A Hybrid Owner’s winter survival guide

Discussion in 'Articles' started by msantos, Nov 20, 2008.

  1. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I had to replace the resistors on mine. I usually left it on 2, and when it burned out, 1 and 2 didn't work while 3 and 4 still did.

    I tested this. With the engine off, each notch of the fan speed dropped the voltage another 0.1V. Then, turning it back down each notch allowed the voltage to rise by 0.1V each time. So high fan IS drawing more power than low fan in my car.

    Volts ........ Fan speed
    12.3 ........ Off
    12.2 ........ 1
    12.1 ........ 2
    12.0 ........ 3
    11.9 ........ 4
    Last edited: Jan 14, 2009
  2. Mike78

    Mike78 Well-Known Member

    Very interesting, I stand corrected. I wonder if the resistor is actually working to bleed off SOME of the electricity (but not all)? Maybe it also has a buck circuit to impede the voltage at a corresponding rate to the resistor's load (so that the resistor does not have to work so hard?). I guess I'll have to check this myself tonight.
  3. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I don't know why. I'm sure they are burning some power into heat, because the resistors do burn out so easily. This is my second car to burn out the #2 resistor, leaving only 3 and 4 working.
  4. Mike78

    Mike78 Well-Known Member

    I think there-in lies part of the answer. On my 2000 Maxima (and several other vehicles I have had resistors go out on) a blown resistor results in fan speed of 4 (high) only. You on the other hand are left with two fan speeds. My laymens knowledge would say this is the return of the dual motor. That is to say I'm speculating motor 1 controls fan speeds 1 and 3 with a 1 stage resitor, while motor 2 control fan speeds 2 and 4 with a 1 stage resistor. There could be other configurations but you get the idea. This is in contrast to other vehicles which have one motor and a three stage resistor. More likely though would be the one resistor is wired to both motors - otherwise two resistors would had to have burned up simultaneously. Other that that the answer would be there have been dramatic changes in the way resistors perform, which I am not aware of.
  5. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I could be wrong, but I had assumed that for each lower speed, it added another resistor, like this:
    Speed 4 = no resistor
    speed 3 = resistor 3
    speed 2 = resistors 3 and 2
    speed 1 = resistors 3, 2, and 1
    0 = switched off

    Since resistor #2 burned out, both 1 and 2 didn't work.

    For the record, it was a Mazda truck and a Honda civic that both lost settings 1 and 2.
  6. Mike78

    Mike78 Well-Known Member

    Boy don't I feel like I dope. I always knew what resistors did and understood their working through personal experience but that was it. I think you're completely right. My experiences though must have always been in relation to resistor 3 (per your illustration) going out, while would disable fan speeds 1 through 3. I just assumed the whole thing was wired together somehow and if part of it failed the whole thing failed, but your explanation makes perfect sense. I guess it also makes sense that resistor 3 would go out the most since it is used more than any other. But it's totally possible to have other conbinations of failure as well (just resistor #1 or #2 as in your example).
  7. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    I'm just guessing. I didn't replace it myself, so I've never actually seen the unit.

    Sorry for the digression, all. Back to winter, I saved myself from window scraping this morning by using a whole-car cover last night. Roll it up, put it away, and drive off, leaving frost everywhere else but on the car.
  8. Jess

    Jess Well-Known Member

    In the mornings and afternoons I have been FASing at stop lights b/c the car has not warmed up yet. However, I have had a forced recharge every day. For experimentation, I have left the engine running in neutral at lights when the car is cold. I take a small hit to the FE, but I have avoided the forced recharge!
    And this afternoon with the battery at 5 bars, assist was not avail for a few minutes, even though it was at first. It wasn't forced recharging, but the system eventually warmed up and with some general recharging the system was assisting again. The battery eventually bumped up to 6 bars. It was such a pleasant experience b/c it normally will assist until the battery is depleted and then it will forced recharge. It's like it realized that it needed to stop the assist until it was able to recharge the pack some more to avoid forced recharging

    So far, throwing the car into neutral vs. FAS when it's cold is a better option. As MSantos has stated before the battery takes quite a hit when it's FAS and cold.

