Starting with full charge, downhill for 2 miles, engine comes on

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10sqmiles

10sqmiles

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All winter, a full charge would get me around 28 miles, starting off with heat on and headed down a 7% grade for 2 miles. The engine never came on.

With warmer weather (around 50 F) I am now showing around 40 miles on a full charge, no heat. I head down the hill and before I get to the bottom, the engine is on. I can simply shut the car at the bottom and when I restart, the engine is off.

Solution?? I charge it "dumb", plug it in when I get home, unplug when I take off in the morning, I am guessing that the app (which I have never used, haven't seen the need) can let me charge less than 100%?
 
In the app (I assume you mean the HondaLink app) you have the ability to set a charging schedule. And I believe you can either set it to charge until full, or specify a time period (from time A to time B). So you can set a time less than 12 hour if you don't want to fully charge your car.
I am more interested about your winter milage. 28 sounds crazily low to me. What's the typical winter temperature in your area?
 
beefChowMien said:
In the app (I assume you mean the HondaLink app) you have the ability to set a charging schedule. And I believe you can either set it to charge until full, or specify a time period (from time A to time B). So you can set a time less than 12 hour if you don't want to fully charge your car.
I am more interested about your winter milage. 28 sounds crazily low to me. What's the typical winter temperature in your area?
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single digit to mid-teens F
 
This sounds like the classic ‘limit regen when the battery is full or nearly full in order to prevent overcharging of the battery by turning on the ICE’. This is well documented behavior among many posters on this forum. It most often happens with extended braking on downhills or hard braking, both of which call for lots of regen.
Although it’s not 100% understood exactly how running the ICE accomplishes this, we have enough evidence to say it does indeed happen.

So either don’t charge it all the way up or run some electrical drain on the battery like cabin heat or defroster and I bet you can prevent the ICE runs right after charging and going downhill.
Also the advice about not turning off the engine and allowing it to reach operating temperature is spot on. That will prevent condensation in the oil sump and exhaust system and will not burn an appreciable amount of gas.
 
10sqmiles said:
All winter, a full charge would get me around 28 miles, starting off with heat on and headed down a 7% grade for 2 miles. The engine never came on.

With warmer weather (around 50 F) I am now showing around 40 miles on a full charge, no heat. I head down the hill and before I get to the bottom, the engine is on. I can simply shut the car at the bottom and when I restart, the engine is off.

Solution?? I charge it "dumb", plug it in when I get home, unplug when I take off in the morning, I am guessing that the app (which I have never used, haven't seen the need) can let me charge less than 100%?
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This has been talked before. If you have a full charge and go down hill, the ice will come on to get rid of excesss regen. charge since the battery cannot accept anymore charge.
 
You’re stuck with how the car works. The app can not stop it from full charging.

Agree if you manually shut the engine off repeatedly while it is cold it is going to cause moisture buildup inside the engine which cannot be purged and could cause damage. As a mechanic I’ve seen more than one car with massive sludge buildup, water contaminated milky oil, and even rusted thru oil pans from the inside back in the day of steel oil pans, and they were always the little old lady low mileage cars who only drove to church and grocery 3 miles from home. People seem to want those cars but they are the absolute worst. There is simply only one faster way to kill an engine than to start it every day and let it idle or run low rpm for only 5 minutes before shutting it down...running it without oil. This is why Honda forces engine to run quite a while after the engine starts up for any reason, regardless of battery state of charge. It purges contaminate by steaming the water out of the engine using heat and time. This is necessary for long engine life. Interrupting this programmed cycle repeatedly will shorten engine life.

The only workaround I am aware of is to simply unplug the car before it finishes charging (random guess), program start time for charging to coincide with 90% charge or whatever at time of unplugging (also a guess) or blast the heat or drive in circles or whatever to burn off some charge somehow before you begin your descent. This whole situation had been discussed here quite a bit this winter if you search back...
 
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@craze1cars, the updated HL app lets you set an stop time for charging so there is another way other than having to unplug at inconvenient times. You still have to do the mental math using the SOC to figure it out though. Glad I don’t live on a big hill.
 
