Burning Gas while fully charged

Discussion in 'Clarity' started by peter sun, Nov 14, 2019.

  1. peter sun

    peter sun New Member

    I have a 2018 Honda clarity hybrid. For last 5 weeks, the car has burned 5 gallons of gas while fully charged all the time. In the mean time, the EV range has dropped to 35 miles per charge (35 to 45 temperature). Is anyone else experiencing this?
  2. ClarityBill

    ClarityBill Active Member

    Sounds pretty normal.

    EV range drops in cold temperatures because you use the heater. (It is an electric heater to warm the passenger compartment.)

    The chief reasons the gas engine starts with a full battery are excessive acceleration, and excessive deceleration. If you press on the accelerator too hard, the gas engine kicks in to provide extra power. If you have a panic brake, the gas engine is used for engine braking, then runs for warm-up and lubrication.

    Have you noticed when the gas engine is running?
    Sandroad likes this.
  3. TomL

    TomL Member

    This response is spot on. I've had my 2018 since June and my EV range has dropped from a high of 66 to a low of 32 this week.
  4. insightman

    insightman Well-Known Member

    That never happens to me. I've stomped hard on the brake pedal in an attempt to remove rust from my Clarity's brake discs after it's been sitting for a while--the ICE never starts. However, it is commonly agreed on this forum that using the brakes--not necessarily in a panic stop--when the battery is fully charged can cause the Clarity PHEV to start its ICE. It's the most mysterious Clarity phenomenon to me.
  5. The Gadgeteer

    The Gadgeteer Active Member

    I have had that happen with the regen paddles. I haven’t tried it with foot brake.
  6. insightman

    insightman Well-Known Member

    But the regen paddles start the ICE only when you've just fully charged the battery, correct?
  7. KentuckyKen

    KentuckyKen Well-Known Member

    Ditto and +1 on range loss to cold weather. We just got over having a high of 22 F and my EV range went from low 60s to mid 40s with seat heat and a little heater use. Used 1.03 kWhs to precondition on EVSE power.

    Also today had the ICE come on less than a 1/2 mile from being fully charged with just 4 chevron paddle selection. Power Gauge As usual indicated just a small amount of regen was allowed. Ambient was 50 F and I had a strange charging graph for this drive when I charged after car was outside all night and morning at a friends instead of garaged. I charged immediately after driving home instead is my usual scheduled charge at 5 am. And I drove sedately at max speed of 55 mph.

    Has anybody seen their charging look like this? It’s a first for me. Do you think it was due to a colder battery not accepting as fast a charge or a hot battery from just being driven? I didn’t hear any cooling fans running however.
    Here is a representative charging graph when scheduled charging occurs after car has sat in unheated garage for 8 hours or so that shows the normal immediate ramp up to 7.12 kW charging rate that stays constant until the tapered ending.
    Reverse engineering and figuring out this technological wonder is a daunting and formidable (but worthwhile and entertaining) task.
    Can the Clarity Brain Trust explain this?
    I’m guessing that the internal temperature of the battery pack is more important than ambient temperatures. So a cold soaked pack will charge not only slower but differently?
  8. dana

    dana Member

    Recently drove 2018 Clarity (purchased Feb, 2018, under 13K miles) solo from South Ogden, Utah to Eagle, Idaho and back to South Ogden over a weekend. Round trip of 636 miles. Battery fully charged and HV mode used entire trip. Weather was nice and winds were relatively calm coming and going. No heat required. Most of trip was at 80 MPH. ICE ran approximately 75% - 80% of the time, mostly in angry bee mode. Averaged 34.64 MPG (manual calculation). Similar trips under similar conditions in the past, the Clarity averaged over 40 MPG with ICE running approximately 40% - 50% of the time and less angry bee mode. Will repeat this trip again next month. Anxious to see how Clarity performs then.
    Last edited: Nov 15, 2019
  9. The Gadgeteer

    The Gadgeteer Active Member

    Yes. You have to be fully charged and regen almost immediately.
    MPower and insightman like this.
  10. AnthonyW

    AnthonyW Well-Known Member

    I’ve only seen this when it really cold like 20 to 30 degrees as the thermistor gradually heats up and accepts more charges. When it is colder then that the shape is similar but it maxes out at 4 kWh. 50 degrees wouldn’t do this. Very strange.

