[WARNING] Running out of gas (Gen III)

Tonight I found that running out of gas in my VZW30 (2010 Prius) completely removes all traction battery power. There is no motive power to get to a 'safe place' to refill. I was able to coast to a parking lot but basicly:

• power steering failure icon - this is the only warning light, IMHO, totally inadequate
• all power indications 'off' - it is as if the car had been shifted into "N"
• shifting to "N", stays in "N" and does not return to "D"

I can buy a new traction battery and have no problem with being put in "EV" mode. But the car would not shift into "D" nor respond to "EV." Compared to the NHW20 and NHW11, this means a valuable safety feature has been lost.

Trying to run out of gas, on flash, the first time it went:

• 122.1 mile
• 56.6 MPG
• 2.156 gallons, 1.6 gallons in handbook

The only indication I got of a problem was "electric steering error" icon flashed up. Not sure what it was, I was going down hill and pulled over into a parking lot and put my spare gallon in. The error indication cleared and I was off to fill-up.

Second running out of gas on flash, it went:

• 132.6 miles
• 60.8 MPG
• 2.18 gallons

However, this time I had just crested a slope on a limited access road with no shoulders. Fortunately, I had momentum and coasted off the road into a parking lot. Had there been stopped traffic or other hazards, I would have been in a four-lane road, 50 mph (80 kph) with a car totally inert:

34 40' 13.35" N 86 34' 25.67" W

You'll notice this is on a limited access highway just as I was approaching a merge lane for traffic from Martin Road. During rush-hour, this area is 'stop and go' and having the ability to move through traffic, even if limited EV mode, would be the difference between a safe and very hazardous stop.

Absent a return to a 'limp to the side of the road mode,' I can no longer support running out of gas as "no big deal." In fact, I believe the former behavior of the NHW20 and NHW11, to continue on traction battery, to be a superior safety feature to this "coast to a stop NOW!" behavior:

• I can buy a new battery even if I damage it getting to a safe place, off the highway.
• Dead because my Prius stopped on an unsafe place and an accident occurred, it would be hard for the dead guy to buy another Toyota battery or Prius. The accident rate for the Prius would go up and potentially, the insurance rates rise. Worse the Prius will lose the justified reputation for a safe vehicle.

Bob Wilson

Re: [WARNING] Running out of gas

Bob,

I agree that this is a safety concern. On the other hand, running out of gas is entirely preventable. In my 40+ years of driving, I have NEVER run out of gas. My practice is to always gas up when I get to 1/4 tank.

Is there something about the Prius gas gauge that makes it less informative, so we can't quite tell if we need to gas up? I'm not being sarcastic: I don't have mine yet, and I have noticed threads that seem to indicate that it's difficult to determine how much gas you have and how far you can go on it.

Re: [WARNING] Running out of gas

I appreciate this discovery has come as a shock to you, and in your eyes this is a step back from the Gen II, but I don't see this as being any different from running out of gas in a conventional car. I would guess thousands of motorist run out of gas in conventional cars and they don't all die in horrible accidents.

Re: [WARNING] Running out of gas

The absence of a bladder suggests the fuel indicator is more accurate than it was with my NHW11 and the reports on the NHW20. That in two fuel exhaustion tests, the remaining fuel values are the same with a very small error, 2.16 vs 2.18 gallons, suggests we can trust the fuel indicator.

Until we get a return of "limp to side of road" mode, even EV limited to 9 mph would be enough, running on flash is risky. It is too risky for me to feel any need to replicate this experiment with one exception. I did not try to turn off the car and then power it up again and hit "EV" mode. But having to do this cycle in the middle of traffic is nuts compared to just switching into "EV" mode and a 'host of errors.'

Properly designed, I would like to see:

• turn on hazard lights - automatic when the fuel runs out, let the operator turn them off but put them on automatically
• fuel oriented flashing lights - all fuel level bars flash ON/OFF
• 9 mph EV mode - this at least lets the vehicle reach a shoulder or safe parking area

I can replace a battery, replacing a life is a lot harder.

Bob Wilson

Re: [WARNING] Running out of gas

It sounds like we have enough data to simply realize that when we're "empty" we still have approximately 2 gallons of gas or about 100 miles to fill up. That should be enough miles for anyone to find gas or a place to pull over and stop.

If many people are unintentionally running out of gas then they need to develop a reserve like on my seadoo. That is you have to turn a knob to access the reserve. That way it's always there when you need it.

Re: [WARNING] Running out of gas

I'm guessing they designed it this way to help protect the battery after some folks have killed their battery by running on it for an extended period.

I'm with Timberwolf -- it's no different than most every other car on the road.

Re: [WARNING] Running out of gas

Bob,

IIRC, on the Gen II, there is a all too brief flashing notice of low fuel
sometime while one pip is showing on the guess-gauge. Far too little
notice in my opinion. ( I'm a "fill up at two pips" kinda guy. Haven't seen
only one pip yet.)

Has there been any change in this irksome detail in the Gen III?

Re: [WARNING] Running out of gas

In over three dozen 'running out of gas' events (planned) with my NHW11, I found:

• 130 miles - longest distance on flash (the first)
• 65-70 miles - median
• 25 miles - shortest (occurred while merging into traffic on a limited access highway ... I simply went on battery to a safe shoulder about 150 meters down the road)

That is the simple technical experiences I've had. Understand the following is a general answer, not specific to anyone, to those who may think the answer is to "never run out of gas."

I consider having an automatic EV mode when the engine runs out of gas just like having a seat belt when having an accident. Sure it is easy to say, "Just don't have an accident" but that is not always avoidable.

