Put a rebuilt HV pack in our 02 - warmup cycle question

Discussion in 'Generation 1 Prius Discussion' started by Tryyn, Mar 13, 2021.

  1. Tryyn

    Tryyn Junior Member

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    Hey, fellow Gen 1 owners!

    Just got a rebuilt battery put in our 2002 (Green Bean Battery) with a new ECU as well. Took the car out yesterday to get some food (curbside pickup and it was 40* outside, didn't want to idle the engine in our '13 Accord just for heat, so we took the Prius.)
    First of all: the new battery seemed to perform great. Consistent with the few G1 videos I've seen from when the car came out.

    Interesting observation: blue coolant light went out, but the engine kept running. On our way to pick up dinner, the engine never stopped running. Ended up having to go inside to pick up the meal. On the way home, the coolant light was off the whole way. The drive included several stops that SHOULD have been long enough to invoke stage-4. The only engine stop was right after leaving a stop sign on our home street. EV'ed maybe a few hundred feet, including up our driveway, and parked the vehicle. Anyone have any info on the Gen 1 warmup cycle? Is there some sort of relearning the hybrid system must do after getting a new HV pack and ECU?
     
  2. Josey

    Josey Member

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    Did you install the battery or did someone else? (IDK how Green Bean works it). If I'd just put a new HV battery in and the ICE seemed to run more that it normally would at first I wouldn't be surprised just because who knows how long the battery had been sitting around and it may be that it still needs to get "topped off" in terms of charge. If Green Bean installs and puts a fresh charge on at the time, then this is irrelevant.

    The other thing that comes to mind is whether or not you were running the heat - you mentioned the thing about not taking the Accord. But the Prius generates cabin heat in exactly the same way - via the ICE. The heating is quite conventional and just comes from running a fan over a heater core containing engine coolant. So if you keep the heat going, the ICE will need to run more often to keep the coolant temp up. Honestly, if it was about 40F out and the car had a nice run, I'd think you should get at least a couple of minutes or more at full stop before the ICE had to run, but I don't really know. I'm really weird and in cold weather tend to turn the heat off whenever I come to a stop.
     
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  3. Tryyn

    Tryyn Junior Member

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    Yes, we had an installer come over and install the pack!
    The auto climate was set to 68, and the trip was a few miles each way. I was under the impression that the Gen 1 had ceramic heating elements sort of like a space heater to provide heat while the ICE wasn't running. Looking at the service manual it shows a so-called "PTC quick heater." The Prius also has an electronic coolant pump (that the Accord doesn't have) to maintain heat with the ICE off.
     
  4. Josey

    Josey Member

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    On the battery install, do you know whether the installer did balancing and charge at the point of install? Or did they just toss one in off the shelf? The latter is not an indication of a problem - just relevant to your question.

    On the question of heat, you can't get something from nothing.

    The "PTC quick heater" exists, but thinking it will heat the car for "free" is problematic on two fronts. One is that they are not very powerful, and the other is that they are electric. (That the heating elements might be made of ceramic doesn't change that they are electrically powered). On the first point, they are not going to keep the car at 68 for very long (if at all) when it's 40 out). On the second point, since they are electric they have to draw from battery power, and that has to be replenished. Even if it could heat your cabin adequately, it still means more ICE time.

    On the subject of the electronic coolant pump, that's just about whether coolant is still circulating when the ICE is off. It doesn't create cabin heat or circumvent any issues with regards to making cabin heat. The electronic pump circulates the coolant through the system, including your heater core. Your HVAC fan is pulling air over the heater core, heating it, the cabin, and you. But this means the heat is pulled out of the ICE coolant - no matter how it is circulated.

    If it's 40-ish F out and you want your cabin at 68-ish F - the heat comes from the ICE. You can't get something from nothing.

    In any case - back to your original question. My guess would be this: the newly installed HV battery still needed a full charge, so your ICE would tend to run more. You were out in the cold with the heat running, so your ICE would tend to run more.
     
  5. Tryyn

    Tryyn Junior Member

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    I UNDERSTAND that the PTC heater isn't very powerful. It's pretty much only there to provide a little warmth before the ICE is warmed up, similar to the heat-pump in the Prime. In your previous comment, you seemed to say that the only way for the Prius to heat the cabin is with heated ICE coolant.
    Sure the quick heater isn't very strong, but it's enough to get a little warm air going without a warmed-up ICE. The electric coolant pump allows coolant to circulate constantly, keeping the heater core hot.
    In a pure ICE vehicle, the coolant won't be moving when the ICE is off. As the heater cools down, no heated coolant will be flowing. The coolant contained within the core will be cold. AS SOON AS the coolant starts moving again, the core will warm back up and you'll have heat again. Tested in the Honda as well.
    Also, I was NEVER suggesting the idea of free heat from any of these sources. I know my thermodynamics.
     