Interestingly this happened to me today and I wasn't going downhill. I typically fully charge at home on 120V. Today I charged at a public 240V charger. I drove about a quarter mile and had to stop for a red signal. I used the paddles and the third arrow blinked and started ICE. I don't remember it happening to me before. It is possible 120V doesn't top off the battery.
 
vin seeram said:
Interestingly this happened to me today and I wasn't going downhill. I typically fully charge at home on 120V. Today I charged at a public 240V charger. I drove about a quarter mile and had to stop for a red signal. I used the paddles and the third arrow blinked and started ICE. I don't remember it happening to me before. It is possible 120V doesn't top off the battery.
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Your High Voltage Battery Charge Level Gauge will tell you when your battery is fully charged. It should look the same after charging with either 240V or 120V.

I would not be surprised if you topped off your battery with your 120V EVSE at the same place where you got the 240V charge, your ICE would start up in the same situation. Unless it didn't--as we know well, the Clarity PHEV's ICE-activation is sometimes unpredictable.
 
10sqmiles said:
"I'm sorry, I can't do that Dave"
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You should not turn the car off just because the motor turned on. It will quickly turn off on its own.

Think about it: We are talking pennies in Gas. Let your motor run the oil through itself as the manufacturer programmed it to do.
 
vin seeram said:
Interestingly this happened to me today and I wasn't going downhill. I typically fully charge at home on 120V. Today I charged at a public 240V charger. I drove about a quarter mile and had to stop for a red signal. I used the paddles and the third arrow blinked and started ICE. I don't remember it happening to me before. It is possible 120V doesn't top off the battery.
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My theory is temperature made a small but big enough difference to cause the engine start during regen. Temperature affects how quickly the Clarity (and all EVs) can take a charge. Too high or too low will be slower charge. Regen is like a really really fast charge for a short period of time. At home in the morning when you first use the car there are some factors which may mean a cooler battery: charge completed hours ago, cooler in the morning, charged at a slower 120 volt rate causes less heat, plus very minor standby losses in charge. Some factors why when you used the public charger your battery might be warmer: You had been recently driving, driving shortly after full charge, fast charging at higher rate, car sitting in the sun, slightly more aggressive driving.
 
That is absolutely nuts. Why doesn't it work the way an EV does, which I think most people would conclude is 'normal' - just 'deactivate' the regen???

The regen on this car sucks compared to my Fit EV. But now that I'm thinking of it, the 'best' 4 bar regen on this car is probably about equal to the 'worst' regen on the Fit when battery was full or when it was too cold. This turning on is a terrible solution which I'm sure frustrates many people. Certainly no one who looks at this car would EXPECT the ICE to turn on with no load/draws and a full SOC, it defies logic.

As a distant secondary solution, it would be nice if you could program the app to turn off charging at a designated %, like 95%, but even then you could avoid ICE at the hill but still ultimately have lower EV range than if you filled.
 
JFon101231 said:
Certainly no one who looks at this car would EXPECT the ICE to turn on with no load/draws and a full SOC, it defies logic.
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I really hope Honda's engineers someday publish a paper to explain this phenomenon. The Insight and Accord Hybrid don't do that. When they need to dispense with regen electricity that cannot go to a fully charged battery, the power coming from the traction motor operating as a generator goes to the starter motor/generator operating as a motor to turn the deadened ICE. So why would the Clairity PHEV not do the same thing? My theory is that the heavier Clarity PHEV needs to dispense with more energy on a long decline than those other hybrids and the only way to do that is to have the starter motor/generator trying to slow down the running ICE. Certainly the ICE doesn't start up and drive the starter motor/generator to generate MORE electricity, so having the starter motor/generator fighting the ICE seems to be the only way to explain how the Clarity PHEV deals with the excess electricity. Just my theory, with nothing to back it up. I made up this diagram to illustrate my theory:

upload_2019-4-29_14-12-29.webp
 

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I assumed the starter motor was turning the dead ICE on the Clarity, also. But the ICE runs after excess regen use is complete, to lubricate and warm up the ICE.

From your comments, sounds like the ICE's on Insight and Accord don't run after excess regen use: But this could be the only difference between the two systems (Insight/Accord vs. Clarity)
 
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