What are you doing more / less during the COVID-19 / SARS-CoV-2 in your area ? - Page 2 - 2018 Honda Clarity Forum
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post #11 of 14 (permalink) Old 04-03-2020, 10:07 AM
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Originally Posted by MPG+ View Post
I am driving to many state parks these days to do some hiking, avoiding the busier ones. It's been wonderful driving locally and on the highways with much less traffic. Something happened yesterday that amazed me. I was on HV Charge, going 65 mph, and my HV range went to 0. I had over 20 EV range at the time, which was enough to get me to my favorite gas station, but the car remained in HV Charge mode, for the next 15 miles, continuing to charge as I watched my EV range increase. It finally changed from HV charge to EV at 28 EV range, and the message said it had reached maximum for HV charge. I guess there must have been enough gas left to do that, even though the HV range "estimate" said 0. Nice to know there's that cushion to fall back on.
When a gas tank runs dry there's still gas in the fuel lines. This is what kept your ICE running after reaching "0" HV miles. This is the worst case scenario for a fuel pump - no gas in the tank to cool it but pumping air into the fuel lines to keep feeding the engine. I'm somewhat surprised your ICE didn't stutter after filling the tank - have you run in HV (Charge) mode since then?

2018 Honda Clarity Touring PHEV - Forest Green w/Tan interior (wife's car)
2017 Volt LT - Heather Gray; black bow ties, Charcoal VoltShelf
2012 Cruze ECO MT (hail totaled 5/8/17 103,600 miles @42.5 MPG)
2010 Mit Lancer GT MT (traded for ECO @31K miles)
2002 Pont Montana AWD - title to son at college graduation
1990 Pont Transport (traded for Montana @240K miles)
1986 Fiero GT MT (traded for Transport - needed more seats)
1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)
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post #12 of 14 (permalink) Old 04-03-2020, 01:11 PM
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When a gas tank runs dry there's still gas in the fuel lines. This is what kept your ICE running after reaching "0" HV miles. This is the worst case scenario for a fuel pump - no gas in the tank to cool it but pumping air into the fuel lines to keep feeding the engine. I'm somewhat surprised your ICE didn't stutter after filling the tank - have you run in HV (Charge) mode since then?
The tank isn't empty at 0 HV miles, it's similar to E on other cars, E on fuel gauges is usually conservative so that it errs on the side of caution. People have reported driving their Clarity up to 30 miles in HV mode after reaching 0 HV. Now I am not saying it's a good idea to keep using gas past 0 because you will eventually run the tank dry. I am surprised that the system stayed in HV charge because that will run the tank dry even quicker.

One time I got down to about 2 HV so I was driving EV and I had plenty of EV range to get to a gas station so I didn't foresee any problems. Then I accelerated too quickly for a fraction of a second and ICE came on, and then of course it insisted on staying on to go through complete warm up. I helplessly watched the HV range quickly go to 1 and then 0 and ICE kept running well past that until it eventually warmed up and shut off. I knew the tank was likely not close to empty, but still it was a little unnerving. Once I realized it does that I now avoid going below about 10 HV no matter how much EV range I have. The fuel warning comes on at about 20 HV miles but I normally fill up well before that.

Some people say this is all a bunch of nonsense and that it's old wives' tales that running out of gas harms anything, that modern cars protect from this. Well they can't prove that to me and unless they are willing to pay for my new catalytic converter or a new fuel pump then I ignore those type of comments and I continue to believe that it is best to not run out of gas even if you do have EV miles to spare.
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post #13 of 14 (permalink) Old 04-03-2020, 03:03 PM
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Some people say this is all a bunch of nonsense and that it's old wives' tales that running out of gas harms anything, that modern cars protect from this. Well they can't prove that to me and unless they are willing to pay for my new catalytic converter or a new fuel pump then I ignore those type of comments and I continue to believe that it is best to not run out of gas even if you do have EV miles to spare.
Modern cars use the fuel in the tank as the coolant for the in-tank fuel pump. Running the tank empty results in the pump running hotter - no coolant => no cooling. Whether or not this shortens the life of the modern fuel pump is an open question. I suspect it does but one or two instances won't make enough difference for most people to ever notice.

Unlike my Volt, the Clarity depends on having both the electric and gas motors available, which is probably why HV Charge will recharge about 40% of the battery. I know from experience that the Clarity needs both gas and electricity in the high mountains of Colorado. My Volt is perfectly happy running on either alone.

2018 Honda Clarity Touring PHEV - Forest Green w/Tan interior (wife's car)
2017 Volt LT - Heather Gray; black bow ties, Charcoal VoltShelf
2012 Cruze ECO MT (hail totaled 5/8/17 103,600 miles @42.5 MPG)
2010 Mit Lancer GT MT (traded for ECO @31K miles)
2002 Pont Montana AWD - title to son at college graduation
1990 Pont Transport (traded for Montana @240K miles)
1986 Fiero GT MT (traded for Transport - needed more seats)
1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)
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post #14 of 14 (permalink) Old 04-08-2020, 11:05 PM
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* Worrying. Typically I don't worry about much, but with my 1st year Resident son working in an overflowing COVID-19 ICU and my wife also continuing to work at a health clinic...well, our family has more on our minds than usual.

LESS:
* Using even less gas than usual with our 2018 Clarity. Since there are no trips out of town, no need to ever use gas.
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