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Ok, I know this subject has been throughly discussed on a two year old thread but I just, for the first time, experienced this problem on my 2018 Touring Clarity on a forty mile drive in 'ECON MODE'. Going up a mile long, not steep hill, the car suffered a sudden loss of power.
What I noticed:
The battery discharged quickly. Usually on this drive, I have enough battery charge to get home. It had 3-4 bars of energy in the battery only mode and quickly discharged down to one bar. The battery has never been below two bars of energy. When it gets to two bars in the past, while in Econ Mode, it switches to hybrid mode and the engine comes on. This did not happen this time. It seemed like the battery was, all of a sudden, requiring maximum energy from the engine with little left over to power the vehicle.
Also, this happened when I was a couple of hundred yards from the top of the hill and the start of a long downhill in which the battery usually recharges 3-4 miles. This did not happen telling me that the battery had been completely discharged (note only one bar of charge, never happened before. That's a bit of info i did not see on the previous thread).
What I'm wondering is, in this interim, has anyone out there has developed any clarity as to what the problem is (sorry, pun intended!). Battery hardware, Software? Any clues would be helpful. I'm charging the vehicle now and will probably take it to the dealer shortly. The car has only 38k on the odometer, out of general warranty, but I believe the battery itself has an 8 year warranty. Also the 12 volt battery is only 3 months old. Thank you all for any input/ideas. Charley
 

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Ok, I know this subject has been throughly discussed on a two year old thread but I just, for the first time, experienced this problem on my 2018 Touring Clarity on a forty mile drive in 'ECON MODE'. Going up a mile long, not steep hill, the car suffered a sudden loss of power.
What I noticed:
The battery discharged quickly. Usually on this drive, I have enough battery charge to get home. It had 3-4 bars of energy in the battery only mode and quickly discharged down to one bar. The battery has never been below two bars of energy. When it gets to two bars in the past, while in Econ Mode, it switches to hybrid mode and the engine comes on. This did not happen this time. It seemed like the battery was, all of a sudden, requiring maximum energy from the engine with little left over to power the vehicle.
Also, this happened when I was a couple of hundred yards from the top of the hill and the start of a long downhill in which the battery usually recharges 3-4 miles. This did not happen telling me that the battery had been completely discharged (note only one bar of charge, never happened before. That's a bit of info i did not see on the previous thread).
What I'm wondering is, in this interim, has anyone out there has developed any clarity as to what the problem is (sorry, pun intended!). Battery hardware, Software? Any clues would be helpful. I'm charging the vehicle now and will probably take it to the dealer shortly. The car has only 38k on the odometer, out of general warranty, but I believe the battery itself has an 8 year warranty. Also the 12 volt battery is only 3 months old. Thank you all for any input/ideas. Charley
Speed? Outside (and battery) temperature? HVAC usage? Raining? Windy?

Any or all of these things can have an impact on battery usage and range.
 

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Discussion Starter · #3 ·
Speed? Outside (and battery) temperature? HVAC usage? Raining? Windy?

Any or all of these things can have an impact on battery usage and range.
Outside temps were @ 45 degrees, no indicator messages re: battery temps, No air conditioning being used, just heating the car to 72 degrees but . . .. both seats were being heated(!) and I rarely use the seat heating; could be a connection. Little wind, little rain.
Ok. So the battery and the engine's capacity to both charge same and power the car can be compromised. That's a big, big safety issue. I was driving at freeway speeds up not too steep of a long hill when this happened; my speed decreased in about 100 yards from 55MPH to under 40 and had I not been near the top maybe even slower than that. Thanks for the input. C
 

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I don't like driving in ECON MODE. The powertrain will maximize fuel savings at the cost of power/performance. This mode I suspect gives the battery more strain. My son always turns it on, but when I get in the driver's seat I almost always turn it off. I notice now that we have 64k mi and change that the engine will fire up at 3 bars sometimes. It never did that before. I suspect the battery is losing some capacity and hence dropped to 1 bar on you before engine fired up...
 

