OTOH..The Prius DOES recharge its batteries while driving - Bob Lutz

[DeadPhish]

There is a very interesting thread going on over at GMI on this very subject based on the InsideLine article.

There's some very good information by what seem to be knowledgable people like herein.

Page 7 has a reply allegedly from Bob Lutz...

IL Corrects Volt Story: Batteries Will NOT Charge When Driving; GM Website Differs - GM Inside News Forum

EDIT: Read 'VOLT' iso 'Prius' in the title

[usbseawolf2000]

That doesn't make sense. How can all the current from the gas engine go through the battery and still drive the car? While the battery is charging, it can not discharge.

[Shawn Clark]

I'm puzzled by this as well. If all of the current is going through the batteries, then discharging from the batteries, there would be additional losses. How it would accomplish this simultaneously I do not know, but I'm not a EE either.

The proper question to ask is, "how much peak horsepower can the car produce once the ICE kicks in?" If it is less than 150 and anywhere near 72 then we have our answer.

Seems that GM doesn't know what they are going to build.

[Mormegil]

From what I read, all the ICE does is kick on to keep the battery at 30% capacity.

The ICE will run at a constant RPM, providing a constant current when on.

Since the electric motor won't likely be drawing that full current except when accelerating hard, the rest goes to the battery until it's at 30%.

[SageBrush]

ok, then the follow-up question to Shawn's is: how much contnuous energy can be drawn down from 30% battery SOC before the car says "ICE only" until I recharge ?

[Dozzer]

So, it must use the ICE/generator to directly power the leccy motors and keep the battery with spec ? Not exactly fuel efficient then.. ideal for a deisel though!

[DeadPhish]

Originally Posted by Mormegil

From what I read, all the ICE does is kick on to keep the battery at 30% capacity.

The ICE will run at a constant RPM, providing a constant current when on.

Since the electric motor won't likely be drawing that full current except when accelerating hard, the rest goes to the battery until it's at 30%.

From comments farther down in the thread it appears that the ICE will kick on and off as needed to keep the 'depleted' battery at about 30-35% of charge. When the upper limit is reached the ICE turns off and the e-motor draws down the battery again. At about 30% the ICE kicks in again and repeats. It appears that the charging would be short bursts.

GM's hope is that the 150 hp e-motor will not draw that much from the battery for say 60 mph cruising on the highway. IOW perfect conditions where the power needed is well less than 75 hp.

However perfect conditions are not always present. In 75 mph traffic, or against a headwind, or in stop and go traffic the 'draw' on the battery is going to be relatively strong - meaning that the ICE will be kicking on and off much more frequently. The statements all say that the ICE will be operating at it's most efficient state with the battery used for load leveling. I'm assuming that this means the Atkinson cycle.

That's something that needs to be monitored. How smooth is the 1.4L ICE? How quiet is it when charging? How often is it On - off - On - off - On - etc.

All the direct motive power to the wheels will be from the e-motor.

[spwolf]

Originally Posted by DeadPhish

From comments farther down in the thread it appears that the ICE will kick on and off as needed to keep the 'depleted' battery at about 30-35% of charge. When the upper limit is reached the ICE turns off and the e-motor draws down the battery again. At about 30% the ICE kicks in again and repeats. It appears that the charging would be short bursts.

GM's hope is that the 150 hp e-motor will not draw that much from the battery for say 60 mph cruising on the highway. IOW perfect conditions where the power needed is well less than 75 hp.

However perfect conditions are not always present. In 75 mph traffic, or against a headwind, or in stop and go traffic the 'draw' on the battery is going to be relatively strong - meaning that the ICE will be kicking on and off much more frequently. The statements all say that the ICE will be operating at it's most efficient state with the battery used for load leveling. I'm assuming that this means the Atkinson cycle.

That's something that needs to be monitored. How smooth is the 1.4L ICE? How quiet is it when charging? How often is it On - off - On - off - On - etc.

All the direct motive power to the wheels will be from the e-motor.

it seems to me that there is a lot of hoping going on at GM... They might suggest to Volt buyers to drive at 25 mph for optimal performance

[donee]

Originally Posted by Mormegil

From what I read, all the ICE does is kick on to keep the battery at 30% capacity.

The ICE will run at a constant RPM, providing a constant current when on.

Since the electric motor won't likely be drawing that full current except when accelerating hard, the rest goes to the battery until it's at 30%.

Hi All,

This is the definition of a series hybrid car.

The battery still has about the same HP as when fully charged. Something around 150 hp, if what I remember is correct.

The Battery will charge beyond 30 percent - on long down hills, of course.

Then on the next long uphill it will drop below 30 percent, and the engine will come on.

They will have hysterisous in this. That is, the engine probably wont shut off until the car reaches something like 40 percent. Then the car runs along down to 30 percent. This way, the engine restarts wont be so numerous to use up the hybrid efficiency.

[donee]

Hi All,

Lets get some reasonable understanding of powers here.

Level cruising without wind on the highway at 60 mph, in this size of cars requires about 15 hp. Not 75.

Level cruising without wind on the highway at 75 mph in this size of car requires about 25 hp. Power required to overcome air drag doubles with only this 25 percent increase in speed. But all the power at 60 mph was not aero-related, there is some rolling resistance, thus the power required is not doubled.

Thus, cruising into a 15 mph head wind requires about 25 hp too. Suprisingly, cruising into a 15 mph 45 degree side wind requires more than 25 hp. Because the CdA of the car goes way up. Both the A and Cd are effected. And this effect is more than the reduction in tangent wind speed.

The volt concept is an ideal way to use a diesel in a Hybrid. If the Volt is successful in the market, I will be supprised if they do not come out with a diesel option.