  6. Josey

    Josey Member

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    Not sure if you were just trying to just teach me something or not.

    I'll just reiterate: "...back to your original question. My guess would be this: the newly installed HV battery still needed a full charge, so your ICE would tend to run more. You were out in the cold with the heat running, so your ICE would tend to run more."

    On the latter point, the PTC or electric cooling pump isn't going to change that by very much.
     
  7. ammdb

    ammdb Junior Member

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    My '01 has a mind of it's own when the IC engine runs or not. I have an after market battery, and a few times now the IC engine ran all the time, and the battery indicator showed it charged all the way to the top, which isn't normal. My guess is once in a while the ECU will occasionally overcharge the battery to help balance out the cells. Last time it happened the IC engine ran for about a half hour. After that the engine shut off like normal. Outside temp makes a big difference. I have a short commute, so engine doesn't have a chance to warm up in the winter, so gas milage goes down below 40mpg. In warmer months I can get closer to 50mpg.
     
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  8. Tryyn

    Tryyn Junior Member

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    Learned a bit more about the Gen 1 warmup. It appears that the ICE blasts flames down the cats for the first 30 secs, to warm them up ASAP. I have definitely observed that the ICE sounds different during that first stage. The first time I heard it, I thought it was a stolen cat! After that, ICE is programmed to run and run and run until the coolant reaches 70 degrees C. Then, one must stop the vehicle for 7-10 seconds to invoke Stage 4.

    Are there any other conditions that will invoke Stage 4, or is a prolonged stop mandatory?
     
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  9. Josey

    Josey Member

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    If this thing has a mechanism that "blasts flames down the cats" I'd like to know where to get info about that. No kidding. I'm asking the question. Anyone?

    It's obviously not relevant to cabin heat, but I still want to know.
     
  10. Tryyn

    Tryyn Junior Member

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    Very late ignition timing (retarded all the way) super-rich fuel mix, and higher idle speed. Boom, flamethrower.
     
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  11. Josey

    Josey Member

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    Oh that. I don't think higher exhaust gas temps (via rich mixture and retarded timing) for heating the catalyst are peculiar to the Prius. But the Prius does it too. I guess I just wouldn't have described it as blasting flames down the cats. Maybe apt tho.

    In any case, if your goal is just to get to golf cart mode, all mine requires is to be up to full operating ICE temps with a "full-enough" HV battery. Sorry that I can't specify precise thresholds for either ICE coolant temp or HV charge. Never went through the trouble to find out. But I don't need to come to a stop after getting the ICE to temp to have the ICE shut down. All I need to do is come full off the accelerator. My dogbone mount is a little sloppy by now so I can tell when the ICE shuts down/starts back. Then if you want to avoid ICE start up, you can't ask for much more from the accelerator than you'd get from laying a feather on it. Super light "coaxing" to keep things up to speed. It doesn't take much for the computer to decide that the MG2 needs help from the ICE. Coming full off the accelerator, whether riding at 70mph down a hill or coming to a full stop it takes I'd say something like 1-5secs for ICE shutdown.

    I re-read your initial description and what you described is not inconsistent with just having had a "new" (rebuilt) HV battery installed that still needed charge and balance. Have you been driving it much? And do you still think it runs too much when you come to stops?

    Top reasons the ICE keeps running at a stop: 1) the engine isn't warm enough; 2) the traction battery needs charge; 3) the A/C is compressor is running.
     
    #11 Josey, Apr 12, 2021
    Last edited: Apr 12, 2021
  12. Tryyn

    Tryyn Junior Member

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    Is "golf-cart mode" EV mode? I read that after 70 C ICE coolant temp, the ICE must do an "idle check" at a stop for 5-10 seconds in order to confirm proper ICE operation (so it's sure the ICE can start instantly if it needs to). Full operating temp cancels that requirement? I am not surprised that it would.

    Regarding A/C, the Gen 1 has a thermally insulated evaporator core that keeps cooling when the ICE shuts off. Evaporator core temp is a factor that can restart the ICE momentarily to run the compressor. The defroster, though, will force the ICE to run.

    The only thing I don't get about the A/C: I have an insulated evaporator that can blow cold air for a few minutes with the ICE off, even if the fan is blasting. Why can't I run in EV mode with the A/C on, except on LO fan speed?

    As it's gotten warmer, I have noticed that there is less of a warmup cycle and the ICE shuts off sooner. Went from mid to high 30s to low 40s MPG.
     