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I don't like driving in ECON MODE. The powertrain will maximize fuel savings at the cost of power/performance. This mode I suspect gives the battery more strain. My son always turns it on, but when I get in the driver's seat I almost always turn it off. I notice now that we have 64k mi and change that the engine will fire up at 3 bars sometimes. It never did that before. I suspect the battery is losing some capacity and hence dropped to 1 bar on you before engine fired up...
Yes. I'm with your son. I'll think about what you suggest.
 

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When on road trips, I allow the battery to get down to about 50% SOC, then turn on HV to maintain a reserve for hill-climbing. This also allows me to run on battery as I go through towns. When anticipating going up long, steep climbs over passes, I'll sometimes run HV+ to give an extra margin. HV+ charges the battery up to about 65%, before dropping back to HV. I then shut off HV and run in EV mode, as I approach my destination. I try to stay in hotels with L2 charging, or at least access to a power receptacle.

If you drive this way, be sure to remember to put the Clarity back into HV mode when you leave gas stations. I've forgotten that more than once, and had to depend on HV+ to give more reserve capacity before a hill climb. I don't like to drive in HV+, because it's loud.

I had a similar event to yours happen shortly after buying a new '11 Chevy Volt. I hadn't yet understood the nuances of "Mountain Mode". Heading up a challenging pass (the Grapevine, in So. CA) at about 80 mi/hr (that's what traffic was doing) in the #2 lane, the car went into "reduced performance mode", and I was suddenly doing 50 mi/hr. Quite unnerving, to say the least. I spent the next quarter hour over in the right lane, with the trucks, listening to the Volt's engine roar, at 50 mi/hr.
 

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Ok, I know this subject has been throughly discussed on a two year old thread but I just, for the first time, experienced this problem on my 2018 Touring Clarity on a forty mile drive in 'ECON MODE'. Going up a mile long, not steep hill, the car suffered a sudden loss of power.
What I noticed:
The battery discharged quickly. Usually on this drive, I have enough battery charge to get home. It had 3-4 bars of energy in the battery only mode and quickly discharged down to one bar. The battery has never been below two bars of energy. When it gets to two bars in the past, while in Econ Mode, it switches to hybrid mode and the engine comes on. This did not happen this time. It seemed like the battery was, all of a sudden, requiring maximum energy from the engine with little left over to power the vehicle.
Also, this happened when I was a couple of hundred yards from the top of the hill and the start of a long downhill in which the battery usually recharges 3-4 miles. This did not happen telling me that the battery had been completely discharged (note only one bar of charge, never happened before. That's a bit of info i did not see on the previous thread).
What I'm wondering is, in this interim, has anyone out there has developed any clarity as to what the problem is (sorry, pun intended!). Battery hardware, Software? Any clues would be helpful. I'm charging the vehicle now and will probably take it to the dealer shortly. The car has only 38k on the odometer, out of general warranty, but I believe the battery itself has an 8 year warranty. Also the 12 volt battery is only 3 months old. Thank you all for any input/ideas. Charley
 

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I have a 2018 Clarity with 38,000 miles on it. This same problem started for me at just over a year ago. I live on a hill that my car has to go up on the last two miles before I get home. I'm usually running out of electric mode at that time and then the car switches to HV mode. The hill puts more of a load on the car, so it continues to draw down the battery until the battery is depleted and then it goes into limp mode. This has happened to me at least 30 times. I've taken it to the dealer serval times but they say they don't detect anything wrong and that is normal operation. I started to go over the mountains one day, I kept it in HV mode to conserve power but after driving uphill for 30 minutes the car drained the reserve of electricity and it started going into limp mode. I had to turn around and go back downhill and then the electric bars started to climb back up which I've never seen before. The dealer says this is normal operation though they have never driven one. They wouldn't go for a ride with me and when I offered to show them a video of the incident, they refused to look at it. It's a problem Honda knows they have but they refuse to acknowledge it. I think it could be solved with a new computer but because they have a shortage of chips that's not going to happen. The dealer started charging me $165. each time I bring it in so I will give up trying to get it fixed. I love the car and would just like to get it fixed but being this new age of electronics, the customer has no way of proving the manufacture is at fault. The dealer offered to buy it back but only because there short on inventory at the moment and they could resell and make more money on it.
 