    I also noticed it's very difficult to increase the SoC when it's cold out. It took me the whole 15 mile commute to bump the battery to one bar. In warmer weather recharging it to full capacity is a non-issue.

  9. msantos

    msantos Eco Accelerometrist

    Hi Jess;

    I suggest you try the following next time it is cold and you're just starting the car:

    Start the car and accelerate gently for roughly 15-20 seconds up to a lower speed of at least 12 MPH and no more than 25 MPH.
    Then for a very brief moment gently apply the smallest amount of pressure on the throttle and withdraw it just as fast without slowing down. You'll notice that a 1 bar regen will appear and stay on. If you are having trouble getting it to appear then a brief shift to "S" will usually do it as well.

    When coasting and it is very cold you may find that the regen brakes don't work at all. To increase the dynamic regen affinity under these conditions simply switch to "S" until the regen appears then switch back to "D". From this point on the brakes regen will work. Note that this incresed regen affinity will be short lived and sometimes not even work until the vehicle reaches Stage 2 of warm-up.


  10. fuzzy

    fuzzy Mild hypermiler

    Resistor 3 should get hottest only in speed 3. Lower speeds should lower the current, and heating varies with the current squared, so temperature rise should fall off sharply in the lower settings. Likewise, R2 will be hottest at speed 2. Of course, R1 is used only at speed 1.

    For my entire adult driving life, my default fan setting has been Speed 1, to try to maintain positive pressure to prevent dust and and CO from leaking in any holes. (As a kid, I watched gravel dust absolutely pour in through weatherstripping gaps around the door. As a young adult, I heard about one or two cases per year of children sleeping in the back seat being found dead of CO poisoning. Maybe these were the reasons I got car sick so often as a child.) But in more than three decades of driving, with the fan nearly always on, I've never had a fan speed control fail.
  11. Mike78

    Mike78 Well-Known Member

    Stay tuned on this one. They seem to be making them cheaper these days. I never had a problem for years of driving (with the same sytyle as you of constantly leaving the fan on low) but then had them go out on both household cars recently (plus lots of other reports from friends and work vehicles). An indicator may also be vehicle make/model as when I used to wash cars for Enterprise I saw more than a dozen go out on GM vehicles.
  12. ksstathead

    ksstathead Moderator


    great article. I've sent several people here for guidance.

    One point occurred to me that might be worth mentioning. Those who have garages used to store stuff should make other arrangements and park in their garage. Particularly for attached or heated garages, there are multiple benefits. 1. Higher starting temp (with or without the block heater). 2. Tolerable cabin temp thus avoiding heater use during warmup. 3. The day's ice & snow can melt off, avoiding cold weather washing. 4. Warmer, dryer car is more likely to be maintained properly (tire pressure, fluids, etc.) 5. Never have to scrape ice in the morning. 6. Since our dog lives in the garage, she gets more love and affection and behaves better.

    My Tacoma gets pushed outside whenever we do a home renovation. My 1.5 mile commute then yields 10mpg on a cold (10F & below) morning. Parking indoors, blocking the grill, and not running the heater yields 15mpg in the same conditions, a 50% improvement. EPA city = 17mpg.

    Anyway, love the info, even for non-hybrids. Less grill block at a given ambient temp for non-hybrids, I'd say.
  13. Jess

    Jess Well-Known Member

    I tried this today and it works. I took my foot off the gas and gave it a quick tap and down came the bar of regen. Awesome. I was able to charge the battery from 5 to 7 bars today.

    Still no forced recharges since I have not FAS at lights when the engine is cold. I've been driving most of the commute, with hills and all, on 5 bars of battery. I've also resisted using more than 2 bars of assist on accelerations and increased the rpms going uphill to avoid using assist at all.

    Thanks again MSantos.

  14. msantos

    msantos Eco Accelerometrist

    Hi Jess;

    Nice to know that it works for you too.

