Prius Prime Plus in my hands

Yes, I have. In fact I'm using 40% thermodynamic efficiency for the Prime and only 38% for the Gen-3.

Bob Wilson

 

There are some excellent, SAE articles describing the Toyota Prius technology. Sad to say, they can be a little pricy.

Bob Wilson

 

Yes but I'd also ran an earlier test in at 50F and seen similar results. This roll-down test in freezing weather was key to my transmission oil studies. I could actually see the effect of changing the transmission oil in how far the car rolled. But the Gen-1 would come to a stop well before the bottom and our BMW i3-REx also stops too soon.

One of Toyota claims is the new transmission has lower drag and I can confirm that is the case.

Bob Wilson

 

So I've updated my entry in www.fueleconomy.gov with:

• 55.1 MPG - 100% highway, 601 miles, 10.9 gal.
• 61.3 MPG - 90% highway, 10% city, 699 miles, 11.4 gal.

I've already started charging the car but haven't found any in-car metrics of kWh. I've done one full charge in North Kingstown, RI, 6.3 kWh. But in Huntsville, unless there is something in the car, there are few, opportunities to get a record of the charge put in the car.

Bob Wilson

 

Every morning, I have the choice between a BMW i3-REx and a Prius Prime Plus. I've just started my EV tests so it is too soon to tell but I have great memories of the BMW i3-REx in EV around town.

Bob Wilson

 

We each vary in our tolerance for fuel costs. So in my case:

	model	MPGe - kWh/100 mi	MPG - gal/100 mi	EV range	gas tank
1	2014 BMW i3-REx	117 - 29 kWh	39 - 26 gal	72 mi	1.9 gal
2	2017 Prius Prime	133 - 25 kWh	54 - 1.9 gal	25 mi	11.4 gal

So we're set. The BMW is the urban king with tolerable highway efficiency at 65-70 mph after 12,000 miles. It is complemented by the Prius Prime with very long and efficient legs and tolerable urban efficiency but with only 1,300 miles.

Using tricks learned from the BMW i3-REx, I'm testing the Prime as a pure EV and after two days, not a drop of gasoline used over 35.9 miles. This mild winter I'm using the heated seat and warm clothing instead of cabin heat. It is a good start including today, a brunch that including: free 3.4 kWh at Whole Foods; haircut a block away, and; buffet with smoked brisket and a smoked hamburger patty.

Funnily enough, I'm using just the 12A, L1 EVSE from the BMW i3-REx for both cars. When I leave, it goes on the car remaining. When I arrive home, it goes on the car that just arrived. It is a reasonable solution.

No charging at work, find free chargers within walking distance of an eatery. Then start looking for your next employer.

Bob Wilson

 

Here you go:

I'm using OpenSource for my spreadsheet but have one copy of excel on another system. Rather than transfer and convert to an xlsx, I just wrapped the OpenSource in a zip file. If a problem, let me know.

Bob Wilson

 

Now I'm getting more data about the end-of-charge in the Prime:

• 5 minute charge probes - initial 3 probes
• 15 minute charge cycles - even during the ramp down
• rather fast ramp down and a sudden drop-off ... hummm

Bob Wilson

 

CARRY BLANKET AND PILLOW - instead of eating lunch near a free charger, lower the seat back, stretch out, and take a nap during the charge. You'll avoid putting on pounds that are not really needed.

KNOW THE L2 LIMITS - the Prius Prime only charges at 16A roughly half the rate of the BMW i3-REx. This means adding 10 miles in an hour of charging or a full charge in 2.5 hours. So I adjust my EV charge+shopping to do more 'longer' shopping rather than the in-and-out of the BMW i3-REx.

LUNCH LIMITS - use ones as close as possible to work is an effective workaround for lack of at-work charging. Having a charger at work encourages EV workers to bring a bag and work through the lunch hour.

Bob Wilson

 

Not that I have seen and the taper at the end is almost a switch OFF.

Bob Wilson

 

I'm seeing 3.3 kWh as the maximum charge rate which matches my understanding of the vehicle AC charging rate, 16A @210 VAC ~= 3.36 kW. We should get a little faster when I put an EVSE on 240 VAC. Let's chat a bit about this:

• L2 chargers - they can run from legs of a commercial 3-phase power or a domestic split phase
  • ~211 VAC comes from two legs of a 3-phase commercial power
  • ~240 VAC comes from both ends of residential, split phase residential power
• 16A max amp limit of the Prime in-car charger - this can be reduced by:
  • state of charge - usually from the taper charge at the end
  • temperature of charger - it will protect itself from melting down
  • temperature of battery - it won't charge the battery into thermal runaway

Now my metrics are coming from JuiceBox Pro 40 emotorwerks:
JuiceBox® Pro 40 - Smart 40-Amp EVSE with 24-foot cable

Originally installed at home for our BMW i3-REx, 31A, where it worked brilliantly. However, I soon realized it would be more useful at a favorite shopping center: PlugShare - EV Charging Station Map - Find a place to charge your car!

Search for Pratt Ave NE, Huntsville, AL 35801
Click on the "Green drop" on Pratt Ave​

Higher rate chargers are needed at shopping centers so people can do a quick charge while shopping or errands . . . an "in and out" charge. At home, charging speed is not so important as I typically spend at least 10 hours with meals, sleeping, and of course, PriusChat.

Now both of our cars, Prime and BMW i3-REx, are configured for maximum rate, immediate charging, and other than the screen settings, I can only slow it down IF there is an advantage ... but there isn't.

So there is one variable and that is charging voltage, 211 VAC or 240 VAC. So the fastest charging set up would be to use a dryer circuit, NEMA 10-30 (3-prong "Y" shaped socket.) This provides 240 VAC into the charger, the fastest rate of power. But two things can limit the current.

The car negotiates with the charger (EVSE) using an analog power signal the maximum current the car will take and the EVSE will allow. Inside the EVSE is a relay that makes noticeable click when it closes (and opens if you are around it.) The relay contacts have a maximum current rating which is the other current limiter:

• 12A - BMW i3-REx which is what I am using at home
• 8A - Prius Prime which is still unused in the back of our Prime

Now the JuiceBox Pro 40 also has the ability to run up to 40A which is 80% of a NEMA 14-50 circuit (see RV park power.) I can limit the current to anything and right now, we're trying to limit the charge to 7.2 kWh in a single charge session. This is primarily to keep the Tesla vampires from hogging the charger by stopping the charge after about 50 minutes. Given no time limits, you'll find Teslas sit on a charger for hours (where did that driver go?)

I am trying to buy a 20A, 120-240VAC EVSE from emotorwerks but they have a supplier problem. But there are others who already sell them. This would be a perfect solution for our Prius Prime as it is very portable and voltage flexible. Configured for 16A, this would provide a maximum charge rate for the Prime at home using the dryer circuit and on the road from any open NEMA 5-20, 120 VAC.

My Prius Prime, EV week ends Sunday so Monday, I'll run the battery down to where the engine runs. Then I'll take it to the JuiceBox 40 Pro and 'wait at the bar.' This will give us an instrumented, full charge and answer any questions about the charge profile (might have to take a nap too.) The only thing I won't have is good record of the charge cycles we've already documented. I'm not sure there is much to gain other than the rather rapid taper.

Bob Wilson