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Discussion Starter · #9 ·
I have a 2018 Clarity with 38,000 miles on it. This same problem started for me at just over a year ago. I live on a hill that my car has to go up on the last two miles before I get home. I'm usually running out of electric mode at that time and then the car switches to HV mode. The hill puts more of a load on the car, so it continues to draw down the battery until the battery is depleted and then it goes into limp mode. This has happened to me at least 30 times. I've taken it to the dealer serval times but they say they don't detect anything wrong and that is normal operation. I started to go over the mountains one day, I kept it in HV mode to conserve power but after driving uphill for 30 minutes the car drained the reserve of electricity and it started going into limp mode. I had to turn around and go back downhill and then the electric bars started to climb back up which I've never seen before. The dealer says this is normal operation though they have never driven one. They wouldn't go for a ride with me and when I offered to show them a video of the incident, they refused to look at it. It's a problem Honda knows they have but they refuse to acknowledge it. I think it could be solved with a new computer but because they have a shortage of chips that's not going to happen. The dealer started charging me $165. each time I bring it in so I will give up trying to get it fixed. I love the car and would just like to get it fixed but being this new age of electronics, the customer has no way of proving the manufacture is at fault. The dealer offered to buy it back but only because there short on inventory at the moment and they could resell and make more money on it.
Ok, that's all helpful. I particularly like the "limp mode" concept. It's exactly like 'sports mode' but, sadly, without the 'sport'! Maybe 'Freeway Dodge Ball?
I purchased my Clarity in 2018 for 35k, got about 8k in rebates and tax credits and could sell it right now for slightly under 30k with the current shortage of used vehicles. The trouble is, I really like this car! It's garaged; it looks brand new; I last gassed it up at the end of August.
Do you know what I think? I think that this is distinctly a safety issue and it could well catch the attention of the NTSB and result in a recall of the vehicle. Being on the freeway and suddenly decelerating from above 60 to below 40 is dangerous, plain and simple! Maybe there's a simple software fix like triggering the engine to come on when there is more of a battery reserve. Thanks for your input! C
 

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When flying down the freeway over the speed limit, anticipating a sustained hill-climb, or other exceptionally high power load, run the battery down to 50% SOC in EV Mode, then engage HV (or even HV+) Mode to retain a battery reserve. The Clarity PHEV might need both the battery and ICE to provide adequate power for excessive loads.

It's the way it works.
 

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The engine needs to be at operational temp before it will achieve full power. 130-155 degrees.

This takes time once the engine kicks on.

If driving fast or up a mountain the power
Demand is excess normal. Either you select hybrid or defaults at low battery. You car will still be drawing excess battery 🪫 amps while the little gas engine operates at 1200rpms for several minutes before the Ecu allows it to try and now catch up power reserves while your still in high power demand.

Solution. Turn on hybrid mode a few miles or minutes before running out of 🪫 or meeting the bottom of the mountain.
 

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Lot's of anecdotes, but here's what's really going on.

