Last weekend I was tooloing down the NY State Thruway when the beep went off telling me to fill up with gas. No problem, I figured, for that meant I still had a gallon left and I could make it to the next exit. Well, there was not an exit coming up soon, and about 20 miles later the gas engine shut off, the big red warning triangle went on, and I coasted on electirc power at 53 MPH (I had the pedal to the floor, but that's the speed it went) another two miles unitl I saw a sign for an exit in 1/2 mile. At that point, the car stasrted slowing down, and I coasted to just before the toll plaza. Not wanting to get stuck in the toll booth, I pulled over to the side, and walked up to the booth to ask the attendent where the nearest gas station was. She said it was 1/2 miel down the road, and I started to walk, when I suddenly thought that I may be able to get a little bit farther on electicity by starting the car up again. I explained the situation to the attendent, paid her, got back in my Prius and started it, and went through the the toll booth on electric power. I continued on down the road, pumping the brakes every so often to generate more power to the electric motor, until I reached the gas station. I called my Toyota dealer the next day to bring the car in to see if I had done any damage to the engine, but he said not to bother, that everything was fine.
You should know that the 'pumping the brakes' thing cost you more power than it generated. And you're right, don't try that at home. IMO going 2.5-3 miles with the accelerator floored really put your HV battery...and your car... at serious risk. It is awefully suprising it ran out of gas only 20 miles after the "Add Fuel" beep.
Yeah 20 miles is short, I always get 1 gallons worth of distance once the last bar starts to flash (based on car MPG) 3 miles is about all you want to go on HV, coasting is better than pumping, and I believe leaving in gear and not Nuetral gains more potential energy for a last ditch "umph". Once your lawst two bars go grey then shut it off! That is the EMPTY signal. Lower than that and you risk damage
Now you have me concerned. Should I ignore what the service manager said, and bring the car in? If so, what specifically should I tell them to look at?
no, there'll be no visible damage and probably no real damage. Bringing it in will just result in documentation that you ran it out of gas and if your battery dies before the warranty expires it could, potentially, be used for denial of warranty service. The thing is that if you had completely drained the battery you would not have been able to restart and you'd either have had to replace the battery or wait a long time for one of the very few chargers that are in the US to come and recharge your battery. Deep discharges can also shorten the life. One of the only ways to completely discharge the HV battery is by forcing the car to drive after running out of gas.
Evan- I love you and rarely disagree with you but this just isn't true. The ECU is still there protecting you from any significant damage. The act of sitting in ready mode until the engine comes on to recharge is about the same amount of discharge. The difference is in how fast the drain occurs and the amount of heat that is built up as a result. Deep discharges are routine with heavy use of the EV button as you know. I would limit the number of occurences to lengthen the life of the battery, but we shouldn't scare people into thinking they may have damaged the battery. Folks- If you run out of gas and are attempting to make it to a station on electric power, follow these steps. 1 Foot off the accelerator. 2 Below 62 mph, shift to neutral if the road ahead is clear. 3 Below 30 mph shift into D and maintain this speed as gently as possible. 4 Only use the brakes for safety. 5 If you don't make it to the station and the car slows to a stop, give up and pull off the road. Do not attempt repeatedly to coax another start out of it. Note: Of course you should maintain safety and follow traffic laws at all times. Slow speeds are more efficient due to wind resistance and heating of the battery, cables, inverter, and motor.
I tend to agree - the ECU definately isn't going to allow the car to damage the battery. Besides, even when the battery meter on the display is totally empty and the car shuts-down, there's probably 20-30% capacity remaining in the cells depending on how Toyota has calibrated the readout - they'd be foolish to design it otherwise. Dave
I think you guys forget one thing. Yes, the ECU will shut the car down if the BSOC gets too low and ICE can't be started to charge it. So then, when you DO put gas in the car, if ECU says BSOC too low, don't go to READY, how do you expect to start the ICE to charge the HV batt? Yes, the ECU will give you a few more tries, but eventually, it will refuse to go to READY. So, you need the dealer to at least force the car to go to READY, and hopefully it will, ICE will start, and all will be well. If all of these do not happen, HV batt will need a charge. Repair manual does say that if HV SOC is too low to do anything, replace it, though I would agree there are probably chargers out there that would revive it.
The car will go to ready even when the battery stops providing forward momentum due to being too low. You can try multiple times to start the car and then add gas and the car will start right up. Don't ask me how I know. I don't eat right either. I went there so you don't have to and you don't have to worry about it. People run these cars out of gas every day and if it were even a slight problem, we would have heard about it here. When there is a problem with this car, people get online and find us. I would guess that the repair manual is talking about a hypothetical "SOC too low to start condition" I would guess this could easily occur if the car sat for a long time due to the self draining characteristics of NiMH batteries. What do you think Dan? Again, it's not a good idea but it is really nothing to worry about. If I need to worry about something, I'll worry about how much ice cream I eat.
I think that if you keep pushing it, restarting with no gas after low SOC shutdown, eventually it will quit for good unless intervened by a dealer. The reason you haven't heard anything is because nobody has pushed it that far. Running out of gas and crawling via EV with Christmas dash is probably scary enough to quit when HV says 'I stop now'.
