Engineering Explained: How much fuel does idling consume?

[euromodder]

Originally Posted by Vman455

25% of the NEDC city test is spent idling (vehicle stopped), compared to 11% of the EPA city test. So, a stop-start system will have an outsized effect on a European rating, but still a significant impact on an EPA rating. I wonder how that compares to a typical driver and trip.

That's the reason they were introduced here ...

On a typical tank, the effect is utterly negligible.
In stop & go traffic, I and many others shut it off so it doesn't constantly stop/start the engine.

On my car, it also stops the A/C which is uncomfortable when that's needed.

[Angel And The Wolf]

My Prius uses stored voltage to start the engine, and that voltage would be subtracted from that available to propel the car when the ICE is off (down grades, etc...)The fuel required to replace that small voltage usage would need to be calculated in. Still, I believe Stop/Start systems do save fuel. The concern about oil pressure could be addressed, as is air conditioning, by driving the oil pump electrically. Super-insulating the Cat can lessen the idle time needed to maintain operating temperature, and keep the ICE from re-starting just for that purpose. The video only addresses Stop/Start at zero vehicle speed. My Prius Stop/Starts in many instances while the vehicle is moving.
These situations should be considered, though I do not believe additional fuel is required to re-start the ICE while the vehicle is in motion.

[Angel And The Wolf]

Originally Posted by ProDigit

Hondas are well made.
However, I believe shouty, when he mentions about certain cars having a regular starter and started stopping technology. Almost every vehicle I know, had to have at least 1x starter exchanged in it's lifetime.

I'm not sure my Prius has a regular starter. When I push the button in the morning, the ICE does not come on for several seconds. I believe the electric motors spin up, and then engage the ICE through the transmission.

[Angel And The Wolf]

Originally Posted by Frank Lee

Re: start/stop systems: I see various comments online about lube specifically no oil pressure starts. They seem to equate cold starts with hot starts and there really shouldn't be much comparison as far as engine wear. They forget that an oil film stays on the moving parts. If I were to subscribe to their theory, all my splash-lube engines should fail prematurely as they NEVER get pressurized oil.

Yes, dry starts are only after hours of being off, not minutes, and it may well be that some Stop/Start engines pre-pressure the oil, electrically, before starting the ICE.

[Angel And The Wolf]

Originally Posted by ProDigit

Priuses use their electric motor to start the engine, so yes, they do use lithium batteries (the trunk battery) to start the engine.

Unfortunately, my 2011 Prius has a nickle metal hydride battery. (I WISH it had a Lithium Ion battery!) However, I believe the "Starter Motors" are the Electric Drive motors. Correct me if I am mistaken.

[Angel And The Wolf]

Originally Posted by ProDigit

Yeah, well, the priuses have as benefit that they depart using the electric motor,.........and once the 12V battery is depleted, they don't generate enough momentum for the engine to start.

The Prius DOES depart using the electric drive motors, but the 12v battery does NOT power those motors,they are powered by a 201.6 V 6.5 Ah battery (traction battery) located uder the rear seat. the 12v battery IS important for the computers, and if depleted, the Prius won't operate.

[Angel And The Wolf]

Originally Posted by redpoint5

The workaround is bring a portable 12v jump pack that you can get for as little as $20. They double as USB phone chargers and flashlights. You can jump the car just like any other too.

Yes, and my portable jump pack has an air compressor for the tires.

[Angel And The Wolf]

Sorry for re-answering what has already been answered here, but I replied as I read through each post.