I don't care if someone else never has to use their seatbelt or air bags. In fact, it is a good day when no one has to use their seatbelt or air bags. But there is no reason for a $24-30,000 car to "protect itself" by stopping in the middle of a hazardous highway or traffic situation instead of using that marvelous traction battery to at least make an effort to get to safe place.

The issue is black and white:

• Save the hardware?
• Save the human?

Those who say, "Just never run out of gas" are echoing the old refrain, "Never have an accident" or "Never be unlucky." Tools serve the man and the accident that kills the out-of-gas driver will also destroy the out-of-gas but fully capable Prius with a charged traction battery.

Before safety interlocks became popular, any manual transmission car could be moved out of traffic by:

• put in first gear
• turn the starter

You won't be going anywhere fast but if you are behind a blind corner, you can get to a shoulder or out of the way so you won't be hit. The safety interlocks are there so folks won't drive through their garages (aka., see "Car Talk".) IMHO, hitting "flash" should disable these interlocks so people could use the starter motor to reach a safe place.

Bob Wilson

Re: [WARNING] Running out of gas

Bob,

My previous question was purely information seeking and technical in
nature. It was not meant to be a goad, or otherwise diminishing to your
underlying concern about safety of human life.

My most sincere apology if I came across as insensitive or flippant.

Re: [WARNING] Running out of gas

Who runs out of gas? :flypig: I always thought that was a myth!
Seriously though, stop running out of gasoline. It IS extremely easy NOT to run out of gas. If you think it's like trying to avoid an accident then you're insane and probably rely on others way too much. Sack up and take responsibility so you don't cause somoene else to hit you on the highway. You're driving dangerously.

Re: [WARNING] Running out of gas

I owe you an apology!

I transitioned from a technical answer to a general reply to those who think it is not important ... 'just don't run out of gas.' Had we all been 'face to face,' my body language would have made it clear that the second part was addressing those who would diminish the importance of this safety feature.

Hopefully I've addressed my NHW11, running out of gas experiences. In over three dozen cases, it has been a bit of a 'crap shoot' on how long the car would go before the engine conked out. It was completely unpredictable and ranged from 25-130 miles. But I always had the safety of being able to pull over to a safe place to refuel.

BTW, this also addresses those who would use fuel starvation to stop the engine. The new mode means the car is going to come to a stop and not proceed. Sorry, but I think losing a safety feature because of a few modifications is wrong, just plain wrong.

Bob Wilson

Re: [WARNING] Running out of gas

Bob, my TCH might have had a different warning system than the Prius. I am interested in the reserve as on daytime trips I really don't see filling up with 100 miles left in the tank when there are gas stations every 10 miles.

So when you are measuring and you say first "flash". Is the miles to empty still reading 30 to 50 and you get the warning light (that's the way my other Toyota's are). Is there more than one flash? My light just comes on and stays on.

Thanks for all the experiments you're doing!

Joe

Re: [WARNING] Running out of gas

Thanks Bob, good to know the amont of fuel remaining at flash.

Re: [WARNING] Running out of gas

mmmm

maybe toyota thinks running down the battery will damage it..
and if you drive off aftere a empty tank like in the prius gen 2 and are able to lose the DTC;s nobody will now there is a maybe damaged battety in the prius.?

or there just needs to be a software upgrade!!!!

even if the prius will not lett you drive on EV.. there needs to be more then the warning you got bob.... not good thing this

Re: [WARNING] Running out of gas

I ran out of GAS twice in my 06 Prius... I agree that if the 3g car does not work in the same way this is bad. I had told many of my friends about what happens when running out of gas in 2g and they thought it was very cool. You can safely get out off the road when running out of gas in 2g Prius, both times I made it to the gas station.

Fun Thread “How Far would you driving on blinking pip, or Guess Gauge Part 2”

http://priuschat.com/forums/gen-iii-2010-prius-main-forum/62505-how-far-would-you-driving-blinking-pip-guess-gauge-part-2-a-2.html#post861988


My fun story post # 7,

Re: [WARNING] Running out of gas

Thanks for this info Bob. I'll be new to the Prius and have been reading lots of warnings about letting the gas go too low. You're tests are proving we all need to be careful not to run it out!

Re: [WARNING] Running out of gas

The two times I checked, it showed "0 miles remaining."

Bob Wilson

Re: [WARNING] Running out of gas

Am I missing something? I have a 2004 and I rely on the mileage screen to gauge my fuel level. I look at the MPG I have achieved on a particular tankful and multiply it by 10 (I know there is an 11.9 tank). I use this as a cushion. I've driven to the point of the last pip flashing and usually take LESS than 10 gallons when the hose clicks off. I am sure this discussion has taken place before but there are lots of newbies here that should read this. I for always procrastinate but I've never ran out of fuel. When that last pip is flashing you really need to gas up.

Re: [WARNING] Running out of gas

One of the negatives we see with our new GenIII is that MPG is not continually shown on the screens, as it was on both our GenII and GenI Prii. To find the MPG now (consumption), you have to find the right display, nd then the MGP is present in VERY small figures, a little dangerous to check when you"re 75 MPH down the Interstate.

Re: [WARNING] Running out of gas

Hello Bob:

Your experiments are hugely beneficial to understanding the characteristics of the new GIII.

But as others have mentioned, running out of gas is now no different than any other ICE powered vehicle. Maybe a step backwards from the GII, but nothing more.

Also, your analogy of saying "don't run out of gas" is like saying "don't get in an accident" is really not a valid comparison. As long as the gas gauge is functioning, you definitely have way more control of not running out of gas than you do of not getting in an accident.

Best wishes,

Frank