    Also note that there are times that it does not appear to work, especially in warmer days but however unsettling, it may actually be working and before you know it your SoC will climb just as well. This is what we call an induced hidden (or micro) regen and the scangauge LOD reading will usually help confirm it (high LOD readings) ;)

    This is essentially what I do everyday when the engine is still cold and it really helps. I usually arrive to my destination with 7 bars SoC and recently 8 bars after I got the latest software updates.

    Now if we could just as easily tap the throttle to make this psycko -33F weather go away ;)


  15. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Hi MSantos,

    After 2 weeks my dealership has come back with "no dice" regarding the (apparently) missing panels, and this was Techline's decision. I'm composing a letter to Honda Canada (attn. Customer Relations).

    The panels in question are described as "Front Floor Undercover", run from the engine covering panel down left and right sides to some short panels in the vicinity of the gas tank (we do have those panels)

    I believe the part nos for the missing panels are:


    So just to recap, we have a long bare stretch down both sides on the underside, the middle portion of the car.

    Other than a letter, can you think of anything? Or something pertinent to include in the letter?
  16. msantos

    msantos Eco Accelerometrist

    Hi Mendel;

    I don't know if I can do much in this area as the vehicle was "accepted as delivered" and that is something similar to what happened to other first year model owners in other areas.

    This was a problem common to 2006 models, particularly vehicles shipped to US and Canada in that there were elements of the car's documented equipment that were not present. For instance, in your case you report you did not have the lateral mid section aero panels. This one I never heard of... perhaps because nobody noticed it before? Anyway, both my cars have the full set of aero under shields.

    The other area I was referring to that affected earlier 2006 owners was the lack of a trunk lid lining. In later production batches this item was included but those who got the car with it missing were out of luck (myself included). The technical reason was that the trunk's left and right arm that allowed the left and right garnish to snap securely into the trunk arms had a missing pre-drilled hole.

    There may be a reason why the panels were not included in your vehicle. I would study the underside to see if they can be attached at all and as documented. In your particular case I suspect you may be subject to an assembly time limitation and there may not be much more Honda can do at this point.

    In the case of the missing trunk lid liner, I ordered the parts myself and I made the holes in the appropriate places. The lid liner snapped in very easily and it looks like a million bucks. You may have to do the same I did, as I doubt Honda will authorize the dealership to do it on their time.


  17. Mendel Leisk

    Mendel Leisk 2010 Prius (CAN Touring) Staff Member

    Thanks for the detailed reply MSantos.

    I've started a thread on the subject in the HCHII section, I realize I'm sort of off-topic here. Harold has chimed in that he also does not have these mid-section panels.

    Regarding the trunk lid lining, I assume this would like kind of like the black fiber panel lining under the engine hood. I have no trunk lining in mine, but see a number of round high points with holes, assumably to accept the push-in fasteners.

    I guess to some extent Honda is victim of their lack of consistency: if they supply in some instances, and omit in others, the non-recipients feel burned.

    I'll check out the underside for push-in fastener hole locations.

    Thanks again for the tips.

    Update: looked under there: looks like I am missing fastener holes, at least the ones for the intermediate fasteners, so that's likely the end of it ;(
    Last edited: Jan 17, 2009
  18. Jess

    Jess Well-Known Member

    Another question around winter driving: As I understand it, if you're going to leave the engine on at a stop light, it's better to do so in N than D. When the HCH II is very cold and I put it in N, it revs higher than in D. It it using more gas when it revs higher in N? Am I better off just leaving it in D?


  19. msantos

    msantos Eco Accelerometrist

    Hi Jess;

    Yes, it is revving higher in N than it does in D but it does not consume more at all.
    Also, this only happens while the engine is in warm-up stage S0 or S1. After this, the engine will consume far less in N than it does in D, sometimes amounting to half as much.
    When the stop light is long then switching to N is always a good thing to do.
    However, for short stops in very cold days switching to N may offer little advantage since the CVT will need extra time to engage and we definitely do not want to abuse the CVT's forward clutch, especially if you want to move forward quickly as it is the case with many folks who drive in stop-n-go traffic.


  20. Kacey Green

    Kacey Green Well-Known Member

    if your pack isn't full you can also switch to "L" for a tiny boost

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