    Sent from my iPhone using Inside EVs
  11. Ray B

    Ray B Active Member

    Yes it has happened to me last winter on cold days. I believe it is a protection built into the charging system by Honda to prevent lithium plating at the anode which reduces capacity, power, and is a potential safety issue as well (increases the chance of an internal short).

    Here's a pdf which describes the degradation mechanisms:
  12. mjpmpg

    mjpmpg New Member

    I also just had a charging session that started at about 4kW for the first hour or so with ambient temp in the high 20s or low 30s in NC, and the rate gradually increased to about 6kW (max and usual rate I get from that particular charger) presumably due to battery heating from charging since I don’t think it actually warmed up outside during the session.

    Agreed that it’s likely just a battery protection thing, but I’m glad I’m not the only one seeing it since I was somewhat concerned when I first noticed it (I don’t think I used L2 charging at all last winter).

  13. ClarityBill

    ClarityBill Active Member

    My guess:
    Going into HV mode with a 'fully charged battery' will limit the amount of regen the battery can accept.

    Once it has entered HV mode with a really full battery, the gas engine will work to maintain that full battery. The regen will not be able to help much, and the gas engine may not be able to charge back to full battery, but it will try. Allowing the battery to drop 5-10 miles of EV range before entering HV mode will allow the system to better utilize regen.

    Also, "no heat required", is an absolute statement. Looks like temperatures in Utah were in high 50's. If fresh air is selected, there will be some heat requirement. At those temperatures, it can be helpful to select recirculated air.
  14. ClarityBill

    ClarityBill Active Member

    The random engine starts do appear most frequent with full-battery regen. I have had that probably 4 times over the summer, but now I monitor my regen every time I leave my house. In winter, I blast the heater to use up the extra regen.

    The panic stop - engine start has only happened to me 3 or 4 times in 40,000 miles, so I guess it is as rare as the system check. It takes more of a kick on the brake pedal, than pressing the brake. Put a cup of coffee on the back window ledge, if you can hit the windshield with your cup, the ICE will be running (exaggeration, but there are lots of quick g's). I had the auto-brake start the ICE the first time it happened to me. The car does not need to stop, just a jolt on the brakes.
    insightman likes this.
  15. dana

    dana Member

    ClimateBill, thanks for your response. As you suggested, 5 - 10 miles of EV range will be used before switching to HV on next trip. Also, "Climate" was never turned on so no heat or air, fresh or recirculated. Thanks again.
  16. bpratt

    bpratt Active Member

    Sounds like you live in Utah as do I. You are finding the same results as I have driving your Clarity at the higher altitudes we have in Utah at 80 MPH. I had the same experience driving from Salt Lake City to Las Vegas at 80+ MPH. My engine also ran about 75 to 80% of the time, mostly in angry bee mode. I also only got about 35 MPG. I don't see those problems driving 65 to 70 MPH on the freeways and I average 40 to 42 MPG at those speeds. The little 1500cc engine really does not have enough power to propel the car at 80 MPH without running at high RPMs at altitudes above 5000 feet.
  17. dana

    dana Member

    bpratt, thanks for your response. Not only do we both live in Utah, it appears our Claritys share the same solar silver color. Good to know my experience is not unique. Take care and thanks again.
  18. JCA

    JCA Active Member

    Just addressing this point -- Spinning the temp dial to "Lo" should give outside fresh air without heat or AC coming on, as long as you go to the Climate menu and turn off the AC. I do this every day. I'll save my rant on how inconvenient the climate controls are for those of us that prefer manually adjusting the air for another time!
    KentuckyKen likes this.
  19. Groves Cooke

    Groves Cooke Active Member

    "I'll save my rant on how inconvenient the climate controls are for those of us that prefer manually adjusting the air for another time!"

    Very, very few new cars have a manual adjust for temp.
  20. mjpmpg

    mjpmpg New Member

    This may sound contrarian, but I can assure you it’s not. Does anyone know if there is an ambient temp below which the Lo setting will actually turn on the heat? This has a practical implication for me as I rarely use the heat during the N.C. “winter”

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