  • The Clarity's power plants are too small. Neither the electric motor nor the gas engine are powerful enough to drive this car under all conditions. Together they can do it.
  • There is a small battery buffer at the bottom of the battery. Notice that under normal driving the gas engine kicks on when the car reaches two bars of battery. As long as you have two bars the electric motors can be used to supplement the gas engine (see first bullet).
  • When the battery buffer is gone, the gas engine must do all the work. Because this engine is underpowered the most it can manage is about 40-45 MPH on level road and 35-40 up any grade steeper than about 2%.
  • It takes about a minute for any internal combustion engine, including the one in the Clarity, to get up to temperature, so if you run out of battery power while climbing a steep grade pull over to the truck lane and put your emergency flashers on as you have just exceeded the car's performance envelope.
Note, there is nothing wrong with the car as built and everything wrong with the power plant design. Chevy had the same issue with the gas engine (electric had more than enough power) in the 2011-2015 Volt and fixed this in the 2016-2019 Volt. Honda's engineers didn't pay attention to their competition when they designed the Clarity PHEV's power plant.
 
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Discussion Starter · #14 ·
The engine needs to be at operational temp before it will achieve full power. 130-155 degrees.

This takes time once the engine kicks on.

If driving fast or up a mountain the power
Demand is excess normal. Either you select hybrid or defaults at low battery. You car will still be drawing excess battery 🪫 amps while the little gas engine operates at 1200rpms for several minutes before the Ecu allows it to try and now catch up power reserves while your still in high power demand.

Solution. Turn on hybrid mode a few miles or minutes before running out of 🪫 or meeting the bottom of the mountain.
Thanks for these thoughts. what you say makes sense. The engine was cold when it had several tasks all at once: maintain freeway speed up a hill and charge the battery at same time. It's just that the car is advertised as a vehicle that can be 'passively' driven, meaning that the driver doesn't have to make calculations as to which mode is safest/most effective. Thanks again for taking time to comment. c
 

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Lot's of anecdotes, but here's what's really going on.

  • The Clarity's power plants are too small. Neither the electric motor nor the gas engine are powerful enough to drive this car under all conditions. Together they can do it.
  • There is a small battery buffer at the bottom of the battery. Notice that under normal driving the gas engine kicks on when the car reaches two bars of battery. As long as you have two bars the electric motors can be used to supplement the gas engine (see first bullet).
  • When the battery buffer is gone, the gas engine must do all the work. Because this engine is underpowered the most it can manage is about 40-45 MPH on level road and 35-40 up any grade steeper than about 2%.
  • It takes about a minute for any internal combustion engine, including the one in the Clarity, to get up to temperature, so if you run out of battery power while climbing a steep grade pull over to the truck lane and put your emergency flashers on as you have just exceeded the car's performance envelope.
Note, there is nothing wrong with the car as built and everything wrong with the power plant design. Chevy had the same issue with the gas engine (electric had more than enough power) in the 2011-2015 Volt and fixed this in the 2016-2019 Volt. Honda's engineers didn't pay attention to their competition when they designed the Clarity PHEV's power plant.
Well put. It's something I learned with ten years of driving an '11 Volt: Have plenty of charge in the battery when heading up hill. In the Volt, the correct mode was "Mountain", to maintain an extra 25% buffer in the battery. In the Clarity PHEV, it's HV (or HV+). I try to approach hills with at least a 50% SOC.
 

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Well put. It's something I learned with ten years of driving an '11 Volt: Have plenty of charge in the battery when heading up hill. In the Volt, the correct mode was "Mountain", to maintain an extra 25% buffer in the battery. In the Clarity PHEV, it's HV (or HV+). I try to approach hills with at least a 50% SOC.
My 2017 (2nd Gen) Volt can climb Vail pass in either electric or gas modes without the assistance of the other engine. Chevy gave the 2nd gen Volt sufficient power plants to handle any load on either fuel by itself.
 

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My 2017 (2nd Gen) Volt can climb Vail pass in either electric or gas modes without the assistance of the other engine. Chevy gave the 2nd gen Volt sufficient power plants to handle any load on either fuel by itself.
I have a 2018 Clarity and on long trips I use HV mode to keep the battery charge up. Even use the HV charge mode when reasonable so I have maximum capacity when the next long grade comes along.
 