  13. Josey

    Josey Member

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    I can't comment on the details of the A/C functions including any form of thermally insulated evaporator core. I'm wondering if some of what you are reading isn't from later/more recent Prius models as the Gen 1 doesn't have a genuine EV mode. With regards to an insulated evap core, whatever it's nature, it can't actually create any cooling because only the compressor can do that and the Gen 1 compressor is belt driven - which means ICE driven. If there's some manner of insulation of the evap core beyond the normal all it would do is make sure that more of the cold goes to the cabin rather than ending up elsewhere. But that couldn't last long. I'm pretty sure that either way in the Gen 1 if the A/C (or defrost - as that usually means compressor running) is on then the ICE is running. I stand to be corrected on that.

    By the standards of the time, the Gen1 was rather innovative, but by today's standards its rather primitive. As I understand it, it doesn't technically have an EV mode. By "golf cart" mode all I meant is having the thing running or stopping without the ICE running. After coolant reaches 70C it will go into hybrid mode and under some conditions shut down the ICE for golf cart. But it can't do much that way. It's really an ICE powered car with electric assist - not an EV at all. It might have a 5-10 sec "idle check" but if it does that would only be after initial warm up, and by my experience it would not require coming to a full stop - just full off throttle. The bottom line though is that the ICE is going to run most of the time while driving. If the HV battery is doing well it should shut down pretty much right away or a w/in a few secs of stopping - unless the A/C is running or the coolant isn't up to temp.

    All ICE engines get better gas mileage when it's warmer. There are a whole host of reasons for worse fuel economy in the cold, including the longer warm up period; denser cold air means more fuel for proper A/F ratio, and more drag; often people don't check their tire pressures which go lower with cold; and so on.

    My '03 gets anywhere from 40-50, but that mostly depends on who drives it most and the season. (My wife is miss crazy foot on the accelerator. My son is not far behind her. My daughter is far better, but I beat them all since I "get it" in terms of how to drive for MPGs). I'd also add that I have a set of winter tires that I can put on the Prius and that drops like 10% mpg as near as I can tell. In the summer with regular passenger tires, and if I stay off the interstates, and if I specifically drive it for MPG I can get low 50s on average. In the winter with winter tires and a good deal of interstate use, even with me driving it it's more like 41-42.
     
  14. Tryyn

    Tryyn Junior Member

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    Gen 1 absolutely has an EV mode. Up to 40 mph under light throttle, with the right conditions, the engine will stop and the vehicle will be propelled solely by MG2, in the same way as a pure electric vehicle, hence the term 'EV'. I've heard other Gen 1 owners call it "stealth" as well.
    You may be confused with the "EV" DRIVE MODE on the Gen3 and up.

    By definition, an "ICE with electric assist" would be something like a Honda Insight Gen 1, or a DIY system where you swapped a powerful electric motor in to replace the alternator. Such a system would provide a low-end torque boost, may help delay transmission downshifting, and would stop the engine when stopped at a traffic light, and spin it back up when the driver lets off the brake. In no way would I consider a dual-motor eCVT drive to be an "electric assist".

    As for A/C, I am SURE this thing has some form of thermally insulated evaporator core. Last summer, it was sunny and 85 F out, we were going for an emissions test, and had to wait in a long line. The ICE was off for several minutes at a time and only ran in approximately 30-second bursts to generate more cold when it was needed. A traditional vehicle would be blowing ambient-temp air within 15 seconds of shutting the engine off. More modern vehicles with auto start-stop have similar thermally insulated evaporators.
     
    #14 Tryyn, Apr 17, 2021
    Last edited: Apr 17, 2021
  15. Josey

    Josey Member

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    Yeah, I already described the conditions for running without ICE above, so I get that. I drive to maximize "EV mode" as you want to call it. I just call it golf cart mode. After 70C coolant, it's basically all about throttle position - and/or heating/cooling. I do associate the specific term "EV mode" with the later models that have a literal EV mode selection. But at that point we're into semantics. It is basically an ICE car with electric assist. You simply can't get much out of the thing without the ICE unless you need almost zero throttle - otherwise the MPGs would be much higher.

    In any case, whatever it is that you're trying to figure out, I'm obviously not helping. So hopefully others will come around and tell you whatever it is you want to know.

    Cheers and best of luck with it.
     
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  16. dolj

    dolj Senior Member

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    Regardless of the mechanics of how it is achieved, it is still not an EV with a gas engine, it is a gas engine with electric assist.

    I do agree the Toyota design is superior to Honda's IMA system.
     
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