Full-battery downhill engine start is a pain!

i think the range meter is adaptive, that is, it's constantly computing kwh/mile used and updating the range. so the miles remaining is not a good indication of SOC.

by the way, i just took a drive right now starting with a full battery again. when i went down the very modest hill near my house (maybe a 50-75ft elevation change) the SOC went up enough for it to start the ICE.

it's too bad toyota does not have an 80% (or even 90%) charge option so that you can avoid starting the ICE when you live on a hill...

i have a scangauge plugged in so i'll try to be more careful about seeing at what SOC it kicks on the ICE.

 

keep in mind, it's not 'firing up the ice'. the ice spins without using fuel to use up the extra charge you're regenerating when your battery is already full. the non pip does the same thing.

 

ok, on my 2nd trip today, the battery was full. the scangauge reported 83.9% SOC after i fired up the car. as i went down the hill the SOC went to 85% and boom, the ICE started. this is a bummer, folks.

i still averaged 99MPG on a 16 mile trip with a 600 foot total elevation change. ICE kicked in a few times, at the start of the trip, as reported, then on the freeway a couple of times as my speed exceeded the threshold. came home with 7 bars showing and EV mode off. pretty good.

 

For 10 days, my night charges are between 3.2 -3.3 kWh

 

excellent! charge it a bit less than full, it won't fire up on the downhill and your electric bill will be lower.

 

well... not so much. i think if the engine is already hot this is the case. but here, since the engine is cold i think they just go ahead and run it. the scangauge shows fuel flow and there was definitely fuel being burned.

 

sure, except that this would require manually monitoring the SoC and unplugging it before it's full... not going to happen on a consistent basis for me.

 

It seems that the only way you can prove the engine is running is by detecting Carbon Monoxide, going to the rear of the car and smelling the exhaust. As far as I am aware, if you hear what sounds like the engine or see the engine driving on the MFD. This can be and is false information and until warm-up stage is initiated, all you are really seeing and hearing is the engine spinning. It is not something to even consider, no less worry about. This same symptom ocurred on all the Prius generations, the real difference is because of the plug-in the car is starting out with a full charge. On other generations this did not occur until the battery was fully charged ( 80 % ) In the 12 years+ of Prius ownership, nobody, ever, worried about the HV Battery charging too much! If you want to be concerned, worry that the HV battery is staying cool.

 

Not sure it would work for PiP as I don't know the charge protocols, but on the Volt you can set charging that uses the time-of-day rate data, and by playing games with the "rates" you can get some interesting charging timing. Telling it to charge at lowest rate, giving it a time to finish well after when you really want to leave (with cheap rates after you really want to leave) you can get it to charge the time you want.

 

[QUOTE
it's too bad toyota does not have an 80% (or even 90%) charge option so that you can avoid starting the ICE when you live on a hill...

That's a good point with the Leaf you can charge 80% or 100%...80% to preserve battery life, but in the case of the PIP it would be a matter of saving electric and gas for those that live on a steep incline. This way the ICE won't have to burn off energy to prevent over charging of the traction battery. It would be easy for Toyota to set the software so you could select to stop the charge short of full. Toyota listening?

 

If it's full you could try turning the car on and then rev the motor a bit to drain the battery.

 

well that is very strange. i wonder if there is a software problem?

 

do not know but as we all know the engine start/warmup 'flowchart' is really complicated on any prius. maybe ken@japan will have something to say eventually.

 

that's true, it might then 'contain' the ICE running to just as long as you tell it to. still, using any gas at all is a bummer. it's the difference between infinite MPG on short trips and triple-digit MPGs...

for me though electricity is just about as expensive as gasoline, so it kind of does not matter from a cost perspective.

 

As far as I know the Plug InPrius will, once the Ice starts, run the full warm up cycle no matter what. (Well you could shut the car off in the middle while costing in Neutral and then maybe restart). Don't think the Ops point was saving the money either but about the principal of the thing.

 

Interesting... Volt uses the loss in the motor and power control unit (inverter) to assist in braking. Heat would built up in both electric motors and the inverters and then waste them on the radiator through coolant.

I sure hope, the inverters are built to last.

 

Prius protects the battery as a top priority.

Have you tried braking harder to engage the friction pads? How about shifting into N to stop the regen?

 

I don't own a pip, just a regular prius but I think you are right here. Going down a hill my prius will regen until the battery is full, then engage engine braking automatically even when in D (to a very high rpm depending on circumstances).

I suspect that once your pip decides to engage engine braking because the battery is full, it also decides to warm up the engine to prevent damage from turning it at high rpm when completely cold (and full of cold coolant and oil) for any length of time. It even kind of makes sense from a reliability and maintenance standpoint since extended high rpms with cold oil/engine could be very damaging long term.

 

interesting point. ^

 

Yes. Definitely! Toyota, please get to work on this.

I live on a hill, and I don't want to have to fiddle with the charge time every time I come home with a little EV juice left in the battery. I just want to plug it in and have it charge up with enough room to top off the battery through regen when I head down the hill...

I know Toyota had some of the prototype PIP's in my neighborhood, and I am surprised that they did not address this situation.