So.. traction battery is the bottle neck?

It is. Also keep in mind that in general part of the power from the ICE goes through MG1 to MG2. Only in a few select cases could you truly add the total power of MG2 to the power of the ICE. This is how the PSD works.

Tom

 

Batteries don't like being quickly discharged. A bank of Ultracapacitors could be used in conjunction with the traction battery for a quick boost in energy during acceleration. The traction battery could also be enlarged from 1.3 kilowatts, but then weight would go up. The problem with the Volt is 16 kilowatts of battery dead weight the car has to lug around until the next charging port is reached. I believe that Toyota has made a good balance between battery weight vs output in the current generation Prius. Any small change can make mileage worse instead of better. Just look at the identical drivetrain in the CT200h as an example.

 

Also note the battery can only discharge 27 kW (36 hp) for about 1 second, thereafter it can only sustain 21 kW (28 hp), giving sustained peak power of 126 hp (98 + 28).

 

It's one of the advantages that PHEVs and EVs have.

The Prius PHV will have more power available due to its larger pack. Of course, in an HEV you're better doing heavy acceleration on the gasoline engine anyway.

 

That's exactly what I pointed out in another thread. The Prius is really tuned to the HSD and vice versa for max fuel economy.

 

MPG wouldn't really be any better with higher discharge rates from the HV battery. if you're asking for 20kw+ of power the ICE would be running in it's maximum efficiency zone.

The limiting factor is really the boost converter. You can allow higher discharge rates, but you won't get more than 25kw onto the 500V bus. This has been enlarged for the upcoming prius PHV.

 

I'm wondering how this would help MPG at all.

A higher battery rate would capture more regen from drivers with a heavy brake foot.

 

Not better at all. Argonne National Laboratory did an extensive tear-down and test of the Prius. One of the interesting findings was essentially no loss of mileage when the HV battery was reduced to half of its initial capacity. In other words, the battery starts out twice as big as it needs to be. Changing that number to four times isn't going to help.

Only under very special driving conditions will a bigger battery help. For most drivers it would only add unneeded weight.

Tom

 

The battery is as big as it is for longer life (relatively smaller range of charge and discharge in normal use).

Efficient power- and energy-dense batteries are Really Hard. That is why we haven't been tooling around in Edison Electrics for the last 100 years.

 

Under the Euro test, the CT200h is getting about the same mileage as the Prius. In fact, slightly better with the 15" wheels, despite being about 40 kg heavier and with CD of 0.28.
Must be that the drivetrain have gone evolutionary refinement and it is tuned differently.

Giora.

 

According to the report, battery capacity is down to 39% after 160K miles.
It doesn't say anywhere there's no loss of mileage.

 

tpfun, as you've never driven a prius you won't know this, but the display in the vehicle covers 40% to 80% SOC window. It's rare to see it get full (8 bars) unless going down a mountain, and it's rare to see it get empty unless crawling for a few miles at consistent very low speeds. My point is that even the 40% SOC window is more than required with the software set the way it is. going down to 39% is going to have such a small difference it would get lost in the noise. It certainly wouldn't be apparent in NEDC or EPA testing.