Prius Prime Plus in my hands

I'm using a JuiceBox Pro 40:
JuiceBox® Pro 40 - WiFi-enabled 40-Amp EVSE with JuiceNet

The EVSE uses WiFi to connect to a server to record charging metrics. For example, charging at 6A 240VAC:


Bob Wilson

 

	Plug-In	Plug-Out	Energy (kWh)	Charging Time	Amps (limit)
1	9:33 PM 7/17/2018	3:33 AM 7/18/2018	5.91	01:54:34	16
2	10:46 AM 7/16/2018	6:56 PM 7/16/2018	6.06	04:27:07	6
3	10:15 AM 7/15/2018	6:50 PM 7/15/2018	5.92	01:49:28	16

• 5.92 kWh, 6.06 kWh, 5.91 kWh.
  • 97.7%, 100.0%, 97.5%.
• The 6.06 kWh is equal to the charge rate of the L1 charger at 12 A.
• Switching power supplies lose efficiency at lower power settings.
  • We have no way to separate AC and fan loads from charging current.
• In subsequent drives, all three max charges delivered over 25 miles EV.

I need to run a full charge at 4 A which would be the equivalent of the L1 at 8 A. I might set the current to 2 A and charge over night to see what metric comes up.

Bob Wilson

FYI:

 

OLD

"Skin in the game" we own(ed) and operate(d) these cars:
199-58 MPG - Prius Prime (11k mi / 11k total) 2018-05
180-40 MPG - i3-REx (27k mi / 33k mi total)

(sold) 52 MPG - ZVW30 (73k mi / 73k mi total)
(sold) 52 MPG - NHW11 (122k mi / 172k mi total)

NEW

"Skin in the game" we own(ed) and operate(d) these cars:
199-58 MPG - Prius Prime (12k mi / 12k total) 2018-05, 08
180-40 MPG - i3-REx (27k mi / 33k mi total)

(sold) 52 MPG - ZVW30 (73k mi / 73k mi total)
(sold) 52 MPG - NHW11 (122k mi / 172k mi total)

Also, with temperatures in the low 70F (22 C), I was happy to see:

Home_base finished charging.
Charging added 6.155 kWh in 1h 54m 59s.​

Bob Wilson

 

During hot weather charging, the capacity drops below 6 kWh. But charging in the coolest part of the night seems to bring capacity above 6 kWh. So I set the EVSE to charge only between 3-9 AM. This should ensure full charging during the coolest part of the day. However this requires testing.

For the next week or so, I will run the car in EV with HV picking up operation once the battery is depleted. I will have to put some gas in but this is from a tank filled eight months ago. I'll wait for the gas-low light, ~1 gal., and only add 2-3 gallons to sustain HV operation.

The one challenge is pre-conditioning the car in the middle of the day. I may have to override the timer to get the cabin cooled.

Bob Wilson

 

My study of hot weather charging requires draining the battery and using HV mode to get home. A day or so ago, the low fuel light came on so this morning, I topped off with 10.5 gallons. Then this evening:

Talk about poor ad placement and timing.

Bob Wilson

 

I suspected something was wrong when my cell phone announced, "Mandatory Entune update." The Prius Prime, Plus trim, has to link via my cell phone but like a sheeple, I took the bait. Now the only way I can play iPhone audio is via bluetooth, not the USB-lightning cable.

When I tried to connect, a message came up that it failed and I needed to read the Owner's Manual. My breakfast had not arrived so I went to the car to fetch it and lookup the problem. The Owner's Manual said see the Navigation Manual. Another trip to the car but breakfast soon arrived and I looked it up.

The instruction said to push the "AUDIO" button which gave me options. Attempts to select USB failed but Bluetooth worked. So now it is permanent Bluetooth to play iPhone audio. Nothing like replacing hardwired with another wireless link. <GERRRRRR!>

Bob Wilson

 

Measuring battery capacity has turned out to be complex as there are two parts:

• EV level - tricky to measure
• HV level - even trickier to measure

BACKGROUND

I started with driving home and recording how much charge was put in the car when charged in the 70-75 F (21-24 C), very early in the morning. I adjusted the time of charge so it ended at sunrise:

• decreasing capacity at 16 A - this really bothered me because it suggested I was losing capacity. More about this later.
• funny 7 A capacity - insights, I figured out the problem,

The last two metrics are here:

During the 16 A series, I had been learning how to arrive at home with 0% SOC. In the beginning, I was driving further in hybrid mode (HV) which digs into the lower part of the traction battery. The earlier charge session included what it took to fill the empty HV part. As an experiment, I left the car parked with the A/C on for ~1 hr which dives deep into the HV part.

The best approach is to drive home with the car in low, unit, % SOC (1-3%.) Continue to drive around the neighborhood, laps around the block, until the SOC reaches 0%. Then measure the charge. This is the only reproducible way to measure the EV traction battery capacity outside of pulling it from the car and using lab instruments.

Now I can measure the 16 A and 7 A battery capacity, again holding fairly constant the charging temperature of very early morning hours. I'll probably add an 11 A sample since three points should give enough to calculate the effective charge as a function of charge current.

Bob Wilson

 

Ok, we have a methodology and it appears to give reproducible results:

1. Drive in EV toward the charger and do loops until the SOC reads "__" and the car kicks into HV mode. Minimize HV driving so the HV battery range does not have to be charged.
2. If sunny and over 85F (30C), configure to charge between 2 AM and sunrise. This avoids A/C trying to keep the battery cool enough to accept the charge. You can drive in HV mode if you need to go out earlier.
3. Cutting the charging current in half had little effect on measured, EV battery capacity, 5.89-5.91 kWh.

Bob Wilson

 

Home_base finished charging.
Charging added 5.636 kWh in 1h 44m 42s.​

Bob Wilson

 

Home_base finished charging.
Charging added 5.812 kWh in 1h 49m 17s.​

Second metric with temperatures in the 70F range.

Bob Wilson

 

Home_base finished charging.
Charging added 5.667 kWh in 1h 45m 40s.​

I'm seeing a consistent +27 miles on the trip meter for the past three, full charging sessions.

1. Charging added 5.636 kWh in 1h 44m 42s.
   
2. Charging added 5.812 kWh in 1h 49m 17s.
3. Charging added 5.667 kWh in 1h 45m 40s.

Bought in December 2016 and approaching 2 years, the range is still within the EPA 25 miles. But I switched to the BMW i3-REx when the temperatures exceeded 80-85F (27-30C).

Bob Wilson