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I have a 2018 Clarity and on long trips I use HV mode to keep the battery charge up. Even use the HV charge mode when reasonable so I have maximum capacity when the next long grade comes along.
Yup. I use HV (to keep SOC at ~50%) whenever I'm on the freeway, and the trip is beyond the battery capacity of about 40 miles.
 

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Lot's of anecdotes, but here's what's really going on.

  • The Clarity's power plants are too small. Neither the electric motor nor the gas engine are powerful enough to drive this car under all conditions. Together they can do it.
  • There is a small battery buffer at the bottom of the battery. Notice that under normal driving the gas engine kicks on when the car reaches two bars of battery. As long as you have two bars the electric motors can be used to supplement the gas engine (see first bullet).
  • When the battery buffer is gone, the gas engine must do all the work. Because this engine is underpowered the most it can manage is about 40-45 MPH on level road and 35-40 up any grade steeper than about 2%.
  • It takes about a minute for any internal combustion engine, including the one in the Clarity, to get up to temperature, so if you run out of battery power while climbing a steep grade pull over to the truck lane and put your emergency flashers on as you have just exceeded the car's performance envelope.
Note, there is nothing wrong with the car as built and everything wrong with the power plant design. Chevy had the same issue with the gas engine (electric had more than enough power) in the 2011-2015 Volt and fixed this in the 2016-2019 Volt. Honda's engineers didn't pay attention to their competition when they designed the Clarity PHEV's power plant.
The ICE is sufficient for 55-65MPH level ground. Above 65mph the ICE needs to supplement with battery for inclines or acceleration. The ECU will select a hold point for the battery based on when you select HV. On the flat ground or downhill the ICE will maintain a large load as it uses the ICE to generate power to recharge. If you go below xx % from the select hold point the ICE clutch will disengage to allow the ICE to rev higher to create more amps. The ICE will vary between: OFF using EV, on without clutch engage, on with clutch direct drive (either charging, EV assist, or ICE power only).

It takes several minutes to warm up to 150 degrees. About 5-7 miles to be exact. Sometimes my ICE will shut off after achieving 130 and other times it doesn't shut off until 170 degrees. But it takes much longer than a minute to warm up. I use a scangaugeII to watch engine temp
 

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The ICE is sufficient for 55-65MPH level ground. Above 65mph the ICE needs to supplement with battery for inclines or acceleration. The ECU will select a hold point for the battery based on when you select HV. On the flat ground or downhill the ICE will maintain a large load as it uses the ICE to generate power to recharge. If you go below xx % from the select hold point the ICE clutch will disengage to allow the ICE to rev higher to create more amps. The ICE will vary between: OFF using EV, on without clutch engage, on with clutch direct drive (either charging, EV assist, or ICE power only).
My experience on inclines tells me the Clarity PHEV's ICE is underpowered on any significant incline at any speed. In the Clarity PHEV the ICE is insufficient to climb any hill in Colorado west of I-25 except in the truck lane. Also, driving across West Virginia and Pennsylvania the ICE was insufficient by itself as well as indicated by the continued dropping of the battery SOC. Again some of this was at low speed.

It takes several minutes to warm up to 150 degrees. About 5-7 miles to be exact. Sometimes my ICE will shut off after achieving 130 and other times it doesn't shut off until 170 degrees. But it takes much longer than a minute to warm up. I use a scangaugeII to watch engine temp
While full temperature takes significantly longer than a minute, it's safe to run an ICE powerplant at full power after about a minute of lubrication and warmup. This is true for all modern automotive internal combustion engines. Modern ICEVs generally go into closed loop operations after about a minute, at which point full power is safe to request. This safety is from an engine wear and tear perspective. I haven't timed my wife's Clarity, but I have timed my Volt - 65 seconds from ICE start to transition off battery to gas regardless of external temperature. The first time I realized this I was doing 75 MPH (75 zone) up a slight incline northeast out of Denver on I-76. Until you realize this time delay is there it's somewhat disconcerting to see 0 miles of battery left and the ICE not providing any power.
 
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