocation, which is about 11.6 kWh on the watt–hour meter and somewhat less (5–10% less?) on the battery.

The watt–hour readings on the app, albeit not to be trusted as on the actual watt–hour meter, should be fairly accurate though. Those app watt–hour readings actually use the MFD SOC—not the SOC reading in the app—and they then scale it by an ~ 11.6-kWh socket energy output for 100% SOC. However, as I said before, the SOC readings on the app's main page are random rubbish due to some bug in the app.

 

Your “watt-hour value” is not universally applicable for every owner. The EV mode power in the 2023 Prius Prime is 10.6 kWh (when the car is new) for all trim levels, all drivers, and non-frigid outside temperatures.

There is no watt-hour meter in the 2023 Primes btw.

The bogus multiplier for the delta bogus charge values the app uses is 10.3 kWh but bogus just the same as the value you asserted.

 

Thank you so much!

 

I am talking about the watt–hour meter on the EVSE or the outlet. No, there is no watt–hour meter on the car.

How much do you guys get on the Level-2-ChargePoint watt–hour meter for 0–100% SOC? The EPA value is 11.6 kWh for Gen 5 and 6.34 kWh for Gen 4 Prius Prime, the latter of which perfectly agrees with the ChargePoint watt–hour meter. Where did the 10.6 kWh come from? Is it something you deduced from a third-party app?

 

I went back and read all your posts about your values derived from the EPA stickers - interesting but does not agree with over 100 data points in my 2023 Prius Prime XSE, nor with almost 100 datapoints from three other 2023 Prius Prime XSE and XSE Premium drivers that average to 10.6 kWh at the battery derived from the car's reported statistics.

The 10.6 kWh EV Mode battery capacity is empirically derived to be what the 2023 Prius Prime software uses for the SOC display of charge remaining percentage.

EV_Mode_Battery_Capacity == ( miles_driven / reported_efficiency_mi_per_kWh ) / delta_reported_SOC == 10.6 kWh on average

Example for a recent 100% usage - 43.6 miles driven displayed 4.1 mi/kWh right before the forced switch to HV mode, therefore:

EV_Mode_Battery_Capacity == ( 43.6 / 4.1 ) / 1.00 == 10.6 kWh

Your EPA derived "wall watts" value is not useful to me as an EV Mode Battery Capacity, but I have no problem that it is for you. I agree that the wall power is what costs, and Level 2 charging is a more efficient source. The level 2 efficiency can be estimated but not measured without knowing the actual power replaced in the battery.

The car provides three values directly related to the battery power used, and so I am trusting the car's reported values.

[I do not have a Level 2 EVSE available, my stock level 1 EVSE efficiency varies between 72% (wall=1.38x batt) to 78% (1.28x) using the 10.6 kWh battery capacity value.]