Stages of Hybrid Operation

[efusco]

A couple of the new folks getting the CC EV mod done have brought up issues about the stages or phases of hybrid operation and what occurs in those phases and when/why the EV mode can't be entered during that time. I found Tosh's old post on the subject where he posted the info contained in the Japanese owner's manual. Here's that post:

You can't get into EV if you press the button when:  

1. Vehicle speed is above 55 km/h (34 MPH)  
2. Vehicle is accelerating and needs ICE assist  
3. ICE is not suffieciently warmed up  
(But you can press the EV button right after the startup (in 7 seconds?) before the ICE starts.)  
4. SOC is low (3 and below?)  

The item #3 is somewhat complicated. According to a Japanese site, there are 4 \"stages\" in THS (1 or 2) depending on the coolant temperature. Obviously, S1 will not allow you to start EV mode.  
Note: all temperatures in celcius.  

S1: (below 40C) ICE runs no matter what.  
S2: (40C - 69C) ICE stops when not in acceleration  
S3: (above 70C) \"half hybrid\" or \"idle check\" stage  
\"If the coolant reaches 70C, the car is in S3. In this stage, if you can't go up to 55km/h, the ICE will not stop no matter what you do until you come to a stop and wait 10 seconds. If you reach 55km/h and above, the ICE stops when your foot is off the gas pedal. But the car will be in S3 until you stop for 10 seconds.\"  
S4: (above 70C) If you stop with shift positon \"D\" in 10 seconds or more, the ICE stops and you are finally in S4 or \"complete hybrid\". The behavior is the same as S2.  

They say it is very important to avoid S3 as much as possible to improve the MPG (or km per litre).  

If you don't see 99.9 MPG when you (think you) are regenerating or gliding with no arrows from the ICE, you are in S3.  

Here's one interesting usage of the EV button. If you are in S3, you can press the button to temporarily stop the ICE. But it won't get you into S4. You have to come to a complete stop and wait for the ICE to stop.  

US owners have a lot of benefit with a thermos to avoid S1 as much as possible. If you park and restart while the system is hot, you start from whatever stage, depending on the coolant temperature.  

Tosh  
Salsa Red BC  
San Diego, CA

Also;

First of all, some corrections in Temperature and speed thresholds. See below  
daniel wrote: › Select ›‹ Expand
ozt wrote: › Select ›‹ Expand

S1: (below 40C) ICE runs no matter what.  
S2: (40C - 72C) ICE stops when not in acceleration  
S3: (above 73C) \"half hybrid\" or \"idle check\" stage  

\"If the coolant reaches 73C, the car is in S3. In this stage, if you can't go up to 60km/h, the ICE will not stop no matter what you do until you come to a stop and wait 10 seconds. If you reach 60km/h and above, the ICE stops when your foot is off the gas pedal. But the car will be in S3 until you stop for 5 seconds.\"  
S4: (above 73C) If you stop with shift positon \"D\" in 5seconds or more, the ICE stops and you are finally in S4 or \"complete hybrid\". The behavior is the same as S2.  

They say it is very important to avoid S3 as much as possible to improve the MPG (or km per litre).  

If you don't see 99.9 MPG when you (think you) are regenerating or gliding with no arrows from the ICE, you are in S3.  

I am a little confused about S3. I think it means the following:  

If the coolant was below 70 C, and it reaches 70 C while the car is moving, and you are moving slower than 55 km/h, you remain in S3 and the ICE will not stop. You can then make the ICE stop, and move into S4 only by either exceeding 55 km/h or by stopping for 10 seconds.  

Can someone tell me if I have this right?  
 


In S3, if you go above 60 km/h, then stop accelerating, the ICE stops. If you end up below 60km/h, then coast, the ICE won't stop. Until you come to a stop for 5 seconds and more, you will stay in this mode forever. If you find the ICE is running, increse your speed above 60 km/h, if you can. This will temporarily stop the ICE. But you are still in S3. I know it's complicated. I'm still not sure if I fully understand it.  

daniel wrote: › Select ›‹ Expand

Aslo, S2 seems to mean that the ICE stops when the car is not accelerating, but the car will not go into electric (stealth) mode, although it can draw power from the ICE and the battery simultaneously.  
Is this correct?  

Hmm, interesting point. But you can press the EV button to force it, though. (At least they confirmed this.)

[rflagg]

Very interesting info, even though I do not own the EV mod - I have noticed being in S3 occasionally, and it was frustrating knowing that I would have to bring the car to a complete stop to 'get out' of this sometimes - and then recently found if I accelerated fairly hard, I could get out of it sometimes as well. Now, knowing exactly what the car is looking for, it'll be hopefully easier to achieve that in those otherwise frustrating moments (which, with this car is few and far between!)

Thanks again, Evan!

-m.

