Full thoughts on the new Prime (quick hits)

I should have said: hoping prices will be right.
Right now we have only Netherlands prices which are promising.

 

thanks, me too! any announcement dates?

 

Well, it is smaller than the traction pack, and it also has to sized to hold a buffer to run accessories while the car is in motion.

But as I alluded too, this could have been a mistranlation error.

 

To my understanding it is much smaller (in capacity) than the auxiliary battery.

 

I'm a power electrical engineer, and I'm racking my brain trying to figure a reason to need a batter between the solar panel and the lithium battery.

I've thought about boost converter isolation, static building up on the solar panel, faults causing shorts of the lithium pack, and so forth.

 

It might have to do with variability of the voltage you'll get out of the Prime solar panel. From my count it looks like there will be 56 cells. If (warning big WAG assumption here) they are connected in series, then the voltage swings may go from 18V (nominal) to 33V (open circuit). So it kind of makes sense to go with a small battery that can handle wide voltage swings but not have to deal with constantly stepping up to the 208V of the traction battery which may also have to deal with constantly variable current as well.


Unsupervised!

 

A small NiMh battery can't handle voltage swings any more than a big Lithium battery can. Certainly not a factor of two. The varying cell voltage has to be turned into nearly-constant voltage charge current by a charge controller anyway.

 

Well from their own videos the ECU is the middle man for all of that anyways. Probably programmed for 3 paths: Solar to NiMH (wide voltage swings to small NiMH voltage), NiMH to Traction (small constant voltage to high voltage), and NiMH to 12V. Like I said a WAG.


Unsupervised!

 

The trip you are showing was not on pure EV. Was it by gaming the sysrem collecting EV miles?

Posted via the PriusChat mobile app.

 

You might have done better in not trying to game it with EV mode use.
Without a plug, all the energy used comes from gasoline. The battery captures some that would have been just thrown away, but the systems wants to keep a minimum charge in it for extended life. Use EV mode too much, which is easy with a small hybrid battery, and the car will end up burning gas wastefully to recharge the battery.

 

Better depends on what the driver wants to achieve.
Sometimes, having more EV available is an advantage (and sometimes even a must) over best total efficiency of the system.

Posted via the PriusChat mobile app.

 

Knowing when to use limited EV is key... hence Prius plugless success.

I have trips I routinely take where I'll be able to take advantage of Prime's charge-on-the-fly ability. The new mode will allow us to replenish EV on the highway for use later when keeping the engine off provides a greater return.

 

I was sort of thinking the other way.

When an ICE is running at very lower power, it's very inefficient. There are 35 zones on several of my routes that use less than 4kW to keep going. Using the ICE there is quite inefficient and I was thinking of using charge mode (if lacking Ev range, obviously) to make the ICE more efficient and then use the energy later.

On the highway, the ICE is already efficient unless you're on a slight downslope.

Thoughts?

 

I routinely take highway trips, some multi-day with no opportunity to plug in, then a bunch of short-distance driving. That makes charge-mode a no-brainer.

 

Inferno can correct me if wrong, but I thought his Prius didn't have a plug.
The gen4 non-PHEV will display EV miles traveled. To me, this just seems to be for ego stroking and boasting, while possibly encouraging inefficient driving.

 

it's in his signature, that's what he was talking about. you don't get that display, or ev tracking in the gen 3.

 

Yeah, don't know why Gen 3 didn't have EV mile summary, I had it on my C. Not really useful for anything other than the occasional hey I've driven 4,800 miles without using a drop of gas... but it's nice to have.

 

But those miles did use a drop, and more, of gas.

Without a plug, the electricity in the battery came from:

• Regenerative braking. This energy would have just been thrown away otherwise, but to get moving to begin with took gasoline at some point.
• Directly charging it by the ICE, through MG1.

Tracking these EV miles separately is misleading; giving the wrong impression on how the hybrid conserves fuel. You can put an ICE car in neutral and shut off the engine while coasting. Many cars actually turn off fuel delivery while coasting now. It took the engine to get it up to speed first though. So claiming those engine or fuel off miles as gas free would be dishonest, but that is what is going on by tracking a non-plug in hybrid's miles under EV operation is.