CHARGE MODE YouTube video

Sad to say, I can not post a comment to this YouTube:

In the video, the unknown author achieves 80% with 0.65 gallons parked in idle. One comment I would leave is:

Idle is notoriously inefficient because the engine throttle plate is mostly closed. The engine runs at less than peak efficiency.​

I ran a shorter, similar test in Alabama heat with the AC: Prius Prime Plus in my hands | Page 24 | PriusChat
His 0.65 gallons versus 1.00 gallons (est.) suggests we are in the same order of magnitude. Just I had the additional AC load.

So I also have metrics from the car running down the road on a standard day and no accessories:
Prius Prime Plus in my hands | Page 25 | PriusChat

With the car running at a modest speed, 36 mph, or modest load, the engine approaches its peak efficiency. So we get:

• 0.362 gal ~= 80% SOC, maximum SOC achieved in CHARGE mode
• ~20 minutes to get 44% -> ~37 minutes to achieve 80% SOC

There is a risk of using idle mode for benchmarks because the engine efficiency will be so much lower than at a peak or even normal urban speed of 36 mph.

I appreciate the unknown author's efforts to take metrics of the Prius Prime. I'm not tossing dirt in part because I used 'parked in idle with AC' to get a rough order of magnitude. Like him, I can not recommend using CHARGE mode while parked. However, rolling down the road at a reasonable speed where the engine will be working close to peak efficiency, the overhead cost of CHARGE is significantly reduced.

Bob Wilson

 

If you do it parked when the engine will be running in an inefficient power setting.

So far, my best CHARGE mode has been at 36 mph and 65 mph is pretty good too.

Bob Wilson

 

Back of the envelope:

• 37 min at 36 mph for 80% charge
• 6.4 kWh * 80% = 5.1 kWh in 37 min
• 5.1 kWh / 37 min ~= 0.138 kW / min
• 0.138 kW / min * 60 min ~= 8.2 kW charge rate per hour
• current, maximum static rate is ~3.6 kW

Pure speculation but it looks like the up to 80% charge rate is well within the typical, 40A limited, L2 charger. If instead of using a separate charging unit, Toyota could adapt feeding L2 voltage and current into the MG2 power electronics, the car would achieve a full charge in an hour using an L2 charger.

Of course if the AC mains can connect to the power electronics, it could become a bi-directional power flow enough to fully power a 7kW house.

Bob Wilson