[daniel]

Hmmmmm. That's different than I thought I remembered. I thought that either getting up to speed or stopping for 10 seconds was the trigger for full hybrid operation. The above seems to state clearly that you must come to a full stop for five seconds in one version, or 10 seconds in the other.

I try to make a stop when I think the engine is warm, but I have no way of knowing for sure when this is.

What possible reason can there by for not simply going into S4 as soon as the ICE is up to temperature???

And what about folks who have to get on the highway before their ICE is fully warm? They'll be stuck in S3 forever!

[efusco]

That's not the way I read it, I read it as exceed 63kph OR stop for 10 sec.

[mikepaul]

Well, the 5-second stop thing may also be working to let me use battery power after stopping at a light outside work, but if I can just make the turn and head in, I must need to speed past 34MPH before I can get away with electric cruising at 25MPH. Easy to do, but only if I knew I needed to do it. I'll have to try to test it out when I'm not coming in to work early anymore.

Coastal needs to add a coolant temperature display...

[mboileau]

Okay, it looks like someone did a good job of translating the Japanese into English. But can anyone translate the English into idiot-speak?? I thought I was pretty good at this stuff, but to be perfectly honest, I feel like I need to have a state diagram glued to the windshield to know what I'm doing....

How about if we just describe the scenario(s) that would keep you in S3 indefinitely. This seems to be the only case we're really concerned about. So if I'm interpreting this all correctly, the worst case would be my driving from my house to the corner store at a speed less than 55km/h (since it's a residential street) and no stop signs or lights between the two locations. I'd be in S3 all the way, right? So if I want to use EV mode for this little jaunt, which would be most likely use of it other than parking lots, I'd have to come to a complete stop part-way there, wait for either 5 or 10 secs and then switch to EV mode for the remainder of the short distance. Not exactly what I hoped for, but I can live with it if I can ever understand it...

[efusco]

Okay, it looks like someone did a good job of translating the Japanese into English. But can anyone translate the English into idiot-speak?? I thought I was pretty good at this stuff, but to be perfectly honest, I feel like I need to have a state diagram glued to the windshield to know what I'm doing....

How about if we just describe the scenario(s) that would keep you in S3 indefinitely. This seems to be the only case we're really concerned about. So if I'm interpreting this all correctly, the worst case would be my driving from my house to the corner store at a speed less than 55km/h (since it's a residential street) and no stop signs or lights between the two locations. I'd be in S3 all the way, right? So if I want to use EV mode for this little jaunt, which would be most likely use of it other than parking lots, I'd have to come to a complete stop part-way there, wait for either 5 or 10 secs and then switch to EV mode for the remainder of the short distance. Not exactly what I hoped for, but I can live with it if I can ever understand it...

Ok, idiot simple....
When the engine is warming up you can't do it.

Listen, there's little point in using EV mode at any time except for moving the cold engine car (i.e. across a parking lot). Or if you will have a segment at start up or at the very end of a trip where there will be multiple slow-downs or stops but you know you don't need the ICE.

When the ICE is up to temp, mid-trip, then just let the car decide what to do, b/c 99 times out of 100 what you chose will be less efficient.

[kam]

What I don't really understand is what is the car expecting when it's in the S3 stage? The engine is warm yet it continues to be run for what purpose? It's all quite fascinating.

[ozt]

Thanks, Evan, for diggin up my old post. I just did another posing in the "I DID IT!" thread.

So, what's the purpose of S3? It is still a mystery among Japanese hybrid geeks. I hope somebody will have a chance to ask this to a Toyota engineer.

If you get into the freeway before the warmup is done, you will be in S3 forever. But this is not really a problem as long as you keep running above 42 MPH. You will be in S4 at the first stop after you get out of the freeway.

The only bad situation I can think of, is when you get into a moderately jammed freeway, where you cannot go above 42 MPH but also cannot stop for more than 5 seconds. If you try to avoid all the negative gehaviors in S3, you will end up hitting the EV button every time you deaccelate, and hitting it again before you acccelerate... I've never been in this situation, though.

Tosh
Salsa BC + EVb
San Diego, CA

[daniel]

That's not the way I read it, I read it as exceed 63kph OR stop for 10 sec.

Tosh says, in the I DID IT thread, if you exceed 55 km/h the engine will stop when not accelerating, but you still need to stop for 10 seconds to get to Phase 4.

However, it seems to me that I've gotten into EV mode (by feathering the pedal) after a brief burst of speed on a warm engine, without ever stopping for more than a second or two at stop signs.

However, the road where I can double-check this is currently closed for construction, and the other one requires great luck at the intersections to avoid stopping long enough to rule out the 10-second stop as a necessary trigger.

A high priority now is to try engaging EV via the switch when the engine is warm but I have not stopped for more than a couple of seconds or gone over 25 mph. Maybe tomorrow morning.